RESUMO
The use of metal inert gas (MIG) stainless steel (SS) welding techniques is rapidly increasing. The possible health hazards of MIG/SS welding fumes are not known; more attention has been paid to manual metal arc (MMA) welding. In this study, 52 male Wistar rats were exposed to MIG/SS welding fumes generated by an automatic welding device for "nose only" exposure. For the retention study, the duration of exposure was one hour per workday for 1,2,3, and 4 weeks. For the clearance study, the duration was 4 weeks, and the follow-up period was 106 days. The retention and clearance of the alloyed metals of SS (chromium (Cr), manganese (Mn), nickel (Ni] and iron were studied in the rats' lungs, and the results were compared with the corresponding results of MMA/SS welding. The multielement chemical analysis was made using instrumental neutron activation analysis (INAA); the concentration of exogeneous iron (Feex) was determined by a magnetic measuring method. Feex and Cr were retained in the ratio expected; Mn, Ni and total Fe were retained slower than expected. The total Fe did not clear at all even though Feex cleared with the half-time of 50 d which corresponded well with that of pure magnetite. The accumulation of Cr in the lungs was very high: it cleared with the half-time of 240 d. The clearance patterns of Mn and Ni were very similar. They followed a double exponential model with half-times of 2 d and 125 d for Mn, and 3 d and 85 d for Ni. The results indicated that even though the retention patterns for MMA and MIG welding fumes were very similar, the clearances differed very much.
