Carcinogens Added to National Toxicology Report


Four carcinogens have recently been added to the U.S. Department of Health and Humans Services’ 13th Report on Carcinogens. The report is a science-based, public health document that recognizes biological, physical, and chemical agents regarded as cancer hazards for people living in the United States. This new report now has 243 listings.

Carcinogens Report

The Report on Carcinogens is a congressionally mandated report prepared by the National Toxicology Program for the U.S. Department of Health and Human Services Secretary, Sylvia M. Burwell. It identifies exposures, mixtures, substances, or agents in two specific categories. One group is “known to be a human carcinogen,” and the other, “reasonably anticipated to be a human carcinogen.”

A listing in the report does not mean the substance will cause cancer; however, a listing does show it is a carcinogen and a cancer hazard.

Linda Birnbaum, Ph.D., director of the National Institute of Environmental Health Sciences and the National Toxicology Program explains, “This report provides a valuable resource for health regulatory and research agencies, and it empowers the public with information people can use to reduce exposure to cancer causing substances. Identifying substances in our environment that can make people vulnerable to cancer will help in prevention efforts.”

Factors that can affect whether a person will develop cancer include an individual’s susceptibility to a substance, and the duration and amount of exposure.

O-toluidine Added as a Known Human Carcinogen

A new cancer study led by the National Toxicology Program added o-toluidine in the group known as human carcinogens. O-toluidine is a synthetic-chemical produced in other countries and imported in high volumes by several companies into the United States.

This carcinogen is used in some medical and consumer products.

The primary usage of o-toluidine is for making dyes, pesticides, and rubber chemicals.

In the workplace, people are at a heightened cancer risk if they expose themselves to the chemical through inhalation and/or skin contact. In addition, tobacco smoke is also a source of exposure.

Three Substances Added as Reasonably Anticipated to Be a Human Carcinogen

Pentachlorophenol is used industrially for treating fence posts, wood pilings, utility poles, and timber or lumber for construction.

Pentachlorophenol and its by-products are complex mixtures of chemicals used as wood preservatives. Since the 1980s, pentachlorophenol was regulated as a “restricted-use pesticide.”

Many exposures have occurred in settings where workers treat lumber or where they have been exposed to treated lumber. People are also exposed to this mixture from breathing contaminated dust or air, or from coming in contact with contaminated soil.

Studies in humans show exposure to this mixture was associated with an increased risk of non-Hodgkin lymphoma. Studies also show pentachlorophenol caused tumors in the liver and other organs in mice.

In many commercial industries, a colorless to pale yellow liquid called 1-bromopropane is used as a solvent to clean metals, electronics, and optics. Foam cushion manufacturers also use it as a solvent for an aerosol-applied adhesive.

When compared to the public, workers in certain occupations may be more exposed to 1-bromopropane; including aircraft maintenance, and dry cleaning.

Exposure to 1-bromopropane caused tumors in rodent’s organs, including the large intestine, lungs, and skin. However, no human studies were identified that evaluated the relationship between exposure to 1-bromopropane and human cancer.

No human studies were identified that viewed the relationship between exposure to the flammable and liquid chemical cumene and human cancer; however, inhalation exposure to cumene caused liver tumors in female mice, and lung tumors in female and male mice.

Cumene is primarily used to make acetone and phenol. The main exposure to cumene for people comes in workplaces that use or produce cumene and through the environment.

Cumene has a gas-like odor and is a natural component of petroleum and coal-tar. It is also found in cigarette smoke and the emission of petroleum products.

More information on carcinogens and their impact on your health, as well as the 13th Report on Carcinogens can be found at the U.S. Department of Health and Human Services website here.

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George Zapo, CPH
George Zapo, CPH is certified in Public Health Promotion & Education. George focuses on writing informative articles promoting healthy behavior and lifestyles. Read more of George's articles at his website: