"Chronic Toxicity Summary for Silica" Study Released

By Loretta Macktal, Executive Assistant to the Vice President, Government Relations

Capitol Update, Nov. 19, 2004 Share this on FacebookTweet thisEmail this to a friend

In April of 2003, the Office of Environmental Health Hazard Assessment (OEHHA) released a draft document titled "Chronic Toxicity Summary for Silica (Crystalline, Respirable)" for public comment. Two public workshops have since been held and on November 4th OEHHA released their revised toxicity study.

The proposed reference standard remains the same at 3 ug/m3 (3 micrograms per cubic meter - a microgram being one millionth of a gram). It also recommends the use of the 4 um measurement standard, the same as that used for occupational exposures. The original proposal would have measured PM10 fractions, so this change addresses an inconsistency in current measurement standards. The full report can be found at www.oehha.ca.gov/air/chronic_rels/silica3.html.

OEHHA's revised report will be heard by the Air Resources Board's Scientific Review Panel (SRP) on November 30th at the South San Francisco Conference Center. Comments were due by November 19th, but will be accepted after that date. The meeting notice and agenda can be found at http://www.arb.ca.gov/srp/srpmeetings.htm.

The South African study used as the primary basis for OEHHA's proposed reference exposure limit is currently being reviewed by CMTA. If you have an interest in this subject and have not been a part of the industry coalition commenting on this standard, please contact CMTA's environmental lobbyist, Mike Rogge at mrogge@cmta.net.

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