Interaction between erythrocyte plasma membrane and silicate dusts.

Lysis of erythrocytes in vitro leading to release of hemoglobin has often been used as a convenient test system for predictive toxicological evaluation of noxious particulates encountered as pollutants in occupational and environmental atmospheres. However, in spite of several studies with silica and silicate dusts, the exact biochemical mechanism for membrane damage is not clear. Therefore, detailed biochemical studies were conducted. Screening of a large number of fugitive dust samples indicated that the dissolution of silica under assay conditions has a qualitative relation to hemolytic potency. The strong capacity of slate mine dust to cause hemolysis was studied in detail. The kinetics of lysis indicated that on prolonged contact the adsorption of hemoglobin altered the lytic index. Coating of dust with serum, albumin or polyvinylpyrrolidone (PVP) and some lipids reduced lytic potency markedly, while EDTA was ineffective. Altering the surface chemistry of dust by heating, alkali treatment, washing with water, and acid washing reduced hemolysis in increasing order. Thus, chemical interactions between dusts and membranes are involved in hemolysis, and it may be concluded that the interaction of dust constituents with biomembranes is one of the likely mechanisms involved in the toxicity of particulate air pollutants.