Extrapolating inerim occupational exposure values from US EPA IRIS data
Owens Woodgeard, Heather Marie
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Occupational exposure values (OEVs) within the United States are developed by various scientific groups which include the United States Department of Labor Occupational Safety and Health Administration (OSHA), the American Conference of Governmental Industrial Hygienists (ACGIH), the National Institute for Occupational Safety and Health (NIOSH), and the American Industrial Hygiene Association (AIHA). These exposure values are believed to provide workers protection to prevent adverse health effects from repeated exposure to a substance day after day. Currently there are approximately 750 chemicals with OEVs, but thousands of chemicals have no established exposure values. The process to establish OEVs is slow and, for many chemicals, limited toxicological data prevent the development of OEVs. Therefore safety and industrial hygiene professionals must make educated assumptions on what is an acceptable chemical exposure concentration. Environmental exposure values, specifically, reference doses (RfD) from the United States Environmental Protection Agency (US EPA) Integrated Risk Information System (IRIS) database do exist for a number of chemicals. In the present analysis, an interim OEV value was derived for 133 chemicals with existing ACGIH Threshold Limit Values (TLVs) using the RfD values from the US EPA’s IRIS database. A comparative analysis was then completed between the interim OEV and the existing TLV. This comparison found that the derived OEV represented a reasonably conservative surrogate value in comparison to the existing TLV, and supports the use of this approach until an OEVs can be established through one of the traditional organizations. Currently the IRIS database contains 200 additional chemicals with no TLV that could be used to develop interim OEVs. Acceptance of this process would provide an interim answer to the limited number of OEVs available for safety professionals and industrial hygienists.