WATERVILLE – A hearing this week on proposed rules for growing Bt corn, a type of genetically modified corn, could raise as many questions as it provides answers.

The Maine Board of Pesticides Control is due to discuss proposed rules for the product – how it could be grown, training required, and what it could be used for – at a Friday hearing, but the issue has become further complicated with the recent release in the Proceedings of the National Academy of Sciences of a new Bt toxin study.

The report raises concerns about the effect of toxins in genetically engineered crops on stream and brook ecosystems. Yet, on the heels of its release, a group of equally concerned scientists is challenging the report’s validity.

Bacillus Thuringiensis corn could be grown for the first time in Maine next year after approval was granted by the Maine Board of Pesticides Control last July. Maine was the last state to allow genetically-modified corn.

Bt corn has been hailed by farmers to help increase their yields because it is resistant to damage by insects. Yet, it is panned by organic farmers as a source of potential crop contamination in their certified fields. Still others have questioned the health ramifications of GE food.

Logan Perkins of Protect Maine Farmers, a group consistently opposed to GE crops, said Tuesday that the study shows conclusively that “there are things we still don’t know” about GE crops. “We need to use the cautionary principle and take a slower approach.”

Perkins said the study indicates there is still a lot of research on the issue that is still undone. “This should give the board pause as they proceed. They should look at this study. It is important, significant and valuable.”

A group of 11 international scientists, however, from the U.S., the Netherlands, India, Italy, Great Britain, Thailand, and Canada, have publicly invalidated the study.

In a letter to PNAS, the scientists wrote the “caddis fly study” contains “egregious methodological flaws and omissions, and presents conclusions not supported by the data.”

They call the study “sloppy experimental design and interpretation that should have been detected by even a cursory peer review.”

Dr. Doug Gurian-Sherman of the Union of Concerned Scientists, echoes Perkins’ concerns and said the letter was not unbiased.

“Virtually all of the scientists [who criticized the PNAS study] are long-standing outspoken supporters of GE, and their positions often include vitriolic criticism of GE critics,” Gurian-Sherman stated in a prepared release. “The question is, in part, whether to take a precautionary approach, or go ahead with planting in Maine, and find the answers later. One difference between Maine and other parts of the country is that farmers are not already planting this.”

Perkins said Bt corn now accounts for approximately 35 percent of corn acreage in the United States and its use is increasing.

Dr. Douglas Johnson of the Maine Biotechnology Information Bureau, said the study and its validity or lack of validity, should not affect the board’s decisions.

“You can’t make scientific policy on recent studies,” Johnson said. “In the case of Bt corn, it has been studied for 10 years or more and the number of studies are huge. The body of evidence strongly states there is no human health or environmental effects.”

Johnson said he hopes that Friday’s discussions do not center on the caddis fly study or prompt the BPC to withdraw its approval or enact “burdensome rules that would tie farmers’ hands in bureaucratic red tape.”

The public hearing will be at 9:30 a.m. Friday, Nov. 16, at the Hampton Inn in Waterville. Written comments will be accepted by the BPC until Nov. 30.