These things may cause cancer, too

The National Institutes of Health has added these eight substances to its lists of known and suspected carcinogens, making the total 240:

Carcinogen What it is Where it is found What it may cause*
Aristolochic acids A naturally occurring plant acid leaf In some botanical products and as a contaminant in some herbal products Bladder and upper urinary tract cancer
Formaldehyde Industrial chemical, laboratory preservative house and factory Household products such as composite wood, papers, plastics, synthetic fibers Throat, sinus and nasal cancer; myeloid leukemia
Captafol A fungicide used on plants leaf Not here; it was banned in the United States in 1999 Tumors in several places in mice and rats
Cobalt-tungsten carbide Metal composite to make cutting and grinding tools and dies factory Primarily found in manufacturing Lung cancer in humans who work with it
Some inhalable glass wool fibers Specific fibers that remain in the lungs for a long time house Insulation is most common use, although fibers in most types of insulation appear less likely to cause cancer Lung cancer in animals
o-Nitrotoluene Organic compound for preparing dyes and chemicals factory Manufacturing settings where it is used or produced. Workers exposed through skin or by inhaling it Tumors in many tissues in rats and mice
Riddelliine A botanical found in Senecio plants in the daisy family leafSome herbal medicines Cancer of blood vessels, liver, leukemia, and lung tumors in animals
Styrene Synthetic chemical used in rubber, fiberglass, plastic and more house and factoryCigarette smoke and indoor air that has styrene vapors from building materials Lymphohematopoietic cancer; genetic damage to white blood cells

*In humans unless noted
SOURCES: National Institute of Environmental Health Sciences, National Toxicology Program.
GRAPHIC: Bonnie Berkowitz and Laura Stanton - The Washington Post. Published June 11, 2011.