Saccharin taken off list of agents causing cancer

Saccharin has become the first substance to be removed from an official list of cancer-causing chemicals, because of new evidence showing that the animal studies which indicated a risk do not apply to humans.

Saccharin has become the first substance to be removed from an official list of cancer-causing chemicals, because of new evidence showing that the animal studies which indicated a risk do not apply to humans.

However, new rules on how to define a carcinogen means that activities as well as chemicals have now been added to the list, drawn up by the American government, including passive smoking, drinking and lying under a sunbed.

The list, which was first published in 1978, contains 218 entries divided into two broad categories: "known" carcinogens and "reasonably anticipated" carcinogens.

Saccharin was added to the "reasonably anticipated" list in 1981 after scientists found that rats fed on the substance developed bladder tumours. It was not banned but labels had to include a warning, which led to a fall in sales and a corresponding increase in the popularity of other artificial sweeteners.

Dr Kenneth Olden, director of the US National Institute of Environmental Health Sciences, which operates the National Toxicology Programme, said the original listing of saccharin was a prudent step to take given the strength of the animal studies.

"However, our understanding of the science has advanced and allows us to make finer distinctions today. Studies now indicate that the rat bladder tumours arise from mechanisms that are not relevant to the human situation," he said. "In addition, we have decades more data from observations of humans using saccharin that adds to our confidence."

Studies that have attempted to assess the risk of saccharin when it first became widely used 60 years ago have failed to identify an "overall association" with bladder cancer, although an occasional association in small, one-off studies means the cancer risk of artificial sweeteners cannot be ruled out, the report states.

The probability of someone developing cancer at some point in their lives is about one in two for men and one in three for women and most scientists believe many cancers may be associated with the environment in which people live and work, the report says.

"In this context, the 'environment' is defined as anything that interacts with humans, including lifestyle choices, such as substances eaten, drunk and smoked, and aspects of sexual behaviour; natural and medical radiation, including exposure to the sun; workplaces exposures; drugs; socio-economic factors affecting exposures and susceptibility; and substances in air, water and soil," the report said.