After years of delays because of pressure from the chemical industry, the U.S. Department of Health and Human Services has added eight substances—including formaldehyde, which is common in household products—to its Report on Carcinogens, a science-based document that identifies chemicals and biological agents that may increase people’s risk for cancer.

Formaldehyde and a botanical known as aristolochic acids are listed as known human carcinogens. Six other substances—captafol, cobalt-tungsten carbide (in powder or hard metal form), certain inhalable glass wool fibers, o-nitrotoluene, riddelliine and styrene—are added as substances that are reasonably anticipated to be human carcinogens. With these additions, the 12th Report on Carcinogens now includes 240 listings. It is available at http://ntp.niehs.nih.gov/go/roc12.

“This report underscores the critical connection between our nation’s health and what’s in our environment,” says John Bucher, Ph.D., associate director of the National Toxicology Program.

The Report on Carcinogens identifies agents, substances, mixtures or exposures in two categories: known to be a human carcinogen and reasonably anticipated to be a human carcinogen. Many factors, including the amount and duration of exposure and an individual’s susceptibility to a substance, affect whether a person will develop cancer.

Formaldehyde–a colorless, flammable, strong-smelling chemical that is widely used to make resins for household items such as composite wood products, paper product coatings, plastics, synthetic fibers, and textile finishes—was first listed in the second Report on Carcinogens as a substance that was reasonably anticipated to be a human carcinogen, after laboratory studies showed it caused nasal cancer in rats. Human studies have now shown that individuals with higher measures of exposure to formaldehyde are at increased risk for certain types of rare cancers, including nasopharyngeal (the nasopharnyx is the upper part of the throat behind the nose), sinonasal, as well as a white blood cell cancer known as myeloid leukemia.

Certain inhalable glass wool fibers made the list based on experimental animal studies. Not all glass wool or man-made fibers were found to be carcinogenic. The report cites only those fibers that can enter the respiratory tract, are highly durable and remain in the lungs for long periods of time. Low-cost, general purpose glass fibers used in home and building insulation appear to be less likely to cause cancer in humans.

Styrene—a synthetic chemical used to make rubber, plastic, insulation, fiberglass, pipes, automobile parts, food containers and carpet backing—is on the list based on human cancer studies, laboratory animal studies and mechanistic scientific information. The limited evidence of cancer from studies in humans shows lymphohematopoietic cancer and genetic damage in the white blood cells, or lymphocytes, of workers exposed to styrene. People may be exposed to styrene by breathing indoor air that has styrene vapors from building materials, tobacco smoke and other products.

Intense lobbying by the chemical industry delayed the release of the Report on Carcinogens for years, Gardiner Harris reports in The New York Times. Dr. Otis Brawley, chief medical officer at the American Cancer Society, told the Times that formaldehyde is worrisome and pervasive. “It’s the smell in new houses, and it’s in cosmetics like nail polish,” he said. “All a reasonable person can do is manage their exposure and decrease it to as little as possible. It’s everywhere.”

President Obama signed a law establishing the first national standards for formaldehyde in composite wood products last year. The Formaldehyde Standards for Composite Wood Act establishes emission standards for hardwood plywood, medium density fiberboard and particleboard sold in the United States. The glue that holds together household composite wood products such as furniture, cabinets and flooring contains formaldehyde. By January 1, 2013, all products sold in the United States will have formaldehyde emissions of 0.09 parts per million or less—the most stringent standard for formaldehyde emissions in the world.

Until then new, be a conscious consumer when it comes to particleboard purchases. Use the PureBond Fabricator network to find formaldehyde-free products, and buy third-party certified furnishings and flooring. Look for the Greenguard Indoor Air Quality Certified Products seal (and check out its searchable database of low-emitting products) and the Green Seal Certified Products seal. The Pharos Project also rates and selects healthy building materials, and Scientific Certification Systems Certified Products offers Sustainable Choice and Environmentally Preferable Products programs.