The US Department of Health and Human Services (HHS) last week (June 10) issued its 12th Report on Carcinogens, adding seven chemicals and biological agents whose exposure may pose an increased risk of cancer. The HHS also upgraded one substance from a "reasonably anticipated to be a human carcinogen" to "known to be human carcinogen." The full list, which now includes 240 potentially harmful substances, is available here. Here's a rundown of the newbies:

Formaldehyde: This industrial chemical, an ingredient in household items such as coatings and finishes and a widely employed medical and scientific preservative, was originally listed in the HHS's 2nd report under the "reasonably anticipated" category of carcinogens after researchers discovered that it caused nasal cancer in rats. Now, with additional evidence of the chemical's toxic effects coming from human studies, its listing has been changed to a "known" carcinogen. Exposure to...

Aristolochic acids: This family of acids occurs naturally in certain plants, and its consumption has been shown to increase the risk of bladder or upper urinary tract cancer in kidney or renal disease patients, warranting its addition as a "known" carcinogen. In 2001, the US Food and Drug Administration issued a warning that effectively ended domestic production of botanical products containing aristolochic acids, but such products can still be purchased online and abroad. Furthermore, the acids may contaminate herbal supplements marketed to treat diseases such as arthritis, gout, and inflammation.

Captafol: This fungicide has been added as a "reasonably anticipated" carcinogen thanks to rodent studies that found that its consumption led to tumors in a variety of tissues. Though it was banned in the United States in 1999, halting its use on crops such as fruits, vegetables, ornamental plants, and grasses, even past exposures may have an effect on health, the HHS warns.

Cobalt-tungsten carbide (in powder or hard metal form): Used to make cutting and grinding tools, dies, and wear-resistant products for industries such as oil and gas drilling and mining, this chemical compound (commonly referred to as cemented or sintered carbides) may cause lung cancer in individuals working in cobalt-tungsten carbide hard metal manufacturing. It was added as a "reasonably anticipated" carcinogen.


Certain inhalable glass wool fibers: Animal studies suggest that fibers able to enter the respiratory tract, are highly durable, and remain in the lungs for long periods of time may be carcinogenic, according to the new report. This definition does not include all glass wool fibers, and in fact, the most commonly used glass wool, such as that used for home and building insulation, is not highly durable or persistent in the lungs, and is not likely to cause cancer.

o-Nitrotoluene: Rodent studies have shown that this compound—a common intermediate of dyes, agricultural chemicals, and pharmaceuticals, among other products—may cause tumor growth in a variety of tissues. Exposure through the skin or inhalation during its production and use may pose a similar risk, prompting the HHS to list the substance as a "reasonably anticipated" carcinogen.

Riddelliine: Found in some plants of the daisy family, common in the western United States, this compound is now listed as a "reasonably anticipated" carcinogen as a result of rodent studies that show it can cause leukemia, liver cancer, lung tumors, and cancer of the blood vessels. While no riddelliine-containing plants are used for food or commercial purposes in the United States, at least 13 species are used in herbal medicines, and may be consumed as food in other parts of the world. Exposure could also result from consuming animal products from species that feed on the plants.

Styrene: Human and animal studies have both provided limited evidence that people exposed to this synthetic chemical, used to make rubber, plastic, and other common materials, are at a higher risk of developing lymphohematopoietic cancer and genetic damage in the white blood cells. Exposure can occur through inhalation of styrene vapors in indoor air or, more commonly, tobacco smoke.

Interested in reading more?

Become a Member of

Receive full access to more than 35 years of archives, as well as TS Digest, digital editions of The Scientist, feature stories, and much more!
Already a member?