Toxicity Criterion for Chemical alpha-HCH Published in Risk Assessment Database
June 7, 2017

A toxicity criterion developed by Integral toxicologists for the chemical alpha-hexachlorocyclohexane (alpha-HCH) has been accepted for inclusion in the International Toxicity Estimates for Risk Assessment (ITER) database—an international database of toxicity criteria relied upon by risk assessors.  Values housed in this database undergo additional peer review that ultimately provides another line of evidence supporting use in risk assessment.

Integral toxicologists Ann Bradley and Judi Durda conducted an evaluation of the carcinogenicity and mode of action and a dose-response analysis to develop the accepted alpha-HCH toxicity criterion.  The assessment was published last year in the journal Regulatory Toxicology and Pharmacology.

The U.S. Environmental Protection Agency (EPA) classifies alpha-HCH as a probable human carcinogen.  alpha-HCH is one of eight structural isomers that have been used worldwide as insecticides.  Although alpha-HCH is no longer produced or used agriculturally in the United States, exposure to HCH isomers is of continuing concern due to past usage and persistence in the environment, and alpha-HCH has been recently added to EPA’s list of unregulated contaminants targeted for monitoring in public water systems.

The ITER database contains human health and risk values and cancer classifications for more than 680 chemicals of environmental concern from organizations worldwide.  The database is a source of information used for evaluating the toxicity of chemicals, including those for which toxicity reference values have not been formally developed by the U.S. Environmental Protection Agency—Integrated Risk Information System.

For more information, contact Ann Bradley at

Read more on the ITER Database.