What Is Hexavalent Chromium?
Hexavalent chromium, Cr(VI), is a hazardous man-made compound found in a variety of industrial processes. The Occupational Safety and Health Administration (OSHA) estimates that more than 558,000 workers in the U.S. are potentially exposed to Cr(VI). Employees can inhale airborne Cr(VI) as a dust, fume or mist while performing tasks using the compound.
What Is Hexavalent Chromium Used For?
Hexavalent chromium is used in producing chromate powders/pigments/chromic acid/dyes or coatings, and employees can also be exposed when working near chrome electroplating, hot work (welding) on stainless steel, or applying and removing chromate-containing paints or coatings. Skin exposure can occur during direct handling of Cr(VI) containing compound solutions, coatings and cements.
How Dangerous Is Hexavalent Chromium?
Hexavalent chromium exposure can be dangerous. Prolonged inhalation of airborne hexavalent chromium can cause lung cancer. In addition to its carcinogenic properties, Cr(VI) exposure can lead to a number of other negative health consequences. Impacts on the respiratory tract can range from irritation to damage of the throat, nose, nasal passages and lungs. Direct contact with chromate dust or chromic acid can cause permanent eye damage. Skin exposure can lead to dermatitis and skin ulcers, and in some cases kidney damage has been linked to high levels of skin exposure.
Hexavalent Chromium OSHA Standard
In order to tailor requirements to the unique circumstances found in general industry, construction and shipyards, OSHA established three standards for governing occupational exposures to Cr(VI):
- General industry (29 Code of Federal Regulations (CFR) 1910.1026)
- Shipyards (29 CFR 1915.1026)
- Construction (29 CFR 1926.1126)
The standards address:
- Requirements for exposure determination
- Preferred exposure-control methods
- Respiratory protection
- Protective clothing and equipment
- Hygiene areas and practices
- Medical surveillance
The permissible exposure limit (PEL) for Cr(VI) and its compounds is five micrograms of Cr(VI) per cubic meter of air (5 µg/m3) as an eight-hour time-weighted average (TWA). The action level is 2.5 µg/m3 calculated as an eight-hour TWA.
Employers conducting work operations where exposure to Cr(VI) is possible must determine the eight-hour TWA exposure for each employee exposed. Employers must perform initial monitoring to determine the eight-hour TWA exposure for each employee on the basis of a sufficient number of personal breathing zone air samples to accurately characterize full shift exposure on each shift, for each job classification, in each work area. Where an employer does representative sampling instead of sampling all employees, the employer must sample the employee(s) expected to have the highest hexavalent chromium exposures.
If initial monitoring indicates that employee exposures are below the action level, the employer may discontinue monitoring for those employees. If monitoring reveals employee exposures to be at or above the action level, the employer must perform periodic monitoring at least every six months. If monitoring reveals employee exposures to be above the PEL, the employer must perform periodic monitoring at least every three months. If periodic monitoring indicates that employee exposures are below the action level, and the result is confirmed by the result of another monitoring taken at least seven days later, the employer may discontinue the monitoring for those employees.
Employers must perform additional monitoring when there have been any changes in the production process, raw materials, equipment, personnel, work practices or control methods that may result in new or additional exposures to Cr(VI), or when there is any reason to believe that new or additional exposures have occurred.
Monitoring for hexavalent chromium is accomplished with a sampling pump and filter. Results are obtained from a laboratory; you cannot use a direct-reading, badge-type monitor for Cr(VI). When monitoring for Cr(VI), employers must collect the sample on a 37 millimeter (mm) diameter polyvinyl chloride filter (5 micrometer (µm) pore size) using a personal sampling pump calibrated to a flow rate of two liters per minute.
Employers are required to provide workers with respirators when feasible engineering and work practice controls are unable to reduce worker exposure to Cr(VI) to levels at or below the PEL. Where respirator use is required, the employer must establish a respiratory protection program in accordance with OSHA’s Respiratory Protection standard (29 CFR 1910.134). The level of respiratory protection depends on workplace conditions and contaminant levels. Respirator manufacturers, such as 3M, suggest the following:
- N95 filters may be used where there are no oil aerosols
- R or P95 filters may be used where oil aerosols are present (refer to packaging for time-use limitations)
- Filtering facepiece respirators (elastomeric half-facepiece respirators and full-facepiece respirators) may be used up to 10 x PEL of 5 µg/m3 with appropriate filters when qualitatively fit tested
- Full-facepiece respirators with appropriate filters may be used to 10 x PEL of 5 µg/m3 when qualitatively fit tested, and may be used up to 50 x PEL of 5 µg/m3 when they are quantitatively fit tested and equipped with appropriate filters
- Loose-fitting facepieces may be used up to 25 x PEL
- Tight-fitting full facepieces, hoods and helmets with supplied air, and powered air-purifying respirators may be used up to 1000 x PEL
Hazard Communication Standard and Cr(VI)
It is critically important that employees recognize the hazards associated with exposure to hexavalent chromium and understand the measures they can take to protect themselves. OSHA’s Hazard Communication standard (29 CFR 1910.1200) establishes requirements for employers to provide workers with information on hazardous chemicals, such as Cr(VI), through comprehensive chemical hazard communication programs that include safety data sheets (SDSs), labels and worker training. The Hazard Communication rule was revised back in 2012 and adopted a standardized format for SDSs and a new labeling system that harmonizes with the Global Harmonization System of Classification and Labeling of Chemicals (GHS). The Cr(VI) standards require all impermeable bags and/or containers of waste, scrap, debris and any other materials contaminated with hexavalent chromium to be labeled in accordance with the revised labeling requirements of the Hazard Communication standard.
Commonly Asked Question
Q: What is hexavalent chromium?
A: Hexavalent chromium is a toxic valence state (+6) form of the element chromium. These compounds are man-made and usually produced by an industrial process such as hot work on stainless steel, chrome alloys or chrome plated steel.