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Written By: Henry P. Shotwell, Ph.D., CIH and Robert E. Sheriff, MS, CIH, CSP, President
March 6, 2020
Is Hexavalent Chromium (Hex Chrome; Chrome VI) Found in Welding Fumes A Carcinogen?
Neither the chromium found in metal plating (like chrome trim on a can) nor the chrome found in medicines like chromium picolinate are in the hexavalent form and are not a carcinogen. In fact, it has a positive value in our systems by assisting in regulating blood sugar levels.
The chromium found in the fumes formed by welding stainless steel and released into a welder’s breathing zone is in the hexavalent state (CR+6) can cause lung cancer if the welder breathes in a high enough dose of chrome VI often enough. Welding on metals other than stainless steel may also contain hexavalent chromium as well, but the potential for overexposure is less. The Occupational Safety and Health Administration (OSHA) has determined that continuous, 8-hour exposure to hexavalent chromium of 0.005 milligrams per cubic meter of air, or less, is an acceptable exposure level (OSHA Regulation 29 CFR 1910.1026). This new regulation was instituted in 2006 with all provisions in effect on December 31, 2008. The PEL for an 8-hour workday is 5 ug/M3 and the Action Level is 2.5 ug/M3.
In 1990, the International Agency for Research on Cancer (IARC), an agency of the World Health Organization (WHO), published its findings on chromium and chromium compounds as carcinogens. Chromium may be isolated in any of three-volume states: Chrome 0 or metallic chromium; Chrome III called “Chrome 3” or Chrome VI called “Chrome 6,” also called hexavalent chromium. Neither Chrome 0 nor Chrome III has shown the ability to cause cancer. Chrome VI, on the other hand, is a well-known lung carcinogen. (DeFlora, S., “Threshold Mechanisms and Site-Specialty in Chromium (VI) Carcinogens,” Carcinogens, Volume 21, No. 4, pages 533-541, April, 2000, Oxford University Press. However, according to DeSilva, the development of lung cancer “…requires massive exposures, as is only encountered in well-defined occupational settings…”
Methods To Control Welding Fumes
Methods to control welding fumes should be instituted if the levels exceed even the Action Level of 2.5 ug/M3. (See 29CFR1910.1026 – General Industry or 29CFR1926.1126-Construction).
Portable welding fume extractors work well in controlling hex chrome and other welding fumes when placed close enough to the point of operation to capture the “smoke” created by welding, thereby reducing or eliminating the “smoke” from entering the welder’s breathing zone. Using a respirator on the welder to filter out the “smoke” particles is the last line of defense. A respirator has to be correctly chosen for the anticipated contaminant, but it also has to be correctly fitted to the worker’s face, and tested to be sure there is no leakage around the edges of the respirator that might allow contaminants to bypass the filter system. OSHA requires that workers be properly trained in the use, cleaning, care, and storage of respirators and fit tested annually.
Where Hexavalent Chromium is Found
Common activities where hex chromium exists are in welding of stainless steel or chrome-plated metals and electroplating of chrome. Printing or painting operations where chromium inks or paints are used may also be a source of hex chrome exposure.
In each of these cases, these activities should be sampled for hex chrome to determine if the exposure levels are safe. If it is a work situation, then compliance with the OSHA Standard for hexavalent chromium (29 CFR 1910.1026) must be addressed. Monitoring the workers while performing hex chrome exposure tasks is also required to ensure that any respirators are the proper ones for the workers and the task performed. The Respiratory Protection Standard is 29CFR1910.134.
For more information contact Atlantic Environmental.
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