Lung epithelium injury biomarkers in workers exposed to sulphur dioxide in a non-ferrous smelter

Serum Clara cell protein (CC16) and surfactant-associated protein D (SP-D) were measured in 161 workers exposed to sulphur dioxide (SO2) in a non-ferrous smelter. Seventy workers from a blanket manufacture served as referents. Exposure to SO2 and tobacco smoking were associated with a decrease of CC16 and an increase of SP-D in serum. Tobacco smoking and exposure SO2 interacted synergistically to decrease serum CC16 but not to increase serum SP-D. While further illustrating the potential of serum CC16 and SP-D, our study confirms that SO2 can cause airways damage at exposure levels below current occupational exposure limits.