Foods derived from genetically modified (GM) crops are not available for human consumption in large parts of the world, including Europe, because of health fears, although there is little or no evidence of any risk. Nevertheless, opponents of GM food claim there is no proof it is safe to eat.
GM food is consumed widely in North America, and advocates for GM crops claim that widespread adoption will be essential to develop the hardy crops necessary to feed the burgeoning population: by 2050 the world will have to grow 70 per cent more food to keep up. The GM food issue is discussed by David Freedman in Scientific American (September 2013) and Mike Gibney in Something to Chew On (UCD Press, 2012).
Traditionally, plant breeders have improved varieties by cross-breeding plants with desirable characteristics, for example high-fruit-yield plants with blight-resistant ones, selecting promising looking progeny and back-crossing these with their parents until eventually a stable new variety emerges with the desired characteristics. The traditional method is slow and unsure, but it works.
For 60 years this method has been supplemented by blasting plants with radiation or chemicals to cause mutations and then picking promising new mutations. Such highly “unnatural” interventions have attracted little public criticism.
In traditional cross-breeding, the progeny of a cross, in addition to inheriting desirable characteristics, also inherits undesirable traits that must be patiently eliminated in tedious back-crossing cycles. New, precise genetic engineering techniques have been developed since the 1970s, allowing a single gene from one organism to be transferred into the genome of another. Genetic engineering can precisely “zap in” the desired characteristic without any accompanying undesirable traits, and can also transfer genes across species, whereas traditional breeding is restricted to crossing varieties within the same species. In principle, genetic technology can tailor plant characteristics to suit any environment.
Applying weed killer
Monsanto, the agri-tech corporation, has genetically engineered the main commodity crops – corn, maize, soya bean and cotton – to become resistant to the herbicide Roundup (glyphosate). Crops can now be doused with Roundup, eliminating weeds without affecting the plants. This reduces the requirement for herbicides and for tillage, improves crop yields, reduces soil erosion and the price of food. However, careless use of this technology has allowed the emergence of Roundup-resistant weeds.
Nearly all the corn and soya beans grown in America are genetically modified, and four countries – the US, Canada, Brazil and Argentina – grow 90 per cent of the world’s GM crops. Little or no GM crops are grown in Europe, India, China or Africa because of fears they are unsafe to eat, thereby forgoing many advantages offered by GM crops. For example, Asian governments have yet to approve insect-resistant higher-yield GM rice, or Golden Rice, engineered to deliver vitamin A (rice normally has no vitamin A), despite the fact that vitamin A deficiency kills and blinds hundreds of thousands people annually.
Billions of GM meals have been eaten over the past few decades without evidence of harming health, and numerous trials have failed to find ill effects. Some studies have reported that GMF poses health risks, but most have been convincingly rebutted by experts.
The American Association for the Advancement of Science, the American Medical Association and the National Academy of Sciences back GM crops. The EU Commission has funded 130 independent research projects, and none identified special risks from GM crops. Opponents say there is no proof that it is safe, but it is difficult to see how this could be proved.
Genetic modification of food was a radical development and it was greeted with appropriate caution. However, decades of strict examination have failed to produce evidence of harm. Is it not time to develop some trust? Freedman suggests that new GM crops should be safety-tested in the same way that new drugs are tested and we should simply accept all that pass the test. The EU’s chief scientific adviser recently said it is unethical to deny access to GM crops to countries threatened with famine. The general acceptance of sensible precautions would allow the wider world to enjoy the considerable advantages of GM crops.
William Reville is an emeritus professor of biochemistry and public awareness
of science officer at UCC. understandingscience.ucc.ie