Lung lesions after combined inhalation of cobalt and nickel.

Rabbits inhaled 0.5 mg/m3 Co2+ as CoCl2, a combination of 0.5 mg/m3 Co2+ as CoCl2 and 0.5 mg/m3 of Ni2+ as NiCl2, or filtered air (controls) for 4 months, 5 days/week, 6 hr/day. The pattern of morphological effects on lung tissue and alveolar macrophages after the simultaneous exposure to Co2+ and Ni2+ was a combination of the patterns seen after exposure to Co2+ and Ni2+ alone. However, nickel seemed to potentiate the specific effect of cobalt, i.e., the formation of noduli of type II cells. Further, the increase in phospholipids, especially in 1,2-dipalmitoylphosphatidylcholine, appeared more pronounced after the combined exposure than after the additive combination.