The U.S. Department of Health and Human Services 14th Report on Carcinogens released in November adds seven new substances to the list of suspected carcinogens, bringing the total to 248.

The chemical trichloroethylene – a solvent used in adhesives, paint removers, typewriter correction fluid and spot removers – the metallic element cobalt, and compounds that release cobalt ions in living organisms were added to the list, as were five viruses that have been linked to cancer in humans.

The five viruses are 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,” said Linda Birnbaum, director of the National Institute of Environmental Health Sciences and National Toxicology Program.

“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,” she said.

The Report on Carcinogens is a congressionally mandated report that identifies environmental factors, collectively called substances, including chemicals, infectious agents such as viruses, physical agents such as X-rays and ultraviolet radiation, mixtures of chemicals that are known to be a human carcinogen and reasonably anticipated to be a human carcinogen.

Released Nov. 3, the report is available at

The National Institutes of Health notes that a listing indicates a cancer hazard but does not by mean a substance or a virus will cause cancer. Many factors, including an individual’s susceptibility to a substance and the amount and duration of exposure can affect whether a person will develop cancer.

In the case of viruses, a weakened immune system may also be a contributing factor. People are advised to talk to their health care providers about decreasing their cancer risk from viruses.

The Report on Carcinogens is prepared by the National Toxicology Program, a federal interagency program whose goal is to safeguard the public by identifying substances in the environment that may affect human health. See

NIEHS supports research to understand the effects of the environment on human health and is part of NIH. For information on environmental health topics see

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