Hexavalent Chromium: OSHA Reduces Exposure LevelsBy Timothy Lundell, PE, CIH
Hexavalent Chromium: OSHA Reduces Exposure Levels
By Timothy Lundell, PE, CIH
On May 30, 2006, dramatic changes to OSHA's rules regulating the use of hexavalent chromium, Cr (VI), became effective. Cr (VI) (pronounced chrome 6) is one of several “valence states” of the element chromium. Chromium is a widely used industrial metal and the rule changes could dramatically affect how manufacturers use chrome.
In the Federal Register , OSHA published major amendments to the Occupational Exposure to Hexavalent Chromium rules. The rules require new handling procedures and lower the permissible exposure limit (PEL) from 52 micrograms per cubic meter (ug/m3) to 5 ug/m3. Virtually all users of Cr (VI), including general industry under 29 CFR Part 1910.1026, shipyards under 29 CFR Part 1915.1026, and construction under 29 CFR Part 1926.1126, are covered by the changes. The few uses that are excluded from the rule include exposure during the application of pesticides and exposure from Cr (VI) in Portland cement. Situations where there are no dusts, fumes or mists in concentrations at or above 0.5 ug/m3 under any expected use are also excluded.
History of the Amendments
The OSHA Cr (VI) PEL prior to May 30, 2006, was 52 ug/m3. The American National Standards Institute originally recommended this limit in 1943 to prevent nasal perforations in chromium-exposed workers. When OSHA was created in 1971, it adopted the 52 ug/m3 value. In 1993, Public Citizen and the Oil, Chemical and Atomic Workers International Union, now part of the United Steelworkers, petitioned OSHA to reduce its PEL from 52 ug/m3 to 0.25 ug/m3 to reduce the risk of lung cancer. After a series of public hearings, OSHA set the PEL at 5.0 ug/m3 and the action level at 2.5 ug/m3. In addition to OSHA standards, the Environmental Protection Agency regulates disposal and air emissions of Cr (VI) and the Department of Transportation regulates its transportation. In the European Union, the RoHS (Restriction of Hazardous Substances) initiative seeks to ban the presence of hexavalent chromium in products above 0.1 percent by weight.
Who is Covered?
To determine whether you are affected by the rule, it is necessary to perform an audit to establish whether chromium in any form is present and then, if chromium is present, to perform indoor air monitoring for Cr (VI). If the test results indicate that hexavalent chromium exposure is above the action level, you must begin additional exposure monitoring and medical surveillance. If CR (VI) is present above the PEL, you must implement all aspects of the rules. If Cr (VI) is detected at any level it is recommended that the sources be identified and ways to reduce exposure be implemented.Chromium has as many names and uses as it does valence states. Chrome is what makes rubies red and emeralds green. The mirrored surfaces on automobile and truck bumpers are usually polished chrome metal. A major component of stainless steel is chrome and consequently chrome is a component of kitchen appliances, pans, eating utensils, faucets and even the kitchen sink. Chrome has unique properties that make it ideal for surgical and dental instruments, implants, stents and needles. It is used in nuts and bolts, bearings and shafts, engines and pumps. The aircraft industry, shipbuilding, construction, agriculture, electronics, microelectronics, and power generation all rely on chrome.
Chromium Facts
To remove all chromium from our lives would be somewhat analogous to removing all gasoline. Fortunately, chromium has many valence forms and the forms that are most functional, are also the least harmful. In general, the chrome containing items that we are exposed to contain non-toxic chrome metal, not hexavalent chromium. Workers however, may be exposed to chrome in its Cr (VI) valence state as it is being converted into a safe form of chrome. Hexavalent chromium has been linked to nasal, oral, nasopharyngeal, oropharyngeal and lung cancers. In contrast, trivalent chromium (Cr (III)) is required in trace amounts for sugar metabolism in humans, and its lack can cause a condition known as chromium deficiency.
Activities where workers may be exposed to Cr (VI) are chrome mining, chrome production, stainless steel manufacturing, welding, painting, paint manufacturing and chrome plating. Cr (VI) is also used as a wood preservative and exposure may occur during application, but that is regulated by pesticide regulations.
Actions for Protection
Once an exposure determination has been made and it is expected that employee exposure can exceed the PEL of 5 ug/m3 as described in the rule, the employer must provide the following:
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