title: Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening.
abstract: To assess the exposure of welders to thorium-232 (232Th) during tungsten inert gas arc (TIG) welding, airborne concentrations of 232Th in the breathing zone of the welder and background levels were measured. The radioactive concentrations were 1.11 x 10(-2) Bq/m3 during TIG welding of aluminum (TIG/Al), 1.78 x 10(-4) Bq/m3 during TIG welding of stainless steel (TIG/SS), and 1.93 x 10(-1) Bq/m3 during electrode sharpening, with 5.82 x 10(-5) Bq/m3 background concentration. Although the annual intake of 232Th estimated using these values did not exceed the annual limit intake (ALI, 1.6 x 10(2) Bq), we recommend reducing 232Th exposure by substituting thoriated electrodes with a thorium-free electrodes, setting up local ventilation systems, and by using respiratory protective equipment. It is also necessary to inform workers that thoriated tungsten electrodes contain radioactive material.
authors.affiliation: National Institute of Industrial Health, 6-21-1, Nagao, Tama-ku, Kawasaki, 214-8585 Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Saito
authors.forename: Naomi
authors.initials: N
authors.lastname: Hisanaga
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Okada
authors.forename: Shoji
authors.initials: S
authors.lastname: Hirai
authors.forename: Heihachiro
authors.initials: H
authors.lastname: Arito
mesh_terms: D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D004566:Electrodes; D006801:Humans; D007564:Japan; D009501:Neutron Activation Analysis; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D013910:Thorium / Q000009:adverse effects*; D014414:Tungsten; D014896:Welding / Q000379:methods*
chemical_list: D000395:Air Pollutants, Occupational; D013910:Thorium; D014414:Tungsten