Falling Cancer Rates Are Evidence that Synthetic Chemicals Pose No Threat to Public Health

Falling Cancer Rates Are Evidence that Synthetic Chemicals Pose No Threat to Public Health
July 1, 1997

Dr. Bruce Ames and Dr. Lois Swirsky Gold, scientists with the National Institute of Environmental Health Science Center at the University of California, Berkeley, came before the U.S. Senate on March 6 to dispute the widely held notion that cancer rates are soaring. Ames and Swirsky Gold told Senators that (after adjusting for age and excluding lung cancer from smoking) cancer rates have actually fallen 15 percent since 1950.

Neither epidemiology nor toxicology supports the idea, also widely held, that synthetic industrial chemicals are important factors in human cancer. Far more important, they told the hearing, are dietary imbalances: for example, the lack of fruits and vegetables in Americans’ diets. The quarter of the population eating the least fruits and vegetables has double the cancer rate for most types of cancer compared with the quarter eating the most, they noted.

Ignoring those and other scientific findings, regulatory policy in the United States focuses on the effects on cancer of trace amounts of synthetic chemicals. That focus on synthetic chemicals is, Ames and Swirsky Gold note, based on misconceptions about animal cancer tests. They explained, for example, that:

  • Rodent carcinogens are not rare. Fully half of all chemicals, both naturally occurring and synthetically produced, are founded to be “carcinogens” in high-dose animal cancer tests;
  • High-dose effects in rodent cancer tests are not always relevant to low-dose human exposures, and this fact helps explain the high proportion of carcinogens; and
  • Regulatory policy remains focused on synthetic chemicals, though 99.9 percent of all chemicals that humans ingest are natural.

Ames and Swirsky Gold pointed out that over 1,000 chemicals have been identified in coffee, of which only 27 have been tested. Nineteen have been found to be rodent carcinogens. Moreover, the plants human regularly eat contain thousands of natural pesticides, which protect them from insects and other predators. Of these thousands of naturally occurring pesticides, 64 have been tested and 35 have been found to be rodent carcinogens.

Regulations that aim at eliminating minuscule levels of synthetic chemicals are enormously expensive, the scientists added. EPA estimates that compliance with its regulations costs $140 billion every year. According to Ames and Swirsky Gold, the U.S. spends 100 times more to prevent one hypothetical, highly uncertain death from a synthetic chemical than it spends to save a life by medical intervention.

Efforts to reduce tiny hypothetical risks may bring unexpected costs, they observed. For example, prohibitions or limits on the use of synthetic pesticides may make fruits and vegetables more expensive, thereby decreasing consumption. Because those foods are believed to be an important part of cancer prevention, decreasing their consumption may increase cancer rates, especially among the poor.

The two scientists expressed their regret that too little money is spent on biomedical research and on educating the public about the hazards of unhealthy lifestyles. Too much money, they said, is spent on regulations that target the wrong issues.

PF: The 12-page testimony of Bruce N. Ames and Lois Swirsky Gold, "Pollution, Pesticides, and Cancer: Misconceptions," is available through PolicyFax. Call 847/202-4888 and request document #2312201.