Kinetics of nickel and chromium in rats exposed to different stainless-steel welding fumes.

The kinetics of nickel and chromium from welding fumes were studied in the rat. To study the retention, the duration of exposure was one hour per working day for one, two, three, and four weeks. For the clearance study the follow-up period after four weeks' exposure was 106 days. Multi-element chemical analysis of the fumes and dried lungs was done using instrumental neutron activation analysis, and the concentrations in the body fluids were determined by atomic absorption spectroscopy. The maximum lung retention of metal inert-gas (MIG) welding fumes was somewhat higher than that of manual metal arc (MMA) welding fumes. The estimated maximum concentrations in the lungs were 9.5 micrograms/g and 150 micrograms/g for nickel after four weeks' exposure to MMA and MIG welding fumes. The corresponding concentrations of chromium were 78 micrograms/g and 310 micrograms/g. The measured concentrations were lower, however. The amounts of nickel cleared from the lungs during the MMA and MIG exposures were 0.9 microgram and 8 micrograms. The corresponding amounts of chromium were 9.6 micrograms and 2 micrograms. Practically all of the lost metals were found in the urine, in which the excretion rates were 0.07 microgram/d (MMA) and 0.39 microgram/d (MIG) for nickel and 0.23 microgram/d (MMA) and 0.11 microgram/d (MIG) for chromium.