Eight substances have been added to the Report on Carcinogens, bringing the total list to 256 substances that are known or reasonably anticipated to cause cancer in humans. These include a chronic bacterial infection, a flame retardant and six water disinfection byproducts.

This is the 15th Report on Carcinogens, mandated by Congress and prepared by the National Toxicology Program (NTP) for the Secretary of the U.S. Department of Health and Human Services. The Report on Carcinogens identifies many different environmental factors, collectively called substances, including chemicals; infectious agents, such as viruses; physical agents, such as X-rays and ultraviolet radiation; and exposure scenarios.

In the new report, chronic infection with the bacterium Helicobacter pylori is listed as known to be a human carcinogen, while the flame-retardant chemical antimony trioxide and six haloacetic acids found as water disinfection byproducts are listed as reasonably anticipated.

Helicobacter pylori is a bacterium that colonizes in the stomach and can cause gastritis and peptic ulcers. Most people do not show symptoms. Chronic infection may lead to stomach cancer and a rare type of stomach lymphoma. Infection primarily occurs from person-to-person contact, especially in crowded housing conditions, and may occur by drinking well water contaminated with H. pylori.

Antimony trioxide is primarily used as a component of flame-retardants in plastics, textiles and other consumer products. The highest exposure occurs among workers who produce the substance or use it to make flame retardants, but low-level exposure can also occur from breathing contaminated outdoor air or dust from the wear and tear of flame-retardant-treated consumer products, such as carpets and furniture.

Haloacetic acids (HAAs) are formed during the disinfection of water from a reaction between the chlorine-based disinfection agents and organic matter in the source water. Approximately 250 million U.S. residents use community water systems and are potentially exposed to HAAs in disinfected water.
The following six HAAs are included in the report:

• Bromochloroacetic acid (BCA)
• Bromodichloroacetic acid (BDCA)
• Chlorodibromoacetic acid (CDBA)
• Dibromoacetic acid (DBA)
• Dichloroacetic acid (DCA)
• Tribromoacetic acid (TBA)

Source: “Eight substances added to 15th Report on Carcinogens,” National Institute of Environmental Health Sciences, Dec. 21, 2021