Abstract
The thought of using ‘genetically modified’ corn or soybeans in our food brings a nasty connotation for most of us. Think again. In spite of conflicting and confusing media reports regarding the safety of genetically modified foods, everything known about them indicates that these foods are just as safe as the foods grown through conventional methods.
So what is ‘genetically modified’ corn or soybean and why do we need them? ‘Biotechnology derived’ (BD) foods is a more accurate term than ‘genetically modified’ because the technique involves transferring the genetic material of a bacterium, known as Bacillus thuringiensis (Bt), which produces a toxin selectively poisonous to insect pests of plants such as corn. Bt corn does not require pesticide sprays because the corn plant itself produces the toxin that kills the insect pests. To ensure the success of the bacterial gene transfer, markers such as resistance to antibiotics (kanamycin/neomycin or ampicillin) or herbicides are also included.
The following important issues have been raised with respect to the potential adverse or untoward effects associated with production and consumption of BD foods.
Direct toxicity of BD foods and unintended adverse effects in consumers.
Allergies from the BD foods.
Effects of antibiotic resistance on human health.
Nutritional value of these foods may change.
BD plant’s production of toxin may kill nontarget organisms.
The possibility of adverse effects arising from the presence of Bt toxin in the plants, either by direct toxicity or gene transfer, is minimal. The safety of Bt toxins in humans is assured because they do not survive the harsh conditions of human or animal digestive tracts.
Extensive studies of the chemical composition, nutritional quality, and levels of potentially toxic components in both the BD and conventional crops have established that the level of safety to consumers of BD foods is no different than that of traditional foods. At present, no verifiable evidence of adverse health effects of BD foods has been reported.
Can these foods increase allergy in individuals already suffering from allergies? Will such foods have more of the substances already known to cause allergies? Will they cause new allergies? In this regard, it is important to keep in mind that eating conventional food is not risk-free; allergies occur with many known and even new conventional foods. Peanuts and kiwi fruit are good examples. The kiwi fruit was introduced into the United States and the European market in the 1960s with no known human allergies. Now people are known to be allergic to this fruit.
Do the antibiotic resistance markers in the ingested BD food present a significant human hazard? Genes for resistance to kanamycin and related antibiotics already occur quite commonly in the microorganisms normally present in the human gut, but the BD foods do not have much impact on this.
After the accidental introduction of StarLink corn (intended for animal use only) into the human foods, a limited number of illnesses were reported. The Centers for Disease Control (CDC) found no evidence that the corn products were responsible, but methodological limitations make these findings less than conclusive. Because of this, StarLink corn is no longer marketed.
Since 1987, the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service conducted over 5000 field trials with more than 70 different BD plant species. With the exception of a change in the color pattern in petunia flowers (an effect known to occur in conventional plant breeding), no other changes were detected.
In the United States, the Food and Drug Administration (FDA) is entrusted with assuring that the nutritional composition of BD foods is equal to that of the nonmodified food. A typical example is the case of Roundup Reddy soybeans. Domestic animal feeding studies with a number of crops, including Roundup Reddy soybeans, have shown no significant changes in nutritional value. The protein, oil, fiber, ash, carbohydrates, and moisture content and amino acid and fatty acid composition in seeds and toasted soybeans were same as conventional soybeans.
Is Bt toxin toxic to nontarget organisms? Detailed risk assessment studies concluded that it is unlikely. Risk to butterflies does not exist in the field because only a negligible portion of the population is exposed to toxic levels of Bt. It is important to recollect that the alternative is to spray corn with synthetic insecticides, which are not as selective as the Bt toxin. In a sweet corn field containing milkweed plants and treated with a synthetic pyrethroid insecticide for insect control, 91% to 100% of the monarch butterfly larvae placed on the milkweed leaves after spraying were killed. In plots where Bt sweet corn was planted and the pollen fell naturally on the milkweed leaves, larval death was much lower (7% to 20%) and was the same as found in untreated non-Bt corn plots.
As consumers, it is important to recognize that it is the food product itself, rather than the process through which it is made, that should be the focus of attention. The level of safety of current BD foods to consumers is equal to that of traditional foods. However, future technology may result in more complex changes in a foodstuff. When such food stuffs become a reality, the consumers may expect the scientists and the gatekeepers to vigilantly test their safety.