Notice of Adoption of Technical Support Document for Exposure Assessment And Stochastic Analysis Aug 2012

The Office of Environmental Health Hazard Assessment (OEHHA) is adopting an updated version of the document, Air Toxics Hot Spots Program Risk Assessment Guidelines: Technical Support Document for Exposure Assessment and Stochastic Analysis. 


OEHHA is required to develop guidelines for conducting health risk assessments under the Air Toxics Hot Spots Program (Health and Safety Code Section 44360(b)(2)).  OEHHA previously developed Technical Support Documents (TSDs) in response to this statutory requirement, including one in 2000 for exposure assessment.  This revised draft TSD replaces the original TSD, and reflects new scientific knowledge developed since the previous guidelines were prepared.  We have updated exposure parameters (e.g., inhalation rate, food consumption rate, etc.) based on the most recent data, including exposure factors for infants and children, in accordance with the mandate of the Children’s Environmental Health Protection Act (Senate Bill 25, Escutia, Chapter 731, Statutes of 1999, Health and Safety Code Sections 39669.5 et seq.).  The revised document also updates the approach to assessing dermal exposure.

A draft version of this TSD was released for public comment on November 7, 2011, and was discussed at public workshops in Oakland and Diamond Bar, CA in December 2011. The document was then revised to reflect public comments, and peer reviewed by the State’s Scientific Review Panel on Toxic Air Contaminants (SRP).  It was initially presented to the SRP on April 5, 2012.  A revised version of the document reflecting comments of the SRP was discussed at a second meeting held on June 25, 2012.  At the latter meeting, the SRP approved the document describing the RELs and their derivation, subject to some additional editorial changes which have been incorporated into the final version.