“When foreign genes are introduced into an organism, creating a transgenic organism, the results for the organism and its environment are almost always unpredictable. The intended result may or may not be achieved in any given case, but the one almost sure thing is that unintended results – non-target effects – will also be achieved.” (The Nature Institute)
Arpad Pusztai was the first to notice a string of non-target effects coming from the GM potatoes he was testing: the insecticidal 'lectin' they had been transformed to generate didn't achieve the expected level of control of aphid pests plus it damaged the natural predators of the aphids, while laboratory rats consuming the potatoes were found to have untoward changes in growth, organ development and immune reactivity. Most disconcerting of all was that the harmful effects couldn't be coming from the lectin-gene itself but must derive from somewhere in the wider genome. (see FEAR THE WAY FORWARD – News, July 2009)
Since then alarming non-target effects continue to emerge, but rarely hit the headlines.
Cabbage transformed to produce Bt toxin certainly killed the targetted pests for a while. But when these insects started to become resistant to the toxin, the increased protein in the GM plants act as a supplement making the pests thrive. Resistant larvae of the diamondback moth (a major problem in the USA) grew twice as fast after eating the GM cabbage leaves. (Cabbage is a traditional staple green vegetable in many countries.)
Bt-containing aubergine being pushed in India has many unexpected and inexplicable qualities. For example, it has 15% fewer calories and a different alkaloid content. Dairy cows fed the GM aubergines were observed to have increased weight, eat more dry roughage matter and increased milk production, as if they were being treated with hormones. Laboratory rats fed a Bt aubergine diet had diahorrea, and reduced liver size. (Aubergine is a widely-eaten traditional food in India.)
Marker genes included in engineered DNA constructs to aid the selection of (the limited number of) successful transformants have received regulatory attention from the early days of GM because of the possibility of their transfer into pathogenic bacteria. Other non-target effects have largely been neglected. This could be a grave omission, because one of the few experiments which looked at foliage consumption by Colorado beetle larvae when the potatoes had been genetically transformed with marker genes only found that one commonly used one (beta-glucuronidase) increased consumption by 50%. (Potatoes are a staple food in many areas.)
Fancier GM techniques may well prove to have fancier non-target effects. GM papaya genetically transformed with mutant (and therefore non-protein-producing) viral DNA designed to stimulate resistance to the Ringspot Virus, has recently been deregulated by the US Department of Agriculture. This approval has been granted despite the GM papaya somehow having repaired the mutatant DNA so that it is able to generate a viral protein, and despite the mechanism of the GM papayas' resistance to the viral disease being unexplained. (In this case, the existence of resistance to Ringspot Virus appears itself to be a non-target effect.)
Within the field of genetic engineering, scientists are so concerned with achieving target effects, that investigation beyond this is unusual, but “when they do investigate, there is usually plenty to see” (The Nature Institute)
OUR COMMENT
Recognising that the facts on non-target effects are rarely reported in the popular press and are often buried in technical scientific articles, The Nature Institute has started the mammoth task of collecting and categorising relevant citations. The literature still to be reviewed is extensive, but if you want to get a flavour of the breadth of examples gathered to date, have a look at http://natureinstitute.org/nontarget/.
At the end of the day, the list of non-target effects may be very long because it may include every single GMO ever devised.
Another reason not to accept GM food.
SOURCES