Cytotoxicity of dust constituents towards alveolar macrophages: Interactions of heavy metal compounds

The interactions between different heavy metal compounds which affect their cytotoxicity towards rabbit alveolar macrophages were investigated. The cells were exposed in vitro to combinations of As 3+, Cd 2+, Hg 2+, Ni 2+, or V 5+ with different concentrations of another heavy metal compound. Toxicity was determined as the depression of zymosan-induced release of superoxide anion radicals. Significant antagonisms occurred in the combinations Cd 2+/Zn 2+, Hg 2+/As 3+, and Hg 2+/Se 4+, while significant synergisms were exhibited by the combinations Cd 2+/Cu 2+, Cd 2+/Sn 2+, Hg 2+/Cu 2+, Ni 2+/Cd 2+, Ni 2+/Cu 2+, Ni 2+/Sn 2+ and V 5+/Cu 2+. In the combinations As 3+/Zn 2+, Hg 2+/Cd 2+ and Hg 2+/Zn 2+, both kinds of interactions were observed depending on the concentrations of the heavy metal compounds. An interpretation of the measured heavy metal interactions with reference to the toxicity of heavy metal-containing dusts is attempted.