The persistence and accumulation of organophosphate cyanophos (cyanox) and pirimiphos-methy (actellic) insecticides, and synthetic pyrethroid fenpropathrin (danitol) and cyfluthrin (baythroid) insecticides in Nile water and Tiplapia nilotica fish species were studied. The effect of boiling in water, as a method of cooking, on the studied insecticides was also examined. The sublethal doses of the insecticides were calculated and applied as a formulated type at rates of 2.5, 2.5, 0.001, and 0.001 ppm, respectively, to the species reared in a glass aquarium containing aerated tap water. The residues were determined at zero time (1 h), and 1, 3, 5, 7, 14, 21, and 28 days after application using HPLC technique. For organophosphorus insecticides, data revealed that the residue of cyanophos was 2.0 ppm after 1 day of application and then decreased to 0.002 ppm after 28 days. For pirimiphos-methyl it decreased from 2.1 to 0.01 ppm at the same time intervals. For pyrethroid insecticides, fenpropathrin and cyfluthrin showed similar rates of degradation. In fish flesh, the rates of accumulation of the studied insecticides varied. The rate of accumulation of cyanophos increased to 3.1 ppm after 3 days of application, while it was 2.7 ppm after 5 days for pirimiphos-methyl. On the other hand, the maximum rates of accumulation for fenpropathrin and cyfluthrin insecticides were 0.008 and 0.009 ppm after 5 days of application. Also, data indicated that boiling fish flesh in water at 100 degrees C for 20 min removed considerable amounts of the insecticides. (C) 1999 Elsevier Science B.V. All rights reserved.
