The decision came seven years after the rules were first proposed. The rules are supported both by environmental groups and the biotech industry, and EPA has been following them informally. However, there had been some dispute over the regulations among researchers who felt they went too far.

Cotton and corn that have been genetically engineered to produce their own pesticides already are in wide use.

Crops that are developed by conventional methods are exempt from the regulations, although manufacturers must report any adverse effects.

The rules include a provision that says all DNA of the gene-altered crops is safe for food use. Any pesticidal substances in the plant, however, could be subject to restrictions.

Industry officials say that the DNA exemption could make it more difficult for the government to demand recalls of food made with StarLink corn, a genetically engineered corn that was discovered in the food supply last fall although it had not been approved for human consumption.

A pesticidal protein in the corn cannot be detected in many processed foods, but the Food and Drug Administration has considered a positive test for StarLink DNA to be an indicator that the protein is also there. Agency officials say they arent sure how the EPA rules will affect their policy.

The Grocery Manufacturers of America said it didnt expect the EPA rules to have any effect on company recall policies.

StarLink corn has been withdrawn from the market, but EPA is deciding whether to renew the licenses of several other varieties, all of which are approved for food use.

EPA said it would take public comment on several other exemptions proposed in 1994 but dropped from the rules that were issued Thursday. One would exempt crops that are altered in ways that only affect the plants, such as producing a waxy coating.