Figure 5. Species sensitivity distribution for animals exposed to diquat. The straight line represents the model fit to all of the data (y = 14.291ln(x) + 13.734; R2 = 0.826). Diquat is not usually applied directly to the water except when controlling submerged weeds. Maximum aqueous concentrations from the literature are much lower than the most sensitive species, indicating a likely margin of safety for terrestrial uses.