According to the United States Department of Health and Human Services (HHS), four new substances were added to a list of chemicals that are considered carcinogens.
A chemical called ortho-toluidine was included to the list of known chemicals which can cause cancer. This chemical is used to make rubber chemicals, pesticides and dyes. A research recently has linked the substance to bladder cancer.
The other three chemicals were also considered "reasonably anticipated to be human carcinogens. These substances include 1-bromopropane which is a cleaning solvent, pentachlorophenol and cumene, both a wood preservative mixture that can be found in fuel products and tobacco smoke.
According to Linda Birnbaum who is a director of the National Institute of Environmental Health Sciences and the National Toxicology Program, "Identifying substances in our environment that can make people vulnerable to cancer will help in prevention efforts," she added that "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."
The chemical Ortho-toluidine was classified primarily as "reasonably anticipated" to be a human carcinogen in 1983. Scientists re-revaluated the chemical and after tests, they found enough evidence to link the said chemical to an increased risk of bladder cancer in humans.
The said chemical, Ortho-toluidine, is no longer being produced in the United States but according to HHS, around 450,000 kilograms of Ortho-toluidine is imported from other countries each year.
For the other three substances, HHS officials claimed that they did not have enough evidence to definitively prove that human exposure can cause cancers. However, in tests done by scientists in rats and mice, they seem to be developing tumors. For the chemical 1-bromopropane, the rodents developed tumors in several organs. In the substance cumene, mice developed lung and liver tumors. The fumes are normally found in coal tar and petroleum smoke. It is also used as an ingredient for acetone and phenol.
