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
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.
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.
For additional information, contact Ms. Joan
Strawson at 910-692-7752.