Effect (Negative, none, positive)

Treatment/Form of tritium

Paper (Review, Original study,)

Dose or Dose Rate

*Yamamoto, T., Seyama, H., Itoh, N., Fujimoto, O.

International journal of radiation biology

Purpose: To investigate the biological effect of tritium on mouse at low dose-rates. Materials and methods: Mice (\[C57BL/6N C3H/He]F) were exposed to beta -rays by continuous administration of tritiated drinking water throughout their lives at low dose-rates of 3.6, 0.9, and 0.2 mG/day. Results: Including the previous study, the tumour frequency was 70 80% for exposure in the range 240 mGy/day to 9.6 mGy/day. Frequency of tumours decreased with decrease of dose-rate to 50% comparable to the controls. Restricting to thymic lymphomas, a linear relationship in a semi-log plot was found between the frequency and the dose-rate above a threshold dose-rate of 12 mGy/day. There was a 'tail' to this relationship down to 0.9 mGy/day. A similar pattern resulted for the relationship between the life-shortening and the dose-rate. The threshold dose-rate of 3H beta -rays, 2 mGy/day (with a tail down to 0.2 mGy/day), was much lower than that of gamma-rays, 20 mGy/day (tail down to 2 mGy/day) derived from other studies. Conclusions: These studies suggest that there exists the threshold dose-rate in the biological effects of radiation, and that the threshold dose-rate for 60Co gamma-irradiation is higher than that for 3H beta-irradiation.

Mammal; rodent; mouse (Mus musculus)

https://drive.google.com/file/d/1dJ14Ogq0adHydnBWNoMmcvjk_xwzW1NZ/view?usp=share_link

International Radiation Protection Association

*Alloni, D., Cutaia, C., Mariotti, L., Friedland, W., Ottolenghi, A.

One of the main issues of low-energy internal emitters concerns the very short ranges of the beta particles, versus the dimensions of the biological targets. Depending on the chemical form, the radionuclide may be more concentrated either in the cytoplasm or in the nucleus of the target cell. Consequently, since in most cases conventional dosimetry neglects this issue it may overestimate or underestimate the dose to the nucleus and hence the biological effects. To assess the magnitude of these deviations and to provide a realistic evaluation of the localized energy deposition by low-energy internal emitters, the biophysical track-structure code PARTRAC was used to calculate nuclear doses, DNA damage yields and fragmentation patterns for different localizations of radionuclides in human interphase fibroblasts. The nuclides considered in the simulations were tritium and nickel-63, which emit electrons with average energies of 5.7 (range in water of 0.42 μm) and 17 keV (range of 5 μm), respectively, covering both very short and medium ranges of beta-decay products. The simulation results showed that the largest deviations from the conventional dosimetry occur for inhomogeneously distributed short-range emitters. For uniformly distributed radionuclides selectively in the cytoplasm but excluded from the cell nucleus, the dose in the nucleus is 15% of the average dose in the cell in the case of tritium but 64% for nickel-63. Also, the numbers of double-strand breaks (DSBs) and the distributions of DNA fragments depend on subcellular localization of the radionuclides. In the low- and medium-dose regions investigated here, DSB numbers are proportional to the nuclear dose, with about 50 DSB/Gy for both studied nuclides. In addition, DSB numbers on specific chromosomes depend on the radionuclide localization in the cell as well, with chromosomes located more peripherally in the cell nucleus being more damaged by short-ranged emitters in cytoplasm compared with chromosomes located more centrally. These results illustrate the potential for over- or underestimating the risk associated with low-energy emitters, particularly for tritium intake, when their distribution at subcellular levels is not appropriately considered.

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1_OoOXEW3Kd6Nhd8m4bxnNGyp8OlVtE-E/view?usp=sharing

*Ashmore, J. P., Krewski, D., Zielinski, J. M., Jiang, H., Semenciw, R., Band, P. R.

American journal of epidemiology

A cohort mortality study of occupational radiation exposure was conducted using the records of the National Dose Registry of Canada. The cohort consisted of 206,620 individuals monitored for radiation exposure between 1951 and 1983 with mortality follow-up through December 31,1987. A total of 5,426 deaths were identified by computerized record linkage with the Canadian Mortality Data Base. The standardized mortality ratio for all causes of death was 0.61 for both sexes combined. However, trends of increasing mortality with cumulative exposure to whole body radiation were noted for all causes of death in both males and females. In males, cancer mortality appeared to increase with cumulative exposure to radiation, without any clear relation to specific cancers. Unexplained trends of increasing mortality due to cardiovascular diseases (males and females) and accidents (males only) were also noted. The excess relative risk for both sexes, estimated to be 3.0% per 10 mSv (90% confidence interval 1.1-4.8) for all cancers combined, is within the range of risk estimates previously reported in the literature.

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1dRTXwqwGDVUYiQbN9e-eHuwY9FSRXcp_/view?usp=sharing

*Atkinson, W. D., Law, D. V., Bromley, K. J.

JOURNAL OF RADIOLOGICAL PROTECTION

Early epidemiological studies of the UKAEA workforce, which followed up the mortality of those who worked to the end of 1979, found a significant excess of prostate cancer deaths in some subsets of the cohort, particularly workers internally monitored for tritium contamination and those employed at the Winfrith laboratories. The excess seemed to be associated with work in heavy-water reactors. We have followed up the mortality in the UKAEA workforce to the end of 1997 and compared the mortality from prostate cancer in the years 1980-97 with the years to 1979. We found a significantly lower mortality from prostate cancer in the later years in many of the subsets of the cohort that were previously identified as high risk. There was no evidence of a continuing raised risk of prostate cancer in any subset. We considered two possible reasons why the observed risk might have declined. There is no evidence that any risk associated with heavy-water reactors would have abated in the later years or that the cohort would be less susceptible to prostate cancer. Our conclusion is that the original observation might have been a chance finding among many significance tests.

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1MgMCXnXiapJjj0HhAwewnyf6681424JH/view?usp=sharing

Primordial germ cells, which are relatively resistant to radiation administered prior or during migration, become sensitive during sex differentiation of the gonad. Sensitivity increases to a maximum during the peak “wave” of mitosis in oogonia, and especially during the final premeiotic division. The oocyte subsequently becomes increasingly resistant to radiation as it progresses from leptotene to pachytene, after which sensitivity increases with the onset of the period of arrested development (diplotene or dictyate stage). Oocytes vary considerably in radiosensitivity with: (i) age, (ii) species, (iii) inbred or outbred strain, (iv) stage of growth of the follicle which surrounds the oocyte, and (v) chromosomal configuration. Those in primordial follicles are highly sensitive in mice, rats and rabbits; moderately sensitive in dogs, cows and pigs; and highly resistant in the guinea pig, monkey and human. The response of oocytes in multi-layered follicles is less variable (2000–4000 R).Reproductive capacity in the irradiated mammal closely parallels the size of the surviving population of oocytes, but the latter appear to be used more efficiently than in controls.The marked species differences in the response of oocytes cannot be fully explained at present. The most important factors are now known to be chromosomal configuration and metabolic activity. A hypothesis to explain differential radio-sensitivity is described.

Mammal; primate; human (Homo sapiens), monkey, rodent; mice, ratts, rabbits, guinea pig, ; canine ; dogs, cows and pigs

https://drive.google.com/file/d/1Q8_ji-UdvGFvgBuks5IBFWRJqYvT4QNo/view?usp=sharing

*Balanov, M. I., Dolgirev, E. I., Likhtarev, I. A.

The transport kinetics of body fluids in man was studied after an intravenous injection, inhalation and ingestion of THO. The excretion of incorporated tritium was followed during 300 days. The mathematical compartment model of THO metabolism was suggested. The full set of model parameters was obtained. The specificity of irradiation of respiratory tract and body soft tissues was considered.

Mammal; primate; human (Homo sapiens)

*Balonov, M. I., Likhtarev, I. A., Moskalev YuI

A wide variety of 3H compounds with different physico-chemical and radiotoxic properties are produced and used throughout the world. For the purpose of worker radiation safety, 3H compounds have been divided into five classes: oxide, gaseous, insoluble, soluble organic substances and precursors of nucleic acids. Based on recent radiobiological and dosimetric data the quality factor for 3H has been suggested (QF = 2). Standards for oxide and gaseous 3H, reduced by a factor of 3-10, as compared with International Commission on Radiological Protection (ICRP) recommendations, have been suggested. New standards, 2-30 times lower than those for 3H oxide, have been worked out for the other three classes of 3H compounds. A limit for removable surface contamination from nonvolatile forms of 3H has been proposed (LSC = 1 kBq cm-2).

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1QlQ0DitW4O4Dwqxwprnsb1o3PTHNmptp/view?usp=sharing

HTO, gaseous 3H

epa-rbe-report-11-04-2013

There is growing evidence to support a relative biological effectiveness (RBE) greater that one for low-energy electrons and photons. Strong justification of an RBE greater than one for low energy electrons comes from radiobiological studies of tritium. Similarly, studies with low-energy photons have indicated an elevated response relative to reference radiations of higher energy. In the field of radiation protection, photons and electrons have been assigned a radiation weighting factor (wR) of one. While this value may be appropriate for radiation protection calculations, it is important in risk considerations to consider the potentially elevated effectiveness of these radiations in efforts to improve the quality of the radiogenic risk estimates. Low-energy electron and photon radiations produce dense ionization clusters which lead to RBE values greater than those of high energy gamma rays. For tritium, RBE values between 2 and 3 are implied by a number of experimental studies. Other radiation sources with similar energy emissions may also exhibit an elevated RBE. In this work, RBE values are derived for electron and photon emissions based on the fractional deposition of absorbed dose for electrons of energies less than a few keV. Using this empirical model, RBE values for monoenergetic electrons, monoenergetic photons, and machine-generated x-rays were derived. In addition, nuclide-specific RBE values were calculated for the radionuclides of ICRP Publication 107 for which neither alpha decay or spontaneous fission is indicated as a mode of decay.

https://drive.google.com/file/d/1Uj_6ZDk-TIAB_HKoLQOguOjWXmvQIDEe/view?usp=sharing

*Beral, V., Inskip, H., Fraser, P., Booth, M., Coleman, D., Rose, G.

BRITISH MEDICAL JOURNAL

An analysis was conducted of 3373 deaths among 39,546 people employed by the United Kingdom Atomic Energy Authority between 1946 and 1979, the population having been followed up for an average of 16 years. Overall the death rates were below those prevailing in England and Wales but consistent with those expected in a normal workforce. At ages 15-74 years the standardised mortality ratios (SMRs) were 74 for deaths from all causes and 79 for deaths from all cancers. Mortality from only four causes was above the national average--namely, testicular cancer (SMR 153; 10 deaths), leukaemia (SMR 123; 35 deaths), thyroid cancer (SMR 122; three deaths), non-Hodgkin's lymphoma (SMR 107; 20 deaths)--but in none was the increase significant at the 5% level. Half of the authority's employees were recorded as having been monitored for exposure to radiation, their collective recorded exposure being 660 Sv (65 954 rem). Among these prostatic cancer was the only condition with a clearly increased mortality in relation to exposure. Of the 19 men who had a radiation record and died from prostatic cancer at ages 15-74 years, nine had been monitored for several different sources of exposure to radiation. The standardised mortality ratios were 889 (six deaths) in employees monitored for contamination by tritium, 254 (nine deaths) in those monitored for contamination by other radionuclides, and 385 (nine deaths) in those with dosimeter readings totalling more than 50 mSv (5 rem); but the same nine subjects tended to account for each of these significantly raised ratios. Because multiple exposures were common and other relevant information was not available the reason for the increased mortality from prostatic cancer in this population could not be determined and requires further investigation. Excess mortality rates of 2.2 and 12.5 deaths per million person years per 10 mSv (1 rem) were estimated for leukaemia and all cancers, respectively. The confidence limits around these estimates were wide, included zero, and made it unlikely that the International Commission on Radiological Protection's cancer risk coefficients were underestimated by more than 15-fold. Thus despite this being the largest British workforce whose mortality has been reported in relation to low level ionising radiation exposure, even larger populations will need to be followed up over longer periods before narrower ranges of risk estimates can be derived.

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1OmnvCIAcT3MjCTuceXJz944w6xA87qxf/view?usp=sharing

*Boice, J. D., Jr, Cohen, S. S., Mumma, M. T., Ellis, E. D., Cragle, D. L., Eckerman, K. F., Wallace, P. W., Chadda, B., Sonderman, J. S., Wiggs, L. D., Richter, B. S., Leggett, R. W.

Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. Cancer mortality was examined among 7,270 workers at the Mound nuclear facility near Dayton, OH where polonium-210 was used (1944-1972) in combination with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium and neutrons. Vital status and cause of death was determined through 2009. Standardized mortality ratios (SMRs) were computed for comparisons with the general population. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 200,000 urine samples were analyzed to estimate radiation doses to body organs from polonium and other internally deposited radionuclides. Cox proportional hazards models were used to evaluate dose-response relationships for specific organs and tissues. Vital status was determined for 98.7% of the workers of which 3,681 had died compared with 4,073.9 expected (SMR 0.90; 95% CI 0.88-0.93). The mean dose from external radiation was 26.1 mSv (maximum 939.1 mSv) and the mean lung dose from external and internal radiation combined was 100.1 mSv (maximum 17.5 Sv). Among the 4,977 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79-0.93), lung cancer (SMR 0.85; 95% CI 0.74-0.98), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 mSv of 1.54 (1.15-2.07)] and a negative dose-response trend for liver cancer [RR (95% CI) at 100 mSv of 0.55 (0.23-1.32)]. For lung cancer the RR at 100 mSv was 1.00 (95% CI 0.97-1.04) and for all leukemias other than chronic lymphocytic leukemia (CLL) it was 1.04 (95% CI 0.63-1.71). There was no evidence that heart disease was associated with exposures [RR at 100 mSv of 1.06 (0.95-1.18)]. Assuming a relative biological effectiveness factor of either 10 or 20 for polonium and plutonium alpha particle emissions had little effect on the dose-response analyses. Polonium was the largest contributor to lung dose, and a relative risk of 1.04 for lung cancer at 100 mSv could be excluded with 95% confidence. A dose related increase in cancer of the esophagus was consistent with a radiation etiology but based on small numbers. A dose-related decrease in liver cancer suggests the presence of other modifying factors of risk and adds caution to interpretations. The absence of a detectable increase in total cancer deaths and lung cancer in particular associated with occupational exposures to polonium (mean lung dose 159.8 mSv), and to plutonium to a lesser extent (mean lung dose 13.7 mSv), is noteworthy but based on small numbers. Larger combined studies of U.S. workers are needed to clarify radiation risks following prolonged exposures and radionuclide intakes.

Mammal; primate; human (Homo sapiens)

Disease; increased risk of Cancer, mortality

https://drive.google.com/file/d/1MgMCXnXiapJjj0HhAwewnyf6681424JH/view?usp=sharing

Radiation Protection Dosimetry

In a previous study, microdosimetric simulations were performed for tritium uniformly distributed in a medium, and for tritium bound to biologically critical sites of dimensions from 10 nm to 2 mm. Results of local energy density, i.e. energy deposition in microscopic regions, are different for these two cases. Based on the spatial distribution of energy deposition, dosemean lineal energies are calculated for tritium in the forms of tritiated water (HTO) and organically bound tritium (OBT).The dose mean lineal energies of OBT are about a factor of 1.7 higher than those of HTO in a wide range of target dimensions of biological interest. The results are consistent with radiobiological findings that OBT is about twice as effective as HTO. In this study, the same calculations were performed for 60Co gamma rays in a wide range of target dimensions of biological interest (10 nm to 2 mm). Compared with 60Co gamma rays, the estimated relative biological effectiveness could vary from 1.3 to 3.5 for HTO, and 2.3 to 5.6 for OBT. The results are consistent with radiobiological findings for various biological endpoints in different biological systems that OBT is about twice as effective as HTO.

https://drive.google.com/file/d/1sORTuYu9oa3cE5ZeYoR0bRtWGifND-y8/view?usp=sharing

*Friday, G. P., Cummins, C. L., Schwartzman, A. L.

