|BACKGROUND: Pesticides is exposed in an aquatic environment and effected to benthic animals. Especially, sediment-associated pesticides is required for determination of sediment toxicity on aquatic organisms. This study was conducted to evaluate the impact of six pesticides (chlorfluazuron, difenoconazole, dithianon, flufenoxuron, flutianil, pendimethalin) onChironomus riparius in aquatic ecosystems.
METHODSANDRESULTS: Chlorfluazuron, difenoconazole, dithianon, flufenoxuron, flutianil and pendimethalin were used as a model compounds, which have a sediment-associated potential (Koc>3). Acute and chronic toxicity tests on Chironomus riparius were performed at six concentrations of each pesticidewith four replicates of each based onOECDtest guideline 235 and 218. The calculated 48-h EC50 values of chlorfluazuron, flutianil, pendimethalin, difenoconazole, dithianon and flufenoxuron were 6.72, 2.55, 2.27, 0.77, 0.30 and 0.11 mg/L, respectively. Flufenoxuronwas the lowest 48-h EC50 value in this study. TheNoObserved EffectiveConcentration (NOEC) and the Lowest Observed Effect Concentration (LOEC) of flufenoxuron for Chironomus riparius in 28-days test were 30 and 60 μg/kg, respectively.
CONCLUSION: Pesticides of the sediment-associated have the potential effect for Chironomus riparius in aquatic ecosystems. Therefore, sediment toxicity assessment of these pesticides should be further investigated to evaluate the impact to benthic organisms.