1. Home
  2. Air
  3. Proposed Reference Exposure Levels for Hexameth...

Proposed Reference Exposure Levels for Hexamethylene Diisocyanate (Monomer and Polyisocyanates) - Scientific Review Panel Draft

The Office of Environmental Health Hazard Assessment (OEHHA) is releasing a draft document summarizing the toxicity and derivation of Reference Exposure Levels (RELs) for Hexamethylene Diisocyanate (Monomer and Polyisocyanates) (HDI).  This document will be reviewed and discussed by the Scientific Review Panel on Toxic Air Contaminants (SRP) at its meeting on March 4, 2019 in Sacramento, CA.  RELs are airborne concentrations of a chemical that are not anticipated to result in adverse non–cancer health effects for specified exposure durations in the general population, including sensitive subpopulations.

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)). In response to this statutory requirement, OEHHA develops RELs for many air pollutants. The HDI RELs were developed using the most recent “Air Toxics Hot Spots Program Technical Support Document for the Derivation of Noncancer Reference Exposure Levels,” finalized by OEHHA in 2008.

A draft of the HDI REL document was released for a 75-day public review and comment period on December 1, 2017.  One set of comments was received.  Those comments and the OEHHA responses to those comments are also available at this time.  We are not seeking further comments from the public on the draft document.

The HDI REL values proposed are as follows:

HDI monomer:
Acute REL (for a 1–hour exposure):  0.3 micrograms per cubic meter (µg/m3)
8–Hour REL (for repeated 8–hour exposures):  0.06 µg/m3
Chronic REL (for long–term exposures):  0.03 µg/m3

HDI polyisocyanates:
Acute REL (for a 1–hour exposure):  4.5 µg/m3
8–Hour REL (for repeated 8–hour exposures):  0.8 µg/m3
Chronic REL (for long–term exposures):  0.4 µg/m3
Please direct any inquiries concerning technical matters or availability of the documents to:

Dr. John Budroe
Chief, Air Toxicology and Risk Assessment Section
Air, Community, and Environmental Research Branch
Office of Environmental Health Hazard Assessment
1515 Clay Street, 16th Floor
Oakland, CA, 94612

E–mail: John.Budroe@oehha.ca.gov
Telephone: (510) 622-3145

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

Downloads