The California Environmental Protection Agency’s Carcinogen Identification Committee (CIC) today listed the two groups of chemical compounds the panel considered in its meeting at CalEPA Headquarters.
The committee members voted 6-0 to list chemical compounds from the Dibenzanthracene family (DBAs). One committee member abstained from the vote. One member of the chemical family Dibenzanthracene [a,h] has been listed under Proposition 65 since 1988 based on its 1981 classification by the National Toxicology Program as “reasonably anticipated to be a human carcinogen.” IARC classified the chemical in 2010 as a “2A” carcinogen—“Probably carcinogenic to humans.”
The committee unanimously voted to list the majority of the N-Nitroso-methyl-n-Alkylamines it reviewed, excluding one compound which had not been studied.
Exposures to chemicals from the DBA family come from incomplete combustion or pyrolysis. OEHHA cites emissions from cars or trucks, cigarettes or marijuana smoke and cooking. Bio-monitoring data has found evidence of DBAs in blood, breast milk and the placenta.
The committee found that each of the three DBA isomers were carcinogenic, and each of their metabolites cause genotoxicity. The members noted each of the DBA isomers share strong structure-activity similarities with six related carcinogens from the polyaromatic hydrocarbon (PAH) family.
The CIC then considered chemicals from the N-Nitroso-methyl-n-Alkyl-amines (NMAs) family. NMAs have been detected in personal care products and household cleaning products, although they are not intentionally added to the products. NMAs can be formed by the reaction of nitrite with amine compounds.
The committee deliberated over ten of the thirteen NMAs, skipping N-Nitroso-dimethylamine and N-Nitrosomethyl-ethylamine, which have already been listed under Proposition 65. One NMA compound had not been studied, and was eliminated from consideration.
The two NMA’s listed under Proposition 65 were categorized as “B2” carcinogens by the U.S. Environmental Protection Agency. IARC and NTP published similar classifications for the chemicals.
No epidemiological studies had been conducted on any of the NMA chemicals, but 90 animal studies provided consistent evidence of carcinogenicity in rats, hamsters and mice, including rare tumors across different species. The test animals in the studies developed tumors in multiple sites in both male and female laboratory animals. The major cancer sites were the lungs, esophagus, nasal cavity, tongue, forestomach and bladder.
The scientific literature also showed that chemicals from the NMA family are genotoxic and form carcinogenic and genotoxic metabolites.
The discussion by committee members was exceptionally brief as most concluded that chemical structure of the NMA compounds all but guarantees that the compounds may have carcinogenic effects. The panel unanimously agreed that the NMA com-pounds were clearly shown to cause cancer.
Following the vote, OEHHA counsel Carol Monahan-Cummings discussed the status of six chemicals under consideration for listing by Proposition 65’s authoritative Bodies’ mechanism.
OEHHA is reviewing comments submitted to the agency on the proposed listings of Beta-Myrcene, Nitrite in combination with amines or amides, six compounds from the atrazine family and ethylene glycol.
The agency is also reviewing whether styrene meets the listing criteria for an authoritative bodies’ listing based on its appearance in NTP’s 12th Report on Carcinogens. Monahan-Cummings also discussed litigation the agency is involved in, noting that on Dec. 5 there will be a hearing in the American Chemistry Council’s lawsuit to overturn the listing of Bisphenol A. She said there may be a final decision in the matter early next year.