Notice of Public Comment Period on Toxic Air Contaminants Program – Proposal for the Adoption of a Unit Risk Factor for Ethylbenzene

Apr 20, 2007

The Office of Environmental Health Hazard Assessment (OEHHA) is soliciting public comments on a draft document describing a unit risk factor for estimating lifetime cancer risk associated with inhalation of ethylbenzene. This draft document has been developed by OEHHA for use in implementing the programs for Toxic Air Contaminants (Health and Safety Code Section 39650 et seq.) and Air Toxics Hot Spots (Health and Safety Code Section 44300 et seq.).

Ethylbenzene, a widespread atmospheric contaminant, is a constituent of various fuels and other hydrocarbon mixtures, and is also emitted by various combustion processes. It is suspected of causing cancer and other adverse health impacts. Ethylbenzene is a Toxic Air Contaminant identified by the California Air Resources Board in 1993 pursuant to Health and Safety Code Section 39657(b).

OEHHA’s proposed unit risk factor is based on the results of recent studies by the National Toxicology Program. The document describes toxicity data on ethylbenzene, and the derivation of the unit risk factor. This toxicity summary, if approved, will be included as an addendum to the Air Toxics Hot Spots Program Risk Assessment Guideline, Part II: Technical Support Document for Describing Available Cancer Potency Factors. OEHHA is seeking comments on this document, including its clarity, and the appropriateness of the methodology and data on which the unit risk is based. Following this public comment period, the document and any comments received, along with OEHHA’s response to these comments, will undergo review by the state’s Scientific Review Panel on Toxic Air Contaminants.

The draft document on ethylbenzene becomes available on the OEHHA Home Page at http://www.oehha.ca.gov on April 23, 2007. The availability of the document on this site will commence a 6 week public review period that will end on June 1, 2007.
A public workshop will be held starting at 10 a.m. on Wednesday, May 23, 2007, in Room 15 (second floor) of the Elihu Harris State Office Building, 1515 Clay St., Oakland, CA.

Please direct any inquiries concerning technical matters or availability of this document to Dr. Andrew G. Salmon at (510) 622-3191 or e-mail to Andy.Salmon@oehha.ca.gov.
Please direct your comments, in writing, regarding the document to:
Dr. Andrew G. Salmon
Chief, Air Toxicology and Risk Assessment Section
Office of Environmental Health Hazard Assessment
1515 Clay St., 16th Floor
Oakland, CA 94612.

Information about dates and agenda for meetings of the Scientific Review Panel can be obtained from the California Air Resources Board’s web page at http://www.arb.ca.gov/srp/srp.htm.