As health and safety professionals, we have all responded to questions such as, "Will the chemicals I am exposed to cause me harm?" or "Will this chemical cause cancer?" To address such questions, we likely consult the scientific literature, evaluate exposures, compare exposure levels to regulated or recommended values, and finally use professional judgment to formulate our response. These questions become increasingly difficult to answer when asked by people who are not employed in traditional industrial settings. Laboratories have processes, practices, and potential exposures that differ substantially from what are found in traditional industries, and the application of occupational exposure values (OEVs) requires special consideration. Although there are numerous agencies and organizations that regulate or recommend OEVs, the Threshold Limit Values (TLVs) have become the most widely recognized and applied. In fact, when the Occupational Safety and Health Administration (OSHA) was established in 1972, it was able to incorporate into standards the approximately 400 chemicals on the 1968 TLV list. Many of the 1968 TLVs are still in use today as OSHA's permissible exposure limits (PELs). Although OSHA's final rule, "Occupational Exposure to Hazardous Chemicals in Laboratories," requires that employers ensure that exposures do not exceed applicable PELs, many chemical hygiene plans also recommend compliance with the TLVs.
Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado