Science Laboratory Safety Guide

SCIENCE, Pakistan

Karachi, Pakistan. 74200

contact@pakchem.net

www.pakchem.net

What Are the Teacher’s Responsibilities?

Teachers and teacher-aides should lead by example and wear personal protective equipment; follow and enforce safety rules, procedures, and practices; and demonstrate safety behavior and promote a culture of safety. They should be proactive in every aspect of laboratory safety, making safety a priority. The following is a checklist for teachers highlighting essential information for working in the high school laboratory. This is a general safety checklist and should be periodically re-evaluated for updates.

Upkeep of Laboratory and Equipment

• Conduct regular inspections of safety and first aid equipment as often as requested by the administration. Record the inspection date and the inspector’s initials on the attached equipment inspection tag.
• Notify the administration in writing if a hazardous or possibly hazardous condition (e.g., malfunctioning safety equipment or chemical hazard) is identified in the laboratory and follow through on the status.
• Never use defective equipment.

Recordkeeping

• Keep organized records on safety training of staff for as long as required by the school system.
• Keep records of all laboratory incidents for as long as required by the school system.

Safety and Emergency Procedures

• Educate students on the location and use of all safety and emergency equipment prior to laboratory activity.
• Identify safety procedures to follow in the event of an emergency/accident.
• Provide students with verbal and written safety procedures to follow in the event of an emergency/accident.
• Know the location of and how to use the cut-off switches and valves for the water, gas, and electricity in the laboratory.
• Know the location of and how to use all safety and emergency equipment (i.e., safety shower, eyewash, first-aid kit, fire blanket, fire extinguishers and mercury spill kits).
• Keep a list of emergency phone numbers near the phone.
• Conduct appropriate safety and evacuation drills on a regular basis.
• Explain in detail to students the consequences of violating safety rules and procedures.

Maintenance of Chemicals

• Perform regular inventory inspections of chemicals.
• Update the chemical inventory at least annually, or as requested by the administration.
• Provide a copy of the chemical inventory to the local emergency responders (i.e., fire department).
• Do not store food and drink with any chemicals.
• If possible, keep all chemicals in their original containers.
• Make sure all chemicals and reagents are labeled.
• Do not store chemicals on the lab bench, on the floor, or in the laboratory chemical hood.
• Ensure chemicals not in use are stored in a locked facility with limited access.
• Know the storage, handling, and disposal requirements for each chemical used.
• Make certain chemicals are disposed of properly. Consult the label and the Material Safety Data Sheet for disposal information and always follow appropriate chemical disposal regulations.

Preparing for Laboratory Activities

• Before each activity in the laboratory, weigh the potential risk factors against the educational value.
• Have an understanding of all the potential hazards of the materials, the process, and the equipment involved in every laboratory activity.
• Inspect all equipment/apparatus in the laboratory before use.
• Before entering the laboratory, instruct students on all laboratory procedures that will be conducted.
• Discuss all safety concerns and potential hazards related to the laboratory work that students will be performing before starting the work. Document in lesson plan book.

Ensuring Appropriate Laboratory Conduct

• Be a model for good safety conduct for students to follow.
• Make sure students are wearing the appropriate personal protective equipment (i.e., chemical splash goggles, laboratory aprons or coats, and gloves).
• Enforce all safety rules and procedures at all times.
• Never leave students unsupervised in the laboratory.
• Never allow unauthorized visitors to enter the laboratory.
• Never allow students to take chemicals out of the laboratory.
• Never permit smoking, food, beverages, or gum in the laboratory.

What Are the Safety Do’s and Don’ts for Students?

Life threatening injuries can happen in the laboratory. For that reason, students need to be informed of the correct way to act and things to do in the laboratory. The following is a safety checklist that can be used as a handout to students to acquaint them with the safety do’s and don’ts in the laboratory.

Conduct

• Do not engage in practical jokes or boisterous conduct in the laboratory.
• Never run in the laboratory.
• The use of personal audio or video equipment is prohibited in the laboratory.
• The performance of unauthorized experiments is strictly forbidden.
• Do not sit on laboratory benches.

