BEWARE: 7 Substances Added to the List of Human Carcinogens

A total of seven more substances were added in the list of carcinogens released by the U.S. Department of Health and Human Services, bringing the total number of known carcinogens to 248.

The newly added substances include five viruses, a chemical and a metallic element. The five viruses added to the list of carcinogens have been previously linked to more than 20 different types of cancers in humans. These viruses include human immunodeficiency virus type 1, human T-cell lymphotropic virus type 1, Epstein-Barr virus, Kaposi sarcoma-associated herpesvirus and Merkel cell polyomavirus.

"Given that approximately 12 percent of human cancers worldwide may be attributed to viruses, and there are no vaccines currently available for these five viruses, prevention strategies to reduce the infections that can lead to cancer are even more critical," explained Linda Birnbaum, Ph.D., director of the National Institute of Environmental Health Sciences (NIEHS) and National Toxicology Program (NTP), in a press release. "The listings in this report, particularly the viruses, bring attention to the important role that prevention can play in reducing the world's cancer burden. There are also things people can do to reduce their exposure to cobalt and TCE."

The updated list of carcinogens now also includes the chemical trichloroethylene (TCE) and the metallic element cobalt and cobalt compounds that release cobalt ions in vivo.

TCE has been listed as reasonably anticipated to be a human carcinogen since 2000. However, recent studies showed that TCE exposure could increase the risk of kidney cancer. TCE is an industrial solvent typically used to make hydrofluorocarbon chemicals. It can be easily released into the air, water and soil and can breakdown slowly.

On the other hand, cobalt and cobalt compounds that release cobalt ions in vivo are being added in the list as reasonably anticipated to be a human carcinogen. Cobalt is a naturally occurring element used to make metal alloys and other compounds. The inclusion of cobalt and cobalt compounds that release ions into the body was based largely on studies in experimental animals.