Toxicity, Bioconcentration, and Depuration of the Herbicide Bolero 8EC in Freshwater Invertebrates and Fish

Abstract

Bolero 8EC, a herbicide used in rice culture, was moderately toxic to four species of aquatic invertebrates and three species of freshwater fishes in actute toxicity tests. The 96-h LC50's or 48-h LC50's ranged from 1.0 to 6.5 mg/l for amphipods Gammarus pseudolimnaeus, daphnids Daphnia magna, juvenile crayfish Orconectes nais, and mature red crayfish Procambarus clarki and from 1.2 to 2.3 mg/l for rainbow trout Salmo gairdneri, bluegills Lepomis macrochirus, and channel catfish Ictalurus punctatus. Bioconcentration of 14C-Bolero during a five day exposure ranged from 10 to 168 for four species of invertebrates and from 48 to 471 for four species of fish. Residues of the herbicide (14C-Bolero) were rapidly eliminated when fish and invertebrates were placed into fresh water. More than 50 percent of the total 14C-radioactivity was eliminated within 24 h by all organisms tested except the red cryafish whose residues in tail tissues declined by 50 percent within 10 days. Judging by the moderately acute toxicity, low bioconcentration, and rapid elimination of residues in fresh water, we suggest that the use of Bolero 8EC will probably result in little environmental hazard to freshwater organisms. © 1982, The Japanese Society of Fisheries Science. All rights reserved.