The state’s Carcinogen Identification Committee (CIC) has declined to list several isomers of diaminotoluene at the committee’s meeting held on Nov. 4.
The chemicals were considered in response to a petition filed by Big Lots Stores that requests that the committee delist diaminotoluene (mixed) because there is confusion about the identity and composition of the mixture. Big Lots petition claims that studies dating back to the mid 1980s did not identify the composition of the mixture, or provide adequate evidence to list the chemical mixture as a carcinogen.
The CIC included several other isomers of diaminotoluene in its consideration to determine which, if any possess carcinogenic properties.
The Personal Care Products Council (PCPC), a trade group representing makers of personal care products, objected to the inclusion of 2-5 diaminotoluene, a chemical widely used in hair dyes.
PCPC wrote in a public comment submitted to the Office of Environmental Health Hazard Assessment (OEHHA) that “There is no scientific basis for the listing of 2,5-diaminotoluene as a Proposition 65 carcinogen. Your committee (the CIC) has been asked to review 2,5-diaminotoluene for listing only because of the confusion surrounding the identity and listing of diaminotoluene (mixed), a commercial mixture of 2,4 and 2,6-diaminotoluene with its own CAS number.
2,4-Diaminotoluene is widely accepted to be carcinogenic, and it was placed on the Proposition 65 list of carcinogens in 1988. In contrast, no regulatory authority has identified 2,5-diaminotoluene as a carcinogen because there is no evidence that it is carcinogenic.
The state’s expert panel eventually concluded that 2-5 diaminotoluene is not carcinogenic, after debate among the panelists about whether the chemical has genotoxic properties.
Dr. David Eastmond, a professor from U.C. Riverside expressed concerns about possible genotoxic effects from the chemical compound, but acknowledged that the science is suggestive of toxicity and did not meet the standard for listing under Proposition 65. The vote was split 3 in favor, 3 against, with one abstention.
The vote to delist diaminotoluene (mixed) was 5 in favor, one against and one abstention. The votes taken on the other isormers were likewise against listing. The committee also considered delisting Nitropyrin, Nitrapyrin (CAS No. 1929-82-4) is the common name for the active ingredient in several nitrogen stabilizer products registered to Dow AgroSciences LLC, a wholly owned subsidiary of The Dow Chemical Company.
Its purpose is to inhibit the nitrification of ammonium-N to nitrate-N in the soil.
Nitrapyrin products are used in conjunction with farm field applications of anhydrous ammonia, urea and other ammonia-based fertilizers or with animal manures. By maintaining fertilizer-applied nitrogen in the root zone for a longer period of time, use of nitrapyrin provides the potential for increased crop yields.
Nitropyrin was listed as a Proposition 65 carcinogen in October 2005 after it was identified as such by the U.S. Environmental Protection Agency in a 2000 report that concluded that Nitropyrin is “likely to be carcinogenic to humans.”
In 2012, US EPA revised the classification of nitrapyrin to “Suggestive Evidence of Carcinogenic Potential” (US EPA, 2012a).
In response to changes in classification by a referring authoritative body that remove the chemical’s identification as a carcinogen, the chemical is referred to the CIC which determines whether the chemical has been “clearly shown through scientifically valid testing according to generally accepted principles to cause cancer.
The panelists reviewing the latest data expressed concerns about statistically significant increases in the incidences of hepatocellular adenomas.
Increases in squamous cell tumors of the non-glandular stomach and (combined papillomas and carcinomas were also observed.