The Acrylonitrile Group (AN Group) unveiled its health effects assessment of acrylonitrile (AN) on December 6 at the Society for Risk Analysis (SRA) Annual Meeting 2004 (www.sra.org) in Palm Springs, California. This review, led by The Sapphire Group (www.thesapphiregroup.com), is a comprehensive evaluation of all human and experimental studies relevant to the development of benchmark exposure levels that are protective of human health. The AN Group sponsored this assessment for use by industry and others conducting acrylonitrile health risk assessments, partially in response to an outdated EPA IRIS (www.epa.gov/iris/index.html) file on acrylonitrile. The SRA presentation was authored by Mike Gargas (Sapphire Group), Jim Collins (Dow), Gary Marsh (University of Pittsburgh), Dale Strother (BP), and Randy Deskin (Cytec).

A draft of the assessment was reviewed by an independent panel of experts organized by Toxicology Excellence for Risk Assessment (TERA). Based on comments from the Panel, the assessment was modified and resubmitted to the Panel for concurrence. The final results are posted in the International Toxicity Estimates for Risk Database (ITER) (http://www.tera.org/iter). The complete assessment and TERA Review report are available at www.tera.org/peer/AN/ANWelcome.htm.

The assessment report takes advantage of an extensive body of research on acrylonitrile. The report presents an updated cancer dose-response analysis using recent information on mechanism of action, epidemiology, toxicity and pharmacokinetics. The assessment highlights the large number of well-conducted epidemiology studies that provide no evidence of a causal association between AN exposure and cancer mortality. Some of the studies include exposures that were far higher than would occur today. The large body of scientific information collected since EPA’s 1983 review shows that low level AN exposure poses much less of a health risk than previously thought. Oral doses below 0.009 mg/kg/day and air concentrations below 0.1 mg/m3 are not expected to pose an appreciable risk to human populations exposed to AN.

In late November, the AN Group presented the results of its assessment to the EPA Air and IRIS Offices. The use of this more current assessment would have a major impact on various regulatory programs under development by federal and state agencies, most notably EPA’s Clean Air Act Residual Risk regulations. The EPA IRIS Office is conducting it’s own assessment of AN, which it has stated will be available for public comment by the end of 2005.

For additional information, please contact: