| MARCH 6, 2014 -- Recently there has been a great deal of controversy about GMOs. GMO stands for “genetically modified organism”. A GMO is a plant or animal that has been genetically engineered with DNA from some other organism. The other organism might be a plant or animal or even a bacterium or virus. With rare exceptions the resulting combinations of genes from different species cannot occur in nature or be produced by traditional crossbreeding.
A large number of GMOs have been produced for biological and biomedical research, experimental medicine, and production of pharmaceutical drugs. The most famous of these is insulin, which used to be extracted from slaughtered pigs and cows but is now produced primarily from genetically modified bacteria. This GMO insulin is based on the human genome, and is both safer and much cheaper than that derived from slaughterhouses.
The GMOs which cause the most controversy are food crops which have been engineered to withstand direct application of herbicide or to produce their own insecticide or to have increased nutritional value or increased yield or greater resistance to adverse environmental conditions. Generally, for the farmer, this is a good thing. The opposition to GMOs falls mostly into one of three categories: (1) some people claim that GMOs have harmful effects on human diet or health; (2) there are claims that genetically modified plants may have harmful environmental consequences; (3) there are concerns that GM foods may introduce new allergens into the diet. Curiously enough, the most common mechanism for artificially injecting DNA into a plant is by use of a bacterium which in its natural state already has the ability to inject DNA into plants as part of its metabolism. Agrobacterium tumefaciens in the wild causes a plant disease called crown gall disease. It does so by inserting some of its own DNA into plants it infects. Manipulation in the lab removes the disease-causing DNA from this bacterium and substitutes DNA which enhances the invaded plant’s ability to resist herbicides or produce insecticide [usually Bt], or be better able to thrive during adverse environmental conditions, such as drought or salty soils.
Despite the fact that there is broad scientific consensus that foods derived from GM crops are no more harmful than non-GM foods, there is a significant minority opinion that GM foods have not been adequately tested and some, mostly anecdotal, evidence of potential harm. Researching these reputedly harmful effects through a literature search is made particularly difficult since most of the published and on-line sources of information are sensationalist and make scary claims not properly documented by reference to verifiable scientific studies. The other side of the question, sources that are supposed to show that GM crops are safe and pose no harm, are almost as bad, as very few properly peer-reviewed studies are cited. The one instance where it was properly documented that GM plants might be harmful to health was a study of GM potatoes. As a result, GM potatoes were never introduced to the commercial market.
One area where it has been shown that some GM crops have had an adverse effect on the environment is in the accidental transfer of herbicide-resistant genes to weed species, resulting in weeds unaffected by ordinary herbicide spraying, which is causing farmers to use more herbicide, which has its own unintended effects. Herbicide-resistant weeds have been reported in 80 different crops in 63 countries. Some of these weeds have evolved herbicide resistance on their own and some have managed to pick up the resistance genes from GM domestic crops.
Another area of concern is what effect GM crops may have on helpful insects. For example, genes introduced into plants which cause them to produce Bt poison, which kills caterpillars, has the unintended side effect of killing many natural pollinators, including honey bees. But the biggest push among the general public is for labeling of foods which have some content derived from GM sources. Member countries of the European Union, for example, must follow strict labeling regulations. “All food products that make direct use of GMOs at any point in their production are subjected to labeling requirements, regardless of whether or not GM content is detectable in the end product.” In contrast, in the United States, there are no federal requirements for GM labels. There is political pressure from some groups to require the US to adopt the European Union standards. Not surprisingly, most food producers and distributors in this country resist this pressure. |
