Figure 4. 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). *Maximum target concentration for Reward® is 0.4 mg/L, indicating minimal effects on aquatic animals (i.e., 0.4 mg/L is lower than LC50 for most species). **Maximum target concentration for Weedtrine-D® is 1.5 mg/L, indicating a lack of a margin of safety for approximately 80% of species.