Arlington, Va. Corn that is genetically engineered to make its own pesticide poses little risk to monarch butterflies, the Environmental Protection Agency said Tuesday after lab tests raised concerns.
While there is a small chance that one in 100,000 monarch caterpillars could be affected by toxic corn pollen, research suggests even those larvae will mature into healthy butterflies, the agency reported.
"The weight of evidence from the reviewed data indicate that there is no unreasonable hazard" to Monarchs or other wildlife, said Zig Vaituzis, an EPA scientist who led a review of the crop's environmental impact.
One possible exception is the karner blue butterfly, an endangered species that feeds on lupine plants that could show up near corn crops in northern Wisconsin. Agency officials said they don't know how significant the issue is but were consulting with the Fish and Wildlife Service on whether to take action to protect the butterflies.
The biotech corn, known as Bt corn for a bacterium gene that makes it toxic to the European corn borer, grabbed worldwide attention in 1999 after a laboratory study at Cornell University showed that pollen from the corn would poison monarch larvae. That finding produced a public outcry in Europe and calls from environmental groups to curb the spread of genetically engineered crops. The monarch larvae's favorite food is milkweed, which is abundant in the Midwest.
Bt varieties account for nearly 20 percent of this year's corn crop.
EPA's conclusion that the corn is relatively harmless to monarch populations is based in part on field studies coordinated last summer by the Agriculture Department in Maryland, Iowa and Minnesota. Data from the studies have not been published yet but were turned over to EPA for review.
The agency has declined to release the data because of confidentiality claims by biotech companies involved in the research. Agency officials said they hoped to release the data before the Sept. 30 deadline for renewing the Bt corn licenses.
Critics of the biotech industry said that the agency should not renew the registrations until it has released the research data and allowed the public to review and comment on it.