Cancer risk of chemicals in the environment uncertain

People are exposed to a massive number of chemicals in the environment, and scientists know very little about their potential role in causing cancer, according to a new report from the President’s Cancer Panel released Thursday.

Government and industry should invest much more money in researching the potential risks of such chemicals — and that research should be done before the chemicals come into wide use, not after large numbers of people have been exposed to them, the report said.

The report makes few concrete recommendations, said the panel chairman, Dr. LaSalle D. Leffall Jr. of the Howard University College of Medicine. “Everyone said, ‘Please, whatever you do, make sure any definitive statement is based on evidence,’ ” he said, and that evidence simply isn’t available yet.

“I think one of the major things to come out of this report will be an improvement of consumer awareness” of the number of potential risks people may be exposed to, he said.

Reaction to the report was mixed.

“We agree that there are many important issues here … but a reader would come away from this report believing that pollutants cause most cancer,” said Dr. Michael Thun, emeritus vice president of epidemiology at the American Cancer Society. In fact, he said, most cancers are caused by tobacco, alcohol, overexposure to ultraviolet light, radiation and sexually transmitted infections. The report “presents an unbalanced perspective” of the relative importance of these various factors, he said.

Thun also took issue with a statement in the report that said the true burden of environmental pollutants is “grossly underestimated.”

That, Thun said, is the view of some “but by no means a clearly established fact.”

Elizabeth M. Whelan, president of the American Council on Science and Health, whose views often coincide with industry’s, noted that despite the growing exposure to chemicals in the environment, “cancer death rates are going down. The so-called environmental trace levels of chemicals play no role whatsoever in the etiology of cancer.”

But Julia G. Brody, executive director of the Silent Spring Institute, formed 15 years ago to investigate environmental links to breast cancer, noted that much of the decrease in cancer rates is because of reduced smoking. Breast cancer rates have remained steady, while hormonal cancers, testicular cancer, children’s cancer and brain cancer are increasing, she said.

Only a quarter of breast cancer is genetic, she said, and “we don’t know what fraction is due to environmental chemical exposure. Because so many women have it, however, even if it is only a small percentage, avoiding those exposures could save thousands of women.”

About 1.5 million Americans develop cancer each year and 560,000 die from it, the report noted. About 41% of the population will develop cancer at some point in their lifetimes. The role of environmental chemicals “is really quite amorphous,” Leffall said. “But if we continue to look at it, maybe it will be less amorphous because we will know more about it.”

The report highlights some potential risks that almost everyone agrees on. Those include: the increasing exposure to radiation as the result of greater use of medical testing and treatment; radon in homes, particularly in the East; and exposure to toxic chemicals during military service and for people living close to military bases.

The President’s Cancer Panel is a three-member committee that reports to the chief executive on the progress of the battle against cancer. Its current members, Leffall and Margaret L. Kripke of the University of Texas M.D. Anderson Cancer Center, were appointed by President George W. Bush. The third member of the panel is normally a public member, usually a cancer survivor.

Cyclist Lance Armstrong was the third member until his term expired. Leffall said President Obama is waiting until a new director of the National Cancer Institute is appointed before nominating a new member.