General Work Procedure

• Know emergency procedures.
• Never work in the laboratory without the supervision of a teacher.
• Always perform the experiments or work precisely as directed by the teacher.
• Immediately report any spills, accidents, or injuries to a teacher.
• Never leave experiments while in progress.
• Never attempt to catch a falling object.
• Be careful when handling hot glassware and apparatus in the laboratory. Hot glassware looks just like cold glassware.
• Never point the open end of a test tube containing a substance at yourself or others.
• Never fill a pipette using mouth suction. Always use a pipetting device.
• Make sure no flammable solvents are in the surrounding area when lighting a flame.
• Do not leave lit Bunsen burners unattended.
• Turn off all heating apparatus, gas valves, and water faucets when not in use.
• Do not remove any equipment or chemicals from the laboratory.
• Coats, bags, and other personal items must be stored in designated areas, not on the bench tops or in the aisle ways.
• Notify your teacher of any sensitivities that you may have to particular chemicals if known.
• Keep the floor clear of all objects (e.g., ice, small objects, spilled liquids).

Housekeeping

• Keep work area neat and free of any unnecessary objects.
• Thoroughly clean your laboratory work space at the end of the laboratory session.
• Do not block the sink drains with debris.
• Never block access to exits or emergency equipment.
• Inspect all equipment for damage (cracks, defects, etc.) prior to use; do not use damaged equipment.
• Never pour chemical waste into the sink drains or wastebaskets.
• Place chemical waste in appropriately labeled waste containers.
• Properly dispose of broken glassware and other sharp objects (e.g., syringe needles) immediately in designated containers.
• Properly dispose of weigh boats, gloves, filter paper, and paper towels in the laboratory.

Apparel in the Laboratory

• Always wear appropriate eye protection (i.e., chemical splash goggles) in the laboratory.
• Wear isposable gloves, as provided in the laboratory, when handling hazardous materials. Remove the gloves before exiting the laboratory.
• Wear a full-length, long-sleeved laboratory coat or chemical-resistant apron.
• Wear shoes that adequately cover the whole foot; low-heeled shoes with non-slip soles are preferable. Do not wear sandals, open-toed shoes, open-backed shoes, or high-heeled shoes in the laboratory.
• Avoid wearing shirts exposing the torso, shorts, or short skirts; long pants that completely cover the legs are preferable.
• Secure long hair and loose clothing (especially loose long sleeves, neck ties, or scarves).
• Remove jewelry (especially dangling jewelry).
•  Synthetic finger nails are not recommended in the laboratory; they are made of extremely flammable polymers that can burn to completion and are not easily extinguished.

Hygiene Practices

• Keep your hands away from your face, eyes, mouth, and body while using chemicals.
• Food and drink, open or closed, should never be brought into the laboratory or chemical storage area.
• Never use laboratory glassware for eating or drinking purposes.
• Do not apply cosmetics while in the laboratory or storage area.
• Wash hands after removing gloves, and before leaving the laboratory.
• Remove any protective equipment (i.e., gloves, lab coat or apron, chemical splash goggles) before leaving the laboratory.

Emergency Procedure

• Know the location of all the exits in the laboratory and building.
• Know the location of the emergency phone.
• Know the location of and know how to operate the following:

1. Fire extinguishers
2. Alarm systems with pull stations
3. Fire blankets
4. Eye washes
5. First-aid kits
6. Deluge safety showers

• In case of an emergency or accident, follow the established emergency plan as explained by the teacher and evacuate the building via the nearest exit.

Chemical Handling

• Check the label to verify it is the correct substance before using it.
• Wear appropriate chemical resistant gloves before handling chemicals. Gloves are not universally protective against all chemicals.
• If you transfer chemicals from their original containers, label chemical containers as to the contents, concentration, hazard, date, and your initials.
• Always use a spatula or scoopula to remove a solid reagent from a container.
• Do not directly touch any chemical with your hands.
• Never use a metal spatula when working with peroxides. Metals will decompose explosively with peroxides.
• Hold containers away from the body when transferring a chemical or solution from one container to another.
• Use a hot water bath to heat flammable liquids. Never heat directly with a flame.
• Add concentrated acid to water slowly. Never add water to a concentrated acid.
• Weigh out or remove only the amount of chemical you will need. Do not return the excess to its original container, but properly dispose of it in the appropriate waste container.
• Never touch, taste, or smell any reagents.
• Never place the container directly under your nose and inhale the vapors.
• Never mix or use chemicals not called for in the laboratory exercise.
• Use the laboratory chemical hood, if available, when there is a possibility of release of toxic chemical vapors, dust, or gases. When using a hood, the sash opening should be kept at a minimum to protect the user and to ensure efficient operation of the hood. Keep your head and body outside of the hood face. Chemicals and equipment should be placed at least six inches within the hood to ensure proper air flow.
• Clean up all spills properly and promptly as instructed by the teacher.
• Dispose of chemicals as instructed by the teacher.
• When transporting chemicals (especially 250 mL or more), place the immediate container in a secondary container or bucket (rubber, metal or plastic) designed to be carried and large enough to hold the entire contents of the chemical.
• Never handle bottles that are wet or too heavy for you.
• Use equipment (glassware, Bunsen burner, etc.) in the correct way, as indicated by the teacher.

