Studies on the effects of paraquat and diquat on cells in culture. Viability of macrophages and fibroblasts incubated with paraquat and diquat.

Paraquat and diquat are of similar toxicity to rat alveolar and peritoneal macrophages in tissue culture. Irreversible damage to macrophages occurs after exposure of 30 min to paraquat or diquat at concentrations as low as 10(-6) mol/l, resulting in the uptake of vital dye. Paraquat and diquat at concentrations of 10(-5) mol/l or less do not reduce viability of fibroblasts as measured by dye exclusion but reduce cloning efficiency. The toxicity of diquat to fibroblasts is approximately ten-fold greater than that of paraquat.