Bruce N. Ames is a professor of biochemistry and molecular biology at the University of California at Berkeley. He is best known for the development of a test that has been used as an indicator of the carcinogenicity (cancer-causing potential) of chemicals. Known as the Ames test, it measures the rate of mutation in bacteria after the introduction of a test substance. His research led to a greater appreciation of the role of genetic mutation in cancer and facilitated the testing of suspected cancer-causing chemicals. He also developed a data base of chemicals that cause cancer in animals, listing their degree of virulence. Ames has been involved in numerous controversies involving scientific and environmental policies relevant to cancer prevention . In the 1970s he vociferously advocated strict government control of synthetic chemicals. In the 1980s, however, the discovery that many natural substances were also mutagenic (causing gene mutation), and...