Spotlight: A Scientist Goes Public


Who is Bruce Ames, and why are environmentalists saying all those terrible things about him?

He's certainly an unlikely candidate for political controversy. At 59, Ames is an internationally known scientist, chairman of the biochemistry department at the University of California at Berkeley, and creator of the Ames screen—a quick, inexpensive, and widely used laboratory test for mutagens, chemicals that cause genetic mutations. He was one of the first scientists to recognize that many mutagens also cause cancer.

Soft-spoken, with a professorial manner that includes illustrating his points by writing on the blackboard or giving visitors handouts, Ames is clearly more at home in the lab or a classroom than in a legislative hearing. "Bruce is a scientist, not a politician," says Jeff Baker, one of his postdoctoral students. "Some of the things he says may not be particularly trendy, but they're based on the data."

And there's the rub. Ames may be first and foremost a scientist, but his devotion to his work, and to the data it has produced, has dragged him into the political arena.

Ames's recent research, summarized in an April article in Science magazine, indicates that the risks of natural carcinogens may far outweigh those of manmade pollution, additives, and toxic wastes. For example, Ames calculates that a single raw mushroom, a gram of dried basil, or a half ounce of beer are nearly 100 times more carcinogenic than the average daily intake of the controversial pesticide EDB. "You can't eat a meal," he says flatly, "that doesn't have carcinogens."

Not that he thinks people should give up eating. On the contrary, Ames's point is that the relative dangers of toxic wastes have been widely exaggerated. He argues that cancer risks are systematically overstated by "worst case" assumptions. Even accepting such assumptions, Ames estimates that the total carcinogenic risk of pesticides is equal to that of drinking two beers a year. "It's crazy to go after hazards so small."

Predictably, such views have drawn him into conflict with environmentalists. Last year, Ames publicly opposed California's "toxics initiative," Proposition 65. It passed overwhelmingly, outlawing the release of any amount of toxic wastes known to cause cancer or birth defects. Ames objected to the zero-level limit on pollutants.

"Human blood wouldn't pass the Toxic Substances Initiative if it got into a stream," he says. "Proposition 65 is a lawyers' welfare act. I don't think it will have any effect on public health."

But California Governor George Deukmejian invited Ames to serve on the committee that determines which chemicals should be listed as carcinogens under Prop. 65. The committee released a list of 29 such pollutants—only those actually proven to cause cancer or birth defects in humans, not those whose danger has been extrapolated from rodent tests.

Environmentalists are outraged. "I've never seen a clearer fox-in-the-coop situation," says Sierra Club spokesman Carl Pope about Ames's presence on the committee. (Ames, however, notes that he does no consulting for the chemical, drug, or food industry, or for law firms—thus avoiding conflicts of interest.)

Ames's own views have evolved since he first began his research. Originally a molecular biologist, he became interested in the carcinogenic hazards of food while working at the National Institutes of Health in the mid-'60s. "I started reading too many labels on packages of potato chips and seeing all these ingredients," he recalls. At NIH, "we were always mutating cells, so I became interested in whether some of the new man-made chemicals coming into the environment might be mutagens."

In the early '70s, he wanted to ban almost any such chemicals that showed up as mutagens on the Ames screen. But, over time, scientists discovered that nature abounds in mutagens, most of which cause cancer. Gradually, Ames came to realize that the hazards of manmade chemicals are "just a drop in the bucket."

He believes there should be a cutoff level below which carcinogenic risks are ignored. "The minute you try to regulate things to one in one million risk, you're lost. It means you're putting your best people on very minor things, when the world is full of one in one thousand or ten thousand risks."

Ames, who enjoys reading the work of Nobel laureate economist F.A. Hayek, notes that manufacturers have strong economic incentives to eliminate carcinogens from their products: "The market is constantly substituting less dangerous things for more dangerous ones."

Like many scientists, Ames believes that the major public health hazards stem from excessive drinking, sunbathing, and especially smoking. "Cigarettes cause 350,000 deaths per year, yet the government in its wisdom subsidizes tobacco farmers," he says in disgust. "You can see where the priorities are—it's all politics, not public health." And it's to change those priorities that Bruce Ames has come out of his lab.

Dale Gieringer is a free-lance writer in Oakland, California.