SUMMARY OF DATA FOR CHEMICAL SELECTION
BASIS OF NOMINATION TO THE CSWG
5-Amino-o-cresol is brought to the attention of the CSWG because it is the most widely used
member of a class of 25 chemicals, the aminocresols and related compounds, defined as amino- and
methyl-substituted phenols, their salts, and ethers. Prior to conducting the class study, the NCI had
submitted seven aminocresols, including 5-amino-o-cresol, to be tested for genotoxicity in the NCI
Short-Term Test Program (STTP). Nearly all produced positive results in either the Ames
Salmonella typhimurium assay for mutagenicity, the mouse lymphoma assay for clastogenicity, or
both. These results warrant investigation of the carcinogenic potential of the class members with
the highest production volume and potential exposure.
5-Amino-o-cresol is used as an oxidative dye coupler in cosmetic hair dye manufacturing.
According to the US Environmental Protection Agency (EPA), the annual production level of 5-
amino-o-cresol is 10,000 to 100,000 lbs. According to a National Institute for Occupational Safety
and Health (NIOSH) survey conducted in 1981 - 1983, approximately 45,000 workers are exposed
to 5-amino-o-cresol; however, no permissible exposure limit (PEL) has been established to regulate
worker exposure to this compound. Use of this compound in hair dye production also leads to
widespread occupational and consumer exposure.
Suspicion of carcinogenic potential of 5-amino-o-cresol is based primarily on its genotoxicity and
subchronic toxicity, as well as some equivocal epidemiologic evidence of carcinogenic potential of
some hair dye formulations.
INPUT FROM GOVERNMENT AGENCIES/INDUSTRY
Dr. John Walker of the EPA provided information on the annual production volume of 5-amino-o-
Action BY CSWG: 7/26/01
- Developmental and Reproductive Toxicity
- Most widely used member of the aminocresols class of chemicals