What's New in Life Science Research

It appears that Bt toxin, found in genetically modified corn and used to kill pests, could wind up in aquatic ecosystems:

Researchers, including Todd V. Royer, an assistant professor in the IU School of Public and Environmental Affairs, established that pollen and other plant parts containing toxins from genetically engineered Bt corn are washing into streams near cornfields.

They also conducted laboratory trials that found consumption of Bt corn byproducts produced increased mortality and reduced growth in caddisflies, aquatic insects that are related to the pests targeted by the toxin in Bt corn.

Caddisflies, Royer said, "are a food resource for higher organisms like fish and amphibians. And, if our goal is to have healthy, functioning ecosystems, we need to protect all the parts. Water resources are something we depend on greatly."

Basically, they found the following:

1. Measured the entry of Bt plant parts--including pollen, leaves and cobs--in 12 streams in a heavily farmed Indiana region. The research team's results demonstrate that these plant parts are washing into local steams. Moreover, during storms, these plant parts are carried long distances and therefore could have ecological impacts on downstream water bodies, such as lakes and large rivers.

2. Collected field data indicating that Bt corn pollen is being eaten by caddisflies, which are close genetic relatives of the targeted Bt pests. Todd V. Royer, a member of the research team from Indiana University, says that caddisflies "provide a food resource for higher organisms like fish and amphibians."

3. Conducted laboratory tests showing that consumption of Bt corn byproducts increased the mortality and reduced the growth of caddisflies. Together with field data indicating that the caddisflies are eating Bt corn pollen, these results "suggest that the toxin in Bt corn pollen and detritus can affect species of insects other than the targeted pest," Tank said.

This study also shows that we need appropriate regulatory models to understand the effects of these foods:

Before licensing Bt corn, the U.S. Environmental Protection Agency conducted trials to test its impact on water biota. But it used Daphnia, a crustacean commonly used for toxicity tests, and not insects that are more closely related to the target pests, Royer said.

This is a point that is too often neglected in public policy decisions (and has implications well beyond GM foods): how you design the regulatory criteria can make something look very good or very bad (a point I've made regarding the antibiotic cefquinome)

Given the stress our aquatic systems are already under, I don't think we need to add this to the mix.

Cited article: Rosi-Marshall et al. 2008. Toxins in transgenic crop byproducts may affect headwater stream ecosystems. PNAS 41 16204-16208. doi: 10.1073/pnas.0707177104