The U.S. Department of Health just added eight substances to its list of chemicals and biological agents that may put people at an increased risk for cancer. Two of them are familiar names--one is used in resins for household items and the other in some takeout food containers.
Formaldehyde was classified as a "known human carcinogen" in the department's Report On Carcinogens. The report says individuals with high exposure to formaldehyde are at increased risk for certain rare types of cancers, including some forms of nasal cancer and a specific cancer of the white blood cells called myeloid leukemia. The chemical is use in resins for composite wood products, paper product coatings, plastics, synthetic fibers and textile finishes, as well as a preservative in medical labs and mortuaries, and in some hair-straightening products.
Styrene, the other well-known name on the list, was classified as a substance "reasonably anticipated" to be a human carcinogen. Limited evidence of cancer from studies in humans show lymphohematopoietic cancer and genetic damage in white blood cells of workers exposed to styrene. The greatest exposure in the general population to styrene is through cigarette smoking, but it's also used to make food containers, carpet backing, insulation, automobile parts, rubber, plastic and many other products. The report noted workers in certain occupations may potentially be exposed to much higher levels of styrene than the general population.
Like formaldehyde, aristolochic acids were called known human carcinogens. High rates of bladder or upper urinary tract cancer have been seen among individuals with kidney or renal disease who consumed botanical products containing aristolochic acids. The U.S. Food and Drug Administration warned consumers in 2001 to stop taking herbal products with those acids, but they still can be purchased on the Internet and abroad, and may be found as a contaminant in herbal products used to treat a variety of symptoms and diseases, such as arthritis, gout and inflammation.
In addition to styrene, five other substances were added on June 10 to the report and labeled as reasonably anticipated to be human carcinogens. They include:
• Certain inhalable glass wool fibers, which can enter the respiratory tract, are highly durable and which remain in the lungs for long periods of time.
• o-Nitrotoluene, which showed tumor formation at many different tissue sites in rats and mice. Used as an intermediate in the preparation of azo dyes and other dyes, including magenta and various sulfur dyes for cotton, wool, silk, leather, and paper. It is also used in preparing agricultural chemicals, rubber chemicals, pesticides, petrochemicals, pharmaceuticals, and explosives.
• Riddelliine, which has been found to cause cancer of the blood vessels in rats and mice, leukemia and liver cancer in rats, and lung tumors in mice. Riddelliine-containing plants, which include certain daisies in the Senecio family that are grown in sandy soil in the western U.S., are not used for food in the United States, and have no known commercial uses. But the report said it would be possible to get exposed by eating or drinking certain foods contaminated by the plants or by eating products from animals that fed on them.
• Captafol, a fungicide that had been used to control fungal diseases in fruits, vegetables, ornamental plants, and grasses, and as a seed treatment. It has been banned in the United States since 1999, but past exposures may still have an effect on health.
• Cobalt-tungsten carbide, which showed limited evidence of lung cancer in workers involved in cobalt-tungsten carbide hard metal manufacturing. Cobalt-tungsten carbide is used to make cutting and grinding tools, dies, and wear-resistant products for many industries.
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