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1751330 
Journal Article 
Cancer Risk and Thoriated Welding Electrodes 
Vinzents, P; Poulsen, OM; Ligaard, R; Simonsen, H; Hansen, EB; Hviid, J; Svane, O 
1994 
0 
Occupational Hygiene
ISSN: 1061-0251 
NIOSH/00219964 
1 
1 
27-33 
The lung cancer risk associated with grinding thoriated electrodes and tungsten inert gas (TIG) welding was examined. Thoriated tungsten welding electrodes containing 1 to 4% thorium-dioxide (1314201) have been widely used in TIG welding because the arcs are easier to start and are very stable. The electrodes contain thorium-228 (14274829), thorium-230 (14269637) (Th230), and thorium-232 (7440291), which are all radioactive and emit alpha particles as they decay. An experiment in which thoriated tungsten electrodes containing 4% thorium-dioxide were ground for 139 minutes with carborundum belts was conducted. The grinding dusts were collected and analyzed for thorium by inductively coupled plasma atomic emission spectrometry. The data were used with industrial hygiene monitoring data to estimate thorium exposures experienced by Danish welders performing TIG welding. The data were then used in conjunction with models in Publication Number 30 of the International Commission on Radiological Protection to estimate the lung cancer risk for TIG welders. The mean concentrations of thorium in the total and respirable dusts generated by grinding the thoriated tungsten electrodes were 401 and 110 micrograms per cubic meter (microg/m3), respectively. The fulltime TIG welding population in Denmark assumed to be at risk was 1,200 welders. The fulltime exposure to thorium during welding was estimated to be 0.1microg/m3 times 360 minutes. The number of lung cancer cases among the population of welders was predicted to range from less than one to approximately 2.5, depending on the amount of Th230 in the electrodes, for 30 years of work. The authors conclude that the number of excess lung cancers associated with TIG welding using thoriated tungsten electrodes is low, ranging from zero to three, for a working life of 30 years. To eliminate the lung cancer risk, it is recommended that the electrodes be replaced by nonradioactive electrodes, possibly those containing lanthanum or cerium alloyed tungsten. 
DCN-219420; Lung cancer; Risk analysis; Radioactive metals; Arc welding; Metal fumes; Abrasive grinding; Mathematical models