Hexavalent chromium (Cr VI) is an IARC-1 human carcinogen. According to the EPA, “The best estimate of the excess risk of lung cancer from exposure to hexavalent chromium…is 8 cases of cancer in every 100 workers exposed.” – Environmental Protection Agency, Chromium VI (CASRN 18540-29-9). Other adverse health effects associated with Hexavalent chromium overexposure include irritation of the nose, throat, and lungs. Repeated or prolonged overexposure can damage the mucous membranes of the nasal passages and cause ulcers to form. In some cases the damage is so severe that the septum (the wall separating the nasal passages) develops a hole. Skin exposure to hexavalent chromium over prolonged periods can cause ulcers to form. Some workers develop an allergic sensitization to chromium. In sensitized workers, contact with even very tiny amounts can cause a serious skin rash. Exposure to Chrome 6 can also cause permanent eye damage in some cases.
Employees performing welding or thermal cutting tasks on chromium – containing metals are likely to be over-exposed to Hexavalent Chrome unless engineering controls and / or respiratory protection are used.
SHA’s new regulation of Chromium VI (29 CFR 1910.1026) requires a “regulated area” to be marked off where exposure to Hexavalent Chromium levels of 5.0 micrograms per cubic meter (0.005 mg/m3) or greater can be reasonably expected. In addition to the requirement for respiratory protection for employees in the regulated area, regulatory requirements include employer-provided clothing, laundering of the clothing, changing rooms, wash facilities and personal medical monitoring for each and every employee who enter the regulated area. Personal welding respirators for the individual employees do not eliminate the need for a regulated area and all the above requirements. The new Permissible Exposure Limit (PEL) of 0.005 mg/m3 is very low and many welding and thermal cutting tasks are likely to require Supplied Air respiratory protection in the absence of engineering controls. Only proven engineering controls (such as source capture air filtration from Air Quality Engineering, Inc) can eliminate the need for the regulated areas. Filtration (rather than simple exhaust to the outside) allows recirculation of expensive conditioned air and reduces the size of the regulated area and reduces the number of affected employees.
Mike Harris, Ph.D. CIH is among the Air Quality Engineering’s consulting professionals. Dr. Harris received an earned research Doctorate from Louisiana State University in 1979 and is President of Hamilin & Harris, Incorporated in Baton Rouge, Louisiana. Mike is an instructor for the American Industrial Hygiene Association “Welding Health and Safety” Professional Development courses.
Dr. Harris has served as an adjunct professor in Industrial Hygiene at L.S.U. In Addition to his academic background, Mike also has work experience as a machinist and an aerospace welder. He applies this unique combination of academic and practical backgrounds to his work in Industrial Hygiene and industrial air cleaning. Mike is available to consult with Air Quality Engineering’s clients at any level from a brief telephone call to on-site air cleaning equipment application.