Westinghouse Savannah River Company

WSRC-TR-96-0231

Since the early 1950s, the Savannah River Site (SRS) released over 50 radionuclides into the environment while producing nuclear defense materials. These releases directly exposed aquatic and terrestrial biota to ionizing radiation from surface water, soil, and sediment, and also indirectly by the ingestion of items in the food chain. As part of new missions to develop waste management strategies and identify cost-effective environmental restoration options, knowledge concerning the uptake and distribution of these radionuclides is essential. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at SRS.

aquatic and terrestrial biota

https://drive.google.com/file/d/1Uq-j4S1m68ZEfqrYiM9Qmi8_QJf-rkLS/view?usp=sharing

*Gao, W. M., Lu, H. M., Dong, J. C., Zhang, W., Zhou, X. Y., Jenkins, L. W., Dixon, C. E.

Neurotoxicology and Teratology

Pregnant adult C57BL/6J mice were randomly assigned to four groups: one sham and three irradiated groups that were exposed to -irradiation from tritiated water (HTO) by a single intraperitoneal injection on Day 12.5 of gestation. The offspring received cumulative doses of 0.036, 0.071, and 0.213 Gy, respectively. The litters were observed for postnatal growth (body weight, brain weight), the development of four physiologic milestones (pinna detachment, eye opening, testes decent, vaginal opening), the acquisition age of several reflexes (cliff avoidance, air righting) and sensory functions (auditory startle, thermal reflex), movement and coordination functions and activity (pivoting, foot splay, continuous corridor activity), learning and memory performance (shock avoidance, conditioning reflex), and the density of CA1-CA4 hippocampal pyramidal neurons. Modest but significant dose-dependent neuronal death and functional impairment were seen in both 0.071 and 0.213 Gy groups. In conclusion, even prenatal low-dose beta-radiation may impair murine central nervous system (CNS) development suggesting the potential importance of minimizing environmental exposure during human pregnancy.

Mammal; rodent; mouse (Mus musculus)

https://drive.google.com/file/d/179jEAdordurBknHkl-81axM8_he7wXEY/view?usp=sharing

*Jean-Baptiste, P., Fourré, E., Baumier, D., Dapoigny, A.

Fusion Science and Technology

Most published results concerning deuterium-hydrogen fractionation in plants are in the range 0.8-1, indicating no bioaccumulation of the heavy isotope. In spite this, an updated compilation of litterature data show that 77% of OBT/TFWT ratios measured in terrestrial plants and food items are greater than one, with a mean value of 1.92. On the other hand, OBT/TFWT ratios for aquatic samples do not show such a tritium anomaly, with 81% of the published ratios being less than 1. This strongly suggests that the cause for excess tritium in terrestrial organic matter has to be found in the atmosphere. We have developed a simple model of tritium incorporation during plant growth, forced by the annual cycle of tritium in precipitation taken from the IAEA/ISOHIS database. The simulated distribution of the OBT/TFWT ratios for terrestrial samples shows many similarities with the observed one. Although other processes such as soil moisture with lower tritium content than atmospheric water vapour can be invoked, our results suggest that the annual tritium maximum which occurs in spring, during the growing season, is capable of creating substantial OBT/TFWT enrichments and has to be considered as well.

*United Nations Scientific Committee on the Effects of Atomic Radiation

Exposures to the public from man-made sources of radiation. (New York: UNITED NATIONS)

This report assesses the levels and effects of exposure to ionizing radiation. Scientific findings underpin radiation risk evaluation and international protection standards. This report comprises a report with two underpinning scientific annexes. The first annex recapitulates and clarifies the philosophy of science as well as the scientific knowledge for attributing observed health effects in individuals and populations to radiation exposure, and distinguishes between that and inferring risk to individuals and populations from an exposure. The second annex reviews the latest thinking and approaches to quantifying the uncertainties in assessments of risk from radiation exposure, and illustrates these approaches with application to examples that are highly pertinent to radiation protection.

Mammal; primate; Human (Homo sapiens), rodent; mouse (Mus musculus), Rat (Rattus)

Genetic; heritable effects, Reproductive; Cancer/disease, carcinogenesis, acute radiation syndrome, haematological radiation syndrome,radiation-induced death; Cellular; cell death

https://drive.google.com/file/d/1z2O-eVU8aj-BCP9TrXRUEsVWv2HKfbpG/view?usp=sharing

Barnacle embryos were reared in millipore cytology monitors containing approximate tritiated water (HTO) concentrations of background plus 0, 10−5, 10−4, 10−3, 10−2, 10−1, and 100 microci/ml. After 32 days the cultures were fixed and the numbers of larvae counted. A “molting index,” the percentage of larvae that molted at least once, was used to evaluate the effects of HTO on normal development. Effects were observed at concentrations as low as 7 × 10−6 microci/ml, and were exponentially related to HTO concentration. Factors affecting sensitivity and possible environmental implications are discussed.

Invertebrates; crustacean; Goose Barnacle (Pollicipes Polymerus)

Physiological; Development, growth

https://drive.google.com/file/d/11fAtmXVtFPG3jPqGil6Bncdi7NYg4TJx/view?usp=sharing

Adam-Guillermin, C., Pereira, S., Della-Vedova, C., Hinton, T., Garnier-Laplace, J.

Reviews of Environmental Contamination and Toxicology

Aquatic ecosystems are chronically exposed to natural radioactivity or to artificial radionuclides released by human activities (e.g., nuclear medicine and biology,nuclear industry, military applications). Should the nuclear industry expand in the future, radioactive environmental releases, under normal operating conditions or accidental ones, are expected to increase, which raises public concerns about possible consequences on the environment and human health. Radionuclide exposures may drive macromolecule alterations, and among macromolecules DNA is the major target for ionizing radiations. DNA damage, if not correctly repaired, may induce mutations, teratogenesis, and reproductive effects. As such, damage at the molecular level may have consequences at the population level. In this review, we present an overview of the literature dealing with the effects of radionuclides on DNA, development, and reproduction of aquatic organisms. The review focuses on the main radionuclides that are released by nuclear power plants under normal operating conditions, γ emitters and tritium. Additionally, we fitted nonlinear curves to the dose-response data provided in the reviewed publications and manuscripts, and thus obtained endpoints commonly associated with ecotoxicological studies, such as the EDR(10). These were then used as a common metric for comparing the values and data published in the literature.The effects of tritium on aquatic organisms were reviewed for dose rates that ranged from 29 nGy/day to 29 Gy/day. Although beta emission from tritium decay presents a rather special risk of damage to DNA, genotoxicity-induced by tritium has been scarcely studied. Most of the effects studied have related to reproduction and development. Species sensitivity and the form of tritium present are important factors that drive the ecotoxicity of tritium. We have concluded from this review that invertebrates are more sensitive to the effects of tritium than are vertebrates.Because several calculated EDR10 values are ten times lower than background levels of γ irradiation the results of some studies either markedly call into question the adequacy of the benchmark value of 0.24 mGy/day for aquatic ecosystems that was recommended by Garnier-Laplace et al. (2006), or the dose rate estimates made in the original research, from which our EDR(10) values were derived, were under estimated, or were inadequate. For γ irradiation, the effects of several different dose rates on aquatic organisms were reviewed, and these ranged from 1 mGy/day to 18 Gy/day. DNA damage from exposure to y irradiation was studied more often than for tritium, but the major part of the literature addressed effects on reproduction and development. These data sets support the benchmark value of 0.24 mGy/day, which is recommended to protect aquatic ecosystems. RBEs, that describe the relative effectiveness of different radiation types to produce the same biological effect, were calculated using the available datasets. These RBE values ranged from 0.06 to 14.9, depending on the biological effect studied, and they had a mean of 3.1 ± 3.7 (standard deviation). This value is similar to the RBE factors of 2-3 recommended by international organizations responsible for providing guidance on radiation safety. Many knowledge gaps remain relative to the biological effects produced from exposure to tritium and y emitters. Among these are: Dose calculations: this review highlights several EDR(10) values that are below the normal range of background radiation. One explanation for this result is that dose rates were underestimated from uncertainties linked to the heterogenous distribution of tritium in cells. Therefore, the reliability of the concept of average dose to organisms must be addressed. Mechanisms of DNA DBS repair: very few studies address the most deleterious form of DNA damage, which are DNA DBSs. Future studies should focus on identifying impaired DNA DBS repair pathways and kinetics, in combination with developmental and reproductive effects. The transmission of genetic damage to offspring, which is of primary concern in the human health arena. However, there has been little work undertaken to assess the potential risk from germ cell mutagens in aquatic organisms, although this is one of the means of extrapolating effects from subcellular levels to populations. Reproductive behavior that is linked to alterations of endocrine function. Despite the importance of reproduction for population dynamics, many key endpoints were scarcely addressed within this topic. Hence, there is, to our knowledge,only one study of courtship behavior in fish exposed to γ rays, while no studies of radionuclide effects on fish endocrine function exist. Recent technical advances in the field of endocrine disrupters can be used to assess the direct or indirect effects of radionuclides on endocrine function. Identifying whether resistance to radiation effects in the field result from adaptation or acclimation mechanisms. Organisms may develop resistance to the toxic effects of high concentrations of radionuclides. Adaptation occurs at the population level by genetic selection for more resistant organisms. To date, very few field studies exist in which adaptation has been addressed, despite the fact that it represents an unknown influence on observed biological responses.

Invertebrates; marine bivalve(s), Pacific oyster (Crassostrea gigas), blue mussel (Mytilus edulis) & Invertebrates; crustacean; brine shrimp (Artemia franciscana), goose barnacle (Pollicipes polymerus), Daphnid (Daphnia Magna); & Invertebrates; Polychaeta; polychaete worms (Ophryotrocha diadema), (Neanthes arenaceodentata) & Vertebrates; Fish; belinoform; Medeka/Japanese Ricefish (Oryzias latipes), salminoform; rainbow trout (Oncorhynchus mykiss gairdneri), Chinook salmon (Oncorhynchus tshawytscha), cryprinodontiform; guppy (Poecilia reticulata), Scorpaeniform; three-spined stickleback (Gasterosteus aculeatus), Pleuronectiform; English sole (Parophrys vetulus), Common Flounder (Paralichthys olivaceus), European plaice (Pleuronectes platessa), Cypriniform; European carp (Cyprinus carpio), Tetraodontiform; puffer; (Fugu niphobles) Esociform; central mudminnow (Umbra limi)

Genetic, DNA damage, Genotoxicity, chromosone aberrations; Physiological, Developmental abnormalities; Reproductive, effects on subsequent fecundity and fertility, Embryo survival, time to sexual maturity

https://drive.google.com/file/d/1hVZUhMlYLj9ZMa5zfReyIZzXinavjhhV/view?usp=sharing

Adams, L.W., Peterle, T.J., White, G.C.

In: Behavior of Tritium in the Environment, IAEA-SM-232/50

Ten curies of tritium as tritiated water (HTO) were experimentally added to an enclosed 2-ha Lake Erie marsh on 20 October 1973. Tritium kinetics in selected plants and animals were determined over a one-year period. Tritium levels in the marsh bottom sediment averaged 1.8 times the marsh water levels during this period, but little evidence of tritium concentration above the marsh water tritium levels was observed in the flora and fauna. The unbound tritium : marsh water tritium ratios in smartweed (Polygonum lapathifolium) and pickerelweed (Pontederia cordata) (both emergents) were lower than the same ratio for pondweed (Potamogeton crispus) (a submergent), presumably because of a differential loss of HTO over H2O in the two emergents. There was some evidence of bound tritium buildup in midsummer, particularly in the pondweed, possibly because of increased photosynthetic activity and plant growth at this time, resulting in more tritium being tied up in organic constituents. Tritium uptake into the unbound compartments of crayfish (Procambarus blandingi), carp (Cyprinus carpio) and bluegills (Lepomis macrochirus) was rapid. For crayfish, maximum HTO levels were observed on days 2 and 3 following treatment for muscle and viscera respectively. Unbound HTO in carp muscle peaked in four hours and the level in carp viscera reached a maximum in two days. Maximum levels of unbound HTO in bluegill muscle and viscera were observed on day 1. Unbound HTO in all species decreased following peak levels, paralleling marsh water HTO activity. Tritium uptake into the bound compartments was not as rapid nor were the levels as high as for unbound HTO in the fauna. The peak bound level in crayfish muscle was observed on day 10 (bound : unbound ratio of 0.34) and the maximum level in viscera was noted on day 20 (bound: unbound ratio of 0.23). Bound tritium in carp muscle and viscera reached maximum levels on day 20 (bound : unbound ratios of 0.25 and 0.39 respectively). In bluegills, peaks were reached on days 5 and 7 (bound : unbound ratios of 0.35 and 0.38 for muscle and viscera respectively). Bound tritium in all species decreased following maximum levels.

Fish; Cypriniform; European carp (Cyprinus carpio), Perciform; bluegills (Lepomis macrochirus) & Invertebrates; crustacean; crayfish (Procambarus blandingi) & Plant; smartweed (Polygonum lapathifolium), pickerelweed (Pontederia cordata), pondweed (Potamogeton crispus)

https://drive.google.com/file/d/17lw9aKLAyHJykfhHxOwVCVFqsdQz8fMv/view?usp=sharing

Radiation Protection Dosimetry

This paper presents an overview of radiobiological dependences governing the occurrence of tissue (organ) reactions that determine the outcomes of chronic exposure to low LET ionizing radiation in humans. The mechanisms involved in the development of tissue reactions to long-term exposures to ionizing radiation and radioadaptation are considered. The overview describes the reactions of the haematopoietic, immune, nervous, reproductive and endocrine systems, lungs, skin and crystalline lens to chronic radiation exposure, which are of fundamental importance in view of radiation protection. It is shown that the individual’s physiological tissue (organ) reserve, and also that induced by radiation-exposure at low dose-rates are of great significance in the context of tissue reaction development.

Mammal; primate; Human (Homo sapiens)

Genetic, epigenetic disturbances; Reproductive, oligospermia, aspermia, menstrual disorders, increased rate of pathologies of pregnancy and childbirth, increased incidences of dysmenorrhea and hypermenorrhea in females; Physiological, immunosuppressive and immunostimulating effects, effects on tissue regeneration; Cellular, disturbances of the intra- and intercellular signaling, cytokine cascades

https://drive.google.com/file/d/1thHuWa9n9_JCx1i1rqaEiawpHo7ZjXmc/view?usp=sharing

Journal of Radiation and Cancer Research

Tritium exposure could be one of the radiation hazards in case of accidental exposure with intestine as one of the major target organs. In the cells, low-energy beta emitted from tritium would traverse a very short distance (a few microns). Hence, the intestinal epithelial cells with nuclear localization of tritium would exert its radiobiological effect also through bystander mechanism. In the present study, the effect of conditioned medium obtained from tritiated thymidine-labeled human normal intestinal epithelial (INT407) cells was studied on respective bystander cells in terms of magnitude of survival and induction of DNA damage. Materials and Methods: The survival and proliferation of bystander INT407 cells treated with control/irradiated conditioned medium were studied using clonogenic and 5-bromo-2-deoxyuridine (BrdU)-labeling assays. The magnitude of DNA double-strand break was measured by immunofluorescence of η-H2AX by confocal microscopy. Intracellular nitric oxide (NO) in these cells was measured using 4,5-diaminofluoresce in diacetate fluorescent dye. Results: Bystander cells treated with conditioned medium from tritiated thymidine-labeled cells showed increased clonogenic survival and BrdU labeling. Cells labeled with tritiated thymidine showed attenuation of η-H2AX foci at longer period (24 and 48 h) of labeling than at 15 h. Moreover, the bystander cells treated with irradiated conditioned medium showed a higher magnitude of η-H2AX foci at 24 h. However, compared to 24 h, 48-h treatment of irradiated conditioned medium resulted in a decrease in η-H2AX foci in the bystander cells. Increased level of intracellular NO was observed in the bystander cells treated with irradiated conditioned medium. Conclusions: Bystander cells treated with conditioned medium obtained from tritiated thymidine-labeled cells showed increased clonogenic survival and proliferation, which was correlated with an increase in DNA double-strand break and NO production in these cells.

