Adoption of Chronic Reference Exposure Levels for Silica (Crystalline, Respirable)

In accordance with Health and Safety Code, Section 44300 et seq. (The Air Toxics Hot Spots Information and Assessment Act, AB 2588, Connelly as amended by SB 1731, Calderon), the Office of Environmental Health Hazard Assessment (OEHHA) hereby adopts a chronic Reference Exposure Level (REL) for SILICA (CRYSTALLINE, RESPIRABLE).

OEHHA is mandated to develop risk assessment guidelines to be used by state and local agencies in implementing the Air Toxics Hot Spots program. Four technical support documents (TSDs) have been adopted, which describe the scientific basis for acute RELs, cancer potency factors, chronic RELs, and exposure assessments.

The TSD, Air Toxics Hot Spots Program Risk Assessment Guidelines. Part III. The Determination of Chronic Reference Exposure Levels for Airborne Toxicants, was adopted on February 23, 2000. A chronic REL is an airborne level of a chemical at or below which no adverse health effects are anticipated in individuals indefinitely exposed to that level. RELs are developed from the best available published scientific data, based solely on health considerations. For various chemicals of concern under the Air Toxics Hot Spots program, the Part III TSD provides a chronic REL, and a summary describing its chemical and physical properties, its chronic health effects, and the data and methods used to calculate the REL. Additional chronic RELs are being developed over time; these are adopted after review and endorsement by the Scientific Review Panel (SRP), and are added to the Part III TSD.

At its November 30, 2004 meeting, the SRP endorsed a Chronic REL for crystalline silica (respirable), bringing the total number of chemicals for which chronic RELs are provided to 80. The expanded list and TSD, with the toxicity summary for silica, are available below. Please follow the links to download the documents as pdf files.

SILICA (CRYSTALLINE, RESPIRABLE)
(silicon dioxide, quartz, tridymite, cristobalite)
CAS Registry Number: 7631-86-9

Downloads

Memo of Adoption of Chronic Reference Exposure Levels for Silica (Crystalline, Respirable)Feb 10, 2005

Adopted Chronic Reference Exposure Levels for Silica (Crystalline, Respirable)Feb 10, 2005

Comments

Chemical Reference

• Silica (crystalline, respirable)

Related Notices

• Draft Chronic Reference Exposure Levels for Silica (Crystalline, Respirable)

  Mar 18, 2004
  Notice of Extension of Public Comment/Workshops on Chronic Toxicity Summary for Silica (Crystalline, Respirable)

  May 16, 2003
  Notice of Public Comment/Workshops for Draft Chronic Toxicity Summary for Silica (Crystalline, Respirable)

  Apr 25, 2003