Notice of Public Comment Period on Draft Air Toxics "Hot Spots" Program Risk Assessment Guidelines Part IV Mar 2000

The Office of Environmental Health Hazard Assessment (OEHHA) is releasing a revised draft document, Air Toxics Hot Spots Program Risk Assessment Guidelines Part IV: Exposure Assessment and Stochastic Analysis Technical Support Document to solicit public comment on the revision and to obtain review by the ARB's Scientific Review Panel (SRP). This draft document is the fourth in a series of five Risk Assessment Guidelines that are being developed by OEHHA for use in implementing the Air Toxics "Hot Spots" Program mandated by the Air Toxics Hot Spots Information and Assessment Act of 1987, as amended. An External Advisory Group composed of scientists from industry, academia, environmental groups, Federal and State agencies met fourteen times to provide scientific input. The original draft document was released in December 1996 for a 90-day public comment period, followed by two public workshops. Staff has reviewed the comments, responded to the comments in writing, and incorporated most of the comment in the revised the draft document.

The original 1996 document contains a description of the risk assessment methodology for evaluating risk from stationary source airborne emissions under the AB-2588 Hot Spots program. A point estimate and stochastic risk analysis approach is described for evaluating inhalation and non-inhalation exposure pathways. The revised document along with the responses to comments received during the first public comment period will be distributed for public review by March 10, 2000. The document will be available on the OEHHA Home Page at The distribution of the document will commence a 30-day public review period that will end on April 10, 2000. We are soliciting public input primarily on the changes made to the original draft during this public comment period. We anticipate discussing this document with the SRP at its next meeting tentatively scheduled for April 13th.

Please direct your written comments regarding the revised draft document to:

Dr. Melanie A. Marty, Exposure T.S.D.,
OEHHA, 1515 Clay St., 16th Floor,
Oakland, CA 94612.