Mammal; primate; human (Homo sapiens)

Genetic, DNA double-strand breaks, increased clonogenic survival and proliferation correlated with increase in DNA double-strand breaks

https://drive.google.com/file/d/16iKeqhv1AHGgRHInhRc_IjwZscKTAbux/view?usp=sharing

https://drive.google.com/file/d/1gwGG55bklwJTxfCJzIkLK58mqDr0mK9T/view?usp=share_link

Amano, H., Atarashi-Andoh, M., Noguchi, H., Yokoyama, S., Ichimasa, Y., Ichimasa, M.

Trace amounts of elemental tritium (HT) were released continuously to the surface atmosphere at a site at Chalk River Laboratories, Canada over the 12-day period 1994 July 27 to August 8. The test area consisted of four agricultural plots, each 5 m square. One plot was left in its natural state, and the other three were cultivated. Cherry tomatoes, radishes and edible Chinese mustard (Komatsuna in Japanese) were grown in the three cultivated fields. After the HT gas reached the surface of the field, some portion of it was converted into the water form (HTO) mainly by microorganisms in the soil. Then, plant absorbs HTO from both soil and air. Photosynthesized organic material in plant contains tritium,also. The main purpose of this research is to analyze the variation with time of tissue free-water tritium (TFWT) and organically bound tritium (OBT) in several plant species during the HT release. The specific activity of HTO in plants increased rapidly after the HT exposure. The HTO concentration in plant leaves almost attained its maximum value in about 10 days, even though there were several precipitation events, which decreased the soil HTO concentration. The specific activity of OBT in plants increased gradually after the start of the exposure. The OBT concentration in plants did not attain steady state over the whole exposure period of 12 days. The OBT/HTO ratio in plants increased gradually during the release. The ratio in Komatsuna leaves changed from 0.06 to 0.24 between 2 and 11 days. The production rates of OBT in plants are fitted to numerical equations.

https://drive.google.com/file/d/11Z6j4WmQocPwB2dbQzwLLxWshfRN4gXv/view?usp=sharing

HT, HTO, OBT, TFWT

In: Tritium in the Physical and Biological Sciences. Vol. II.

Bacteria of the strain B31 thy -/Sr, which required thymine and are streptomycin-resistant, had their DNA labelled with tritiated thymidine. The radioactivity measurements were made with a liquid scintillation counting system, with two photomultipliers mounted in coincidence. Under these conditions, the efficiency of the measures was 4.5% and the background 130 counts/min. The radioactive bacteria were kept in sealed tubes either at 0°C or at — 196°C and their survival studied. These experiments showed that the radioactive bacteria are inactivated exponentially as a function of the number of tritium atoms disintegrated. The inactivation is temperature dependent. In both cases the killing efficiency per nuclear transmutation was determined and found as very low. The number of ion pairs generated by the β-particles emitted as a consequence of the transmutation of H3 was evaluated and found quite comparable with the one found in the case of X-rays. The suicide caused by the H3 disintegrations seems to be directly linked with the ionizations produced by the β-particles inside the bacterial DNA.

Bacteria; E. coli (Escherichia coli)

Genetic/Cellular, bacteria inactivation, cell suicide,

https://drive.google.com/file/d/1Wg7JelbovGF0c-PA4PBErcYw_hM52-6A/view?usp=sharing

Arcanjo, C., Adam-Guillermin, C., El Houdigui, S.M., Loro, G., Della-Vedova, C., Cavalie, I., Camilleri, V., Floriani, M., Gagnaire, B.

Tritium (3H), a radioactive isotope of hydrogen, is ubiquitously present in the environment. In a previous study, we highlighted a mis-regulation of genes involved in muscle contraction, eye transparency and response to DNA damages after exposure of zebrafish embryo-larvae from 3 hpf to 96 hpf at 0.4 and 4 mGy/h of tritiated water (HTO). The present study aimed to link this gene mis-regulation to responses observed at higher biological levels. Analyses on spontaneous tail movement, locomotor activity and heart rate were performed. Histological sections of eyes were made to evaluate the impact of HTO on eye transparency and whole embryo immunostainings were realized to assess DNA double strand breaks repair using gamma-H2AX foci. We found a decrease of basal velocity as well as a decrease of response in 96 hpf larvae exposed at 0.4 mGy/h after a tactile stimulus as compared to controls. Histological sections of larvae eyes performed after the exposure to 4 mGy/h did not show obvious differences in lens transparency or retinal development between contaminated and control organisms. Gamma-H2AX foci detection revealed no differences in the number of foci between contaminated organisms and controls, for both dose rates. Overall, results highlighted more detrimental effects of HTO exposure on locomotor behavior in 96 hpf larvae exposed at the lowest dose rate. Those results could be linked to mis-regulation of genes involved in muscle contraction found in a previous study at the same dose rate. It appears that not all effects found at the molecular scale were confirmed using higher biological scales.These results could be due to a delay between gene expression modulation and the onset of physiological disruption or homeostatic mechanisms to deal with tritium effects. However, crossing data from different scales highlighted new pathways to explore, i.e. neurotoxic pathways, for better understanding HTO effects on organisms.

Fish; Cypriniform; zebrafish (Danio rerio)

Physiological, locomotion, impact on nervous system coupled with muscular impairments

https://drive.google.com/file/d/1s-DOiCV_2BkhiGg3dcnm572DOI88ntu3/view?usp=sharing

Arcanjo, C., Armant, O., Floriani, M., Cavalie, I., Camilleri, V., Simon, O., Orjollet, D., Adam-Guillermin, C., Gagnaire, B.

Tritium (3H) is a radioactive isotope of hydrogen. In the environment, the most common form of tritium is tritiated water (HTO). The present study aimed to identify early biomarkers of HTO contamination through the use of an aquatic model, the zebrafish (Danio rerio). We used the zebrafish embryo-larvae model to investigate the modes of action of HTO exposure at dose rates of 0.4 and 4 mGy/h, dose rates expected to induce deleterious effects on fish. Zebrafish were exposed to HTO from 3 hpf (hours post fertilization) to 96 hpf. The transcriptomic effects were investigated 24 h and 96 h after the beginning of the contamination, using mRNAseq. Results suggested an impact of HTO contamination, regardless of the dose rate, on genes involved in muscle contraction (tnnt2d, tnni2a.4, slc6a1a or atp2a1l) and eye opacity (crygm2d9, crygmxl1, mipb or lim2.3) after 24 h of contamination. Interestingly, an opposite differential expression was highlighted in genes playing a role in muscle contraction and eye opacity in 24 hpf embryos when comparin dose rates, suggesting an onset of DNA protective mechanisms. The expression of h2afx and ddb2 involved in DNA repair was enhanced in response to HTO exposure. The entrainment of circadian clock and the response to H2O2 signalling pathways were enriched at 96 hpf at 0.4 mGy/h and in both stages after 4 mGy/h. Genes involved in ROS scavenging were differentially expressed only after 24 h of exposure for the lowest dose rate, suggesting the onset of early protective mechanisms against oxidative stress. Effects highlighted on muscle at the molecular scale were confirmed at a higher biological scale, as electron microscopy observations revealed sarcomere impairments in 96 hpf larvae for both dose rates. Together with other studies, the present work provides useful data to better understand modes of action of tritium on zebrafish embryos-larvae.

Fish; Cypriniform; zebrafish (Danio rerio)

Genetic, DNA damage, increase of micro-nuclei and DNA strand breaks; Physiological, disorganization of the skeletal muscles; Cellular; effect on pathways involved in skeletal and cardiac muscle contraction, muscle cell development, or sarcomere assembly, effect on fin development, hatching and swimming

https://drive.google.com/file/d/1DI5Syy9-iNy1E3pqlDPdr3nLVvFupCyW/view?usp=sharing

Arcanjo, C., Maro, D., Camilleri, V., Cavalié, I., Simon, O., Beaugelin-Seiller, K., Carasco, L., Orjollet, D., Adam-Guillermin, C., Gagnaire, B.

Journal of Environmental Radioactivity

Tritium (3H) is mainly released into the environment in the form of tritiated water (HTO) by nuclear power plants and nuclear fuel reprocessing plants. To better understand how organisms may be affected by contamination to 3H it is essential to link observed effects to a correct estimation of absorbed dose rates. Due to quick isotopic exchanges between 3 H and hydrogen, 3H measurement is difficult in small organisms such as zebrafish embryo, a model in ecotoxicological assay. This work aimed to optimise tritium measurement protocol to better characterise internalisation by early life stages of zebrafish. Zebrafish eggs were exposed at one HTO activity concentration of 1.22 × 105 Bq/mL. This activity was calculated to correspond to theoretical dose rates of 0.4 mGy/h, where some deleterious effects are expected on young fish. A protocol for the preparation of biological samples was adapted from the method classically used to segregate the different forms of tritium in organisms. To deal with very quick isotopic exchanges of 3H with hydrogen, the impacts of washing by nontritiated water as well as the bias induced by absorbed tritium around organisms on the measured activity concentration were studied. We managed to develop protocols to perform total tritium and total organically bound tritium (OBT) activity concentrations measurements in zebrafish eggs and larvae. The measurement of these both forms allowed the calculation of tissue-free-water-tritium (TFWT). To better understand total tritium internalisation, a study of total tritium kinetics from 4 hpf (hour post fertilization) to 168 hpf was performed. OBT and TFWT were also assessed to complete the total tritium internalisation kinetics. The internalisation is a rapid phenomenon reaching a steady-state within 24 h after the beginning of contamination for total tritium and TFWT, with concentration factors and TFWT/HTO close to unity. OBT formation seemed to be slower. It appeared that OBT content in organisms was low with an OBT/TFWT ratio of about 8% for both stages (24 hpf and 96 hpf). To verify absorbed dose rates at key developmental stages (24 hpf eggs and 96 hpf larvae), they were calculated from total tritium activity concentrations after exposure at 1.22 × 105 and 1.22 × 106 Bq/mL, as these two activity concentrations were used to assess effects of tritium in another part of the study. Dose rates calculated from total tritium activity concentrations measured in 24 hpf eggs and 96 hpf larvae were consistent with the nominal ones, which validates the robustness of the protocol developed in the present study.

Fish; Cypriniform; zebrafish (Danio rerio)

https://drive.google.com/file/d/1YyaEXW-X077oakEkgvBlk8EMTD8dhTlw/view?usp=sharing

Asakawa, J., Kamiguchi, Y., Kamiya, K., Nakamura, N.

Estimates of genetic risks from radiation delivered to humans are derived largely from mouse studies. In males, the target is spermatogonia and a large amount of information is available. In contrast, in females, immature oocytes are the target, but extrapolations from mice to humans are not very definitive because immature mouse oocytes are highly sensitive to radiation and die by apoptosis, which is not the case in humans. Since mouse offspring derived from surviving immature oocytes have to date not shown any signs of mutation induction, two alternative hypotheses are proposed: 1. Apoptotic death effectively eliminates damaged oocytes in mice and therefore human immature oocytes may be highly mutable; and 2. Immature oocytes are inherently resistant to mutation induction and apoptotic death is not relevant to mutagenesis. To test these hypotheses, rat immature oocytes, which are not as sensitive as those in mice to radiation-induced apoptosis were exposed to 2.5 Gy of gamma rays and the offspring were examined using a two-dimensional DNA analysis method. Screening of a total of 2.26 million DNA fragments, we identified 32 and 18 mutations in the control and exposed groups, respectively. Of these, in the two groups, 29 and 14 mutations were microsatellite mutations, two and one were base changes, and one and three were deletions. Among the four deletions most relevant to radiation exposure, only one was possibly derived from the irradiated dam (but not determined) and three were paternal in origin. Although the number of mutations was small, the results appear to support the second hypothesis and indicate that immature oocytes are generally less sensitive than mature oocytes to mutation induction.

Mammal; rodent; mouse (Mus musculus)

*Tritium not mentioned. Reproductive, prolonged menstrual cycle, germ cell mutations

https://drive.google.com/file/d/1FFqELa9kCkYXwdkhsodmaHDLAxO8DyOb/view?usp=sharing

Audette-Stuart, M., Ferreri, C., Festarini, A., Carr, J.

Fatty acid composition was identified as a potential biological indicator of the effects of environmental exposure to radiological contaminants. This end point was measured in muscle tissues of Mink frogs ( Rana septentrionalis ) obtained from a radiologically contaminated pond and from a non-contaminated pond. It was also measured after the frogs obtained from both ponds were exposed to a 4 Gy (60)Co γ radiation dose delivered in vivo at a dose rate of approximately 8 Gy/min. Statistically significant differences for the increase of a couple of polyunsaturated omega-3 fatty acid residues and the decrease of a polyunsaturated omega-6 fatty acid residue were observed between radiologically contaminated and non-contaminated frogs, indicating a partial remodeling of muscle lipids in response to a chronic low-dose tritium exposure. The effects of an acute high-dose exposure to (60)Co γ radiation, either for the radiologically contaminated or non-contaminated frogs indicated fast post-irradiation fatty acid changes with an increase of polyunsaturated and decrease of saturated fatty acid contents. Fatty acid composition was found to be a sensitive marker that may be useful to study and monitor biota health in environments that are radiologically contaminated, as well as for understanding the differences between low chronic and high acute stress responses.

Amphibians; Anura; frogs; mink frog (Lithobates septentrionalis)

Physiological; changes in fatty acid composition

https://drive.google.com/file/d/1uq8NISHuA2AxgFt8Yo1RIDa5XZgopmJY/view?usp=sharing

Audette-Stuart, M., Kim, S. B., McMullin, D., Festarini, A., Yankovich, T. L., Carr, J., Mulpuru, S.

Journal of Environmental Radioactivity

Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-back-ground levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms.

Amphibians; Anura; frogs; northern leapord frog (Rana pipiens), Mink frog (Lithobates septentrionalis)

Genetic, DNA damage,DNA damage resistance, decreased sensitivity to radiation damage in liver cells

https://drive.google.com/file/d/1zjzROg_nP5bu5nyh_ASC0Y55mmzHwOq_/view?usp=sharing

Audette-Stuart, M., Kim, S.B., McMullin, D., Festarini, A., Yankovich, T.L., Ferreri, C., Carr, J., Mulpuru, S.

In: Biomarkers of Radiation in the Environment

Adaptive responses can be used as biological indicators of chronic low dose exposure to ionizing radiation. The micronucleus assay has been used to demonstrate this, in vivo and in vitro, in liver cells obtained from amphibians collected in radiologically-contaminated locations (with tritium being the main contaminant) and in locations that had signifcantly lower radiological contamination. In addition, under controlled laboratory settings, evidence that bystander effects can prompt adaptive responses were also observed. This later fnding indicates that membranes may play a role in the induction of adaptive responses. In support of this hypothesis, muscle fatty acid composition analysis indicated a partial remodeling of muscle lipids in response to a chronic low dose tritium exposure and different responses to a subsequent higher dose between control amphibians and amphibians that have been chronically exposed to ionizing radiation.

Amphibian; Anura; frogs; northern leopard frog (Rana pipiens), Mink frog (Lithobates septentrionalis), American Bullfrog(Lithobates catesbeiana)

Physiological, partial remodeling of muscle lipids; Cellular,partial remodeling of muscle lipids

https://drive.google.com/file/d/13x4l8HJTyRYh76S9qOXZ1sSAS_VRxsYY/view?usp=sharing

Azizova, T. V., Grigorieva, E. S., Hunter, N., Pikulina, M. V., Moseeva, M. B.

Journal of Radiological Protection

Mortality from circulatory diseases (CD) (ICD-9 codes 390-459) was studied in an extended Mayak worker cohort, which included 22,377 workers first employed at the Mayak Production Association in 1948-1982 and followed up to the end of 2008. The enlarged cohort and extended follow-up as compared to the previous analyses provided an increased number of deaths from CD and improved statistical power of this mortality study. The analyses were based on dose estimates provided by a new Mayak Worker Dosimetry System 2008 (MWDS-2008). For the first time in the study of non-cancer effects in this cohort quantitative smoking data (smoking index) were taken into account. A significant increasing trend for CD mortality with increasing dose from external gamma-rays was found after having adjusted for non-radiation factors; the excess relative risk per unit dose (ERR/Gy) was 0.05 (95% confidence interval (CI): >0, 0.11). Inclusion of an additional adjustment for dose from internal alpha-radiation to the liver resulted in a two-fold increase of ERR/Gy = 0.10 (95% CI: 0.02, 0.21). A significant increasing trend in CD mortality with increasing dose from internal alpha-radiation to the liver was observed (ERR/Gy = 0.27, 95% CI: 0.12, 0.48). However the ERR/Gy decreased and lost its significance after adjusting for dose from external gamma-rays. Results of the current study are in good agreement with risk estimates obtained for the Japanese LSS cohort as well as other studies of cohorts of nuclear workers.

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1axG1zxuXen30U7_Dwg5RmXysTfC4Yq5x/view?usp=sharing

Baeza, A., García, E., Paniagua, J. M., Rodríguez, A.

Journal of Environmental Radioactivity

The Almaraz nuclear power plant (Spain) uses the water of Arrocampo reservoir for cooling, and consequently raises the radioactive levels of the aquatic ecosystem of this reservoir. From July 2002 to June 2005, monthly samples of surface water, bulrushes (Typha latifolia) and carp (Cyprinus carpio) were collected from this reservoir. They were analyzed to determine the temporal evolution of the levels of (3)H in surface water and of its transfer from the surface water to free-water in the tissues (TFWT) of the aforementioned two organisms. The tritium levels in the surface water oscillate with a biannual period, with their values in the study period ranging between 53 and 433 Bq/L. The incorporation of tritium to bulrushes and carp was fairly similar, the respective mean concentration factors being 0.74 and 0.8 (unitless, as Bq/L tissue water per Bq/L reservoir water). The temporal evolution of the levels fairly closely followed that observed for the surface water tritium, although detailed analysis showed the dominant periodicity for the bulrushes to be annual. This difference reflects the influence on the incorporation of tritium to bulrushes of diverse environmental and metabolic factors, especially evapotranspiration and the seasonal growth of this plant.

Fish; Cypriniform; European carp (Cyprinus carpio) & Plant; bulrush (Typha latifolia)

https://drive.google.com/file/d/1TQLGDqWpzYeoTIrsZ_e3zGOx0rwT6yQg/view?usp=sharing

HTO, OBT, TFWT

Baglan, N., Kim, S.B., Cossonnet, C., Croudace, I.W., Fournier, M., Galeriu, D., Warwick, P.E., Momoshima, N., Ansoborlo, E.

Within the last ten years there has been increasing interest in tritium behaviour and distribution in the environment. This is based partly on empirical findings that tritium discharged mostly as HTO can become transformed into organic forms in environmental samples. An international workshop was convened in France in 2012 to gather the scientific community interested in organically bound tritium to share their experience and to establish a current state of knowledge. This paper summarises the outcome of the workshop, which aimed to improve skills concerning OBT (Organically Bound Tritium) determination, transfer and behaviour in the environment. In order to improve OBT measurement credibility, it was decided to conduct and promote OBT analysis through inter-laboratory exercises. This practice will reduce uncertainty in OBT analysis results, providing better OBT model validation data and public dose assessments.

https://drive.google.com/file/d/13jQ4-loq0j8IukLvIelFLpCGDxJKXJXi/view?usp=sharing

Baigazinov, Zh. А., Lukashenko, S. N., Karatayev, S. S., Panitski, A. V., Mamyrbayeva, A. S., Baigazy, S. A., Kozhakhanov, T. Ye., Subbotina, L. F.

Journal of Environmental Radioactivity

Following a continuous intake of tritium (T) by laying hens’ over a 55 day period, an increase of НТО concentration both in eggs and meat was observed over the first 2 weeks for intakes via inhalation and ingestion of water and grass meal. After this time, equilibrium of the T in these products occurred. It was found that when the intake of HTO is from water, air and grass meal, the ratio of its activity concentration in muscular tissue to that in eggs does not exceed 1, 4, and 6 respectively. The ratio of ОBТ concentration to that of НТО in the meat of hens (ОBТ/HTO) when intakes were from water, air and grass meal were 0.08, 0.09 and 0.7, respectively.

Bird; Galliformes; chicken (Gallus gallus domesticus)

https://drive.google.com/file/d/1K20Fgrh-z71CJ1CSD97jJe7rgVQ9JdN_/view?usp=sharing

Journal of Geophysical Research

Regular measurements of tritium in the surface water of the North Pacific during the period 1960–1961 indicate that the residence time in this layer, on the basis of a simple ‘box’ model, is less than 3.5 years. If the average depth of this layer is assumed to be 75 meters, precipitation contributes one-half of the input to the system. Alternatively, if precipitation is the only source, the effective depth to which this tritium is being mixed is about 40 meters. The total amount of tritium deposited in the northern hemisphere is estimated to be about 40 kilograms.

https://drive.google.com/file/d/1eYeAljx0SequkOGT34V1u4O45Lp9Q5I8/view?usp=sharing

Baiocco, G., George, I., Garcia-Argote, S., Guardamagna, I., Lonati, L., Lamartinière, Y., Orsière, T., Rousseau, B., Ottolenghi, A., Jha, A., Lebaron-Jacobs, L., Grisolia, C., Malard, V.

Tritium has been receiving worldwide attention, particularly because of its production and use in existing fission reactors and future nuclear fusion technologies, leading to an increased risk of release in the environment. Linking human health effects to low-dose tritium exposures presents a challenge for many reasons. Among these: biological effects strongly depend on the speciation of tritiated products and exposure pathway; large dosimetric uncertainties may exist; measurements using in vitro cell cultures generally lack a description of effects at the tissue level, while large-scale animal studies might be ethically questionable and too highly demanding in terms of resources. In this context, three-dimensional models of the human airway epithelium are a powerful tool to investigate potential toxicity induced upon inhalation of radioactive products in controlled physiological conditions. In this study we exposed such a model to tritiated water (HTO) for 24 h, with a range of activity levels (up to similar to 33 kBq mu l(-1) cm(-2)). After the exposures, we measured cell viability, integrity of epithelial layer and pro-inflammatory response at different post-exposure time-points. We also quantified tritium absorption and performed dosimetric estimates considering HTO passage through the epithelial layer, leading to reconstructed upper limits for the dose to the tissue of less than 50 cGy cumulative dose for the highest activity. Upon exposure to the highest activity, cell viability was not decreased; however, we observed a small effect on epithelial integrity and an inflammatory response persisting after seven days. These results represent a reference condition and will guide future experiments using human airway epithelium to investigate the effects of other peculiar tritiated products. (C) 2021 by Radiation Research Society

Mammal; primate; human (Homo sapiens)

https://drive.google.com/file/d/1nu324fcMAKZLbkurmEGwX8gcc3bCElHQ/view?usp=sharing

Journal of Reproduction and Fertility

The effect of tritiated thymidine on the developing oocytes of mice was presented. Pregnant mice were injected a total of 7 times with 4 40 or 400 mcCi tritiated thymidine at 12-hour intervals between pregnancy Days 13 and 16. Animals were sacrificed on Day 17 or allowed to give birth. Radioactive label was detected by autoradiography. A high proportion of the oocyte nuclei on Day 17 of gestation and up to 1 month after birth contained tritium. The total number of oocytes in the ovaries was reduced in proportion to the isotope dose. The numbers of oocytes in the 40- and 4-mcCi groups were reduced to 1% and 50% of the control values respectively by 5 months of age. Mice born from mothers in the 400 mcCi group were lighter than those from controls (p less than .001). Fertility (no eggs or young) ovarian weight (p less than .001) and the capacity of the ovary to undergo compensatory hypertrophy after unilateral ovariectomy were affected in this group. It was concluded that mouse oocytes are highly sensitive to internal beta radiation from tritiated thymidine during embryonic development.

Mammal; rodent; mouse (Mus musculus)

Reproductive; reduced number of oocytes, Fertility, ovarian weight, and the capacity of the ovary to undergo compensatory hypertrophy after unilateral ovariectomy were negatively affected, physiological; reduced body weight in irradiated litters

https://drive.google.com/file/d/1ZdqHpbErorqV6sC18wxNKeOQSrg27Bgx/view?usp=sharing

Balonov, M. I., Kudritskaia, O., Bruk, G.

Radiobiology (Radiobiologiia)

It was shown that low-level beta-radiation of tritium is much more effective than gamma-radiation of 137Cs with respect to reduction of the mouse testis weight. The RBE coefficient increases from 1.8 at a dose of 1 Gy to 2.2-2.3 at 0.1 Gy. On the basis of the data obtained by the authors and those reported in the literature a quality factor is proposed for tritium: QF = 2. Using THO and Na36Cl labels a mean water content of the testis cells, necessary for the estimation of a tritium-radiation dose absorbed, has been determined: gamma ct = 0.70 +/- 0.02 ml/g.

Mammal; rodent; mouse (Mus musculus)

Reproductive, reduction of the mouse testis weight

https://drive.google.com/file/d/1-94BS0YKeL_xO12Kl5A2lDRaeK4Myf9-/view?usp=sharing

Balonov, M. I., Muksinova, K. N., Mushkachevat, G.S.

Abstract-This review briefly describes techniques and basic results of experimental investigations in mice and rats on metabolism, dosimetry, and radiobiological effects of tritium oxide and some tritiated biogenic compounds (glucose, amino acids, and nucleosides) during the last 10 to 15 years in Russia. The content of water in tissue cells of mammals is shown to be 15 to 40% less than in whole tissue. The kinetics of tritium incorporation from oxide (HTO) and its retention in DNA of hemopoietic tissues were studied. The contribution of bound tritium to dose strongly depends on the chemical form of tritium and reaches 90% when labeled L-lysine is injected. Specific features of the action of HTO on hemopoietic tissue were investigated in tests of damage and repair of DNA, induction of chromosome aberrations in cells, content of nucleic acids, kinetics of cell populations, immunity parameters, carcinogenesis, decrease of life span, induction of dominant lethal mutations in germ cells in male mice, and reciprocal translocations in mouse spermatogonia. According to these tests, the radiobiological effects of tritium beta radiation in the form of oxide is 2 to 6 times higher than for gamma radiation of 13’Cs. The frequency of dominant lethal mutations induced by labeled lysine, thymidine, and deoxycytidine is 3 to 12 times higher than those induced by equal HTO activity. The results of these investigations are used to standardize HTO and the various biogenic compounds of tritium, improve techniques of indirect dosimetry, provide medical aid to personnel, and estimate population risk. Health Phys. 65(6):713-726;

Mammal; rodent; mouse (Mus musculus), Rat (Rattus)

Genetic, DNA damage, chromosone aberrations, induction of dominant lethal mutations in germ cells in male mice, and reciprocal translocations in mouse spermatogonia; Phsyiological/cellular, Changes in lymphopoiesis, reduction in cell immunity; Reproductive/cellular; Disease/cancer, malignant tumors

https://drive.google.com/file/d/1ZOYI0fQKDZZnvNLH4BTSZyXI9yaP_hK9/view?usp=sharing

Bannister, L., Serran, M., Bertrand, L., Klokov, D., Wyatt, H., Blimkie, M., Gueguen, Y., Priest, N., Jourdain, J. R., Sykes, P.

The toxicity of tritium is a public health concern given its presence and mobility in the environment. For risk predictions using radiological protection models, it is essential to allocate an appropriate radiation weighting factor (WR). This in turn should be consistent with the observed relative biological effectiveness (RBE) of tritium beta radiation. Although the International Commission on Radiological Protection (ICRP) currently recommends a WR of 1 for the calculation of committed effective dose for X rays, gamma rays and electrons of all energies, including tritium energies, there are concerns that tritium health risks are underestimated and that current regulatory tritium drinking water standards need revision. In this study, we investigated potential cytotoxic and genotoxic effects in mouse spleen after one month and eight months of chronic exposure to low-dose tritiated water (HTO). The dose regimes studied were designed to mimic human chronic consumption of HTO at levels of 10 kBq/l, 1 MBq/l and 20 MBq/l. The total doses from these radiation exposures ranged from 0.01 to 180 mGy. We also compared the biological effects of exposure to HTO with equivalent exposure to external whole-body 60Co gamma rays. Changes in spleen weight and somatic intrachromosomal recombination (DNA inversions) in spleen tissue of pKZ1Tg/+ mice were monitored. Our results showed no overall changes in either spleen organ weights and no increase mouse splenic intrachromosomal recombination frequencies, indicating that current drinking water standards for tritium exposure in the form of HTO are likely to be adequately protective against cytotoxic and genotoxic damage in spleen. These results demonstrate no evidence for cytotoxicity or genotoxicity in mouse spleen following chronic exposures to HTO activities (or equivalent gamma doses) up to 20 MBq/L.

Mammal; rodent; mouse (Mus musculus)

Genetic, no genotoxic effect; Cellular, no cytotoxic effect

https://drive.google.com/file/d/19a41SDfYAi69ZOz5fRIaafkQZB8dpzE6/view?usp=sharing

American Industrial Hygiene Association journal

The electrons of importance biologically in the absorption of energy from beta particles emitted by tritium have energies below 1 keV. These electrons have extremely short ranges which prompt the examination of absorbed energy on some basis other than average dose, such as ergs/gm. Tentative MPC's for tritiated water and tritiated thymidine are derived in this paper without reference to absorbed dose. The MPC's thus obtained are 10 to 100 times present recommended values.

Mammal; Primate; human (Homo sapiens) & rodent; mouse (Mus musculus)

Genetic; no detectable human chromosonal damage

https://drive.google.com/file/d/1IWLq3UG1BJZIITg2F1DXx_RMblN6EiWV/view?usp=sharing

HTO, 3H-thymidine

Barescut, J., Lariviere, D., Stocki, T., Fournier, M., Jaunet., P

Radioactive releases in the environment around civilian nuclear facilities have significantly decreased over the last few decades, with the exception of tritium. In late 2007, papers published in the UK (RIFE 11 report, study by the HPA’s Advisory Group on Ionising Radiation (AGIR)) raised questions as to the behaviour of tritium in the environment. Given this context, ASN wanted to get a clear analysis of the existing studies into the issue and in early 2008 decided to establish two independent pluralistic working groups. Two main points of the discussions are on the bioaccumulation and the biological effects.

https://drive.google.com/file/d/1EIwbFTOfQDr_xDFFS54MX-MV0y86Dxmz/view?usp=sharing

Barry, P.J., Watkins, B.M., Belot, Y., Davis, P.A., Edlund, O., Galeriu, D., Raskob, W., Russell, S., Togawa, O.

Journal of Environmental Radioactivity

This paper describes the results of a model intercomparision exercise for predicting tritium transport through foodchains. Modellers were asked to assume that farmland was exposed for one hour to an average concentration in air of 104 MBq tritium m~3. They were given the initial soil moisture content and 30 days of hourly averaged historical weather and asked to predict HTO and OBT concentrations in foods at selected times up to 30 days later when crops were assumed to be harvested. Two fumigations were postulated, one at 10.00 h (i.e., in day-light), and the other at 24.00 h (i.e., in darkness). Predicted environmental media concentrations after the daytime exposure agreed within an order of magnitude in most cases. Important sources of differences were variations in choices of numerical values for transport parameters. The different depths of soil layers used in the models appeared to make important contributions to differences in predictions for the given scenario. Following the night-time exposure, however, greater differences in predicted concentrations appeared. These arose largely because of different ways key processes were assumed to be affected by darkness. Uptake of HTO by vegetation and the rate it is converted to OBT were prominent amongst these processes. Further research, experimental data and modelling intercomparisons are required to resolve some of these issues.

Plants (unspecified) & Mammals; cattle (others unspecified)

https://drive.google.com/file/d/1Fpd5r7KQW84d6QoU7-Bu-8P7H2B4gVeE/view?usp=sharing

Baserga, R., Lisco, H., Kisieleski, W. E.

