The Office of Management and Budget has signed off on a Food and Drug Administration proposal to strengthen requirements that processed foods be labeled if they contain detectable sulfites, a chemical preservative that has been linked to more than 500 reports of illness and 12 deaths.

Capitol Hill and agency sources said yesterday that OMB approved the rule after the FDA came under sharp attack at a House hearing Wednesday. Members criticized the FDA for failing to move against sulfite preservatives, despite concerns that 10 percent of the nation's 9 million asthmatics may be in danger of severely adverse reactions to the chemicals.

"The hearing probably pushed them over the line," one source said. A staff member of the House Energy and Commerce subcommittee on oversight and investigations said FDA Commissioner Frank E. Young phoned subcommittee Chairman John D. Dingell (D-Mich.) with the news late Wednesday.

Some members of Congress and consumer groups are urging far stronger action, including a ban on using sulfites to keep salads and fruits, as well as pre-cut potatoes, looking fresh in restaurants.

But internal documents made available at the hearing showed that even FDA's modest processed-food labeling proposal -- as well as another, unapproved proposal to label drugs -- ran into resistance when they were sent to the Health and Human Services Department last year for approval. The roadblock in both cases appeared to be Robert B. Helms, the acting assistant secretary for planning and evaluation.

After FDA sent the processed-foods proposal in June 1984, Helms objected to it, largely on the grounds that an outside safety review was still under way and that the agency should instead develop an overall strategy for labeling ingredients that pose a risk to small segments of the population.

In July, Young called the proposal a "minimum first step to assure the safety of the use of sulfites" and urged action "as soon as possible." But the proposal sat in the department until HHS Secretary Margaret M. Heckler signed it March 2 -- after the outside review was completed and the Dingell hearing scheduled.

The other proposal appears to be "lost in some black hole," complained Rep. Gerry E. Sikorski (D-Minn.) at Wednesday's hearing.

Last August, Young sent a five-page memorandum to Heckler, seeking approval for a proposal requiring that all drugs containing sulfites be labeled and that over-the-counter products also contain a "precautionary statement" that sulfites "may cause serious allergic-type reactions in certain susceptible persons, especially asthmatics."

The memo said that because sulfites pose no hazard to the general population, there is no need to ban their use in drugs. But it urged that the labels be changed "as soon as possible so that susceptible persons will have a means to avoid drugs containing sulfites."

A Sept. 13 memo said staff in the offices of the assistant secretary for health and of the secretary had all signed off on the proposal, but Helms' office had not. In his "non-concurrence," Helms argued that there was "insufficient data that sulfites pose a risk severe enough to warrant an additional warning label," that a warning label for sulfites "seems contradictory to early decisions" and that "it seems unreasonable" in terms of the cost -- estimated at $241,000 -- to industry.

Helms noted that the department had decided not to require that aspirin labels warn of the potential risk to children of the deadly Reye's syndrome, and he urged a more general policy statement on food and drug warning requirements.

FDA disagreed sharply in an Oct. 3 memo, citing the possible hazards to nearly 1 million asthmatics. It said that "to place individuals at risk of severe, life-threatening reactions because of earlier decisions is unjustifiable."

But, bending to Helms' concerns, Young sent a proposal Dec. 18, asking only that labels be required to say when sulfites are present in certain drugs.

Nonetheless, Helms filed another "non-concurrence," saying the "need for regulation is unproven at best" and asking FDA instead to develop "a comprehensive policy or risk assessment guidelines to deal with the literally thousands of ingredients in foods, drugs and cosmetics to which a few persons may be allergic or sensitive."