How Should Chemical Containers Be Labeled?

No unlabeled substance should be present in the laboratory at any time!

Labeling Basics

• Use labels with good adhesive.
• Use a permanent marker (waterproof and fade resistant) or laser (not inkjet) printer.
• Print clearly and visibly.
• Replace damaged, faded, or semi-attached labels.

Commercially Packaged Chemicals

Verify that the label contains the following information:

• Chemical name (as it appears on the MSDS)
• Name of chemical manufacturer
• Necessary handling and hazard information

Add:

• Date received
• Date first opened
• Expiration or “use by” date (if one is not present)

Secondary Containers and Prepared Solutions

When one transfers a material from the original manufacturer’s container to other vessels, these vessels are referred to as “secondary containers.”

Label all containers used for storage with the following:

• Chemical name
• Name of the chemical manufacturer or person who prepared the solution
• Necessary handling and hazard information
• Concentration or purity
• Date prepared
• Expiration or “use by” date

Containers in Immediate Use

Label all containers in immediate use with the following:

• Chemical name
• Necessary handling and hazard information

Chemical Waste

All containers used for chemical waste should be labeled with the following:

• “WASTE” or “HAZARDOUS WASTE”
• Chemical name
• Accumulation start date
• Hazard(s) associated with the chemical waste

Peroxide-Forming Substance

Peroxide-forming chemical must be labeled with the following:

• Date received
• Date first opened
• Date to be disposed of

How Should Chemicals Be Stored?

First, identify any specific requirements regarding the storage of chemicals from (1) local, State, and Federal regulations and (2) insurance carriers.

General Rules for Chemical Storage

Criteria for Storage Area

• Store chemicals inside a closeable cabinet or on a sturdy shelf with a front-edge lip to prevent accidents and chemical spills; a ¾-inch front edge lip is recommended.
• Secure shelving to the wall or floor.
• Ensure that all storage areas have doors with locks.
• Keep chemical storage areas off limits to all students.
• Ventilate storage areas adequately.

Organization

• Organize chemicals first by COMPATIBILITY—not alphabetic succession (refer to section entitled Suggested Shelf Storage Pattern—next page).
• Store alphabetically within compatible groups.

Chemical Segregation

• Store acids in a dedicated acid cabinet. Nitric acid should be stored alone unless the cabinet provides a separate compartment for nitric acid storage.
• Store highly toxic chemicals in a dedicated, lockable poison cabinet that has been labeled with a highly visible sign.
• Store volatile and odoriferous chemicals in a ventilated cabinet.
• Store flammables in an approved flammable liquid storage cabinet (refer to section entitled Suggested Shelf Storage Pattern).
• Store water sensitive chemicals in a water-tight cabinet in a cool and dry location segregated from all other chemicals in the laboratory.

Storage Don’ts

• Do not place heavy materials, liquid chemicals, and large containers on high shelves.
• Do not store chemicals on tops of cabinets.
• Do not store chemicals on the floor, even temporarily.
• Do not store items on bench tops and in laboratory chemical hoods, except when in use.
• Do not store chemicals on shelves above eye level.
• Do not store chemicals with food and drink.
• Do not store chemicals in personal staff refrigerators, even temporarily.
• Do not expose stored chemicals to direct heat or sunlight, or highly variable temperatures.

Proper Use of Chemical Storage Containers

• Never use food containers for chemical storage.
• Make sure all containers are properly closed.
• After each use, carefully wipe down the outside of the container with a paper towel before returning it to the storage area. Properly dispose of the paper towel after use.

