'Seven new substances added to list of carcinogens'

Seven newly reviewed substances, including five viruses, chemical and a metallic element, have been linked to cancer risk in humans, bringing the total list of carcinogens to 248, according to a new report.
The five viruses include human immunodeficiency virus (HIV) type 1, human T-cell lymphotropic virus type 1, Epstein-Barr virus, Kaposi sarcoma-associated herpesvirus and Merkel cell polyomavirus.
The chemical trichloroethylene (TCE), the metallic element cobalt and cobalt compounds that release cobalt ions in vivo, were also added to the list in the US Department of Health and Human Services 14th Report on Carcinogens.
"Given that about 12 per cent 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 US National Institute of Environmental Health Sciences (NIEHS) and National Toxicology Programme (NTP).

"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," said Birnbaum.
All five viruses are being added to the category of known to be a human carcinogen. Collectively, these viruses have been linked to more than 20 different types of cancers.

Human immunodeficiency virus type 1 (HIV-1) is a virus that is spread through unprotected sexual activity, infected drug needles, during pregnancy from mother to child, and through infected breast milk.

Human T-cell lymphotropic virus type 1 (HTLV-1) is a virus that people are exposed to through contact with contaminated cells or biological tissues, such as breastfeeding, sharing of needles or syringes with infected individuals, or unprotected sexual activity. It is not transmitted by casual contact.
Epstein-Barr virus (EBV) is a herpesvirus, transmitted primarily through saliva. It is a common virus, infecting more than 90 per cent of adults worldwide.
Most people infected with EBV remain healthy and without symptoms. In some cases, EBV can cause infectious mononucleosis, also called mono.
Kaposi sarcoma-associated herpesvirus (KSHV) is a herpesvirus transmitted from person to person primarily through saliva. It can be transmitted through sexual contact, primarily among men who have sex with men.

It can also be spread through blood, and transmitted from an infected mother to a child. Healthy individuals can be infected with the virus and show no signs or symptoms.
Merkel cell polyomavirus (MCV) is a common virus that lives on the skin, though it rarely produces symptoms or leads to cancer.
Healthy people continuously shed MCV from the skin surface. Close personal contact with saliva or skin of an infected individual may be how people are exposed to the virus.