In its “12th Report on Carcinogens,” The US Department of Health and Human Services (HHS) expands the list of chemicals and biological agents that may put people at increased risk for cancer. As of June 2011, HHS considers the following substances as reasonably anticipated to be human carcinogens:
• 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. Formaldehyde is also commonly used as a preservative in medical laboratories, mortuaries, and some consumer products, including some hair straightening products. First listed in the 2nd Report on Carcinogens, there is now sufficient evidence from studies in humans to show 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 specific cancer of the white blood cells known as myeloid leukemia.
• Aristolochic acids: A family of acids that occur naturally in some plant species. Aristolochic acids have been shown to cause high rates of bladder or upper urinary tract cancer among individuals with kidney or renal disease who consumed botanical products containing aristolochic acids.
• Captafol: A fungicide that had been used to control fungal diseases in fruits, vegetables, ornamental plants, and grasses, and as a seed treatment. Captafol was found to induce cancer in experimental animal studies, which demonstrated that dietary exposure to captafol caused tumors at several different tissue sites in rats and mice.
• Cobalt-tungsten carbide (in powder and hard metal form): Used to make cutting and grinding tools, dies, and wear-resistant products for a broad spectrum of industries, including oil and gas drilling, as well as mining. Evidence of lung cancer in workers involved in cobalt-tungsten carbide hard metal manufacturing.
• Certain inhalable glass wool fibers: Particularly, premium, special purpose fibers. These fibers that can enter the respiratory tract, are highly durable, and are biopersistent, meaning they remain in the lungs for long periods of time.
• o-Nitrotoluene: 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. Experimental animal studies showed tumor formation at many different tissue sites in rats and mice.
• Riddelliine: A botanical agent, found in certain plants of the genus Senecio, a member of the daisy family; common names for Senecio plants are ragwort and groundsel. Found to cause cancer of the blood vessels in rats and mice, leukemia and liver cancer in rats, and lung tumors in mice.
• Styrene: A synthetic chemical used worldwide in the manufacture of products such as rubber, plastic, insulation, fiberglass, pipes, automobile parts, food containers, and carpet backing. People may be exposed to styrene by breathing indoor air that has styrene vapors from building materials, tobacco smoke, and other products. 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.
Interested readers may access the “12th Report on Carcinogens” covering 240 substances, at: http://ntp.niehs.nih.gov/go/roc12.
