Opponents of genetically modified (GM) crops raise a number of questions and objections to growing them and including them in the food supply. Although they cite scientific research to support their claims, a careful review of the literature suggests there is very little evidence to support any of the claims about harmful health effects of GM food. For this reason, combined with the many potential benefits, governments should not restrict the use of genetically modified organisms (GMOs).
Opponents place a great deal of emphasis on the fact that many GM crops have been engineered to be resistant to glyphosate, the active chemical in Roundup herbicide. Glyphosate is used with genetically modified corn, soybeans, sugar cane, canola, and other crops grown in the US. Critics claim that glyphosate is an endocrine disrupter. It allegedly harms gut bacteria, and contributes to a variety of health problems including cancer, autism, allergies, obesity, and Alzheimer’s.
The claims about the negative health effects of glyphosate are not borne out by epidemiological studies of glyphosate and health outcomes or glyphosate and cancer. The most prominent arguments for the harmful health effects of glyphosate are not presented by people with expertise in relevant fields such biology, epidemiology, or chemistry. Consequently, the European Union just voted to renew the license for glyphosate use, siding with sound science against radical activists.
There is also little evidence of harm caused by consuming GM foods. Several scientific organizations including the American Medical Association and the World Food Organization have issued statements that GMOs are not likely to present risks for human health. Many scientists have rigorously tested assertions of anti-GMO advocacy groups, such as the Institute for Responsible Technology, about the health effects of GMOs, and have found little statistical evidence of toxicity caused by GMOs.
Studies that have found harmful effects have been found to be flawed or have results that have not been replicated by follow-up studies. For example, one study claiming that GM corn causes cancer involved a breed of rats that are naturally prone to tumors and was subsequently retracted by the journal.
GM foods have not been around long enough to determine whether they have harmful long-term health effects on humans. Thus, some argue that GMOs should be prohibited until we know more about their long-term effects. If governments used a precautionary principle to prohibit the use of every technology that might someday be found to have harmful effects, many improvements that have raised our standard of living, improved health, and extended lives would never have become commercially available.
After biotech crop varieties, many of which were resistant to glyphosate, became commercially available in 1996, numerous farmers around the globe adopted them. Using glyphosate to control weeds means farmers can save time and fuel with reduced soil erosion by not plowing to control weeds.
Although research studies have generally been unable to find evidence of harmful health effects from glyphosate, some evidence suggests it does cause some other harmful consequences, such as reducing earthworm populations. It may also harm other beneficial bacteria that live in the soil. The longer it and other chemical herbicides and pesticides are used, the more weeds evolve to adapt to it so that higher and higher doses are required.
Life inevitably involves tradeoffs. We accept some risks (e.g., of dying in an accident commuting to work) to reduce others (starving for lack of income). This principle applies to environmental risks just as much as to any others.
The environmental harms that can be attributed to glyphosate and GMOs should be compared to the benefits. Glyphosate is often used instead of more toxic herbicides. Likewise, some crops have been genetically modified to be resistant to insects, reducing the need for pesticides. Genetic modification combined with the use of glyphosate reduces production costs and increases yields. It enables farmers to conserve energy, soil and water, reducing their production costs and the amount of soil washing into rivers and streams.
Over time, there may be a need to find new and better ways to control weeds and insects, as existing weeds and insects develop resistance to herbicides and natural pesticides released by GM crops. Nevertheless, genetic modification, herbicides, and pesticides have made important contributions to the supply of abundant, low-cost food that has benefitted billions around the world. As I’ve noted before, genetic modification offers promise for the development of more nutritional varieties of crops that can be grown in parts of Africa, where malnutrition continues to contribute to death and the poor health of millions.
Herbicides and pesticides increase yields in a cost-effective way or farmers would not use them. Careful research, government regulation, and consumer choice have led to the demise of many of the most harmful pesticides and herbicides, with insect resistant crops and glyphosate replacing them. According to one estimate, the adoption of GM insect resistant and herbicide tolerant technology has reduced global pesticide spraying by 8.1%. A recent study estimated that banning glyphosate in the UK would decrease yields of wheat and oilseed rape by 12–14 percent due to more weeds.
Because of modern agricultural methods including pesticide and herbicide use, GMOs, chemical fertilizers, and factory farming, food has become much more abundant and affordable in many parts of the world today than it was even 30-40 years ago. The improvement in human health and wellbeing from a more abundant and nutritious food supply far exceeds any side effects that may have occurred from the use of pesticides or herbicides. Good research continues to discover new crop varieties and alternatives to the most harmful pesticides and herbicides and may also reveal better alternatives than some existing GMO crop varieties. In many cases, developing, planting, and cultivating genetically modified crops can improve nutrition and contribute to better stewardship of the land and soil.
Tracy Miller, Ph.D., is an economist, Senior Policy Research Editor at the Mercatus Center, George Mason University, and a Senior Fellow of The Cornwall Alliance for the Stewardship of Creation.