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External Scientific Peer Reviews

Toxicology Excellence for Risk Assessment (TERA) is organizing an expert external peer review of the carcinogenic sections of the TCEQ Development Support Documents (DSDs) for Hexavalent Chromium and Isoprene.


TCEQ has prepared draft DSDs that outline the hazard assessment and dose-response processes used to derive health-protective Effects Screening Levels (ESLs) and Unit Risk Factors (URFs) for hexavalent chromium and isoprene. These toxicity values are used in the evaluation of air permit applications and ambient air data, and were developed using RG-442 TCEQ Guidelines to Develop Toxicity Factors.

Each final peer review report can be found on the Final Development Support Documents webpage.

Isoprene (draft dated April 2013)

This peer review was conducted as a letter review only.

The draft Isoprene DSD includes Section 4.2, which documents the derivation of an inhalation unit risk factor (URF) based on liver carcinoma incidence in mice and air concentrations corresponding to the policy-based 1 in 100,000 excess risk level.

Visit TERA's Isoprene Peer Review Web Page to view the report and for updated information.

Hexavalent Chromium (draft dated March 2013)

This peer review was conducted as a letter review with a follow-up conference call. 

The draft Hexavalent Chromium DSD includes Section 4.2, which documents the derivation of a URF and air concentrations corresponding to the policy-based 1 in 100,000 excess risk level based on lung cancer mortality.

Visit TERA's Hexavalent Chromium Peer Review Web Page to view the report and for updated information.

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