Lung function changes in workers exposed to cobalt compounds: a 13-year follow-up.

The objective of the study was to examine the influence of cobalt exposure on lung function changes in workers from a cobalt-producing plant in a health monitoring program implemented between 1988 and 2001. A total of 122 male workers with at least 4 (median = 6) lung function tests (FEV(1) and FVC) during the follow-up period were assessed longitudinally. Cobalt exposure significantly decreased over the follow-up period, as reflected by the measurements in air and urine. The possible association of spirometric changes with cobalt exposure was examined by a random coefficients model, taking into account other potential influential variables, such as smoking, age, previous respiratory illness, exposure to other lung toxicants, or the presence of glutamate in position 69 in the HLA-DP beta-chain, an HLA polymorphism possibly associated with hard-metal-induced lung diseases. The main finding of the follow-up study was that cobalt exposure contributed to a decline in FEV(1) over time, and only in association with smoking. No influence of glutamate in position 69 in the HLA-DP beta-chain polymorphism was detected. Although the amplitude of the additional FEV(1) decrement associated with smoking exposure was relatively small (< 20%) compared with the expected decline in a non-cobalt-exposed smoker, the results indicate that further efforts to reduce cobalt exposure and to encourage workers to quit smoking are still warranted.