Weight of evidence assessment of effects of sulfoxaflor on aquatic invertebrates: sulfoxaflor environmental science review part II.

Abstract

Effects of sulfoxaflor (SFX) on aquatic invertebrates were assessed by comparing concentrations predicted to occur in or measured in surface waters to thresholds for adverse effects. Due to the specific mode of toxic action, fishes are relatively tolerant of the effects of SFX. Daphnia magna with an LC₅₀ of 378 mg SFX L^-1 (SD = 19.13) was similarly tolerant of the effects of SFX, while the LOEC was >110 mg SFX L^-1. A threshold for effects on aquatic insects, based on the chironomid midge, C. tentans, had LOAEL and NOAEL values of 0.0455 and 0.0618 mg L^-1, respectively. The acute-to-chronic ratio was 18. Simulation models and parameters selected for a range of applications to crops predicted environmental concentrations (EECs) in surface waters to range from 2.2 to 7.7 µg L^-1. Based on these EECs, the maximum hazard quotient (HQ) was 0.11, which is less than the US EPA level of concern (LOC) of 0.5, which would normally be the threshold to trigger regulatory action or higher-tier assessments. The risks posed by SFX to aquatic organisms are predicted to be de minimis. Hazard quotients based on EEC values predicted in the standard, USEPA farm pond estimated by use of the Pesticides in Water Calculator (PWC version 1.52) for scenarios of maximum application rates for cotton and LOAEL and NOAEL values for aquatic insects for SFX were less than or similar to those for other insecticides including neonicotinoids and organophosphorus compounds.