Are genetically modified crops a health risk?

Natural genetic alteration in humans, animals, and plants occurs constantly; that is what evolution is all about. However, since the early 1980s scientists have been experimenting with plant genes to produce crops that are more resistant to plagues and droughts, weeds and pests, and which produce higher yields. While some see these genetically modified (GM) crops as a solution for food scarcity, others see them as risky interventions in nature and a way to make profit by patenting the seeds. Meanwhile, according to the USDA, about 90 percent of corn, cotton, and soybean crops in the US are a GM variety.

From an environmental perspective, there are several concerns about GM crops. How do they affect the surrounding ecosystem? Could there be health risks for humans and animals that consume GM foods? Thousands of articles have been published addressing these concerns. Fortunately, there are also many meta-analyses to help us understand what the evidence says.

Nicolia et al., a group of Italian researchers, after reviewing papers and scientific reports about GM crop safety, reject potential hazards to the environment, humans, and animals from either GM crops or associated soil microorganisms. With respect to biodiversity issues, there is little to no effect on non-target species, such as birds and microfauna. Even though early papers showed negative effects on insects and arachnids, newer papers reject this conclusion. GM crops do affect biodiversity in target species such as weeds and pests in an area, but such a reduction is the intended effect of GM plants. Similar effects are expected from the use of pesticides on non-GM crops.

The studies show that it is almost impossible to avoid cross-pollination between GM crops and wild plants. In spite of this, there is no evidence of negative interactions between the two types. The authors also note that gene flow from agricultural species into wild species is not unique to GM crops: Non-GM crops have frequently become invasive species or swamped native genetic pools, and wild plants naturally develop herbicide resistance without genetic transfer.

Because of the fear of potential health impacts, the safety of GMOs for human consumption is the issue that dominates much public debate. In this area, the research studies are primarily on the potential effects on human health resulting from the consumption of animals that were fed with GM products. Again, there are many papers addressing these effects.

Nicolia et al. conclude that the technical possibility of modified DNA transferring to humans is extremely unlikely. There is no intrinsic difference between GM and unmodified DNA that would make this remote possibility any more probable or dangerous. Associated RNA has had a history of safe use, but more specific studies are needed to be conclusive.

An earlier review by a group of European scientists analyzed 12 long run and 12 multigenerational studies that assess the effects of a GM diet (maize, potatoes, soybeans, rice, and triticale) on several kinds of animals. The authors make suggestions on how to improve some experimental designs, such as a proper comparison between non-GM and GM crops and the samples size of some of the studies. However, they conclude that the studies show no significant difference between a GM and a non-GM diet in terms of nutritional benefit or health risk.

Finally, another review of recent studies, conducted by Polish researchers, covers primarily studies that the reviews above do not. Importantly, this review focuses on food-producing animals (livestock, poultry, and fish). Still, the results are similar: There is no relevant difference in the metabolic parameters of the animals fed by GM and non-GM crops. Moreover, the quality of food products—meat, milk, eggs—obtained from these animals was not significantly affected.

Thousands of studies have shown that concerns about genetic modification are unfounded. So far, the science is conclusive about the safety of GM foods. There are no health threats to humans, animals, or the environment beyond those presented by traditional agricultural crops. Although there may be other problematic issues associated with GMs, consumption-related health concerns should not be one of them.

Article Source:  An overview of the last 10 years of genetically engineered crop safety research, Nicolia et al, Critical Reviews in Biotechnology. Informa healthcare, 2013

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