The widely used preservative formaldehyde, and styrene, which is found in food containers and coffee cups, are among eight agents added to a list of known and suspected carcinogens by the National Institutes of Health.
Formaldehyde, which has been linked to leukemia and a rare type of nasal cancer, is "known to be a human carcinogen," according to the congressionally mandated report published Friday on the health agency's website. Researchers categorized styrene as "reasonably anticipated" to be cancer-causing.
The compounds bring the total number of substances linked to cancer to 240. Aristolochic acids, found in herbal products that are used to treat arthritis and gout, were also listed as a known carcinogen because they can cause bladder or urinary-tract cancer in people with kidney disease.
The Food and Drug Administration cautioned consumers in 2001 against taking supplements containing aristolochic acid, according to the report.
"A listing in the report does not by itself mean that a substance will cause cancer," John Bucher, associate director of the National Toxicology Program of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., said in a conference call with reporters.
The cancer-causing risk from formaldehyde and styrene comes from the products' widespread use in industrial applications and less from their presence in consumer products, Bucher said.
Cal Dooley, president and CEO of the American Chemistry Council, a Washington trade group, said in a statement that the report made "unfounded classifications" about formaldehyde and styrene that would scare consumers.
The American Composite Manufacturers Association, a trade group based in Arlington, Va., disputed the link between styrene and cancer.
"The styrene-based composite material system has been used safely for over 60 years," the association said in a statement. Its members include Owens Corning Inc. of Toledo, Ohio, and Pittsburgh-based PPG Industries Inc.
Styrene is a component of the polystyrene used in food and drink containers, as well as the manufacturing of plastics, fiberglass, insulation, carpet backing, and other products, according to the National Toxicology Program. Cigarette smokers face higher risks of exposure than others because the smoke contains styrene, the agency said.
Consumers don't need to worry about polystyrene cups and food containers, although they should seek versions of products such as cosmetics that don't contain formaldehyde, said Otis Brawley, chief medical officer of the Atlanta-based American Cancer Society.
"I see no problem with Styrofoam cups," Brawley said Friday in a telephone interview. "If I were using nail polish or nail-polisher remover, I would try to get formaldehyde-free versions of those, which are available."
The report is the 12th issued by the United States since the National Toxicology Program was established in 1978.