title: Toxicity bioassay of technical and commercial formulations of carbaryl to the freshwater catfish, Clarias batrachus.
abstract: The acute toxicity of the carbamate insecticide, carbaryl, in technical and commercial formulations was investigated in the freshwater catfish, Clarias batrachus, after exposures of 24, 48, 72, and 96 hr. The "trimmed Spearman-Karber method" with 10% trimming was employed for the determination of median lethal concentration (LC(I)50). The LC(I)50 values of the commercial carbaryl (162.60, 134.08, 123.36, 107.66 mg/liter) decreased gradually with increase of exposure duration from 24, to 48, 72, and 96 hr, respectively. Similarly, the LC(I)50 values of technical grade carbaryl (61.14, 53.65, 48.58, 46.85 mg/liter) decreased with increasing length of exposure. This reflects a time-dependent adaptability of the fish to the toxicant. Further, the technical grade compound was 2.5 times more toxic than the commercial preparation. This demonstrates the involvement of carbaryl as the active principle in acute toxicity testing, rather than the additive substances. Dermal desquamation was observed as a characteristic change in response to carbaryl exposure.
mesh_terms: D000818:Animals; D012721:Carbaryl / Q000633:toxicity*; D002397:Catfishes / Q000502:physiology*; D004781:Environmental Exposure; D007928:Lethal Dose 50; D010573:Pesticide Residues / Q000633:toxicity*; D013997:Time Factors; D014873:Water Pollutants / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010573:Pesticide Residues; D014873:Water Pollutants; D014874:Water Pollutants, Chemical; D012721:Carbaryl