Toxicity of fipronil and its enantiomers to marine and freshwater non-targets.
Fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (S,+) and (R,-) enantiomers and the racemic mixture of fipronil were assessed using Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Results showed that S. vittatum IS-7 was the most sensitive freshwater species to the racemic mixture of fipronil (LC50 = 0.65 microg/L) while P. pugio was the most sensitive marine species (LC50 = 0.32 microg/L). Procambarus clarkii were significantly more sensitive to the (S,+) enantiomer while larval P. pugio were significantly more sensitive to the (R,-) enantiomer. Enantioselective toxicity was not observed in the other organisms tested. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. These results indicate that the most toxic isomer of fipronil is organism-specific and that enantioselective toxicity may be more common in crustaceans than in other aquatic organisms.
Overmyer
Jay P
JP
Department of Entomology, University of Georgia, Athens, GA 30602, USA. jayo@uga.edu
Rouse
David R
DR
Avants
Jimmy K
JK
Garrison
A Wayne
AW
Delorenzo
Marie E
ME
Chung
Katy W
KW
Key
Pete B
PB
Wilson
W Aaron
WA
Black
Marsha C
MC
D000818:Animals; D003400:Astacoidea / Q000187:drug effects / Q000254:growth & development; D001681:Biological Assay; D049872:Bivalvia / Q000187:drug effects / Q000254:growth & development; D017753:Ecosystem; D004781:Environmental Exposure; D004784:Environmental Monitoring; D007306:Insecticides / Q000737:chemistry / Q000633:toxicity*; D033541:Palaemonidae / Q000187:drug effects / Q000254:growth & development; D010839:Phytoplankton / Q000187:drug effects / Q000254:growth & development; D011720:Pyrazoles / Q000737:chemistry / Q000633:toxicity*; D012843:Simuliidae / Q000187:drug effects / Q000254:growth & development; D013045:Species Specificity; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014877:Water Pollution, Chemical; D014982:Xenopus laevis / Q000254:growth & development
D007306:Insecticides; D011720:Pyrazoles; D014874:Water Pollutants, Chemical; C082360:fipronil