Farmers will be allowed to continue growing genetically engineered corn because the government has decided it is not a threat to human health or the environment.

The Environmental Protection Agency is renewing for seven years registrations for varieties of biotech corn that produce their own toxin to kill an insect pest, a moth larva called the European corn borer. The crop is known as Bt corn for a bacterium gene it contains.

The EPA said yesterday it is taking steps to ensure that farmers comply with planting restrictions designed to prevent the development of insects resistant to the toxin.

"Bt corn has been evaluated thoroughly by EPA, and we are confident that it does not pose risks to human health or to the environment," said Steve Johnson, assistant administrator of the EPA's Office of Prevention, Pesticides and Toxic Substances.

A laboratory study that was reported in 1999 raised concerns that the corn could harm monarch caterpillars, which feed on milkweed in and near cornfields. But studies published recently in the Proceedings of the National Academy of Sciences played down the threat. The scientists estimated that, at most, 500 in a million caterpillar larvae would die from eating corn pollen deposited on the milkweed.

The EPA has been reviewing the crop, first approved in 1995, for two years.

"For the consumer, my customer, they should feel at ease, because this really reaffirms the safety of this product," said Illinois farmer Leon Corzine, a spokesman for the National Corn Growers Association.

Biotech seed companies are being required to monitor use of the crops to ensure that they do not lead to insect resistance or have unexpected effects on human health or the environment. Farmers will be required to sign papers each year stating that they are aware of planting restrictions for the corn.

To prevent insect resistance, farmers must plant at least 20 percent of their corn acreage with conventional varieties. However, nearly a third of farmers last year violated that restriction, according to a survey submitted to the EPA.

The plantings of conventional corn are designed to ensure that there are plenty of corn borer moths susceptible to the toxin in the biotech crop. Insects naturally become immune to the toxin as they are exposed to it, but the trait will not be passed onto successive generations if they mate with nonresistant moths.

"The safeguards incorporated into these registrations will ensure that farmers can continue to use an effective, low-risk pest control alternative, which helps to protect the environment by reducing the amount of conventional pesticides used," Johnson said.

Monsanto Co., DuPont Co., Syngenta AG and Dow Chemical Co. hold registrations for Bt corn.

The EPA's decision does not apply to StarLink, the biotech corn variety that was withdrawn from the market last year after its discovery in the food supply led to recalls of taco shells and other products. StarLink had never been approved for food use because of questions about its potential to cause allergic reactions. ** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. **