Suggested Shelf Storage Pattern

A suggested arrangement of compatible chemical families on shelves in a chemical storage room, suggested by the Flinn Chemical Catalog/Reference Manual, is depicted on the following page. However, the list of chemicals below does not mean that these chemicals should be used in a high school laboratory.

• First sort chemicals into organic and inorganic classes.
• Next, separate into the following compatible families.

*Chemicals deserving special attention because of their potential instability.

How Should Compressed Gas Cylinders Be Stored, Maintained, and Handled?

Compressed gases can be hazardous because each cylinder contains large amounts of energy and may also have high flammability and toxicity potential.

The following is a list of recommendations for storage, maintenance, and handling of compressed gas cylinders:

• Make sure the contents of the compressed gas cylinder are clearly stenciled or stamped on the cylinder or on a durable label.
• Do not identify a gas cylinder by the manufacturer’s color code.
• Never use cylinders with missing or unreadable labels.
• Check all cylinders for damage before use.
• Be familiar with the properties and hazards of the gas in the cylinder before using.
• Wear appropriate protective eyewear when handling or using compressed gases.
• Use the proper regulator for each gas cylinder.
• Do not tamper with or attempt to repair a gas cylinder regulator.
• Never lubricate, modify, or force cylinder valves.
• Open valves slowly using only wrenches or tools provided by the cylinder supplier directing the cylinder opening away from people.
• Check for leaks around the valve and handle using a soap solution, “snoop” liquid, or an electronic leak detector.
• Close valves and relieve pressure on cylinder regulators when cylinders are not in use.
• Label empty cylinders “EMPTY” or “MT” and date the tag; treat in the same manner that you would if it were full.
• Always attach valve safety caps when storing or moving cylinders.
• Transport cylinders with an approved cart with a safety chain; never move or roll gas cylinders by hand.
• Securely attach all gas cylinders (empty or full) to a wall or laboratory bench with a clamp or chain, or secure in a metal base in an upright position.
• Store cylinders by gas type, separating oxidizing gases from flammable gases by either 20 feet or a 30-minute firewall that is 5 feet high.
• Store gas cylinders in cool, dry, well-ventilated areas away from incompatible materials and ignition sources.
• Do not subject any part of a cylinder to a temperature higher than 125 °F or below 50 °F.
• Store empty cylinders separately from full cylinders.

What Are Some Strategies to Reduce the Amount and/or Toxicity of Chemical Waste Generated in the Laboratory?

All laboratories that use chemicals inevitably produce chemical waste that must be properly disposed of. It is crucial to minimize both the toxicity and the amount of chemical waste that is generated.

A waste management and reduction policy that conforms to State and local regulations should be established by the school or school district.

Several things that can be done to minimize hazards, waste generation, and control costs follow:

• Purchase chemicals in the smallest quantity needed.
• Use safer chemical substitutes/alternatives such as chemicals that have been determined to be less harmful or toxic.
• Use microscale experiments.
• Chemical experiments using smaller quantities of chemicals
• Recycle chemicals by performing cyclic experiments where one product of a reaction becomes the starting material of the following experiment.
• Consider detoxification or waste neutralization steps.
• Use interactive teaching software and demonstration videos in lieu of experiments that generate large amounts of chemical waste.
• Perform classroom demonstrations.
• Use preweighed or premeasured chemical packets such as chemcapsules that reduce bulk chemical disposal problems (no excess chemicals remain).

Possible substitutions

Storing Chemical Waste

• Store all waste in containers that are in good condition and are compatible with their contents.
• Clearly and permanently label each container as to its contents and label as hazardous waste (refer to section entitled How Should Chemical Containers Be Labeled? for specific information).
• Store waste in a designated area away from normal laboratory operations and to prevent unauthorized access.
• Store waste bottles away from sinks and floor drains.
• Do not completely fill waste bottles; leave several inches of space at the top of each waste container.
• Cap all waste bottles.

