After nearly being exonerated as a suspected health hazard, saccharin--the artificial sweetener--is to remain on the government's list of possible human carcinogens. An advisory panel to the National Toxicology Program (NTP) on 31 October voted to keep saccharin in the federal Report on Carcinogens, which has listed the chemical as an "anticipated human carcinogen" since 1981.
Saccharin made the list after studies in the 1970s showed it could cause bladder tumors in male rats. At the time, the relevance of those studies was questioned by industry groups and some scientists, who claimed the rats were fed the equivalent of thousands of cans of diet soda and noted that studies of people who consume artificial sweeteners found no cancer risk. After considering this evidence as well as new studies suggesting that bladder tumors develop only under urinary conditions specific to rats, two NTP scientific committees in a draft report suggested delisting saccharin (ScienceNOW, 28 October).
But in a 4-to-3 vote, the NTP panel decided to keep saccharin in the report. The panel was concerned about epidemiological studies that suggested some saccharin-consuming subgroups might run an elevated risk for bladder cancer, according to the National Institute of Environmental Health Sciences, which runs the interagency NTP. The panel also noted that in some of the rat studies, saccharin doses were not as high as was claimed in the '70s.