Mammal; rodent; mouse (Mus musculus)

Disease, Tumorigenesis; Physiological, shortened lifespan

https://drive.google.com/file/d/1HgrcIO_YIT1q0Yinb6eiPIyOCwnX2C1f/view?usp=sharing

Baserga, R., Lisco, H., Kisieleskt, W.

Proceedings of the Society for Experimental Biology and Medicine

Thymidine labeled with tritium or with carbon-14, when incorporated into DNA of proliferating cells, produces a selective mode of irradiation of cells and cell nuclei. Single and multiple injections of radioactive thymidine have been found to shorten the life span and to produce an increased incidence of tumors in CaFl mice. The incidence of tumors increased with dose and it was greater in animals injected as young adults than in animals injected later in life. Labeling of embryos in utero with tritiated thymidine likewise increased the incidence of malignant tumors.

Mammal; rodent; mouse (Mus musculus)

Disease/cancer, shortened life span, induction of malignant tumors

https://drive.google.com/file/d/1-N5P-Mgd0bzkL-PRtneTxJxoR6gadbId/view?usp=sharing

TRITIATED thymidine solution with an activity of 200 µc./ml. was injected intraperitoneally into male mice 2 months old and weighing about 40 gm. The solution was given in six fractions of 0.25 ml. over 2 days, making a total dose per mouse of 300 µc. The purpose of this fractionation, which was uniform labelling of a wide band of maturing sperm, was attained.

Mammal; rodent; mouse (Mus musculus)

Genetic, transmutations; reproductive, decreased sperm count

https://drive.google.com/file/d/1r8-ytd04Bn6uS4rzUr_ZUBZBMHhNNIY3/view?usp=sharing

Batlle, V.L., Sweeck, J., Wannijn, J., Vandenhove, H.

Journal of Environmental Radioactivity

The potential radiological impact of releases from a low-level radioactive waste (Category A waste) repository in Dessel, Belgium on the local fauna and flora was assessed under a reference scenario for gradual leaching. The potential impact situations for terrestrial and aquatic fauna and flora considered in this study were soil contamination due to irrigation with contaminated groundwater from a well at 70 m from the repository, contamination of the local wetlands receiving the highest radionuclide flux after migration through the aquifer and contamination of the local river receiving the highest radionuclide flux after migration through the aquifer. In addition, an exploratory study was carried out for biota residing in the groundwater. All impact assessments were performed using the Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tool. For all scenarios considered, absorbed dose rates to biota were found to be well below the ERICA 10 mGy h1 screening value. The highest dose rates were observed for the scenario where soil was irrigated with groundwater from the vicinity of the repository. For biota residing in the groundwater well, a few dose rates were slightly above the screening level but significantly below the dose rates at which the smallest effects are observed for those relevant species or groups of species. Given the conservative nature of the assessment, it can be concluded that manmade radionuclides deposited into the environment by the near surface disposal of category A waste at Dessel do not have a significant radiological impact to wildlife.

https://drive.google.com/file/d/1-xZQqPQJuEV8k4r6-CkSo2N2MR6fKsGG/view?usp=sharing

Analytical and bioanalytical chemistry

Denaturation experiments show that the larger part of organically bound tritium (OBT) consists of “buried tritium” and is not bound to carbon, as has been traditionally assumed. The logistical growth analysis of hydrogen isotopes in dry plant matter reveals a larger rate of increase of OBT than organically bound hydrogen (OBH).This is reflected by tritium accumulation for 1.4 and 2 in the primary hydration shell and in the base-pairing hydrogens of DNA respectively. If tritons and protons are considered as quantum mechanical entities, the accumulative tritium transfer from water to the hydrogen bonds of biopolymers is generally valid. Growth experiments confirm the assumed rapid isotope exchange “in vivo”, which is not observed “in vitro” by denaturation.

https://drive.google.com/file/d/1pSCE5vZkPB0FIGb3uMVR2Gs6OqS4eyF5/view?usp=sharing

Science of the Total Environment

Tritium entering the aquatic environment can confer a whole body internal radiological dose to aquatic organisms. Multiple stressors inherent in natural environments, however, confound estimates for observable radiation specific responses. To disentangle differences between field and laboratory outcomes to tritium exposures, a multivariate analysis comparing biomarkers for radiation exposure at the cellular level with changes in biological processes within tissues is described for fathead minnows (Pimephales promelas). Over tritium activity concentrations up to 180,000 Bq/L, DNA damage in the field were lower than DNA damage in the laboratory. This finding does not support an increase in morbidity of biota in field exposures. Energy deposited by tritium decay produces oxidised free radicals, yet the biological responses in brain, muscle and liver to oxidative stress differed between the studies and were not related to the tritium. For both studies, DNA damage in gonad and blood increased with increased tritium as did the fluorescence associated with lysosomal function in spleen. The studies differed in spleen phagocytosis activity were, in the laboratory but not the field, activity increased with increased tritium—and was correlatd with lysosomal function (Spearman coefficient of 0.98 (p = 0.001). The higher phagocytosis activity in the field reflects exposures to unmeasured factors that were not present within the laboratory.

Fish; Cypriniform; fathead minnow (Pimephales promelas)

Genetic DNA damage, lysomal mutations

https://drive.google.com/file/d/1KuwxaFSad3tAhGGoiJx-sQJbCF0MEpCg/view?usp=sharing

Becker, A. J., McCulloh, E. A., SIMINOVITCH, L., Till, J. E.

A technic capable of estimating the fraction of hemopoietic colony-forming progenitor cells in DNA synthesis in vivo has been described. The technic is based on the ability of tritiated thymidine to inhibit the growth of those colony-forming cells which, by virtue of their presence in the S-phase during a 20-minute incubation in vitro, in the presence of 500 microcuries ml. of H3TdR, have incorporated large amounts of the nucleoside. The method has been applied to transplanted colony-forming cells proliferating in spleens of heavily irradiated recipients as well as to cells from normal fetal liver, normal marrow, and normal spleen. In situations where the hemopoietic system is expanding fetal liver and regenerating transplants, a large fraction, 40-65 per cent, of the stem cells are in DNA synthesis. In the steady-state situations adult marrow and spleen, the fraction of cells in DNA synthesis is almost imperceptible using this technic. It is concluded that control mechanisms which govern the rate of hemopoiesis operate, at least in part, by altering the generative cycle of bloodforming progenitor cells. Author

Mammal; rodent; mouse (Mus musculus)

Cellular, cell growth rates and cell viability

https://drive.google.com/file/d/1DIzXkeRnpxhaq44IGlXdpAEHM_lhb-0L/view?usp=sharing

Bedford, J. S., Mitchell, J. B., Griggs, H. G., Bender, M. A.

With the use of two mammalian cell lines (L5178Y and V79), a comparison was made of the efficiency of cell killing by gamma rays and beta particles from tritiated water and incorporated tritiated thymidine. For the latter, cells were incubated with tritiated thymidine for one generation (unifilar labeling) or for four generations (bifilar labeling). To prevent cell division during exposures, irradiations were carried out with cells held in the frozen state or, in one case, at 5?C. There was no significant difference in cell killing efficiency for unifilar or bifilar modes of tritiated thymidine incorporation. In the frozen state an increase in Do was observed for all modes of irradiation, but an apparent increase in killing efficiency was observed for irradiations following incorporation of tritiated thymidine relative to that observed for irradiations with gamma rays. For cells irradiated at 50C, the efficiency of cell killing by beta particles from tritiated water or incorporated tritiated thymidine was not appreciably different, but both were more efficient than gamma irradiation delivered under similar conditions. For killing of V79 cells at 50C, and at a dose rate of 20 rad/hr, the relative biological effectiveness (RBE) of tritium beta particles relative to cobalt-60 gamma rays was estimated to be approximately 1.7-1.9.

Mammal; rodent; mouse (Mus musculus) & Chinese hamster (Cricetulus griseus)

Genetic, DNA damage; Cellular, cell death

https://drive.google.com/file/d/1AcwrbfCOMLT0L8jVhrrU8LFEUajbQSdR/view?usp=sharing

HTO, 3H-thymidine

Oak Ridge National Laboratory

There is growing evidence to support a relative biological effectiveness (RBE) greater that one for lowenergy electrons and photons. Strong justification of an RBE greater than one for low energy electrons comes from radiobiological studies of tritium. Similarly, studies with low-energy photons have indicated an elevated response relative to reference radiations of higher energy. In the field of radiation protection, photons and electrons have been assigned a radiation weighting factor (wR) of one. While this value may be appropriate for radiation protection calculations, it is important in risk considerations to consider the potentially elevated effectiveness of these radiations in efforts to improve the quality of the radiogenic risk estimates. Low-energy electron and photon radiations produce dense ionization clusters which lead to RBE values greater than those of high energy gamma rays. For tritium, RBE values between 2 and 3 are implied by a number of experimental studies. Other radiation sources with similar energy emissions may also exhibit an elevated RBE. In this work, RBE values are derived for electron and photon emissions based on the fractional deposition of absorbed dose for electrons of energies less than a few keV. Using this empirical model, RBE values for monoenergetic electrons, monoenergetic photons, and machinegenerated x -rays were derived. In addition, nuclide-specific RBE values were calculated for the radionuclides of ICRP Publication 107 for which neither alpha decay or spontaneous fission is indicated as a mode of decay.

https://drive.google.com/file/d/1Uj_6ZDk-TIAB_HKoLQOguOjWXmvQIDEe/view?usp=sharing

Conference: Summer School on Radioecology

Tritium is of interest in plant and animals because of its potential for human uptake by consumption of vegetal and animal food. When considering the behaviour of tritium in plants and animals, we have mainly to deal with tritiated water. It has been shown that there is no significant direct uptake of tritiated hydrogen in plant leaves (Garland and Cox 1980, Dunstall et al 1985), and only a very small conversion of that gas in animal guts. Tritiated water on the contrary is readily absorbed and retained by plants and animals because of the similarity between tritiated water and natural water. As will be shown, the plant water contamination constitutes the primary path for incorporation of tritium into organic molecules which can move up the food chain and arrive at man. While the relative mass difference of tritium with respect to protium is large, the mass difference of tritiated water with respect to natural water is not so large, since hydrogen has only a small contribution to the mass of water. The consequence is that the vapour pressure and molecular diffusion coefficient of tritiated water are only 10% and 5% less, respectively, than those of natural water. The behaviour of tritiated water in plants and animals is then very similar to that of natural water, with no important physical of chemical isotopic effects, and absence of biomagnification. This means that tritium transport and conversion of tritiated water in plant and animals can be inferred from the transport and conversion of natural water. Nevertheless, it should be remembered that the individual tritiated water molecules are not attached to the nearby light water molecules, and that in consequence the water specific activity is not conservative property. While the two categories of molecules move together in convective flow, they behave independently in diffusive transport, the movement of each isotopic species depending on its own concentration gradient.

Invertebrate; (ICRP Earthworm) Phytoplankton (FASSET Phytoplankton) Detritivorous invertebrate (FASSET Woodlouse, Ground Beetle) Vascular plant (FASSET Vascular plant) Non-detritivorous invertebrate (Spider) Zooplankton (FASSET Zooplankton) Gastropod (ICRP Snail) Insect larvae (FASSET Insect larvae, Banded Demoiselle larvae, Scarce Chaser larvae) Amphibian (ICRP Frog, Alpine Newt) Gastropod (FASSET Gastropod) Reptile (FASSET Snake) Bivalve mollusc (FASSET Bivalve mollusc, Zebra Mussel, Swan Mussel) Small reptile (e.g. Common Lizard) Crustacean (FASSET Crustacean, Caspian Mud Shrimp) Flying insects (ICRP Bee, Butterfly, Ladybird, Grasshopper) Amphibian (ICRP Frog, Alpine Newt) Insect (Ant) Benthicb fish (FASSET Benthic fish, European Chub) Mammal (ICRP Rat) Benthic fish e small (e.g. Common Goby, Stone Loach, Eurasian Ruffe) Mammal (Rabbit, Hare) Benthic fish e large (e.g. Northern Pike, European Perch, European Eel) Mammal (Small mouse) Pelagica fish (ICRP Salmonid/Trout, Roach, Bleak, Silver Bream, Brown Bullhead) Mammal (ICRP Deer) Pelagic fish e small (e.g. Three-spined Stickleback, Nine- spined Stickleback) Mammal (Fox) Fish egg (Salmonid egg) Bird (ICRP Duck, e.g. Common Kestrel, Tawny Owl, Black Woodpecker, Common Buzzard, Grey Partridge, European Honey-buzzard)Bird (ICRP Duck) Small bird (e.g. Tree Pipi, Spotted Flycatcher, Eurasian Skylark, Common Redstart, House Sparrow, Eurasian Tree Sparrow, Common Linnet, Common kingfisher) Mammal (ICRP Rat, Water Rat) Very small bird (e.g. Willow Tit) Bird egg (ICRP Duck egg) Small bird egg (e.g. Willow Tit) Lichen & bryophytes (ICRP Bryophite, Cladonia, Cladina, Coltricia perennis) Grasses & Herbs (ICRP Wild grass, e.g. Milkwort, Hairy Rupturewort, Heath Cudweed, Marsh Gentian, Common Cottongrass) Grass roots Large shrub/grasses and herbs (e.g. Creeping Willow, Petty Whin) Tree (ICRP Pine tree)

https://drive.google.com/file/d/1lqGuYvPen53jAq_ptvHh59GsjjBaG1ox/view?usp=sharing

HTO, OBT, TFTW

Bender, M. A., Gooch, P. C., Prescott, D. M.

Metaphase chromosomal aberrations were produced by tritium-labeled thymidine and by tritium-labeled uridine incorporated into human peripheral leukocytes in vitro. The distribution of aberration types is different from that of aberrations induced by X rays, and one type of lesion was produced by tritium that has not been seen in material treated with X rays. No correlation between the distribution of chromosomal breaks and the distribution of label in autoradiographs was observed, although more aberrations occurred, as expected, in heavily labeled cells. The breakage frequencies observed correspond to single acute doses of up to about 100 r of hard X rays.

Mammal; primate; Human (Homo sapiens)

Genetic; chromosonal aberations/damage, isochromitid deletion,

https://drive.google.com/file/d/1jC4Snklj0ne8jxe-3t3hBezD4G152dLY/view?usp=sharing

Bertho, J. M., Kereselidze, D., Manens, L., Culeux, C., Magneron, V., Surette, J., Blimkie, M., Bertrand, L., Wyatt, H., Souidi, M., Dublineau, I., Priest, N., Jourdain, J. R.

The increased potential for tritium releases from either nuclear reactors or from new facilities raises questions about the appropriateness of the current ICRP and WHO recommendations for tritium exposures to human populations. To study the potential toxicity of tritium as a function of dose, including at a regulatory level, mice were chronically exposed to tritium in drinking water at one of three concentrations, 10 kBq.l-1, 1 MBq.l-1 or 20 MBq.l-1. Tritium was administered as either HTO or as tritiated non-essential amino acids (TAA). After one month's exposure, a dose-dependent decrease in red blood cells (RBC) and iron deprivation was seen in all TAA exposed groups, but not in the HTO exposed groups. After eight months of exposure this RBC decrease was compensated by an increase in mean globular volume - suggesting the occurrence of an iron deficit-associated anemia. The analysis of hematopoiesis, of red blood cell retention in the spleen and of iron metabolism in the liver, the kidneys and the intestine suggested that the iron deficit was due to a decrease in iron absorption from the intestine. In contrast, mice exposed to external gamma irradiation at equivalent dose rates did not show any change in red blood cell numbers, white blood cell numbers or in the plasma iron concentration. These results showed that health effects only appeared following chronic exposure to concentrations of tritium above regulatory levels and the effects seen were dependent upon the speciation of tritium.

Mammal; rodent; mouse (Mus musculus)

Physiological, no change/effect on either hematologic parameters or iron metabolism; Cellular, red/white blood cells

https://drive.google.com/file/d/1xiU9YW5dlmebQxOMUOH985ikkbuk8CsU/view?usp=sharing

HTO, TAA (tritiated amino acids)

Radiobiology, Radiotherapy (Radiobiologia, radiotherapia)

The metabolism of tritiated water in the central nervous system of mice was examined for information of radiation hazard of tritium in biological tissue. The brain of young adult male Swiss albino mice (6-8 weeks) was studied at 1, 3, 7, 15 and 20 days after a single exposure of tritiated water (370 kBq/g body weight). Depths of the cortical areas 29 C, 29 D, 8 and 41 showed a statistically significant gradual decline from day 7th onward. Cell packing density showed a sharp decline on 7th day, while glia density showed statistically significant reduction only on day 15 and 30 post injection. Neutron packing density did not exhibit any appreciable change. Glia index increased reaching maximum on 15th day. Nucleocytoplasmic ratio too showed a gradual increase from 1st to 30th days after injection.

Mammal; rodent; mouse (Mus musculus)

Physiological, brain weight decrease

https://drive.google.com/file/d/1sGc7mUG20zeSeu-KFKPrRUUGDhWAwzc9/view?usp=sharing

A qualitative and quantitative study on the effect of fractionated doses of tritium on the testes of Swiss albino mice during post-natal development was undertaken. Examination of the testes at the end of the 6th week of post-natal life showed the following: the doses applied do not result in any major histopathological change except for a dose-dependent fibrosis in the tunica albuginea and hyperaemia. At a dose of 5.0 ..mu..Ci a few pyknotic nuclei and necrotic cells and exfoliation of the germ cells also occurred; quantitative study revealed different variations in the germ cell population of the seminiferous epithelium. A dose of 1.25 ..mu..Ci does not bring about any statistically significant variation in number of the different spermatogenic cells except for the decrease in pachytene in the populations of spermatocytes and spermatids; doses of 1.25 and 2.50 ..mu..Ci, however, raised the spermatogonial population above the norm (statistically nonsignificant); primary spermatocytes showed a dose-dependent reduction in number; in all the groups, the number of spermatids was among all the seminal cell types the most reduced; a dose of 5.0 ..mu..Ci produced the most significant signs of degeneration and necrosis in the testes of the experimental animals.

Mammal; rodent; mouse (Mus musculus)

https://drive.google.com/file/d/14644jpj56nXqL8MmjLy0BoeZ-ap7hmWr/view?usp=sharing

Radiobiology, Radiotherapy (Radiobiologia, radiotherapia)

The present study is an attempt to evaluate the possible radiobiological effects of tritiated water (HTO) on the testes of Swiss albino mice during postnatal development. Mice were continuously irradiated with different doses providing 46, 93 and 185 kBq of HTO per ml drinking water (after a priming injection) from day 1 after brith up to 6 weeks of age. Qualitative and quantitative studies were made at 6 weeks old mice testes and were compared with the sham-irradiated controls. A dose-dependent damage is noticed in the testes in the form of various radiopathological lesions such as intertubular edema, necrotic and pycnotic cells at various stages, mild cytoplasmic vacuolation, fibrosis, sclerosis, cellular edema etc. The number of various germ cells at their different phases were greatly reduced. 185 kBq/ml affect severely the spermatogonia and spermatid populations. The primary spermatocyte level was maintained at the range 64 +- 3.5%

Mammal; rodent; mouse (Mus musculus)

Reproductive & Cellular, in testes: intertubular edema, necrotic and pycnotic cells at various stages, mild cytoplasmic vacuolation, fibrosis, sclerosis, cellular edema, germ cell reduction

https://drive.google.com/file/d/1ffem1YOQtBXUACG9-udNCZYtyfT-1Sei/view?usp=sharing

46, 93 and 185 kBq of HTO

Bulletin of Environmental Contamination and Toxicology

Tritium, a heavy and unstable isotope of hydrogen (half-life-12 .36 yrs, atomic mass 3), finds its way to the environment from two sources, natural and man made. In nature it is formed by interactions of cosmic rays with the gases of upper atmosphere. Large quantities are also released from nuclear energy operations as a significant by-product, thereby proving hazardous to human population due to a bound gradual increase. Thus tritium has emerged of primary concern due to a persistence and ubiquitous distribution in the environment and in biological system. However, asa radiation hazard of biological significance it has largely been ignored because of its rapid turnover from the body, its low average beta energy(5 .7 KeV), and short range in the tissue (6.0 x 10TM'cm.). In all the available reports of the investigations, little research effort has been noticed on the age-specific consequences of HTO-irradiation of mammals in the perinatal to pubertal stages of life as compared to the adult stages.

Mammal; rodent; mouse (Mus musculus)

Reproductive, tubules with giant cells; Cellular, cytoplasmic vacuolation; Genetic, smaller or crenated nuclei

https://drive.google.com/file/d/1KfcvDmWZEYW04FsFdyeUwNWbA0t6T_ef/view?usp=sharing

Radiotherapy (Strahlentherapie)

Pregnant mice were continuously irradiated (5 micro Ci/ml of drinking HTO; 0.9 rd/day) from the 16th day post coitum. Quantitative and qualitative studies were made on testis of mice 3, 4 and 5 weeks post partum. Testes showed various histopathological lesions like cytoplasmic vacuolation, exfoliation, giant cell formation, denudation, haemorrhage, hyperaemia and sclerosis. Three weeks old mouse testis was found histopathologically more damaged. The population of spermatogonia types A, intermediate and B were maintained at approximately 80%, 70% and 60% of the controls respectively; while that of spermatocytes was maintained at roughly 70%. The population of spermatids at 4 and 5 weeks was approximately 45%.

Mammal; rodent; mouse (Mus musculus)

Reproductive & Cellular, "Testes showed various histopathological lesions like cytoplasmic vacuolation, exfoliation, giant cell formation, denudation, haemorrhage, hyperaemia and sclerosis"

https://drive.google.com/file/d/1DJoq0oiuB9LeL8DyVOsCe1b6_yWobyfL/view?usp=sharing

Radiotherapy (Strahlentherapie) und Onkologie

The brains of postnatally developing mice were studied at one, two, three, four, five and six weeks of age after injecting one day old neonates (1.95 +/- 0.35 g) with 11.1 kBq and 111 kBq/ml of body water. The HTO-exposed developing animals though do not show any significant decline in their brain and body weight, their DNA concentration was found significantly depleted at one week by 19% after the treatment with 111 kBq dose and subsequently recovered by six week reaching 93% of the control. Protein concentration showed significant deficit in both the dose groups at all the postnatal intervals. Protein/DNA ratio increased in one and two weeks old mice and reduced from four weeks onward. RNA/DNA ratio has also been found consistently low in irradiated groups.

Mammal; rodent; mouse (Mus musculus)

Genetic, DNA concentration depletion/damage

https://drive.google.com/file/d/19LU6wYFopIC6m-k8J3sD-1NsMxClKBuj/view?usp=sharing

Mammal; rodent; mouse (Mus musculus)

Reproductive; giant cells in testes

https://drive.google.com/file/d/118bk5ob_9EogVgibsMBVC4AkM140Xe4y/view?usp=sharing

International Nuclear information system

Radiation is invisible, but exists in various types, in the form of particles and/or energy bundles. The effects of low-level radiation seem very abstract since these can not be perceived by our sensory organs. The increase in natural background radiation from various inadvertent sources like tritium has the prospect of altering the entire scenario of billions of years' slow and steady biogenetic evolution. Mankind, by developing atomic technologies, is unleashing forces which it does understand but not beyond experimental findings. There is no wise sorcerer who can undo the damage we are causing. Tritium is a radioactive form of hydrogen that is produced in the reactor core. The released tritium replaces hydrogen in water. Tritium in water when gets ingested, causes continuos internal low-level beta radiation exposure over a long period. Proposed presentation will focus on the possible long term damage caused by its low-level exposure is dependent on the length of duration living tissue spends in the radiation field, not on the relative radiation field strength. As internal radiation pulses never stop, impact is continuous by the ambient radiation atmosphere. There is no chance to heal at the molecular level, except small chances of DNA repair since the organically bound tritium has greater severe influence with the slow turnover. Though the situation needs not be alarming with tritium, the studies on radiation damage on various parameters have given evidence of two compartments of radiation damage; the reparable or potentially lethal and the irreparable or lethal. With emerging new reports on the stochastic effects, those for which the probability, rather than the severity of an effect from tritium occurring as a function of dose also can not be ruled out. Biotoxicity of tritium in the form of induction of cancer, hereditary effects, teratogenesis and life shortening really needs an exhaustive investigation and warrants careful evaluation. However, a positive trend of acclimatization to tritium exposure is always there along with the presence of radiation-induced repair mechanism. But the danger is that the low level exposure may effect in unpredictable ways not only human kind but also its evolving process which may or may not have visible and beneficial (?) influence, what people are calling hormesis. They will act not only on people, but on those biological systems which support us. Because these changes may be beyond the ability of scientists to judge, and in so many disparate ways, we will not notice the decline in the spiritual and physical quality of our world. When finally the effects of this process are so bad that no one can disagree, it will be too late to put the genie back in the bottle. In biological systems the same degree of damage has not been produced by the same absorbed dose of different types of radiation. This difference in the radiobiological effectiveness (RBE) needs to be taken into account if we wish to add doses of different radiation to obtain the total biologically effective dose. For this, the absorbed dose of each type of radiation is required to be multiplied by a Quality Factor (QF). For the sake of simplicity, QF for tritium has been assigned a value of unity (ICRP, 1977). Radiotoxic effects of long term tritium exposure are consistent and apparently higher with those expected from an equivalent absorbed dose from external X-irradiation. Hence, a possibility for a higher RBE for tritium can not be ruled out. Four main areas of tritium studies are proposed for the education and careful evaluation:- (1) Specific models and their validity and suitability to predict environmental transfer of tritium released from various sources especially from thermonuclear devices. (2) The organically bound tritium (OBT) in the food chain and its possible biological consequences (3) The need for evaluation of the chemical form of tritium in environmental samples and their fate after interaction/dissociation from microorganisms (4) The studies on effects at low doses and low dose rates were urgently needed; and doubts were expressed on the validity of extrapolating not only between species but between specific strains in one species. (5) The need for continuing collaboration in educating low level radiation exposure between scientists in Europe, Canada, USA and Japan. European scientists had concentrated their efforts in ecology; the North American scientists on large scale animal experiments; and Japanese scientists on molecular and cellular studies.

Mammal; primate; Human (Homo sapiens)

Reproductive, reprotoxic effects on embyros and fetuses; Disease, induction of cancer

https://drive.google.com/file/d/1y9v8Fb7UJBzUUjAIf0bLSFRXf2_sE1jh/view?usp=sharing

HTO (tritiated water), OBT (organically bound tritium), HT (tritiated gas), TT (tritium gas)

Blayiock, B.G., Hoffman, F.O., M. L. Frank, M. L.

Radiation Protection Dosimetry, 16(1-2), 65-71.

Tritium is of environmental importance because it is released from nuclear facilities in relatively large quantities and because it has a half life of 12.26 y. Most of the tritium released into the atmosphere eventually reaches the aqueous environment, where it is rapidly taken up by aquatic organisms. This paper reviews the current literature on tritium in the aquatic environment. Conclusions from the review, which covered studies of algae, aquatic macrophytes, invertebrates, fish, an the food chain, were that aquatic organisms incorporate tritium into their tissue-free water very rapidly and reach concentrations near those of the external medium. The rate at which tritium from tritiated water is incorporated into the organic matter of cells is slower than the rate of its incorporation into the tissue-free water. If organisms consume tritiated food, incorporation of tritium into the organic matter is faster, and a higher tritium concentration is reached than when the organisms are exposed to only tritiated water alone. Incorporation of tritium bound to molecules into the organic matter depends on the chemical form of the "carrier" molecule. No evidence was found that biomagnification of tritium occurs at higher trophic levels. Radiation doses from tritium releases to large populations of humans will most likely come from the consumption of contaminated water cather than contaminated aquatic food products.

algae, aquatic macrophytes, invertebrates, fish,

https://drive.google.com/file/d/1xnJ-U58vhp4Vo__GUtpym8sd9-Hw27oa/view?usp=sharing

IAEA Symposium, Environmental Aspects of Nuclear Power Stations

CONF-700810--6

Mammal; rodent; mouse (Mus musculus) & rat (Rattus)

Genetic, possible genetic effects in the germ cells; Physiological, effect on organ weight

https://drive.google.com/file/d/1Y-ZPW5Na5AhU2TkysBDt69d-k6BkkL3T/view?usp=sharing

Annual Review of Physiology

Since the last review in this journal (2) covering the subjects to be reviewed here ("Modification of Radiation Effects by Chemical M eans, and Post-I rradiation Restoration of Tissues"), a large number of pertinent publications have appeared. Some degree of selection has been necessary, and many papers have not been discussed in the detail they deserve because of space limitations. A number of articles with interesting titles, published in foreign journals, were not available for review. The problems concerned with the physical and chemical effects of radiation on pure and simplified systems in general are not considered, except where they appear to apply directly to ma mmalian effects. Reports from the Atomic Energy Commission contract laboratories and the Department of Defense are listed only when they bear heavily upon one of the major topics under review, since most are eventually published in the open literature.

Mammal; rodent; mouse (Mus musculus) & rat (Rattus)

https://drive.google.com/file/d/1uDQQaJnGUjCqLUpbpW7ZJ66-GfRm19h9/view?usp=sharing

It appears from a study of available data that the degree of early somatic biological effect from intranuclear 3H is that anticipated on the basis of calculated average absorbed dose to the cell nucleus, at least down to doses of 5 rad or less. This result indicates: (a) the absorbed dose concept holds down to the order of 10−11 g or less, and somatic effects can be predicted on this basis; (b) the distribution of 3H atoms incorporated into DNA as 3HTdR (and ion pairs from the beta particles) are randomly distributed as far as dose calculations for the purpose of predicting somatic effects are concerned; (c) every part of the cell nucleus lies within one 3H beta range of some part of a chromatid, and the nucleus contains no sizeable contiguous “insensitive” volume of a radius exceeding the effective range of 3H beta rays (1–2 μ); (d) the origin of 3H beta tracks in, or their close juxtaposition to the DNA molecule does not appear to enhance the degree of somatic effect. “Transmutation” effects of the disintegrating 3H nuclide in DNA appear to have been demonstrated to produce genetic mutations in microorganisms, and data suggestive of this mechanism in Drosophila are available. The degree to which this factor in addition to absorbed dose must be taken into account in estimating possible genetic effects in the mammal cannot be assessed adequately at this time, but appears to be small. From available data, it appears that the degree of genetic effect in mammalian cells can be approximated closely from the average absorbed dose to the nucleus. The “intrinsic” RBE of 3H beta particles appears to be 1.0 (compared to 250 kVp X-rays), rather than the value of 1.7 currently used for radiation protection.

Mammal; primate; human (Homo sapiens) & rodent; mouse (Mus musculus) & Invertebrate; insect; fly (Drosophila)

Genetic, Transmutation effects, chromatid and chromosone type aberrations; Cellular, cell killing, mitotic delay; Disease/cancer;

https://drive.google.com/file/d/16nu3dbZJERkfym-gqOyR8fIJyAccQbXu/view?usp=sharing

Bondareva, L., Kudryasheva, N., Tananaev, I.

Tritium is a byproduct of many radiochemical reactions in the nuclear industry, and its effects on aquatic organisms, particularly low-dose effects, deserve special attention. The low-dose effects of tritium on aquatic microbiota have been intensively studied using luminous marine bacteria as model microorganisms. Low-dose physiological activation has been demonstrated and explained by the signaling role of reactive oxygen species through the “bystander effect” in bacterial suspensions. The activation of microbial functions in natural reservoirs by low tritium concentrations can cause unpredictable changes in food chains and imbalances in the natural equilibrium. The incorporation of tritium from the free form into organically bound compounds mainly occurs in the dark and at a temperature of 25 ◦C. When tritium is ingested by marine animals, up to 56% of tritium is accumulated in the muscle tissue and up to 36% in the liver. About 50% of tritium in the liver is found in non-exchangeable forms. Human ingestion of water and food products contaminatedwith background levels of tritium does not significantly contribute to the total dose load on the human body.

