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Air Toxicology and Epidemiology

Materials for Consideration by the Scientific Review Panel at Their Next Meeting (August 30, 2011)
Air Toxics Hot Spots Program – Proposed Reference Exposure Levels For Caprolactam And Nickel
[07/29/11]

Notice of Adoption of Revised Reference Exposure Levels For Nickel And Nickel Compounds
[03/23/12]

The Office of Environmental Health Hazard Assessment (OEHHA) is presenting draft documents for discussion by the Scientific Review Panel on Toxic Air Contaminants (SRP) at its meeting on August 30, 2011 at the California Environmental Protection Agency building (1001 I Street, Sacramento, CA: see http://www.arb.ca.gov/srp/srpmeetings.htm for details and agenda).  The documents comprise two separate items:

1. Proposed Reference Exposure Levels (RELs) for caprolactam.
2. Proposed Reference Exposure Levels (RELs) for nickel and nickel compounds.

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 has developed Technical Support Documents (TSDs) in response to this statutory requirement, including the Technical Support Document for the Derivation of Noncancer Reference Exposure Levels, which was adopted in December 2008. 

The documents describing the proposed RELs for caprolactam and nickel are now undergoing review by the SRP (Health and Safety Code section 39670 et seq.). These RELs were developed using the current guidelines, which include methodology to protect infants, children and other sensitive subpopulations.  Previous versions of the documents were discussed by the SRP at the last meeting on May 3, 2011.  The document on caprolactam was also discussed initially at the meeting on January 21, 2011.  Versions incorporating revisions (shown in the posted files dated July 2011) to address the SRP’s comments are now presented for further consideration by the panel.  Earlier drafts of the documents were presented for public comment.

For caprolactam, values proposed are: Acute REL 50 µg/m3 (11 ppb), 8 hour REL 7 µg/m3 (1.4 ppb), and Chronic REL 2.2 µg/m3 (0.5 ppb).  Proposed values for nickel are: Acute REL 0.2 μg Ni/m3; 8-Hour REL 0.06 µg Ni/m3; Chronic REL for Nickel and Nickel Compounds except Nickel Oxide (NiO) 0.014 µg Ni/m3; Chronic REL for NiO 0.02 µg Ni/m3 and Chronic oral REL for Nickel and Nickel Compounds 0.011 mg Ni/kg-day (the chronic and oral RELs for nickel are unchanged from the previous version).

When finalized and adopted, these RELs and the supporting documents will be added to the compound-specific toxicity reviews and summary tables which appear as appendices to the Technical Support Document for the Derivation of Noncancer Reference Exposure Levels.

Please direct any inquiries concerning technical matters, availability of documents or comparison between these and previous versions to Dr. Andrew G. Salmon at (510) 622-3191 or Andy.Salmon@oehha.ca.gov.