Restaurants no longer would be able to serve fresh, pre-cut potatoes preserved with sulfites under a ban proposed by the Food and Drug Administration last week. But they could continue to serve frozen, dehydrated and canned potatoes containing the preservative, a difference that has upset legislators, consumer groups and even the National Restaurant Association.

Instead of peeling and paring potatoes themselves, some restaurants purchase fresh, pre-cut potatoes for use in such dishes as cottage fries, french fries or hash browns. The ban would cover only these pre-cut potatoes -- 3 percent of the total potato market -- and not the frozen, dehydrated or canned potatoes that restaurants also use. It would also not affect frozen, dehydrated or canned potato products sold in supermarkets, though all packaged foods that contain sulfites must be labeled. Fresh, whole potatoes with skins sold in produce sections of supermarkets or at restaurants do not contain sulfites.

Critics are charging that FDA has backed down from its own conclusion that sulfites be banned on all types of unlabeled potatoes. In a 1986 draft proposal, the agency stated that "a consensus no longer exists ... that the use of sulfiting agents on potatoes that are intended to be served or sold unpackaged and unlabeled to consumers is safe."

The agency's final proposal, said Sen. Albert Gore (D-Tenn.) last week, "fails to adequately protect consumers. FDA realized last year that banning sulfites only in fresh potatoes was inadequate because consumers would still be exposed to sulfites in canned, frozen and dehydrated potatoes in restaurants."

The National Restaurant Association has repeatedly urged the FDA to ban sulfites on all types of unlabeled potatoes, according to NRA spokesperson Ann Papa. "If sulfites are dangerous, they should be banned across the board," she said. It is often impossible for waiters to know for the benefit of diners whether the supplier of the restaurant's dehydrated, canned or frozen potatoes uses sulfites, Papa added.

In a press release issued last week, the FDA said that four deaths have been linked to consumption of raw potatoes treated with sulfites. The agency estimates that up to a million people, primarily asthmatics, may be allergic to the preservative, which is added to potatoes to inhibit oxidation and browning and to maintain crispness.

In its draft proposal the agency said it had received 54 reports involving potato products that "can be classified as life threatening and apparently caused by sulfites." The agency concluded that an accurate breakdown of specific processing methods was not possible because the potato products were described in various ways, by both the complaintants and the investigators.

"FDA has admitted they can't tell the difference between the various potato processing methods. This just proves that what the agency should have done is ban sulfites from all unlabeled potato products, rather than just banning them from fresh potatoes," said Mitch Zeller, an attorney with the Center for Science in the Public Interest.

Zeller said he surmises that the FDA reneged on its original plan because it would have cost approximately $100 million. The current proposal is estimated to cost between $2 and $18 million, according to the FDA.

According to Richard Williams, a staff economist with FDA who worked on the economic impact report, the costs for banning sulfites for all classes of potatoes would include the price of chemical alternatives and processing alterations.

In addition to pre-cut fresh potatoes, dehydrated potatoes constitute 8 percent of the market, frozen constitute 27 percent and canned make up 2 percent. The remaining 60 percent of the market includes fresh unpeeled whole potatoes, chips, shoestrings and other, all of which are not likely to contain sulfites, according to FDA.

Richard Ronk, acting director of the FDA's Center for Food Safety and Applied Nutrition, said that economics did not enter into the agency's decision. He said that if the agency banned sulfites from all potatoes that are sold in restaurants, that it would have to ban them from all sulfited potatoes that are sold in supermarkets. Packaged foods that contain more than 10 parts per million of sulfites must state so on the label when sold in supermarkets, whereas potatoes sold to restaurants in the same state end up being sold unlabeled to consumers.

Nevertheless, Ronk said that there are about as many agency people for as against the current proposal and that comments for the broader policy are being solicited and considered. Ronk said a person allergic to sulfites should order only whole fresh unpeeled potatoes in restaurants.