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Evaluation of the risk of mixtures of paddy insecticides and their transformation products to aquatic organisms in the Sakura River, Japan
Author(s) -
Iwafune Takashi,
Yokoyama Atsushi,
Nagai Takashi,
Horio Takeshi
Publication year - 2011
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.569
Subject(s) - fenthion , daphnia magna , diazinon , acceptable daily intake , toxicology , pesticide , biology , hazard quotient , fenitrothion , toxicity , agronomy , chemistry , ecology , contamination , organic chemistry , malathion
To assess the risk of mixtures of six paddy insecticides and their transformation products (TPs) to aquatic organisms in the Sakura River, Japan, their concentrations in the river water were monitored during the rice cultivation season in 2008 and 2009, and acute toxicity tests for Cheumatopsyche brevilineata (caddisflies) and Daphnia magna (daphnids), surrogate test species for caddisflies and cladocerans, respectively, were conducted. The mixture of fipronil, applied in the rice nursery box, and its desulfinyl, sulfide, and sulfone TPs were detected in the river for several months after transplanting, and they were more toxic to C. brevilineata than the other tested compounds. The toxicities of the parent compound and its TPs, such as fipronil and its TPs, may be related to their hydrophobicities. Risk quotients for mixtures (RQ mix ) of only parent compounds did not exceed 1, but, in mid‐June 2009, the RQ mix of parent compounds and TPs for caddisflies exceeded 1. Diazinon, fenitrothion, and fenthion sprayed on the rice crop and their TPs posed a sporadic risk for cladocerans, depending on the application timing, whereas fipronil TPs contributed to the RQ mix for caddisflies for several months after transplanting. The risk of mixtures of insecticides and their TPs differed seasonally between caddisflies and cladocerans, depending on insecticide application timing and the persistence and toxicity of TPs. Environ. Toxicol. Chem. 2011; 30:1834–1842. © 2011 SETAC