“The authors’ conclusions cannot be regarded as scientifically sound,” pronounced the exceedingly cautious European Food Safety Authority in a statement summarizing independent evaluations of Séralini's work by Belgium, Denmark, France, Germany, Italy and the Netherlands. Séralini founded the Committee of Research and Independent Information on Genetic Engineering (CRIIGEN) because he regarded safety studies of GM food as inadequate; he has received funding from anti-GM organizations, such as Greenpeace; and he has offered journalists a preview of his upcoming publications only if they agreed not to discuss the research with any other scientists—a strategy science writer Carl Zimmer called "a rancid, corrupt way to report about science." Many journalists agreed anyway.
In other instances the media has exaggerated or essentially manufactured apprehension about Bt toxins. In 2011, a Canadian study claimed to find evidence of a cry toxin—Cry1Ab—circulating in the blood and umbilical cords of pregnant women. Although the study itself hardly mentioned health risks, alarming headlines proliferated. In truth, there was never any cause for concern. Some cry toxins—indeed many different proteins we eat—may in fact survive the journey from intestines to blood more or less whole, but it is by no means an easy feat. First of all, cooking and industrial processing break down and inactivate most cry toxins. The vast majority of food ingredients made from Bt corn and soybeans are mixed into highly processed products like cereals and cooking oils, although some U.S. farmers grow a single variety of Bt sweet corn for the produce aisle (which, presumably, most people would eat cooked). Secondly, cry toxins evolved to work in the high pH environment of the insect gut; our much more acidic low pH stomachs easily destroy them (which has been demonstrated in animal studies and confirmed with experiments using imitation stomach acid). And, if a cry toxin did get past the stomach and intestines into the blood, it would have no way to bind to our cells; it evolved to attach to insect cells that have very different surface proteins. Finally, any rogue cry toxins circulating in our blood are not necessarily from Bt crops. In fact, a far more likely source is organic food that has been treated with Bt sprays or any food with soil residues containing B. thuringiensis. Most of us eat small amounts of Bt every day.
Even if cry toxins in our food do not enter the bloodstream, our gut bacteria could grab Bt genes and start pumping out toxins, some researchers and GM opponents have proposed. This is biologically feasible, but highly unlikely. Many bacteria are famous for their ability to sponge up DNA from their surroundings and exchange genes with other bacteria and even with organisms from different kingdoms of life, such as plants. In Japan some people’s gut bacteria stole a gene for digesting seaweed from ocean bacteria on raw seaweed the people ate. Perhaps our gut bacteria could pick up the Bt gene from Bt corn. Perhaps, but they have had a similiar opportunity for millions of years because people have always eaten food with some traces of B. thuringiensis-laced soil. And there is no reason our intestinal companions would pilfer genes from GM food specifically, rather than from foods of all kinds and the many bacteria they harbor. Plus, if the microbes in our intestines did manage to acquire the Bt gene, they do not necessarily have the right cellular equipment to make the toxin; and even if they made the toxin, it would be harmless to human cells.
Despite the prodigious evidence of Bt’s safety, some people still worry about unanticipated illness and worst-case scenarios. A decade-old ruckus surrounding one particular type of Bt maize illustrates that the government can swiftly retract any GM products that slip past safety regulations. In 1998 the U.S. Environmental Protection Agency approved an Aventis (now Bayer) CropScience variety of Bt corn known as StarLink for use in animal feed, but did not allow farmers to grow it for human consumption. Tests indicated that the cry toxin (Cry9C) produced by StarLink plants did not degrade as easily in the human gut as other toxins and might cause allergies, even though it did not match the molecular structure of any known allergens.