The National Toxicology Program (NTP) today added three new chemicals to the "Report on Carcinogens," the government's warning list of known and potentially carcinogenic substances.

The substances are 1-bromopropane, also known as n-propyl bromide, which is used in cleaning solvents and spray adhesives; cumene, which is used to make phenol and acetone; and a complex mixture of pentachlorophenol and by-products of its synthesis, which is used as a preservative to treat wooden utility poles. All three are listed as "reasonably anticipated to be a human carcinogen" in the latest version of the report.
In addition, NTP upgraded the listing for o-toluidine, elevating its classification to a known carcinogen. Previously this substance was listed as "reasonably anticipated to be a human carcinogen." o-Toluidine is used in making rubber, pesticides, and dyes, as well as some medical and consumer products.
The report is a valuable resource for regulatory and research agencies, says Linda S. Birnbaum, director of NTP and the National Institute of Environmental Health Sciences, and it "empowers the public with information people can use to reduce exposure to cancer-causing substances." Now in its 13th edition, the report includes 243 listings.