The State of California Adopts an Occupational Exposure

Limit of 0.2 f/cc for Refractory Ceramic Fiber (RCF)

On December 17, 2009, the state of California’s Occupational Safety and Health Standards Board (the Board) adopted a permissible exposure limit (PEL) for RCF of 0.2 f/cc.  This recommendation was approved by the California Office of Administrative Law on February 3, 2010 and will be effective in California on August 3, 2010.  The PEL will be published in the list of regulated airborne contaminants under Section 5155 of California’s General Industry Safety Orders, http://www.dir.ca.gov/title8/5155a.html on Table AC1 http://www.dir.ca.gov/title8/5155table_ac1.html.

In its Final Statement of Reasons for the recommendation, the Board “applaud[ed] the RCF industry’s support of research on the potential hazards of RCF, and the product stewardship effort of RCF producers.” 

Enforcement of California’s occupational health standards is the responsibility of the Division of Occupational Safety and Health.  In its Final Statement of Reasons, the Board noted that it “appreciates the concerns raised by RCFC that, although measurements of airborne exposure to RCF for some operations have averaged below 0.2 fibers/cc, the variability of the results indicates that employers cannot assume that a single sample on any particular day will always indicate an 8-hour TWA exposure that does not exceed this level.”  In recognition of this concern, the Board stated: “The Division has determined that the time has come to confront the manner in which current enforcement approaches are affected by variability in exposure assessment and has expressed a commitment to begin discussion of this issue publicly.” 

The Board’s Final Statement of Reasons goes on to embrace what is known as the “worker lifetime” principle embodied in Labor Code Section 144.6 by stating, “One enforcement option consistent with this principle could allow an employer to demonstrate that, although individual samples may exceed 0.2 f/cc on occasion, it has reliably characterized 8-hour TWA exposures overall to be below 0.2 f/cc for workers in similar exposure scenarios, the Division would accept these results if the enforcing officer’s own sampling on a single occasion indicates that the level of 0.5 f/cc has not been exceeded.”

The RCFC and its member companies, remain committed to assisting distributors and end users of RCF products with reducing and controlling workplace exposures through actions taken under the industry’s product stewardship program. 

A copy of the Board’s Final Statement of Reasons is attached.  For more information, please contact your RCF supplier or visit the web site listed above.      

Final Statement of Reasons

Occupational Safety and Health Standards Board

California Code of Regulations

TITLE 8: Division 1, Chapter 4, Subchapter 7, Group 16, Article 107,

Section 5155 of the General Industry Safety Orders

Airborne Contaminants (Pages 30-31)

The Standards Board would like to note that it applauds the RCF industry's support of research on the potential hazards of RCF, and the product stewardship effort of RCF producers. The RCF industry has collected exposure data under a quality assurance project plan designed in conjunction with Federal EPA. These data have been shared with the Division as well as U.S. Department of Labor and other interested regulators. These data show that, with the help of RCF producers, users have achieved average TWA exposures well below the voluntary limit of 0.5 f/cc and in most circumstances at or below the proposed PEL of 0.2 f/cc. Therefore, in light of the totality of evidence cited by ACGIH and NIOSH on the potential for RCF to cause or contribute to respiratory disease, the Standards Board believes that a PEL for refractory ceramic fiber of 0.2 f/cc is feasible and necessary to protect workers.

The Standards Board appreciates the concerns raised by RCFC that, although measurements of airborne exposure to RCF for some operations have averaged below 0.2 fibers/cc, the variability of the results indicates that employers cannot assume that a single sample on any particular day will always indicate an 8-hour TWA exposure that does not exceed this level. These employers will have the option of supplementing engineering controls with respirator use or finding ways to improve engineering controls.

The problem of variability in assessments of worker exposures has been a subject of active research and controversy since the 1970’s. The comments made by RCFC have highlighted this issue. The Division has determined that the time has come to confront the manner in which current enforcement approaches are affected by variability in exposure assessment and has expressed a commitment to begin discussion of this issue publicly.

However, a third option appears warranted in connection with the permissible exposure limit for RCF. In a workplace where it appears all feasible engineering controls for RCF have been implemented but the employer is not statistically certain that an individual sample result will never exceed 0.2 fibers/cc: In recognition of the commonly encountered high variability of airborne personal sampling results and the narrow interpretive value of a single sample with respect to overall employee exposure in a work environment, the Division has indicated that it will explore utilization of an enforcement strategy designed to promote (1) robust and proactive sampling by employers before they are targeted for enforcement inspections and (2) better characterization of mean exposures employees are experiencing in their work.

This approach would recognize that robust sampling strategies based on statistically driven, multiple-sample approaches and carried out in accordance with sound industrial hygiene practice and documentation, can allow for the drawing of significantly more competent and reliable conclusions about probable 8-hour TWA exposures than are possible with single-sample strategies. These types of sampling strategies are the subject of discussion in recent scientific literature.

In addition to promoting greater employer attention to making accurate conclusions about employee exposure, this kind of sampling and analysis would be better calculated to quantify the exposure environment in terms of the “working lifetime” principle embodied in Labor Code Section 144.6. One enforcement option consistent with this principle could allow an employer to demonstrate that, although individual samples may exceed 0.2 fibers/cc on occasion, it has reliably characterized 8-hour TWA exposure overall to be below 0.2 fibers/cc for workers in similar exposure scenarios, the Division would accept these results if the enforcing officer's own sampling on a single occasion indicates that the level of 0.5 fibers/cc has not been exceeded. This is not meant in any way to imply that the Division should refrain from using multiple sampling and statistical approaches where it chooses to develop them, but it is meant to promote utilization of the best information available to assess the actual exposure of workers for the purpose of compliance assessment.