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Agency for Toxic Substances and Disease Registry Chromium Toxicity Case Studies in Environmental Medicine (CSEM) What are the Standards and Regulations for Chromium Exposure? Learning Objectives Upon completion of this section, you will be able to • Identify the OSHA permissible exposure limit (PEL) for chromium. • Identify EPA’s maximum contaminant level (MCL) for chromium in drinking water. Introduction The government has developed regulations and guidelines for chromium. These are designed to protect the public from potential adverse health effects. Workplace Guidelines OSHA The Occupational Safety and Health Administration (OSHA) has established an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 μg/m³). This is a considerable reduction from the previous permissible exposure limit (PEL) of 52 μg/m³ [Federal Register 2006]. OSHA’s standard is based upon the best evidence currently available that at the previous PEL for Cr(VI), workers face a significant risk to material impairment of their health. The evidence in the record for this rulemaking indicates that workers exposed to Cr(VI) are at an increased risk of developing lung cancer. The record also indicates that occupational exposure to Cr(VI) may result in asthma and damage to the nasal epithelia and skin. [Federal Register 2006]. The final rule also contains ancillary provisions for worker protection such as • requirements for exposure determination, • preferred exposure control methods, including a compliance alternative for a small sector for which the new PEL is infeasible, • respiratory protection, • protective clothing and equipment, • hygiene areas and practices, • medical surveillance, • record keeping, and • start-up dates that include four years for the implementation of engineering controls to meet the PEL [Federal Register 2006]. For Cr(II) and Cr(III) compounds, the PEL is an 8-hour TWA of 500 μg Cr/m³. For chromium metal and for insoluble compounds, the PEL is 1,000 μg Cr/m³[OSHA 2006]. NIOSH The National Institute for Occupational Safety and Health (NIOSH) has recommended a 10-hour TWA exposure limit for all Cr(VI) compounds of 1 μg Cr(VI)/m³. For chromium metal and Cr (II) and Cr(III) compounds, the recommended exposure limit is 500 μg /m³ as an 10-hour TWA [NIOSH 2005]. On the basis of current evidence, NIOSH considers all Cr(VI) compounds potential occupational carcinogens. Page 22 of 67
Agency for Toxic Substances and Disease Registry Chromium Toxicity Case Studies in Environmental Medicine (CSEM) Environmental Guidelines Air The U.S. Environmental Protection Agency (EPA) regulates chromium emissions under the Clean Air Act of 1990. EPA uses technology-based standards for categories of industries, rather than numerical emissions standards, to reduce chromium levels in ambient air. These maximum achievable control technology (MACT) standards are based on emissions levels already achieved by the best-performing similar facilities. Drinking Water EPA has an enforceable maximum contaminant level of total chromium in drinking water of 100 μg/L (100 ppb) for public water systems [EPA 1999 h]. Table 1. Regulations and Guidelines for Chromium Agency Focus Level Comments American Conference of Governmental Industrial Hygienists Air: workplace 10 μg/m³ as Cr Advisory; TWA* to avoid carcinogenic risk from insoluble Cr(VI) compounds National Institute for Occupational Safety and Health Occupational Safety and Health Administration Air: workplace Air: workplace 50 μg/m³ as Cr TWA for water-soluble Cr(VI) compounds 500 μg/m³ as Cr TWA for chromium metal and Cr(III) compounds 1 μg/m³ as Cr Advisory; TWA (10-hour) for chromic acid and all Cr(VI) compounds 500 μg/m³ as Cr Advisory; TWA (10-hour) for chromium metal and Cr(II) and Cr(III) compounds 5 μg/m³ as Cr Regulation; PEL† for chromic acid and chromates, (8-hour TWA) 500 μg/m³ as Cr PEL for Cr(II) and Cr(III) compounds (8-hour TWA) 1,000 μg/m³ as Cr PEL for chromium metal and insoluble compounds (8-hour TWA) Page 23 of 67
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