Occupational Safety and Health Administration (OSHA) Cr6+ Permissible Exposure Limit (PEL)
The current OSHA Cr6+ PEL (permissible exposure limit) was issued on February 28, 2006 reduced the upper limit for exposure of workers to hexavalent chromium (as Cr) to 5 µg m-3 from its previous 52 µg m-3, measured as 8-hour time-weighted averages. This drastic reduction affects any industrial process that could generate Cr6+ air emissions, including hard chrome plating, chromic acid anodizing, priming and painting, chromate conversion, welding, and rework of materials containing chromium. The limit applies to all forms of Cr6+, including chromium trioxide, chromic acid and chromates.
The OSHA rule, based on the fact that inhaled Cr6+ is a known human carcinogen, mirrors purely advisory limits for Cr6+ set by other organizations:
- The ACGIH (American Conference of Governmental Industrial Hygienists) recommends several different TLVs (threshold limit values) for chromium, chromates and other chromium compounds.
- For water-soluble Cr6+ compounds such as CrO3 the TLV is 50 µg m-3 (as Cr)
- For insoluble Cr6+ compounds the TLV is 10 µg m-3.
- The NIOSH (National Institute for Occupational Safety and Health) has recommended a 10-hour time-weighted average for all Cr6+ compounds of 1 µg m-3.
In addition to reducing the PEL for Cr6+, the new OSHA rule places a number of burdens on employers, who are now required to:
- Monitor employee exposure to Cr6+
- Establish separate regulated areas when Cr6+ levels are expected to exceed the PEL
- Provide respirators for workers exposed above the PEL
- Provide other PPE (personal protective equipment) as necessary for eye and skin protection, together with change rooms and wash facilities
- Institute housekeeping activities to control spills and releases of Cr6+
- Provide medical surveillance for employees who are exposed above the PEL, show signs or symptoms of Cr6+ exposure, or are exposed in an emergency
- Train workers about Cr6+ hazards, and use signs and labels to communicate the hazards
- Keep records of exposure, surveillance and training.
The PEL action level, which is the threshold that determines when ongoing monitoring is necessary, is 50% of the PEL or 2.5 µg m-3. However, if Cr6+ concentrations are shown to be <0.5 µg m-3 under all expected conditions, then the OSHA rule does not apply at all.
This regulation was held up in lawsuits for several years, but is now being aggressively enforced, including enforcement at DoD repair depots.