Genetic, DNA mutation; Cellular, Cytotoxicity, plant cell death, activation and inhibition effects, increase in the bacterial luminescence intensity; Physiological

https://drive.google.com/file/d/1MdpN5dNwTvfPufSDdyCh3kaRH_b64l5a/view?usp=sharing

Boyer, C., Vichot, L., Frommc, M., Losset, Y., Tatin-Frouxa, F., Guétat, P., Badot, P.M.

Environmental and Experimental Botany

The aim of this paper is to provide an overview of the literature regarding the fate of tritium in plants. At first, some prerequisites about the sources, chemical and physical characteristics, biological effects and potential risks associated to tritium are presented. The general scheme of tritium transport and cycling in the environment, the different tritium fractions in biological organisms and the corresponding techniques for sampling and measurement are discussed. Then, the main processes of uptake, incorporation and conversion of tritium into plants are described, based on experimental data. As tritium incorporated into the organic fraction may be the major contributor to the dose of radiation received following its ingestion by man, the biological mechanisms and kinetics of organically bound tritium (OBT) production are a major focus. Some predictive models of short-term or chronic exposure are described. Finally, the pending questions, concerning the fate of tritium in plants, are tackled.

https://drive.google.com/file/d/17q27SQVMZ1NCuRUvVzVlKFsq9btbUsp6/view?usp=sharing

HTO, OBT (exchangable and non-exchangable), 3H gas, tritiated, molecular hydrogen (HT), tritiated methane (CH3T), TFWT, tritiated formaldehyde (CHTO)

Mammal; rodent; Chinese hamster (Cricetulus griseus)

https://drive.google.com/file/d/1GttsZ5nKCNyptRTBdsvnAn6qf2T2aCUU/view?usp=sharing

Bridges, B.A., Elliot, A.T., Hill, M.A., Lambert, B.E., Little, M.P., Waters, R., Phipps, A.W., Stather, J.W., Walker, H.,

Health Protection Agency

The Advisory Group on Ionising Radiation (AGIR) is a body that advised the then Health Protection Agency (now Public Health England) on the biological and medical effects of ionising radiation relevant to human health. AGIR set up a subgroup on tritium, with a remit to take into account a wide range of views and provide a scientifically sound consensus on the doses and risks resulting from internal exposure to tritium.

Mammal; primate; Human (Homo sapiens) & Rodent; mouse (Mus musculus), Rat (Rattus)

Genetic, chromosome aberrations (in Peripheral blood, spermatogonia, bone marrow, mouse zygotes, lymphocytes, sperm ) and micronuclei in mammalian cells, chromosone breakage, transmutation effects, Dominant lethals in oocytes and spermatogonia in mice, ; Reproductive, Dominant lethals in oocytes and spermatogonia in mice, testes weight loss in mice, oocyte death in mice,Teratogenic effects; Disease/cancer, myeloid leukaemia, various forms of cancer, Leukaemia in rats, Mammary tumours in rats; Physiological, dominant skeletal mutations, Testes weight loss in mice, Thymus weight loss in rats, Teratogenic effects; Cellular, oocyte death in mice, Thymus weight loss in rats,

https://drive.google.com/file/d/1s3skGAL1FNTf-KXIvrWpv0YmoFma6gkZ/view?usp=sharing

HTO, OBT, 3H-thymidine, 3H-leucine, 3H-lysine, 3H-glucose, 3H-glucosamine, 3H-uridine, tritiated amino acids, TFWT,

Nuclear Regulatory Commission, Washington, DC (USA)

This report summarizes information and references used in developing regulatory guidance on programs for the bioassay of tritium as well as information useful in planning and conducting tritium bioassay programs and evaluating bioassay data. A review of literature on tritium radiobiology is included to provide a ready source of information useful for estimating internal doses of tritium and risks for the various tritium compounds and forms, including elemental (gaseous) tritium. Simplified and conservative dose conversion factors are derived and tabulated for easy reference in program planning, safety evaluations, and compliance determinations.

https://drive.google.com/file/d/1xUZ8eRP8VfhQ-yLJ6yh5Bvxx-bNpqCO8/view?usp=sharing

HTO, 3H gas, 3H-thymine, 3H-thymidine, 3H-uridine, 3H-methionine, tritiated nucleic acid precursors, OBT

Brooks, A.L., Carsten, A.L., Mead, D. K., Retherford, J. C., Crain, C. R.

Chromosomal damage in the livers of mice exposed to continuous intake of triated water (HTO) was evaluated. Hale-Stoner Brookhaven mice were maintained on HTO (3 MCi/ml) for 90, 330, (500, 560), and 700 days. The experimental animals and age- matched controls were partially hepatectomized to stimulate liver cell division and thefrequency of chromosome aberrations in metaphase cells of the liver was used as an index of radiation-induced change. When liver cell chromosomes from mice on HTO water were compared with those from age-matched controls, there was a higher level of damage in the animals on HTO. This was true for both hyperdiploid and diploid cells. At the 5% level, however, the increase was not statistically significant. When the data were analyzed without four animals, one with a clone of abnormal cells and three with an unusual distribution of chromosome damage, there was a significant increase in the level of chromosome damage in the livers of mice on HTO for either 330 or (500, 560) days. The level of chromosome damage following HTO ingestion was similar on a per rad basis to that seen in Chinese hamster livers after protracted "0Co gamma exposure or internally deposited '"Ce, an energetic beta emitter. The data support the concept that on a per rad basis the risk for chromosome breakage following tritium exposure as HTO is similar to that from other beta-gamma emitters.

Mammal; rodent; mouse (Mus musculus)

Genetic; Chrosomomal damage/deletions/aberrations

https://drive.google.com/file/d/1Dy8YhGoo8w3tjtxJp4gJOV81nSrtEvQL/view?usp=sharing

HTO (tritiated water)

A comparison was made between the incidence of chromosomal aberrations in G2-phase first division Chinese hamster cells exposed to tritium labelled thymidine (dose range 54-522 rad) or to 250 kV X-rays (dose range 98-711 rad) at--196 degrees C. The dose-response relationship for chromatid aberrations, expressed as breaks per cell, appeared to be linear for intranuclear tritium whereas that for X-rays was curvilinear. For the dose range studied, cells exposed to X-rays were markedly less sensitive than tritium-incorporated cells where a transmutation effect may operate.

Mammal; rodent; Chinese hamster (Cricetulus griseus)

Genetic; Chrosomomal damage/deletions/aberrations

https://drive.google.com/file/d/1x-DAWOU6ytDe24f-ELTnK5m1Gj2wLckI/view?usp=sharing

International Nuclear information System

The distribution of environmental tritium in the free water and organically bound hydrogen of trees growing in the vicinity of the Chalk River Nuclear Laboratories (CRNL) has been studied. The regional dispersal of HTO in the atmosphere has been observed by surveying the tritlum content of leaf moisture. Measurement of the distribution of organically bound tritium in the wood of tree ring sequences has given information on past concentrations of HTO taken up by trees growing in the CRNL Liquid Waste Disposal Area. For samples at background environmental levels, cellulose separation and analysis was done. The pattern of bomb tritium in precipitation of 1955-68 was observed to be preserved in the organically bound tritium of a tree ring sequence. Reactor tritium was discernible in a tree growing at a distance of 10 km from CRNL. These techniques provide convenient means of monitoring dispersal of HTO from nuclear facilities.

https://drive.google.com/file/d/1Q4QealwRgY8iNfvbBKdOlvMGnUAtLm1e/view?usp=sharing

Journal of the National Cancer Institute

Dose-survival curves were obtained for normal hematopoietic and transplanted lymphoma colony-forming cells of mice to high specific activity tritiated thymidine administered by repeated intraperitoneal injections for 24 hours. While the curve for normal cells decreased to a plateau value of about 20 percent of normal value at the maximum dose studied (6 mc/mouse), the curve for lymphoma cells decreased to a value less than 0.1 percent at this dose. An experiment in which the responses of normal and lymphoma colony-forming cells were measured in the same host showed that this difference was not due to differences between normal and lymphoma-bearing hosts. Furthermore, the survival time of mice bearing transplanted lymphoma was significantly increased (from 6.5 to 13 days) if they were given injections of 6 mc of tritiated thymidine over a period of 24 hours. The results indicate that most normal cells do not pass through deoxyribonucleic acid synthesis in 24 hours, but that most lymphoma cells do and consequently may incorporate tritiated thymidine and be killed during this period. The difference between the cycle of normal hematopoietic colony-forming cells and malignant colony-forming cells may explain the action of chemotherapeutic agents that kill cells passing through cycle.

Mammal; rodent; mouse (Mus musculus)

Cellular, decrease in the number of normal colony-forming cells, decrease in the number of lymphoma colony-forming cells

https://drive.google.com/file/d/1oOMv3KyKm_Lwwr1WMTkbwbRurxbr_PfJ/view?usp=sharing

Brudenell, A.J.P., Collins, C.D., Shaw, G.

Journal of Environmental Radioactivity

A knowledge of the dynamics of HTO in crops and soils is required to validate models, such as the UK Ministry of Agriculture, Fisheries and Food STAR-H3, which predict the ingestion dose following release of tritium. Deposition velocities to cabbage, lettuce and soil have been determined. The loss of HTO from cabbage is described by a double exponential decay; the faster component ( 53 min) is attributed to vapour exchange and transpiration, and the slower component ( 15 h) to decontamination of stem and root tissues. Due to the long half-time () of the second component, the loss of the last 5% of the applied HTO would appear to be complete within 48 h. This represents a considerable increase over the 6-h loss period predicted by the current STAR-H3 model. As these components can now be resolved from the above data, this may be a useful addition to the STAR-H3 model. Our data indicate that HTO loss predictions should be more pessimistic than the default STAR-H3 parameters allow. The effect of dark treatment on uptake and loss of HTO has been examined. Pooled data for soils are also well described using a double exponential fit to the loss data.

https://drive.google.com/file/d/1JjLsLJIW_MTtN0xIBWZqqxLMtCTR9tVw/view?usp=sharing

Society for Experimental Biology and Medicine

The 30-day median lethal dose of H32 for CF No. 1 female mice is about 1 mc per g body weight when given in a single injection. The estimated radiation dosage is about 800 rep in the first 3 days and about 1000 rep in the first 12 days after injection. It is concluded that no unexpected factor of biological effectiveness exists for tritium β rays in relation to X or γ rays.

Mammal; rodent; mouse (Mus musculus)

https://drive.google.com/file/d/1u1uUVhaN7tyevj7g6mo0OfMKJby4Il4N/view?usp=sharing

In: Tritium in the Physical and Biological Sciences. Vol. II.

The bacterial flora in the bovine rumen is mainly composed of strictly anaerobic species supplying the host with large amounts of volatile fatty acids (VFA's) as the main energy source. Long time in-vitro irradiations of the flora with T2O in a so-called ''artificial rumen'' under anaerobic conditions have shown that doses up to 75 Krad had no inhibitory effect on bacterial growth and VFA-production. Stimulatory effects resulting in acceleration of cell division and increased amounts of VFA's were observed after irradiating the resting flora at 0°C with a total dose of about 300 Krad within 20 d, but reproducibility was unsatisfactory because of the heterogeneity of the material. Further experiments were carried out on pure cultures of selected strains of rumen bacteria. Doses up to 150 Krad (5 d) did not markedly influence anaerobic growth and carbohydrate metabolism. However, if oxygen was present during the irradiation of resting cells a strong reduction in viable numbers was noted. Oxygen per se was found to exert a lethal effect on these species following a logarithmic order of decline. It is assumed that secondary radiation products, especially H2O2, are mainly responsible for the action of T2O on these microorganisms which are devoid of catalase. Some confirmatory results are still to be obtained. (author)

Mammal; bovine; cow & Bacteria; (Streptococcus bovis), (Butryrivibrio fibrisolvens), (Ruminococcus albus)

Physiological/Cellular, bacterial resistance to tritium radiation

https://drive.google.com/file/d/1Wg7JelbovGF0c-PA4PBErcYw_hM52-6A/view?usp=sharing

Brungs, W. A., McCormick, J. H., Neiheisel, T. W., Spehar, R. L., Stephan, C. E., Stokes, G. N.

Water Pollution Control Federation

Phsyiological, reduced immune ability (Hatchability, incidence of abnormalities, latent mortality, and depressed growth were not observed)

https://drive.google.com/file/d/1nJMoRQb1M03aigV6dxr3bRIGbBbuxLDo/view?usp=sharing

In the time since Japan's triple earthquake, tsunami, and nuclear disaster in 2011, much has improved in the ocean offshore from the Fukushima Daiichi Nuclear Power Plant (FDNPP). Concentrations of cesium isotopes, some of the most abundant and long-lived contaminants released, are hundreds of thousands of times lower than at their peak in April 2011. Since mid-2015, none of the fish caught nearby exceed Japan's strict limit for cesium of 100 Bq/kg (1, 2). Yet, enormous challenges remain in decommissioning the reactors and clean-up on land. Small, and sometimes unexpected, sources of contaminants still continue to enter the ocean to this day (3). Two of the biggest unresolved issues are what to do with the more than 1000 tanks at the site that contain contaminated water and the impact of releasing more than 1 million tons of this water into the ocean.

https://drive.google.com/file/d/12XFvns_Ii6hqQS1Bkec0x64ehb_-fQfE/view?usp=share_link

Burki, H. J., Bunker, S., Ritter, M., Cleaver, J. E.

DNA single-strand-breakage efficiency was measured in frozen Chinese hamster cells (V79-S171) after they accumulated disintegrations from incorporated tritium. The results are compared to the single-strand-breakage efficiency of X-rays at dry ice or liquid nitrogen temperatures, which is reduced by a factor of 4 from the strand-breakage efficiency found at 370C. 8H decays in cells that incorporated [5-8H]uridine into RNA after a 30-min pulse were 20% as effective as those in ['H]thymidine-labeled cells in causing single-strand breaks in DNA. This difference in DNA strand-breakage efficiencies for [-'H]uridine and [aH]thymidine is almost the same as the difference in efficiencies of cell killing from the two macromolecular locations of tritium within the nucleus of the cell. In cells labeled in one or both strands of DNA with [3H]thymidine the breakage efficiencies were 2.2-2.3 breaks per 3H decay, equivalent to 0.5 rads per decay-a value very close to that predicted for the dosimetry of 8H beta particles. Irradiation by 8H decays from tritiated water added to the medium before freezing was intermediate between P[H] uridine and [3H]thymidine in producing single-strand breaks. Isolation of 'H-labeled DNA and freezing in solution at a concentration less than that found in the cell nucleus produced a lower strand-breakage efficiency because of a reduction in the dose to the DNA by the short-ranged beta particles.

Mammal; rodent; Chinese hamster (Cricetulus griseus)

https://drive.google.com/file/d/1KjOixNQ0og-CwaScCLToOrFVgRd7jh-x/view?usp=sharing

methyl-3H-thymidine, 3H- thymidine, 3H-uridine, 3H-toluene, HTO

Haploid and diploid yeast cell strains of Saccharomyces cerevisiae were labeled with (6-/sup 3/H)uracil, a general precursor of nucleic acids. Damage from tritium decay was accumulated at 4/sup 0/C. Tritium-induced reporductive death, gene conversion, and mutation were compared to the same effects produced by gamma radiation. In all cases, the results were qualitatively similar to gamma rays, suggesting that the genetic hazard from incorporated environmental tritium in eucaryotic cells is similar to an equivalent dose of x rays. The most sensitive genetic assay for the effects of tritium decay in diploid yeast is the induction of genetic recombination. This induction of genetic recombination also occurs during normal growth of cells at 30/sup 0/C at total activities of as little as 1 ..mu..Ci/ml. Therefore, many experiments, using small amounts of tritium precursors, may be affected by tritium-induced genetic recombination. This effect of tritium should be considered in experimental designs, using tritium isotopes.

