“If the Bt protein is going to kill an insect, won’t it also harm me?”
First, let’s take a look at how exactly the Bt protein works. Joe Ballenger over at Biofortified, has described the process – in all its scientific details – like this:
Bt toxin requires a high (basic) pH to be active, and must be activated by specific protein-cutting-proteins in the insect gut. The Bt toxin is comprised of a bunch of smaller proteins that work together by teaming up to form holes in the membranes of the cells that form the gut. The holes that are formed are small, and allow salts and other small solutes to get in. When the salts rush in, water follows. When the water flows in, the cells burst. When enough cells burst, the midgut becomes full of large holes. At this point the gut contents spill into the body cavity of the insect, resulting in the death of the insect.
(Source: How Does BT work?) But that still seems a bit scary. As some people have described it, the Bt protein essentially makes the bug’s stomach “explode.” How do we know that the Bt protein won’t do the exact same thing to our bodies?
As Joe clarified: “In humans, the Bt protein is very quickly digested in vitro, and this is due in part to the fact that human and insect stomachs are very different.” (You can check out a study on how scientists tested this here.) In part, this is because the ph of our stomachs is about 2, and the ph of an insect’s stomach is about 10. The ph is one factor that determines whether a protein is going to work or not.
Furthermore, Michael Eison, also at Science 2.0, explained that the Bt protein has evolved over the years to act as a natural pesticide for specific insects, but not for humans. He clarified:
Given what we know about Cry [Bt] proteins, there is very little reason to be concerned about the safety of eating it. These are proteins that have evolved to kill insects – and not just insects in general, but very specific subsets of insects. And humans are not insects. Regulatory agencies in the US and Europe have consistently rejected claims that plants that produce their own Cry cause problems in either humans or farm animals.
(Source: How Bt Corn And Roundup Ready Soy Work – And Why They Should Not Scare You.) In other words, the Bt protein does not bother us because our bodies are, quite simply, created differently than that of an insect – and thankfully so!
Again, our human bodies are significantly different from a dog’s body. Some of those differences allow us to safely eat certain foods that dogs – or insects – cannot. The Bt protein in genetically modified sweet corn uses this same basic and familiar concept. That’s how it can kill an insect, but doesn’t hurt us.
Of course, scientists also studied the effects Bt sweet corn had on humans prior to the product becoming commercially available (though use is still somewhat limited). Because Bt is considered a pesticide – it is routinely used on organic farms – the EPA was also involved in studying the sweet corn and screening it for safety. (You can check out this article on Biofortified for more information on the safety assessments.)
Biotechnology can sometimes seem “scary” because most of us cannot really comprehend the nitty gritty scientific details. No doubt some of the negative reaction to GMOs is caused by this difficulty. But, in reality, many times we are more familiar with the scientific concepts and ideas than we might imagine. The Bt protein’s use in sweet corn, compared with my dog’s inability to safely eat chocolate, is the perfect example.
