The whiskey industry has agreed to limit levels of the cancer-causing substance urethane in its products starting in 1989, the Food and Drug Administration announced yesterday.

FDA Commissioner Frank E. Young said the agreement to limit urethane to 125 parts per billion (ppb) in whiskeys -- scotch, bourbon, rye and various blends -- is "appropriate" in view of the limited health data on urethane, an unintentional byproduct of the fermentation and distillation process.

But consumer advocates said the standard accepted by the FDA is too lenient to protect the public against an unacceptable cancer risk posed by urethane, and they criticized the agency for failing to regulate manufacturers of brandies, liqueurs and wines that contain higher levels of the hazardous substance.

Urethane causes cancer in laboratory animals and is considered a potential human carcinogen. But the extent of cancer risk to humans is not known. Young said he has urged federal agencies to speed research on the chemical.

The FDA found urethane in 54 of 248 wines and liquors sampled 18 months ago, prompting an industry effort to reduce the contaminant. Although the substance can vary in concentrations among bottles of the same brand, it reached levels as high as 890 in corn whiskey, 550 ppb in bourbon and 140 ppb in scotch, 12,000 ppb in brandy and 270 ppb in table wine. Many products were lower.

Nancy L. Buc, attorney for the Distilled Spirits Council of the United States, said while the industry was unable to determine how urethane is produced, it has managed by "good old-fashioned trial and error" to limit the substance in whiskey to a maximum of 125 ppb. She insisted, however, that the accord does not represent an acknowledgment of urethane's health risks, which she said are hypothetical. "You try to get the levels as low as you can practically as a gesture," she explained.

Bruce Silverglade, legal director of the Center for Science in the Public Interest, said the FDA considers it unacceptable if a substance increases the risk of cancer by one cancer per million people exposed, and the results of an FDA study suggested that whiskey, at the 125 ppb limit, would exceed that. In 1986, he said, an FDA scientist had studied the 150 ppb standard that Canada set for bourbons the year before, and determined that the additional lifetime risk from regular consumption would range from 10 to 100 additional cancers for every million people exposed.

"It appears that the FDA settled for too little," Silverglade said. His nonprofit consumer group petitioned the FDA last year to set a urethane limit of 75 ppb, which he said, is the level most whiskeys contain.

Silverglade also criticized the FDA for stretching out the target date of the accord to Jan. 1, 1989. After the aging time of whiskey is factored in, he said, consumers will have to wait years before they can "find pure whiskey products."

The FDA's failure to reach agreements with the wine, liqueur and brandy industries shows "the limits of voluntary programs," he said.

FDA spokesman Chris Lecos said the agreement reflects the agency's efforts to reduce urethane in all alcoholic beverages to "the lowest possible levels." He said negotiations with wine and other liquor producers are ongoing. He noted the difficulty of regulating a carcinogen for which there are no solid risk estimates.