BOARD MEETING DATE: March 7, 2003
AGENDA NO. 33

Notification of OEHHA’s Finalization of a Cancer Potency Factor

SYNOPSIS: 

The March 2000 amendments to Rule 1402 – Control of Toxic Air Contaminants from Existing Sources require that staff notify the Board and affected parties when the state adds chemicals or changes risk values for toxic air contaminants. On December 20, 2002, the Office of Environmental Health Hazard Assessment finalized the Cancer Potency factor for one compound, methyl tert-butyl ether (MTBE). At the May 2003 Board meeting, staff will propose amendments to Rule 1401 and report on potential impacts to facilities subject to Rules 1401 and 1402.

COMMITTEE: 

Not applicable.

RECOMMENDED ACTION:

Receive and file.

Barry R. Wallerstein, D.Env.
Executive Officer

Background

On March 17, 2000, the Board adopted amendments to Rule 1402 – Control of Toxic Air Contaminants from Existing Sources. In conjunction with the amendments to Rule 1402, the Board directed staff to notify them and affected facilities after the Office of Environmental Health Hazard Assessment (OEHHA) finalizes changes to a toxic air contaminant (TAC) or risk value, and to establish a 12-month lead time (or shorter, if the Board approves another schedule through an official Board action) for using the new TAC or risk value in a risk assessment for Rule 1402. This notification fulfills that Board directive.

OEHHA establishes risk values for TACs and the State’s Scientific Review Panel (SRP) reviews and finalizes these values. Final action is taken when the Director of OEHHA signs the document and posts the information on the internet. The SRP met and approved the Cancer Potency Factor for methyl tert-butyl ether (MTBE) on November 19, 1999 and the Director of OEHHA finalized and adopted the factor on December 20, 2002. The internet posting also occurred on December 20, 2002. MTBE (CAS No. 1634-04-4) was assigned a risk factor of 2.6E-07 (µg/m³)^-1. This corresponds to a screening value of 127 pounds/year per one-in-a million cancer risk. Under industrial applications, MTBE is most widely used as an oxygenate in unleaded gasoline to improve combustion efficiency.

Prior to adding or updating risk values, Rule 1402 also requires staff to report to the Board within 150 days of final action by OEHHA on potential impacts for facilities subject to Rule 1402. Similarly, Rule 1401 – New Source Review of Toxic Air Contaminants, also requires an analysis of these same compounds that are used for New Source Review. A report containing analysis of the impacts of the new risk factor on facilities subject to Rules 1401 and 1402 and proposed amendments to Rule 1401 to update the tables relative to MTBE will be presented at the May 2003 Board meeting.

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