The Occupational Safety and Health Administration (OSHA) has established an 8-hour time-weighted average (TWA) exposure limit of 1 microgram per cubic meter (1 µg/m3) in its proposed rule for hexavalent chromium, which is significantly lower than the agency's current general industry and construction standards (see sidebar). OSHA acted to comply with a ruling of the U.S. Court of Appeals for the Third Circuit, which required the agency to publish a proposed rule by Oct. 4, 2004, and a final standard by Jan. 18, 2006.
According to former OSHA Administrator John Henshaw, "The risks involved in the occupational use of hexavalent chromium can be serious and potentially life threatening." He said the proposed rule "will substantially reduce the risk to workers potentially exposed to hexavalent chromium."
Proposed Changes
The 8-hour TWA of 1 µg/m3 will apply to all hexavalent chromium (CrVI) compounds in general industry, construction and shipbuilding. The proposed permissible exposure limit (PEL) is set at the lowest level that OSHA believes to be economically and technologically feasible in all affected industry sectors.
To address the risks associated with occupational exposure to hexavalent chromium, OSHA has also established an action level (AL) of 0.5 µg/m3. The AL applies for general industry only.
In addition to establishing the new lower PEL for CrVI, the proposed rule would require employers to:
- Monitor employee exposure in general industry.
- Establish regulated areas in general industry when exposures may be expected to exceed the PEL.
- Implement engineering and work practice controls to reduce exposures.
- Provide respiratory protection in emergencies or when engineering and work practice controls are not feasible or are insufficient.
- Provide other protective clothing and equipment as necessary for eye and dermal protection.
- Provide hygiene facilities and housekeeping activities in some situations.
- Provide medical surveillance for employees experiencing signs or symptoms of CrVI exposure or who are exposed in an emergency, as well as for employees exposed above the PEL in general industry.
- Train workers about hexavalent chromium hazards.
- Use signs and labels to communicate hazards to workers.
- Keep records related to the standard.
Not all of the proposed requirements are applicable to the construction and shipyard industries. OSHA's Maritime Advisory Committee for Occupational Safety and Health recommended that OSHA issue a separate proposed rule for hexavalent chromium for shipyards rather than include them in the general industry proposal.
OSHA's proposed standard for construction specifically excludes CrVI exposure from portland cement.
Health Effects
The primary routes of exposure to hexavalent chromium are inhalation, ingestion and dermal contact. Hexavalent chromium can be inhaled when hexavalent chromium dust, fumes or mists are in the air. Particles of chromium dust can contaminate hands, clothing, food, etc. and lead to ingestion of the metal.
According to OSHA, the major illnesses associated with occupational exposure to hexavalent chromium are lung cancer and dermatoses. OSHA estimates that 1 million workers are exposed to hexavalent chromium on a regular basis in all industries, and studies of workers in the chromate production, plating and pigment industries consistently show increased rates of lung cancer.
Direct eye contact with chromic acid or chromate dust can cause permanent eye damage. Hexavalent chromium can also irritate the nose, throat and lungs. Repeated, prolonged exposures can ulcerate the nasal passages. Prolonged skin contact can result in dermatitis and skin ulcers. Some workers even develop allergic sensitization to chromium.
When to Take Action
To comply with the current and proposed OSHA standards, facilities handling any form of hexavalent chromium should know their employees' exposure levels. Facilities may need to implement engineering controls or changes in work practices to be in compliance with the proposed lower PEL and AL.
References
This article is based in part on information from OSHA's Web site. For more information on hexavalent chromium and the proposed rule, go to www.osha.gov/SLTC/hexavalentchromium/index.html#Recognition and www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=11056.
Sidebar: Current Occupational Exposure Limits
The OSHA general industry ceiling limit of 100 µg/m3 (as CrO3) applies to all forms of hexavalent chromium, including chromic acid and chromates, lead chromate and zinc chromate. The current construction industry PEL for hexavalent chromium is 100 µg/m3, expressed as an 8-hour TWA.
In contrast, the National Institute for Occupational Safety and Health (NIOSH) has established a Recommended Exposure Limit (REL) of 1 µg/m3 for hexavalent chromium, expressed as an 8-hour TWA.
The American Conference of Governmental Industrial Hygienists (ACGIH) recommends several different Threshold Limit Values (TLVs) for chromium, chromates and other chromium compounds. These range from 0.5 µg/m3 to 500 µg/m3 (as Cr). The TLV for water-soluble inorganic hexavalent chromium compounds is 50 µg/m3. The TLV for certain water-insoluble hexavalent chromium compounds, including zinc chromates, is 10 µg/m3. The TLV for strontium chromate is 0.5 µg/m3.
Ronald T. Dobos, CIH, CSP, is a senior consultant with Clayton Group Services' occupational health and safety practice, working in their Atlanta regional office. He has more than 21 years of experience advising clients on occupational health and safety issues, including managing projects, developing and auditing programs, conducting training, and developing proposals and reports. Dobos has provided industrial hygiene, indoor environmental quality and safety-related consulting services to clients in the automotive, aviation, chemical, healthcare, insurance and manufacturing industries as well as to schools and public institutions and commercial establishments. His experience includes regulatory and compliance issues for the Occupational Safety and Health Administration (OSHA) and other agencies.