A study indicates saccharin's ability to cause cancer may be limited to rats, suggesting there is no need for the warning label on the sugar substitute.

"It would appear that saccharin is an example of a chemical that can cause cancer in rats but not in mice and not in humans," said the study's chief author, Dr. Sam Cohen, vice chairman of pathology and microbiology at the University of Nebraska Medical Center in Omaha.His research was funded by the National Cancer Institute and the International Life Sciences Institute, which represents food and beverage companies, including saccharin manufacturers. Nevertheless, Cohen's research and integrity were praised by other scientists.

"This work is excellent. I think it is a valid conclusion" that saccharin probably doesn't cause human cancer, said Dr. Bob Scheuplein, director of toxicological sciences at the Food and Drug Administration's food safety center.

More research is needed to confirm Cohen's conclusion, but "if Congress is so disposed, they could look at Sam's work and other work and say, `Why do we have a warning label?' " Scheuplein said by telephone from Washington.