The Food and Drug Administration revealed yesterday that Justice Department officials "clarified" the FDA's rationale for approving two cancer-causing dyes for use in cosmetics and drugs so that it would stand a better chance of surviving a legal challenge.

FDA Commissioner Frank E. Young told the House subcommittee on intergovernmental relations and human resources that the clarification was adopted without the knowledge of agency scientists.

Public Citizen, a consumer advocacy group based in Washington, has filed a lawsuit challenging the FDA decision to approve dyes Orange No. 17 and Red No. 19.

FDA officials testified yesterday on the agency's enforcement of the Delaney clause, which is a 1960 law that bars the sale of color additives found "to induce cancer in man or animal."

When Young approved the two dyes for external use last August, he didn't dispute that the dyes had been shown to induce liver cancer in rodents. But he argued that the Delaney law didn't apply because the risk of human cancer posed by the dyes was so negligible that it should be disregarded.

In its lawsuit, Public Citizen challenged the claim of negligible danger, arguing the FDA violated the Delaney rule and broke with previous interpretations of the law.

Subcommittee Chairman Ted Weiss (D-N.Y.) and member John Conyers Jr. (D-Mich.) said they were not disputing FDA's claim that improved technology for detecting carcinogens shows the law to be excessively rigid. Instead, they said they were concerned that the agency had not sought relief from Congress, but instead had taken what Weiss called "a detour around the law because you think it's wrong or inconvenient."

Young conceded in congressional testimony yesterday that he had violated an agency rule by failing to write memos on his contacts with Assistant Attorney General Richard K. Willard and Deputy Assistant Attorney General Robert K. Cynkar concerning the Justice clarification. He said he had "no clear recollection" of which Justice official had insisted upon the change. Justice Department officials declined to testify and would not identify the official.

Similarly, FDA's Chief Counsel Thomas Scarlett said he hadn't written memos about phone conversations with a drug industry lawyer about the decision.

The conversations were with Peter Barton Hutt, a predecessor to Scarlett who now represents the Cosmetic, Toiletry and Fragrance Association. CTFA has pressed the FDA for years to approve the dyes.

Weiss warned that the FDA was jeopardizing its reputation by having lawyers rather than scientists decide what additives "induce cancer." He cited notes that FDA's Scarlett had written: "Problem is that legislative history makes clear that 'induces cancer' is a matter of scientific discretion."

The Justice Department represents the FDA, which is not authorized to represent itself. Justice lawyers said the FDA's justification would be hard to defend.

In the end, Justice and FDA agreed to say that the two dyes are safe because their cancer risk for lab animals is "not within the meaning" of the Delaney clause.

Young called this a "clarification" of the FDA justification. Weiss and former FDA Counsel Richard M. Cooper called it a "reversal." Top FDA scientist Sanford A. Miller -- who hadn't been consulted -- called it "confusing." Environmental activist Norton Nelson of New York University called it "bizarre," "nonsense" and "slick."

The federal appeals court, which heard the Public Citizen case in March, may have the last word. Young said he will welcome its decision.