The US Department of Health and Human Services has added seven new substances to its list of carcinogens deemed harmful to human health.
The US Department of Health and Human Services (HHS) has added seven new substances to its list of carcinogens deemed harmful to human health. The new carcinogens include two chemical compounds and five viruses that have been linked to cancer.
The two compounds added to the carcinogens list are the chemical trichloroethylene (TCE) and the metallic element cobalt (as well as cobalt-based substances that release cobalt ions). The five viruses are:
The HHS made the additions as part of its 14th Report on Carcinogens, bringing the total number of substances on the list to 248. Prepared by the National Toxicology Program and mandated by Congress, the report has historically identified environmental factors, including chemicals, infectious agents (such as viruses), physical agents (such as x-rays), and chemical mixtures known to be human carcinogens or “reasonably anticipated” to be human carcinogens.
All are being added to the “known to be a human carcinogen” category and, collectively, they have been linked to more than 20 different types of cancers. For example, individuals with weakened immune systems due to HIV-1 are thought to be at increased risk for non-Hodgkin’s and Hodgkin’s lymphomas, anogenital cancers, Kaposi’s sarcoma, liver cancer, non-melanoma skin cancer, and eye cancer, and possibly lung cancer. Additionally, human epidemiological studies and molecular studies have shown that human T-cell lymphotropic virus type 1 causes adult T-cell leukemia-lymphoma, while EBV can lead to Burkitt lymphoma, Hodgkin’s lymphoma, immune suppression—related non-Hodgkin’s lymphoma, nasal-type extranodal natural killer (NK)/T-cell lymphoma, nasopharyngeal cancer, and some types of stomach cancer. Kaposi’s sarcoma-associated herpesvirus can, of course, lead to Kaposi’s sarcoma as well as primary effusion lymphoma and a specific plasmablastic variant of multicentric Castleman disease. Finally, Merkel cell polyomavirus has been shown to cause Merkel cell carcinoma.
However, according to HHS, although the report lists these viruses as “cancer hazard[s],” their inclusion does not “mean that a substance or a virus will cause cancer.” There are many factors mitigating an individual’s cancer risk following exposure to these viruses, including their individual susceptibility and “the amount and duration of exposure.”
“Given that approximately 12% 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,” Linda Birnbaum, PhD, director of the National Institute of Environmental Health Sciences and National Toxicology Program said in a statement released with the report. “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.”
Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.