Science in Society Archive

Human Studies on GM Food Risks

The UK Medical Research Council has established an Expert Group to consider GM food risks and feasibility of human studies to assess the risks. Their Report, published June 2000, acknowledged GM food risks, but dismisses existing evidence from toxicological and epidemiological studies, and does not call for more research before GM foods are grown for human consumption. Instead, it proposes long term studies on humans, and that "randomised controlled trials" could be conducted on infants and people receiving "a free supply (to promote compliance) of a key staple food". Dr. Mae-Wan Ho and Angela Ryan report.

The Expert Group considered many of the health impacts highlighted by critics, such as altered nutritional quality of foods (and attendant impact on various chronic non-communicable disease pro-cesses), acute and chronic toxic effects, immune effects, transfer of antibiotic resistance genes to human pathogens and risk of infectious diseases (from viruses used as gene vectors).

It also advocates removal of antibiotic resistance genes from GM constructs used in the production of food, but falls short of calling for their removal in animal feed; despite growing evidence that bacteria can pass from farm animals to human beings - E. coli 0157 is a well known example.

One notable omission is genetic damage due to random insertion of the constructs into animal and human cells, which has the potential to trigger cancer.

The Report is critical of the principle of substantial equivalence in risk assessment, and acknowledges that the principle does not address unintended effects. It recommends using both state-of-the-art and routine methods to screen for unintended changes in gene expression and metabolites.

However, the more contentious half of the report proposes human studies to assess the risks. Is it ethical to do so when there is already abundant evidence suggesting that GM foods may be unsafe? (see "The Precautionary Principle and Scientific Evidence", this issue). This is a blatant example of the anti-precautionary principle being applied in risk assessment. Regulators and pro-GM scientists alike are still saying, "there is no evidence that GM foods are harmful", and hence we must accept GM foods. Whereas what they should be saying, at the very least, is, "there is no evidence that GM foods are safe and hence we must not approve them for release".

The report criticises established toxicological studies using cells, cell cultures and animals, on the spurious grounds that "whole foods represent a bulky and complex chemical mixture, only limited quantities of which can be fed to animals". And this was considered one of the major shortcomings of Pusztai experiment. In effect, it is dismissing existing evidence from animal studies already indicating the GM foods may be unsafe.

Similarly, it finds fault with epidemiological studies because of the lack of "firm hypotheses as to what the adverse effects of GM foods are" and "the difficulty in assessing the extent of GM food exposure". In this way, it also disposes of circumstantial evidence that soya allergies had gone up 50% in the UK within a year, coinciding with the increased import of GM soya (see "GM soya and increased soya-associated allergy" ISIS News #3, December 2000 <>).

It transpires that "prospective studies" have already begun several years ago with "detailed personal and dietary information" that can be obtained from major supermarkets, and blood samples have been taken and put into storage. Other prospective studies have also collected blood and other biological samples from individuals and "these would allow markers of GM food consumption in blood to be assessed as a measure of exposure, should such markers be developed."

The most controversial proposal is for "randomised controlled trials".

"Theoretically, the most effective studies are likely to be those where the GM food selected forms a major and consistent part of the diet. Randomisation of infants, whose whole or predominant source of nutrition happens to be infant formula, to formulas based on GM versus non-GM soya should be a good example. Another would be the random assignment of individuals or families to a free supply (to promote compliance) of a key staple food (that exists in GM or non-GM form) e.g. potatoes, bread or rice."

The most immediate group of people who would qualify for such trials is the starving, who could be asked to volunteer as guinea pigs in order to obtain food. In effect, this may already be happening, as GM foods are being dumped as 'food aid' on the Third World and Latin American countries.

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