What's Off, What's On

By Jeffrey Kluger

Of all the things that could one day kill you, a diet soda should not be high on the list. Twenty years ago, however, diet soda seemed like lethal stuff--or at least the saccharin it contained did. According to studies at the time, saccharin was a direct cause of bladder cancer. Of course, in order for the sweetener to do you harm, it had to make up at least 3% of the gross weight of food you ate every day--no easy task for a substance consumed by the quarter-teaspoonful. Oh, and it also helped if you were a laboratory rat, the only creature in which the saccharin-cancer link had ever been conclusively established.

Nonetheless, in 1981 saccharin was added to the government's official list of cancer-causing agents and dropped from most products. Last week, having never harmed any known human consumer, it was formally cleared of carcinogenic charges. In the ninth edition of the federal list, saccharin was omitted, along with a lesser-known manufacturing chemical.

The listing ritual was first mandated by Congress in 1978 under a law requiring the Department of Health and Human Services to compile and publish the names of substances known or thought to cause cancer. Each time the report is released, substances are either added, bumped up from the suspected to the known category or deleted.

How the report is compiled is something of a black art to folks outside HHS, but the process is fairly simple. Investigators from the government's National Toxicology Program ask scientists around the country to submit "nominees" for the list. The feds then review the candidates to determine which indeed deserve to be considered carcinogenic and where on the list they belong. Getting dropped from the list works the same way, except that the push for removal may come from industry groups eager to redeem what they consider a wrongly condemned substance. Saccharin's exoneration, for instance, was championed by the Calorie Control Council, a dietetic-food-and-beverage manufacturers' group.

The list released last week includes 218 known or suspected carcinogens. Of these, 14 are new additions and six are upgrades. Tobacco products were new entries, never listed before because in the past the government considered only individual chemicals that make up a product (the benzopyrene in cigarette smoke, for example) rather than the product itself. Environmental carcinogens like ultraviolet radiation are also included for the first time. (For highlights of the report, see captions.)

SACCHARIN A lot of rats died to study saccharin, but so far no humans have joined them. Not only were the saccharin doses that caused cancer in the animals extremely high, but the manner in which the chemical crystallized in rat bladders simply did not occur in humans. With the risk disproved, saccharin fell from the list

ALCOHOL Cirrhosis of the liver isn't the only damage alcohol does: it can also lead to cancers of the mouth, larynx and esophagus. The report links drinking with liver and breast cancer as well

ETHYLENE OXIDE Used to sterilize hospital instruments, it can increase the risk of non-Hodgkin's lymphoma and leukemia. Patients aren't in danger, since the volatile chemical leaves no trace. It's people who work with the stuff who are at risk

SNUFF & SMOKELESS TOBACCO It's more than disgusting. It's deadly. The next time a ballplayer comes to the plate with a chaw in his cheek, remember the cancers of the mouth, lip and tongue he might develop. A truly big-league health risk

PHENOLPHTHALEIN Now mostly used as a reagent in labs, this chemical was common in over-the-counter laxatives--until products with phenolphthalein were pulled from the shelves. Check the ingredients of packages that have been sitting around in your medicine cabinet for a time

DIESEL EXHAUST Grimy fumes from buses and trucks may boost lung-cancer rates. The Clinton Administration has called for new, low-sulfur fuel use in all diesel engines starting in 2007, perhaps cutting carcinogens 90%

SOLAR RADIATION & SUN LAMPS A deep tan may look nice, but is it worth the melanoma and other skin cancers it leads to?

BENZIDINE-BASED DYES Nothing harmful about these compounds, which are used to color textiles and paper--until they're inhaled or enter the mouth. Once in the body, though, they break down into free benzidine, a cause of bladder cancer

SECONDHAND SMOKE Big Tobacco may howl, but the government's verdict is in, and secondhand smoke is now considered a known human carcinogen, leading to lung cancer even in nonsmokers

TOBACCO A no-brainer. Cigarettes are the leading preventable cause of cancer in developed countries and are implicated in malignancies of the lung, larynx and esophagus

TAMOXIFEN This one, the government concedes, is tricky. Tamoxifen is considered an effective drug for staving off breast cancer in high-risk women and preventing a recurrence in women who already have the disease. But it's also known to increase the risk of uterine cancer. The Food and Drug Administration has nonetheless determined that the benefits of the drug outweigh the risks, and HHS scientists are concerned that the new report could discourage some women who could be helped by tamoxifen from taking it