Appendix A. Common Safety Symbols

lammable                                                         Oxidizer

Explosive                                                Low Level Hazard

Corrosive                                                 Severe Chronic Hazard

Poison                                                Environmental Hazard

Appendix B. Recommended Safety and Emergency Equipment for the Laboratory

The following are checklists for safety and emergency equipment for the laboratory:

Personal Protective Equipment

• Chemical splash goggles
• Face shields
• Lab coat
• Lab apron
• Gloves (selected based on the material being handled and the particular hazard involved)

Safety and Emergency Equipment

• Hand-free eye-wash stations (not eye-wash bottles) that conform to ANSI Z358.1–2004
• Deluge safety showers that conform to ANSI Z358.1–2004
• Safety shields with heavy base
• Fire extinguishers (dry chemical and carbon dioxide extinguishers)
• Sand bucket
• Fire blankets
• Emergency lights
• Emergency signs and placards
• Fire detection or alarm system with pull stations
• First-aid kits
• Spill control kit (absorbent and neutralizing agents)
• Chemical storage cabinets (preferably with an explosion proof ventilation system)
• Gallon-size carrying buckets for chemical bottles
• Laboratory chemical hood (60–100 ft/minute capture velocity, vented outside)
• Ground-fault interrupter electrical outlets
• Container for broken glass and sharps
• Material Safety Data Sheets (MSDSs)
• Emergency Action Plan for the institution

Appendix C. How Does a Chemical Enter the Body?

• A chemical can enter the body through different routes.
• These different routes of exposure and the types of exposure (acute or chronic) can affect the toxicity of the chemical.
• The most probable (primary) route(s) of exposure to a chemical will be identified in the MSDS.
• Three principal routes of exposure include: dermal exposure (skin), inhalation, and ingestion (oral).

Dermal Exposure

Although the skin is an effective barrier for many chemicals, it is a common route of exposure. The toxicity of a chemical depends on the degree of absorption that occurs once it penetrates the skin. Once the skin is penetrated, the chemical enters the blood stream and is carried to all parts of the body. Chemicals are absorbed much more readily through injured, chapped, or cracked skin, or needle sticks than through intact skin. Generally, organic chemicals are much more likely to penetrate the skin than inorganic chemicals.

Dermal exposure to various substances can also cause irritation and damage to the skin and/or eyes. Depending on the substance and length of exposure, effects of dermal exposures can range from mild temporary discomfort to permanent damage.

Inhalation

Inhalation is another route of chemical exposure. Chemicals in the form of gases, vapors, mists, fumes, and dusts entering through the nose or mouth can be absorbed through the mucous membranes of the nose, trachea, bronchi, and lungs. Unlike the skin, lung tissue is not a very protective barrier against the access of chemicals into the body. Chemicals, especially organic chemicals, enter into the blood stream quickly. Chemicals can also damage the lung surface.

Ingestion

Ingestion involves chemicals entering the body through the mouth. Chemical dusts, particles and mists may be inhaled through the mouth and swallowed.

They may also enter through contaminated objects, such as hands or food that come in contact with the mouth. Absorption of the chemicals into the bloodstream can occur anywhere along the length of the gastrointestinal (GI) tract.

Appendix D. General Guidelines to Follow in the Event of a Chemical Accident or Spill

• Assess the overall situation.
• Determine the appropriate action to resolve the situation.
• Follow the pre-existing, approved local emergency plan.
• Act swiftly and decisively.

Below are some recommended actions for specific emergencies. Some of the actions have been proposed by the Council of State Science Supervisors in Science & Safety: Making the Connection.

Chemical in the Eye

• Flush the eye immediately with water while holding the eye open with fingers.
• If wearing contact lens, remove and continue to rinse the eye with water.
• Continue to flush the eye and seek immediate medical attention.

Acid/Base Spill

• For a spill not directly on human skin, do the following:
• Neutralize acids with powdered sodium hydrogen carbonate (sodium bicarbonate/baking soda), or bases with vinegar (5% acetic acid solution).
• Avoid inhaling vapors.
• Spread diatomaceous earth to absorb the neutralized chemical.
• Sweep up and dispose of as hazardous waste.

For spills directly on human skin, do the following:

• Flush area with copious amounts of cold water from the faucet or drench shower for at least 5 minutes.
• If spill is on clothing, first remove clothing from the skin and soak the area with water as soon as possible.
• Arrange treatment by medical personnel.

Mercury Spill

• Evacuate the affected area.
• Close off interior doors and windows, and heating and air conditioning vents in the incident room.
• Open exterior doors and windows to move the inside air outside

Appendix E. Glossary

Acid

A substance that dissolves in water and releases hydrogen ions (H+); acids cause irritation, bums, or more serious damage to tissue, depending on the strength of the acid, which is measured by pH.

