title: Acute toxicity to zebrafish of two organophosphates and four pyrethroids and their binary mixtures.
abstract: BACKGROUND
  Environmental pollutants, including metals, pesticides and other organics, pose serious risks to many aquatic organisms. The acute toxicities to zebrafish (Brachydanio rerio Hamilton & Buchanan) were determined for two organophosphorus insecticides, four pyrethroid insecticides and 50:50 binary mixtures.
  
  
  RESULTS
  At 24, 48, 72 and 96 h after treatment, LC(50) of permethrin, tetramethrin, bifenthrin, etofenprox, dichlorvos and phoxim to zebrafish were 0.0052-0.0025, 0.0782-0.0460, 0.0065-0.0032, 0.0969-0.0791, 51.3-13.0 and 1.28-0.469 mg L(-1) respectively. LC(50) of permethrin + dichlorvos, permethrin + phoxim, tetramethrin + dichlorvos, tetramethrin + phoxim, bifenthrin + dichlorvos, bifenthrin + phoxim, etofenprox + dichlorvos and etofenprox + phoxim were 0.0082-0.0046, 0.0078-0.0042, 0.264-0.124, 0.141-0.121, 0.0251-0.0154, 0.0154-0.0087, 0.396-0.217 and 0.213-0.0391 mg L(-1).
  
  
  CONCLUSIONS
  Toxicity levels of all pyrethroid insecticides to the zebrafish were high or very high. The organophosphate dichlorvos showed low toxicity, but phoxim showed high or intermediate toxicities to zebrafish, and the toxicities of binary mixtures of permethrin and dichlorvos or phoxim, bifenthrin and dichlorvos or phoxim and etofenprox and phoxim (48, 72 and 96 h exposure) were very high. The toxicities of binary mixtures of tetramethrin and dichlorvos or phoxim, etofenprox and dichlorvos and etofenprox and phoxim (24 h exposure) were high.
authors.affiliation: Institute of Food Safety Research and Inspection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Yu
authors.forename: Dong-Lan
authors.initials: DL
authors.lastname: Wang
authors.forename: Hai-Juan
authors.initials: HJ
authors.lastname: Yan
authors.forename: Xian-Jin
authors.initials: XJ
authors.lastname: Liu
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004347:Drug Interactions; D007306:Insecticides; D007928:Lethal Dose 50; D010755:Organophosphates / Q000633:toxicity*; D011722:Pyrethrins / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D015027:Zebrafish
chemical_list: D007306:Insecticides; D010755:Organophosphates; D011722:Pyrethrins