IARC Evaluates Carcinogenic Risks Related to Welding Exposures
Three new monographs published by the International Agency for Research on Cancer address the carcinogenic risks to humans of welding, molybdenum trioxide, and indium tin oxide.  IARC classifies both welding fumes and ultraviolet radiation from welding as Group 1 carcinogens, the agency’s designation for agents that carry sufficient evidence of carcinogenicity in humans. According to the monograph, welding fumes cause lung cancer, and positive associations have been observed with kidney cancer. UV radiation from welding can cause ocular melanoma.  For all other cancers, studies considered by IARC presented inadequate evidence for the carcinogenicity of welding fumes. IARC had previously classified welding fumes as “possibly carcinogenic to humans,” or Group 2B, in 1989. The agency stated that the new classification is based on “substantial new evidence” from observational and experimental studies. Exposure to asbestos and tobacco smoking, which can confound associations with cancer, were determined to be insufficient to explain the excess risk of lung cancer for welders observed in the studies.
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The agency stated that the new classification is based on “substantial new evidence” from observational and experimental studies.