Acute toxicity

Adverse effects resulting from a single dose, or exposure to a substance for less than 24 hours.

Allergy

An exaggerated immune response to a foreign substance causing tissue inflammation and organ dysfunction.

Asphyxiant

A substance that interferes with the transport of an adequate supply of oxygen to the body by either displacing oxygen from the air or combining with hemoglobin, thereby reducing the blood’s ability to transport oxygen.

Base

A substance that dissolves in water and releases hydroxide ions (OH−); bases cause irritation, burns, or more serious damage to tissue, depending on the strength of the base, which is measured by pH.

Carcinogen

A substance that causes cancer.

Ceiling limit

The maximum permissible concentration of a material in the working environment that should never be exceeded for any duration.

Chemical hygiene plan

A written program that outlines procedures, equipment, and work practices that protect employees from the health hazards present in the workplace.

Chemical hygiene officer

A designated person who provides technical guidance in the development and implementation of the Chemical Hygiene Plan.

Chronic toxicity

Adverse effects resulting from repeated doses of, or exposures to, a substance by any route for more than three months.

Central Nervous System (CNS)

The central nervous system is the part of the nervous system that consists of the brain and spinal cord.

Combustible liquid

A liquid with a flashpoint at a temperature lower than the boiling point; according to the National Fire Protection Association and the U.S. Department of Transportation, it is a liquid with a flash point of 100 °F (37.8 °C) or higher.

Compatible materials

Substances that do not react together to cause a fire, explosion, violent reaction or lead to the evolution of flammable gases or otherwise lead to injury to people or danger to property.

Compressed gas

A substance in a container with an absolute pressure greater than 276 kilopascals (kPa) or 40 pounds per square inch (psi) at 21 oC, or an absolute pressure greater than 717 kPa (40 psi) at 54 oC.

Corrosive

A substance capable of causing visible destruction of, and/or irreversible changes to living tissue by chemical action at the site of contact (i.e., strong acids, strong bases, dehydrating agents, and oxidizing agents).

Explosive

A substance that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature.

Exposure limits

The concentration of a substance in the workplace to which most workers can be exposed during a normal daily and weekly work schedule without adverse effects.

Flammable

As defined in the FHSA regulations at 16 CFR § 1500.3(c)(6)(ii), a substance having a flashpoint above 20 oF (−6.7 oC) and below 100 oF (37.8 oC). An extremely flammable substance, as defined in the FHSA regulations at 16 CFR § 1500.3(c)(6)(i), is any substance with a flashpoint at or below 20 oF (−6.7 oC).

Flashpoint

The minimum temperature at which a liquid or a solid produces a vapor near its surface sufficient to form an ignitable mixture with the air; the lower the flash point, the easier it is to ignite the material.

Hazardous substance

As defined in the Federal Hazardous Substances Act (FHSA) at 16 CFR § 1500.3(b)(4)(i)(A), any substance or mixture of substances that is toxic, corrosive, an irritant, a strong sensitizer, flammable or combustible, or generates pressure through decomposition, heat, or other means, if it may cause substantial personal injury or illness during or as a proximate result of any customary or reasonably foreseeable handling or use, including reasonably foreseeable ingestion by children.

Hepatotoxin

A chemical that can cause liver damage.

Highly toxic substance

As defined by OSHA (Appendix A of 29 CFR 1910.1200) and in the FHSA regulations at 16 CFR § 1500.3(b)(6)(i), a substance with either (a) a median lethal dose (LD50) of 50 mg/kg or less of body weight administered orally to rats, (b) a median lethal dose (LD50) of 200 mg/kg or less of body weight when administered continuously on the bare skin of rabbits for 24 hours or less, or (c) a median lethal concentration (LC50) in air of 200 parts per million by volume or less of gas or vapor, or 2 mg/L by volume or less of mist or dust, when administered by continuous inhalation for 1 hour or less to rats.

Ignitable

A substance capable of bursting into flames; an ignitable substance poses a fire hazard.

International Agency for Research on Cancer (IARC)

An agency of the World Health Organization that publishes IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. This publication documents reviews of information on chemicals and determinations of the cancer risk of chemicals.

