Extension of Public Comment Period for Proposed Revised Reference Exposure Levels For Toluene Diisocyanate And Methylene Diphenyl Diisocyanate

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)). 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.) requires OEHHA to explicitly include consideration of possible differential effects on the health of infants, children and other sensitive subpopulations.  OEHHA has developed a Technical Support Document (TSD) in response to these statutory requirements describing acute, 8-hour and chronic RELs, which was adopted in December 2008.

These guidelines have already been used to develop updated RELs for several chemicals.  On April 23, 2010, OEHHA published a notice in the California Regulatory Notice Register announcing the availability of draft updates to the RELs for two further chemicals: toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI).  Publication of that notice initiated a 60‑day public comment period that would have closed on June 22, 2010.  OEHHA has received a request from an interested party seeking an extension of the comment period to allow more time for the preparation of comments on the proposed MDI and TDI RELs.  OEHHA hereby extends the public comment period for MDI and TDI to 5 p.m., Thursday, July 22 2010.

Please direct your comments on the documents, in writing or by e-mail, and any inquiries concerning technical matters or availability of the documents to: