Peer Review of the Development Support Document (DSD) for

1,3-Butadiene Prepared by the

Texas Commission on Environmental Quality (TCEQ)

Peer Review Report is now Available

Final Development Support Document is now Available 

What:    Letter peer review of the DSD for 1,3-Butadiene prepared by TCEQ.  Six to eight experts will review the document and supporting materials and submit written comments addressing the charge questions.  A follow up conference call will be held approximately 2 weeks after written comments have been received.

When:   Review package will be distributed to the experts and posted on this webpage at the end of August 2007.  Written comments will be due in September; the follow up conference call is tentatively scheduled for early October 2007.

Where:   The public is invited to listen to the follow up conference call.  Please check this site for call-in information which will be provided once it is available.

TERA is supporting the Texas Commission on Environmental Quality (TCEQ) in conducting an expert external peer review of  Development Support Document for 1,3-Butadiene, Proposed August 2007, being scheduled for August-September 2007.  This peer review is being conducted as a letter review with a follow up conference call.  The Toxicology Section (TS) of the Chief Engineer’s Office has prepared a Development Support Document that outlines the hazard assessment and dose-response processes used to derive Effects Screening Levels (ESLs), Reference Values (ReV), and Unit Risk Factors (URFs) for 1,3-Butadiene (Cas. No. 106-99-0). The toxicity values were developed using RG-442 Guidelines to Develop Effects Screening Levels, Reference Values, and Unit Risk Factors (TCEQ 2006). ESLs are chemical-specific air concentrations set to protect human health and welfare. Short-term ESLs are based on data concerning acute health effects, odor potential, and vegetative effects, while long-term ESLs are generally based on data concerning chronic noncarcinogenic and/or carcinogenic health effects. ESLs are used in the evaluation of air permit applications as well as proposed rules and regulation (e.g. Permits by Rule). ReVs and URFs, used as the basis of ESLs, are used in the evaluation of air monitoring data and in the development of Protective Concentration Levels for remediation sites.

The TCEQ document relies on the US EPA Health Assessment of 1,3-Butadiene (EPA/600/P-98/001F), released in October 2002, to provide detailed information on the following topics for 1,3-butadiene: overview of exposure, pharmacokinetics, mutagenicity, reproductive and developmental effects, toxicity in animals, epidemiologic studies of carcinogenicity, hazard characterization, and pharmacokinetic modeling.   However, TCEQ has incorporated new data and statistical analyses not available to US EPA in 2002, and therefore, has derived new dose-response assessments for 1,3-butadiene.

The 1,3-Butadiene DSD, panel biographical sketches, and review materials will be posted when they become available.  Prior to the follow-up conference call, the experts’ comments will also be posted.  A meeting report summarizing discussions and conclusions will be posted on the website following the meeting.   

Meeting Documentation

For additional information, contact Dr. Michael Dourson