GM-free Scotland

Feature

In response to concerns about the human health effects of GM materials now widespread in animal feed, our food regulators have issued assurances that “safety assessments” have been carried out and all is well.

The Food Standards Agency (FSA), taking its lead from the European Food Safety Authority (EFSA), tells us on its website:

“To date, a large number of experimental studies with livestock have shown that recombinant (engineered) DNA fragments or proteins derived from GM plants have not been detected in tissues, fluids or edible products of farm animals like broilers, cattle, pigs or quails”.

“Biologically active genes and proteins” cannot be a problem because “After ingestion, a rapid degradation into short DNA or peptide fragments is observed”.

GM feed ... 'is very unlikely to contain viable GMOs'.

GM feed ... 'is digested by animals in the same way as conventional feed'.

(You can read the full text at www.food.gov.uk/gmfoods/gm-animal. Most of it describes the regulatory framework, and the extent of GM feed cultivation, import and use. Only two out of eleven paragraphs are devoted to safety.)

So, GM DNA and proteins in animal feed are dead and, like conventional DNA and proteins, are degraded by the digestive processes down to tiny fragments, as proven by their absence from the tissues and fluids of livestock.

These statements have, so far, let the supermarkets off the hook. Their representative, the British Retail Consortium, said “Our view is that all the evidence shows that there is no transference of GM material from feedstuffs to meat and dairy products. Given that this is the case, there is nothing to be gained from labelling the use of GM feed”.

But, is the science, as we know it, so comforting?

A recent review of published studies on the fate of DNA in food revealed:

five studies indicating that viral DNA ingested by mice ended up in many of their organs, including in the foetus, and that it entered the cell nucleus where it could become incorporated into their DNA

studies on livestock have found plant DNA in the tissues of cows (1 study), of pigs (3 studies), of chickens (1 study) and in cows' milk (2 studies)

one study has found food DNA in human tissue, but the current picture emerging is that identifiable dietary DNA seems to be absorbed and circulated in the blood, diminishing after a few days or weeks without normally being taken up by cells.

These findings are of particular importance in interpreting safety assessments because it is technically tricky to identify “recombinant DNA fragments” in tissues. Often, there are components in the test material which interfere with the analysis, and raise the possibility of false negative results. The analysis can only be carried out if the precise structure of the DNA being searched is known. The recombinant DNA which has been accurately engineered in a test tube, undergoes a succession of transitions: from test-tube to bacteria for bulking up the quantities, from bacterium to plant cells in tissue culture, from tissue culture to whole plants, and after breeding with other GM or non-GM strains, from plants to whole crops, which are processed and digested by livestock and by their gut bacteria. At any one, or all, of these stages, the DNA can become rearranged. After such rearrangement, the actual DNA present might not be detected by a test designed to find the original DNA construct. Again, there is a possibility of false negative results.

Put another way, the likelihood of false negatives in looking for recombinant DNA in animal tissues is so great that even a few positive findings assume a much greater significance than the 'large number' of negative findings referred to.

The EFSA, FSA and supermarkets seem simply to have ignored the experimental evidence of incorporation of dietary DNA into animal tissue.

There are many scientific reasons to be concerned at this omission.

The idea that an entire plant-gene conferring herbicide-tolerance or insect resistance could become absorbed and incorporated into animal DNA so as to churn out a functional novel protein is not realistic. However, the suggestion that DNA and proteins will be degraded into small inert fragments during digestion is also unrealistic: the efficiency of digestion will always depend on the health of the digestive system and on the composition of the diet; and, as described above, identifiable dietary DNA has in fact been detected in the tissues of a number of animals.

What could be unsafe about the absorption of partially digested DNA or protein?

DNA itself is now recognised as able to stimulate the immune system, the physiological effects of engineered constructs is unknown.

We know from the cumulative prion proteins of the BSE epidemic that unusual proteins can pass through the digestive system without deactivation.

Moreover, artificial DNA constructs contain many non-gene segments of DNA, such as viral-type promoters, which are needed to drive the desired transgene expression. These are small in size compared with the DNA which forms the actual gene, and have a realistic potential to become functional in any organism. The work on mice fed viral DNA described above suggests we should be very concerned about the fate of such particles, because the health effects of these in our genome could reasonably include cancers, autoimmune disease and foetal abnormalities.

Finally, it is true that animal feed is unlikely to contain viable GMOs, but this is of little relevance since all of the above concerns refer to the fate of recombinant DNA and unusual proteins from non-living, processed material.

In light of all these considerations, it is hardly reassuring to read that GM feed is digested in the same way as conventional feed.

Also quietly ignored by the regulators has been the acknowledged possibility of incorporation of functional recombinant DNA into the millions of bacteria in the digestive tract. Regulatory attention has confined itself to the fate of antibiotic resistance genes (which have been banned in the EU, but are still here). The outcome of gut microbes making use of, for example, Bt-toxin genes or viral promoters could be to turn a probiotic bacterium into a pathogenic one, or a healthy bowel into an irritable one.

The much-touted “safety assessments” are largely confined to compositional analysis interpreted according to the undefined parameter of 'substantial equivalence', backed up at best by short-term feeding-studies in laboratory animals and acute toxicological effects of analogues of the novel protein. Very few of these studies have been published or are directly applicable to humans (see WHO'S LIABLE IN A GM-SHAPED WORLD? - News, January 2008). To investigate the emergence of problems arising from the effects of active DNA being incorporated into animal tissue would require long-term studies and long-term clinical trials.

Think about all this before you take your next mouthful of pork sausage, or mince, or chicken nuggets, or yoghurt. Unless it's organic, there is a good possibility it was fed GM feed. Check out SILENT INVASION – News, January 2008).

SOURCES

• Daily Mail, 15.11.07
• www.eco-risk.at
• Institute of Science in Society, Press Release 30.11.07