Fungi; Saccharomycetales; brewers yeast (Saccharomyces cerevisiae)

https://drive.google.com/file/d/1VxkbfDKUSgccxoFxBfuxULO9E6hE2Ele/view?usp=sharing

The killing efficiency of tritium disintegrations in frozen mammalian cells labeled with tritiated uridine, histidine, and lysine was compared with the killing efficiency of incorporated tritiated thymidine. In each case, the distribution of tritium in the cells was determined by chemical fractionation as well as by radio- autography. Of all tritium disintegrations, by far the most effective were those occurring in DNA molecules within frozen cells; such incorporated tritium has a killing efficiency of 0.006. When cells were incubated with tritiated uridine for 10 min to label nuclear RNA, the killing efficiency was 0.0015. When the cells were pulse labeled with tritiated uridine and permitted to grow in nonradioactive media for 10hr before freezing in order to incorporate tritium into cytoplasmic RNA, the killing efficiency was reduced to 0.0010. The results suggest that decay of tritium in nuclear RNA is more effective than that in cytoplasmic RNA. When the cells were labeled with tritiated histidine or lysine for 30 min, tritium atoms were found mainly in the acid soluble rather than in the protein fraction and the killing efficiency in each case was approximately 0.0007. The results of these suicide experiments indicate that the killing efficiency of tritium disintegrations depends on where tritium is located within the cells. Tritium disintegrations in the nucleus are more effective in killing the cell than that in cytoplasm; and tritium disintegrations on DNA in the nucleus is more effective in killing the cell than that of nuclear RNA.

Mammal; rodent; mouse (Mus musculus)

Genetic; DNA damage, differential effects of radiation from 3H in nucleus and cytoplasm.

https://drive.google.com/file/d/1B3UlCvfdC4utoOEFDbh-ecu2bo7godXl/view?usp=sharing

Deoxyribonucleic acid of mammalian cells (L5178Y) in culture was labeled uniformly in one of the following three ways: Incubation with tritiated thymidine for one generation (unifilar labeling), incubation with tritiated thymidine for four generations (bifilar labeling), and incubation with tritiated thymidine for four generations plus one generation without tritiated thymidine (reverse unifilar labeling). The cells were frozen and stored in liquid nitrogen. After various storage times, their survivals were estimated. The survival curves of cells with unifilar labeled DNA were approximately exponential. The survival curve of the cells with bifilar labeled DNA was similar to that of the unfilar labeled cells to around 20 % survival. Below 20 % survival, the slope of the survival curve was greater by a factor of 2 than that of the unifilar labeled cells.

Mammal; rodent; mouse (Mus musculus)

Genetic, local damage to DNA; Cellular, cell killing

https://drive.google.com/file/d/1Nmd6s5bYDxkjcw20yLxm7QnWMXdMCxaW/view?usp=sharing

New Research Directions in DNA Repair

Genetic, DNA damage, mutagenisis mentioned

https://drive.google.com/file/d/1Txn0CjdvenmOcDXebjvUsj5zcQz7BPTI/view?usp=sharing

Over the past 10 years 309,000 urine samples have been radioassayed for tritium in SRP's health physics program. Most of these were analyzed using a liquid scintillation counting technique developed at SRP. In 310 cases the tritium concentration in urine was at least 20 μc/l. The biological half life values for these cases ranged from 4 to 18 days, with an average of 9.5 ± 4.1 days (90 per cent confidence level). Factors which influence biological half life, such as outdoor temperatures, amount of tritium assimilated, and age of employee were studied. During the warmer months, the average half life was observed to be lower; this was attributed to increased water intake. Data showed no correlation between the amount assimilated and biological half life. A trend toward a shorter half life was observed for increasing age.

Mammal; primate; Human (Homo sapiens)

https://drive.google.com/file/d/1WDclbRRYygz6pC9pvO7EKMve9kVkNPvw/view?usp=sharing

The relative biological effectiveness was determined using sex-linked recessive lethals induced in Drosophila spermatozoa as the biological effect. The sex-linked recessive lethal test, a measure of mutations induced in germ cells and transmitted through successive generations, yields a linear dose-response curve in the range used in these experiments. A dose-response curve was determined from three exposures to tritiated water and three exposures to 60Co gamma radiation. The ratio of the slopes of these two response curves is 2.7 +/- 0.3, yielding a relative biological effectiveness that suggests the tritium beta particle is 2.7 times more effective per unit of energy absorbed in inducing gene mutations transmitted to successive generations than 60Co gamma radiation. The increase in relative biological effectiveness with higher linear energy transfer for tritium beta radiation strongly suggests that single-strand breaks are repaired by a nearly error-free repair mechanism. Ion tracks with a high density of ions (high linear energy transfer) are more efficient than tracks with a low ion density (low linear energy transfer) in inducing transmissible mutations, suggesting interaction among products of ionization. Since most transmitted mutations induced by ionizing radiation result from strand breakage, interaction probably occurs at this level with double-strand breaks being repaired by an error-prone mechanism yielding transmissible mutations.

Invertebrate; insect; fly (Drosophila)

Genetic, induction of gene mutations to succesive generations, DNA strand breaks

https://drive.google.com/file/d/1bKA1Y2Ugamm0xJUHc6r0gqARWNGwvWRZ/view?usp=sharing

Pregnant rats were maintained at constant body activities of tritiated water ranging through 1-100 jCi/ml of body water throughout pregnancy. These activities provided total-body doses to the embryo and fetus of approximately 0.3-30.0 rads/day. Regardless of the activity level of progeny were grossly normal with respect to external and internal morphology. Statistically significant findings at various HTO levels included: micrencephally, sterility, stunting, litter size reduction, and increased resorption. Decreases in the absolute and relative weights of a number of term fetus organs were closely proportional to dose. Histologically all organs were normal except the gonads.Tritium incorporation into fetal organs was directly proportional to, and 20-30 percent of, the average maternal body water HTO activity prevailing during gestation. Postnatal observations showed that by 180 days stunting was no longer evident in irradiated females but persisted in males irradiated at 50-100 MCi/ml. Within 270 days 5 tumors had arisen in irradiated animals compared to 1 in a control animal. Continuous exposure to an HTO activity of 1 jCi/ml during pregnancy was found to be consistent with the production of offspring in which the only deviations from the controls noted were an increased length and a slight increase in weight of the liver and heart evident only in neonates.

Mammal; rodent; rat (Rattus)

Reproductive, micrencephally, sterility, stunting, litter size reduction, and increased resorption, reduction/absence of ovaries, ; Physiological, increased length of offspring, Stunting (significant reductions in body weight and crown-rump length of term fetuses) weight reduction in testes and brains of term fetuses, weight Reductions in the spleen, thymus, kidney, and heart, Disease, Tumorgenisis (lymphocytic thymoma, two ovarian arrhenoblastomas, and two probable mammary stromal tumors)

https://drive.google.com/file/d/1nddSQXqwLia7vLuo4G3lCvxEpk-z5K1v/view?usp=sharing

Canadian Nuclear Safety Commision

Canadian Nuclear Safety Commission

CC172-101/2013E

Tritium is a radioactive isotope of hydrogen that occurs both naturally and as a by-product of the operation of nuclear and research reactors. It emits low-energy beta radiation, which can be absorbed by paper, plastic, glass or metal. Tritium can pose a health risk if it is ingested by drinking water or eating food that contains it, or if it is inhaled or absorbed through the skin in large quantities. In Canada, the control of tritium releases to the environment is important, as Canadian-designed CANDU (CANada Deuterium Uranium) reactors produce more tritium than most other types of reactors. Some of the tritium generated in power reactors is recovered and used to produce self-luminescent lights and paints. Tritium is processed commercially in products such as exit signs, airport runway lights, watch dials and gun sights. The Canadian Nuclear Safety Commission (CNSC) regulates and carefully monitors environmental releases of man-made tritium in order to protect the health and safety of Canadians and the environment. In 2007, the CNSC launched the Tritium Studies Project, a series of research studies on tritium releases in Canada to expand the body of knowledge on the subject and to further enhance regulatory oversight of tritium-related activities. One of those studies, Tritium Activity in Garden Produce from Pembroke in 2007 and Dose to the Public, revealed unexpected results regarding the ratio of organically bound tritium (OBT) to tritiated water (HTO) in soil and in a small number of food items – the OBT/HTO ratios were greater than 1, higher than the expected finding. Although the radiation doses from tritium are very low and orders of magnitude below doses known to cause health effects, the CNSC launched another study to better understand the mechanisms underlying the observed OBT/HTO ratios greater than 1. This report describes the results of CNSC-funded research, conducted by the University of Ottawa, on the distribution of tritium in soils, garden produce, animal fodder and animal products near sites of long-term, sustained atmospheric releases of tritium gas and/or tritiated water near four nuclear facilities: SRB Technologies, Shield Source Incorporated, the Darlington Nuclear Generating Station and the Gentilly-2 Nuclear Generating Station.

https://drive.google.com/file/d/129twbPbJasSQXeQIGh6L57EFxeapjvbC/view?usp=sharing

Canadian Nuclear Safety Commision

Canadian Nuclear Safety Commission

CC172-58/2010E

Mammal; primate; human (Homo sapiens) & rodent; mouse (Mus musculus)

Genetic, chromosone aberrations; Reproductive effects on oocytes; Disease/cancer, carcinogenicity, induction of cancer, tumoregenesis, induction of of myeloid leukaemia, induction of lethality/higher mortality; Physiological, Teratogenic effects

https://drive.google.com/file/d/1tIzY2M389LzS29yRi45FKQ9OPVpQDj_i/view?usp=sharing

Canadian Nuclear Safety Commision

Canadian Nuclear Safety Commission

In January 2007, the Canadian Nuclear Safety Commission (CNSC) Tribunal directed CNSC staff to initiate research studies on tritium releases in Canada. In response, staff initiated a“Tritium Studies” project with several information gathering and research activities extending to 2010. The objective of this major research project is to enhance the information used in the regulatory oversight of tritium processing and tritium releases in Canada. The Standards and Guidelines for Tritium in Drinking Water report is part of this project.

https://drive.google.com/file/d/1n3IwS8G-5w7qQbP6WBLIM-eXSzu0X7xn/view?usp=sharing

The reduction of testis mass of the mouse following single injections of tritiated thymidine (1.0–20 wCi tritium/g body mass) or tritiated water (100 microCi tritium/g body mass) and 60Co gamma-rays (delivered to match the dose-rate vs time curve in the 40 wCi tritium/g body mass tritiated water group) was investigated at times from 1 hr to 24 weeks after injection. Measurements of the testicular retention of tritium were also made at these times. There was a progressive loss in mass, up to 30% after 4–5 weeks, followed by an irregular recovery which was more delayed in the case of the tritiated-thymidine-injected animals. The effectiveness of tritium compared with 60Co gamma-rays, calculated using the average absorbed dose to the testis, was 1.43 for tritiated water and 2.07 for tritiated thymidine. A significant effect on the testis mass was seen after the injection of tritiated thymidine at 1.0 microCi tritium/g body mass, which delivered an average absorbed dose to the testis of about 3.5 rad (0.035 Gy) during 16 weeks. Calculations suggest that tritium from tritiated thymidine “fixed” in the testis was about twice as effective as the more labile and uniformly distributed tritium from tritiated water and that in terms of injected amount tritiated thymidine is unlikely to be more than five times as effective as tritiated water even at very low injected amounts.

Mammal; rodent; mouse (Mus musculus)

https://drive.google.com/file/d/1rCtRnwUL3AXzzU1y71p5ZI8PdLfaiPY3/view?usp=sharing

3H-Thymidine HTO

Brookhaven National Lab

BNL-31581; CONF-820736-1

The increased use of nuclear reactors for power generation will lead to the introduction of tritium into the environment. The need for assessing possible immediate and long-term effects of exposure to this tritium led to the development of a broad program directed towards evaluating the possible somatic and genetic effects of continuous exposure to tritiated water (HTO). Among the parameters measured are the genetic, cytogenetic, reproductive efficiency, growth, nonspecific lifetime shortening, bone marrow cellularity and stem cell content, relative biological effectiveness as compared to 137Cesium gamma exposure, and related biochemical and microdosimetric evaluations. These parameters have been evaluated on animals maintained on HTO at 10 to 100 times the maximum permissible concentration (0.03 - 3.0 μCi/ml) for HTO. Dominant lethal mutations, chromosome aberrations in regenerating liver, increased sister chromatid exchanges in bone marrow and reduction in bone marrow stem cell content have been observed at the higher concentrations. The relative biological effectiveness for HTO ingestion as compared to external 137Cesium gamma exposures has been found to be between 1 and 2

Mammal; rodent; mouse (Mus musculus)

Genetic, Dominant lethal mutations, chromosome aberrations in regenerating liver, increased sister chromatid exchanges in bone marrow and reduction in bone marrow stem cell content have been observed at the higher concentrations; Cellular, significant increase in the number of abnormal liver cells

https://drive.google.com/file/d/18FZfaeAUfcjWGVRgpFxI0wtPBdwDjJsb/view?usp=sharing

The possible genetic consequences of continued ingestion of tritiated water (HTO) have been investigated in Hale-Stoner-Brookhaven strain mice maintained on HTO (3 yCi/ml). Second-generation females on HTO were sacrificed in late pregnancy and the corpora lutea, viable, nonviable embryos (early death and late death) and pre- implantation loss determined to calculate the mutation rate. The breeding efficiency (pregnancy rate and litter size), was also measured. Analysis of results by both para- metric and nonparametric tests has indicated a significant reduction in the number of viable embryos resulting from matings between animals maintained on the tritium regimen, with no effect on breeding efficiency. The integrated radiation dose to the testes and ovary, based on average tissue tritium content from fetal origin through breeding of the 8-week-old animals, was calculated.

Mammal; rodent; mouse (Mus musculus)

Genetic, DNA damage, Increase in dominant lethal mutations; Reproductive, Significantly fewer viable embryos, consequently smaller litters; Physiological, early death

https://drive.google.com/file/d/1kDIpRf8J6YlEHkSSheUwAO3ioPENcSxC/view?usp=sharing

Journal of the Belgian Society of Radiology, (Journal of the Belgian Society of Radiology (Journal belge de radiologie))

Radiation hazards associated with tritium release increase with nuclear power industry development. We discussed the various factors used in the calculation of the standards for allowable radiation. We show how the IRCP values for tritium maximum permissible body burden and maxium permissible concentrations are not devoid of incertainties.

https://drive.google.com/file/d/1tkdWeU5bUGKRhFROsQCq7URZdSJlVOfg/view?usp=sharing

Chao, T. C., Wang, C. C., Li, J., Li, C., Tung, C. J.

International Journal of of Radiation Biology

Purpose: The assessment of radiotoxicity for heterogeneously distributed tritium should be based on the subcellular dose and relative biological effectiveness (RBE) for cell nucleus. In the present work, geometry-dependent absorbed dose and RBE were calculated using Monte Carlo codes for tritium in the cell, cell surface, cytoplasm, or cell nucleus. Materials and methods: Penelope (PENetration and Energy LOss of Positrins and Electrons) code was used to calculate the geometry-dependent absorbed dose, lineal energy, and electron fluence spectrum. RBE for the intestinal crypt regeneration was calculated using a lineal energy-dependent biological weighting function. RBE for the induction of DNA double strand breaks was estimated using a nucleotide-level map for clustered DNA lesions of the Monte Carlo damage simulation (MCDS) code. Results: For a typical cell of 10 μm radius and 5 μm nuclear radius, tritium in the cell nucleus resulted in much higher RBE-weighted absorbed dose than tritium distributed uniformly. Conversely, tritium distributed on the cell surface led to trivial RBE-weighted absorbed dose due to irradiation geometry and great attenuation of beta particles in the cytoplasm. For tritium uniformly distributed in the cell, the RBE-weighted absorbed dose was larger compared to tritium uniformly distributed in the tissue. Conclusions: Cellular- and micro-dosimetry models were developed for the assessment of heterogeneously distributed tritium.

https://drive.google.com/file/d/1uNduDe0gVvPvccdCvgFEXR9Ge8HYBnPA/view?usp=sharing