On the mechanism of silica toxicity

Abstract

Silicic acid in its polymerized form is toxic to leucocytes in tissue culture and depresses leucocyte respiration, effects which appear to be paralleled by its inhibition of the cytochrome oxidase enzyme system. There is evidence that silicic acid acts on this system by combining with and inactivating cytochrome c and it is suggested that its effect in vivo may have a similar basis. The inhibitory effect of silicic acid on the two other respiratory enzyme systems studied is considerably less intense and probably non-specific.