Hexavalent Chromium (CrVI): A Not So Silent Enemy
Chromium in various forms has been with us since before the beginning of recorded time. It was used to cover the bronze spearheads of warriors in ancient China to harden and prevent rust on the tips.
Modern uses of chromium include the making /welding of stainless steel, welding on steel that contains chromium, and the chrome plating of consumer products for motorcycles, automobiles and furniture. Hexavalent chromium is created when chromium metal is heated and through other chemical processes.
Unfortunately, the same properties that make this metal useful also cause severe illness and even death if we are exposed to airborne concentrations exceeding OSHA permissible exposure limits (PEL). Health effects can vary from skin ulceration to kidney and liver damage. Hexavalent chromium is also a known carcinogen (causes cancer).
Chromium can cause other health effects such as contact dermatitis. On February 2, 2010, OSHA issued a Standard Letter of Interpretation which states “…work with cement is regarded as the most common cause of (hexavalent chromium) induced dermatitis”. The clean-up of any dusts that may contain hexavalent chromium should be performed using a HEPA filtered vacuum and appropriate PPE to prevent employee contact. The hexavalent chromium in the cement comes primarily from the grinding media (high chromium steel) used to reduce the “clinkers” to a fine powder during the production process. Clinkers are the small round by-products of the raw materials after they are exposed to high temperatures.
If Hexavalent Chromium is present in your workplace the following steps are recommended to help limit employee exposures:
- Communicate Hexavalent Chromium hazards to all affected workers.
- Label the workplace with signs to clearly identify areas where the PEL for Hexavalent Chromium may be exceeded.
- Provide employees in these areas with respiratory protection, as outlined in 29 CFR 1910.134.
- Provide protective clothing, change areas (to separate work from personal clothing), wash facilities and designated eating areas.
- Schedule air sampling to ensure interim respiratory protection measures are adequate.
- Implement an engineering plan (with the assistance of an outside vendor or consultant) to reduce Hexavalent Chromium exposure levels through the use of exhaust ventilation.
- Schedule follow-up air sampling to confirm engineering controls reduce the Hexavalent Chromium to levels below the OSHA Action Level -- or that respiratory protection remains adequate (in the event exhaust ventilation is not feasible).
OSHA has also published a guide entitled, “Small Entity Compliance Guide for the Hexavalent Chromium Standard” to help small businesses comply with the standard and a general facts sheet that can be very helpful in understanding the health effects of Hexavalent Chromium.
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