Congress and the National Cancer Institute should lead an effort to change the ways animal data are used to predict whether a chemical would cause cancer in humans, the medical director of a consumer-education organization said Jan. 26.
Gilbert Ross, a physician who directs the American Council on Science and Health, was summarizing some of the key recommendations made in a book, America's War on "Carcinogens": Reassessing The Use of Animal Tests to Predict Human Cancer Risk, which the council unveiled through panel discussions held at the Cato Institute.
The council describes its top priority as helping Americans distinguish between real and hypothetical health risks. The Cato Institute seeks to promote "limited government, individual liberty, free markets and peace."
America's War on "Carcinogens" argues that a fundamental assumption underlying federal and state agencies' use of animal test data is flawed.
The assumption is that tumors that result when laboratory animals, typically rats or mice, are exposed to high doses of a synthetic chemical, indicate the chemical could also cause human cancers, said Elizabeth Whelan, president of the American Council on Science and Health.
Criticism of Delaney Clause
The Delaney Clause, part of the 1958 Federal Food, Drug, and Cosmetic Act, requires the Food and Drug Administration to ban from certain products -- food additives, color additives, and animal drugs -- any synthetic chemical that causes cancer in animals, said Michael Bracken, an epidemiology professor at Yale University School of Medicine.
Hence, the book argues, FDA revoked approval of red dye #2 based on two questionable studies in 1976. Yet FDA had virtually no information about the substitute chemical, red dye #40, Bracken said.
Pointing to techniques that allow investigators to detect a chemical at a parts-per-trillion or lesser level, Bracken said it is time for Congress to overturn the Delaney Clause.
"Under no circumstance" said Whelan, "should we act [to ban or restrict a chemical] on the basis of one or two rodent studies."
She said regulator agencies should look at all evidence they have about a chemical not just one or two animal studies.
National Toxicology Program
Whelan criticized the National Toxicology Program's classification of chemicals, drugs, and other agents in its biennial Report on Carcinogens. She said NTP fails to consider risk and benefits of the substances named in the report and fails to distinguish between substances that are clearly human carcinogens, such as cigarettes, and substances that cause cancer only in certain circumstances, such as high-dose animal studies.
As mandated by Section 301 (b) (4) of the Public Health Services Act, the Report on Carcinogens lists substances that are known or reasonably anticipated to cause human cancer.
John Bucher, deputy director of the National Institute of Environmental Health Sciences' Environmental Toxicology Program, which manages the National Toxicology Program, pointed out that the Report on Carcinogens provides extensive information about the studies that prompted the classification of a compound as a known or reasonably anticipated carcinogen.
As to weighing risks, Bucher said, the report was never designed to do that.
America's War on "Carcinogens" makes several recommendations including urging the National Cancer Institute to develop formal recommendations on the benefits and limitations of animal testing "preferably in the form of a document that would provide a basis for the National Toxicology Program and the Environmental Protection Agency to modernize their definitions and classifications of carcinogens to reflect the best current scientific evidence."
EPA Declined to Comment on Book
Representatives of EPA declined to comment on the book or its recommendations.
Bucher said NTP has participated in a variety of efforts to improve scientists' ability to know whether a tumor found in rodents exposed to a particular substance would suggest the substance also might cause cancer in humans. He cited NTP's work on a strategy to help risk assessors determine whether there is sufficient data to understand the critical biological events, or mode of action, by which a chemical causes cancer in laboratory animals and whether those biological events would be likely to cause cancer in humans.
In addition, NTP is conducting a comprehensive review of its testing, Bucher said, referring to "A National Toxicology Program for the 21st Century: A Roadmap for the Future."
Panelists discussing the criticism of rodent tests by the American Council on Science and Health said they were hopeful a National Academies panel EPA has asked to review toxicity tests would make recommendations that would address some of their concerns. They were referring to the Committee on Toxicity Testing and Assessment of Environmental Agents.
Even if the academies panel makes sound recommendations, panel member Henry Miller, a fellow at Stanford University, said he is skeptical EPA would implement the panel's recommendations...
Council on Science, Health Urges Changes in Use of Animals to Predict Risk to Humans
By ACSH Staff — January 27, 2005
By ACSH Staff