The Environmental Protection Agency has decided it will permit growers and importers of table grapes to sell grapes bearing residues of sulfite as long as 40 percent of the bunches carry warning labels.

California grape growers had said previously they had reached a compromise with EPA that called for 20 percent of the bunches in each treated box to carry labels warning of sulfite treatment.

A spokesman for the EPA said the agency decided that a larger percentage of bunches should carry the warnings to assure that consumers are aware of the chemicals.

The new policy, effective immediately, will extend only to Dec. 31, and EPA requested public comment on whether it should be extended to May 1989.

Sulfites have been used on grapes for more than 40 years to prevent rot and mold in shipping and storage. But some people, particularly asthmatics, are allergic to the residues, and last year the Food and Drug Administration removed sulfites from the "generally recognized as safe" list. This forced grocers and restaurants to stop treating food with sulfite compounds to make it seem fresher.

That action also required EPA to set a permissible concentration of sulfur dioxide, the principal residue, on and in treated crops such as grapes.

In December, the agency said that while it collected data to decide on permissible residues, it would allow shipment of grapes treated with sulfites if the shipper could certify that they contained no detectable residues of sulfur dioxide.

The labeling policy announced Thursday is intended as an alternative to certification.

A spokesman for the grape industry said that EPA, by requiring twice as many tagswould cost the industry an extra $4.5 million. "The EPA is not to be trusted," said Bruce Obbink, president of the California Table Grape Commission.

The EPA announcement also drew criticism from consumer groups.

Tagging 40 percent of the bunches is "completely inadequate," said Mitch Zeller, an attorney for the Center for Science in the Public Interest. Zeller said tagging all grapes is the only way to protect public health.

Jay Feldman, coordinator of the National Campaign Against the Misuse of Pesticides, said the labeling of some treated bunches but not others "will be confusing for the consumer" and could lead buyers to conclude incorrectly that the unlabeled bunches had not been treated.

He estimated that tens of thousands of people are allergic to sulfur dioxide and a few hundred are so sensitive that the reaction to eating treated food, a narrowing of the air passages to the lungs, could be fatal.