The artificial sweetener saccharin, which for 20 years has been dogged by suspicion that it causes cancer, was denied science's equivalent of parole when a board of independent experts recommended that it remain on the government's list of suspected carcinogens.
The 4-3 vote was a surprise. Most scientists had expected the panel to decide that saccharin, perhaps the most studied food additive, should become the first substance to be struck from the carcinogen roster.
That now appears unlikely. The panel's advice is not binding, but it carries great weight with the National Toxicology Program, the branch of the National Institutes of Health that keeps the list.
"The closeness of the vote indicates . . . the large body of scientific studies that can be looked at in different ways," said Michael Jacobson, executive director of the Center for Science in the Public Interest, which had pressed for saccharin to remain on the list.
The toxicology program's scientists, having reviewed 14 animal and more than 30 human studies involving saccharin, recently concluded that it was unfairly placed on the list in 1981. Although saccharin in high doses has been shown to cause bladder cancer in rats, recent research has suggested that the studies are not applicable to humans.
But the expert panel was split over contradictions in those studies and was unable to settle the question of whether saccharin poses a health threat to people. In the end, some panel members said, they preferred to err on the side of caution.
"De-listing is going to lay very heavy on my conscience if I'm wrong," Dr. Nicholas Hooper of the California Department of Health Services said after the panel's discussion Friday at the toxicology program's offices in Research Triangle Park, N.C.
The vote is unlikely to have any effect on the availability of saccharin. The sweetener continues to be used in many low-calorie and sugar-free foods, including soft drinks, baked goods, jams, canned fruit, candy and salad dressings.
It's also the main ingredient in Sweet 'N Low, which like all foods that contain saccharin carries a congressionally mandated warning label that might be removed should saccharin lose its designation as a suspected carcinogen.
Saccharin's troubles began in 1977 when a Canadian scientist identified it as a possible carcinogen. The Food and Drug Administration proposed a ban in keeping with a federal law that bars from the nation's food supply substances found to cause cancer in animal studies.
But the FDA's plan generated a public outcry. Consumers complained and diabetics, who rely on artificial sweeteners, argued that they needed saccharin. In a compromise, Congress passed a law preventing the ban but requiring warning labels. In 1981, saccharin went on the list, which now has 169 suspected carcinogens.