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[July 2006]
New Document from US Looks at Exposure to Refractory Ceramic Fibres
A comprehensive scientific document on occupational exposures to refractory ceramic fibres (RCFs) is now available from America’s National Institute for Occupational Safety and Health (NIOSH). The document is said to provide a thorough critical review of scientific information concerning occupational exposures to RCFs, recommends an exposure limit to address potential work-related health effects and outlines a recommended strategy to minimise exposures in the workplace.
The document, 'Criteria for a Recommended Standard: Occupational Exposure to Refractory Ceramic Fibers' - DHHS (NIOSH) Publication No. 2006-123 - incorporates an intensive NIOSH evaluation of the published scientific literature, as reflected by more than 230 cited references. It also incorporates comments by independent scientific peer-reviewers and diverse stakeholder representatives.
NIOSH estimates that approximately 31,500 workers are potentially exposed to RCFs during manufacturing, distribution, handling, installation and removal of these materials. RCFs are synthetic fibres produced by the melting and blowing or spinning of calcined kaolin clay or a combination of alumina, silicon dioxide or other oxides. They are used in commercial applications requiring lightweight insulation that is capable of withstanding high temperatures, such as furnace and kiln insulation.
The 203-page criteria document covers the following:
-- It critically surveys scores of studies, from the U.S. and abroad, that are relevant for determining potential health effects from work-related exposures from RCFs, and for designing good control and stewardship measures. These include studies on the chemical and physical properties of RCFs, evaluations of industrial processes in which the materials are produced and used, exposure assessments and data from human health assessments and from laboratory studies.
-- It recommends an exposure limit of 0.5 fibre per cubic centimetre of air as a time-weighted average for up to a 10-hour work shift during a 40-hour work week. The recommended exposure limit is consistent with a limit contained in a product stewardship programme developed by the RCF industry in 2002. NIOSH estimates that this recommended limit will minimise the risk of potential adverse health effects associated with workplace exposures, ranging from eye irritation and upper-respiratory irritation, to a potential risk for lung cancer suggested by some studies in the peer-reviewed literature. The criteria document recommends that efforts continue to reduce exposures even further whenever possible.
-- It outlines recommendations for strategic programmes to reduce work-related exposures, including engineering controls, work practices, respiratory protection, sampling and analysis, sanitation and hygiene, sampling and analysis, medical monitoring, labelling and posting, and smoking cessation.
-- It suggests further steps in interdisciplinary research needed for resolving current uncertainties. These include studies and programmes to 1) better define the chemical or physical properties of refractory ceramic fibres that might pose health risks, 2) better understand the biological processes that might lead to adverse effects from exposures, and 3) expand health surveillance in order to better identify potential cases of occupational illness associated with RCFs and potential trends in cases.
"The new criteria document builds on the rich body of scientific information that has entered the published literature since NIOSH’s pioneering 1977 review of occupational exposures to man-made mineral fibers," said NIOSH Director, Dr John Howard. "The document recommends prudent measures for minimizing exposures, consistent with good practices already established by the industry. It also points to areas of research that continue to be necessary, in the interim, to resolve ongoing scientific uncertainties."
The criteria document is available in electronic form on the NIOSH web page at www.cdc.gov/niosh/docs/2006-123/
ENDS