Incompatible materials

Substances that can react to cause a fire, explosion, violent reaction or lead to the evolution of flammable gases or otherwise lead to injury to people or danger to property.

Ingestion

Taking a substance into the body by mouth and swallowing it.

Inhalation

Breathing a substance into the lungs; substance may be in the form of a gas, fume, mist, vapor, dust, or aerosol.

Irritant

A substance that causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.

Known human carcinogen

A substance for which there is sufficient evidence of a cause and effect relationship between exposure to the material and cancer in humans.

Lacrimation

Excessive production of tears when the eye is exposed to an irritant.

LC50 (Median Lethal Concentration 50)

The concentration of a chemical that kills 50% of a sample population; typically expressed in mass per unit volume of air.

LD50 (Median Lethal Dose 50)

The amount of a chemical that kills 50% of a sample population; typically expressed as milligrams per kilogram of body weight.

Mutagen

A substance capable of changing genetic material in a cell.

Neurotoxin

A substance that induces an adverse effect on the structure and/or function of the central and/or peripheral nervous system.

Oxidizer

A substance that causes the ignition of combustible materials without an external source of ignition; oxidizers can produce oxygen, and therefore support combustion in an oxygen free atmosphere.

Peroxide former

A substance that reacts with air or oxygen to form explosive peroxy compounds that are shock, pressure, or heat sensitive.

pH

A measure of the acidity or basicity (alkalinity) of a material when dissolved in water; expressed on a scale from 0 to 14.

Radioactive material

A material whose nuclei spontaneously give off nuclear radiation.

Reactivity

The capacity of a substance to combine chemically with other substances.

Reproductive toxicity

Adverse effects on sexual function and fertility in adult males and females, as well as developmental toxicity in the offspring (International Programme on Chemical Safety [IPCS] Environmental Health Criteria 225, Principles for Evaluating Health Risks to Reproduction Associated with Exposure to Chemicals).

Secondary containment

An empty chemical-resistant container/dike placed under or around chemical storage containers for the purpose of containing a spill should the chemical container leak.

Short-Term Exposure Limit (STEL)

The maximum concentration to which workers can be exposed for a short period of time (15 minutes).

Systemic

Affecting many or all body systems or organs; not localized in one spot or area.

Teratogen

A substance which may cause non-heritable genetic mutations or malformations in the developing embryo or fetus when a pregnant female is exposed to the substance.

Threshold Limit Value (TLV)

Term used by the American Conference of Governmental Industrial Hygienists

(ACGIH) to express the recommended exposure limits of a chemical to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.

Toxic substance

In general, as defined in the FHSA regulations at 16 CFR § 1500.3(b)(5), any substance (other than a radioactive substance) that has the capacity to produce personal injury or illness to man through ingestion, inhalation, or absorption through any surface of the body.

This term is further defined by OSHA and in the FHSA regulations:

As defined by OSHA (Appendix A of 29 CFR 1910.1200), a substance with either, a median lethal dose (LD50) of more than 50 mg/kg but not more than 500 mg/kg of body weight administered orally, a median lethal dose (LD50) of more than 200 mg/kg but not more than 1,000 mg/kg of body weight when administered by continuous contact with the bare skin of rabbits, or a median lethal concentration (LC50) in air of more than 200 parts per million but not more than 2,000 parts per million by volume of gas or vapor, or more than 2 mg/L but not more than 20 mg/L of mist, fume, or dust, when administered by continuous inhalation for one hour.

As defined in the FHSA regulations at 16 CFR § 1500.3(c)(2)(i), a substance with either, a median lethal dose (LD50) of 50 mg/kg to 5,000 mg/kg of body weight administered orally in rats, a median lethal dose (LD50) of more than 200 mg/kg but not more than 2,000 mg/kg of body weight when administered by continuous contact with the bare skin of rabbits for 24 hours, or a median lethal concentration (LC50) in air of more than 200 parts per million but not more than 20,000 parts per million by volume of gas or vapor, or more than 2 mg/L but not more than 200 mg/L by volume of mist or dust, when administered by continuous inhalation for 1 hour or less.

Water reactive material

A substance that reacts with water that could generate enough heat for the item to spontaneously combust or explode. The reaction may also release a gas that is either flammable or presents a health hazard.

SCIENCE, Pakistan

By

MUHAMMAD HASNAIN

hasnain@pakchem.net

www.PakChem.net