The uptake and in vivo metabolism of the organophosphate insecticide fenitrothion by the blue crab, Callinectes sapidus.

Callinectes were exposed to [14C]fenitrothion at a level of 5.2 micrograms/liter in either 22 degrees C, 34 ppt; 22 degrees C, 17 ppt; or 17 degrees C, 34 ppt seawater. Uptake from the water, as measured by a decrease in fenitrothion, and the distribution of radioactivity throughout the Callinectes were determined. The nature of radiolabeled metabolites in the water and hepatopancreas was also determined. Fenitrothion was absorbed more rapidly from the water at the higher salinity and temperature. Radioactivity was detected in all the organs assayed by 24 hr postexposure, though the levels increased in most tissues throughout the experiment. The highest concentrations of radioactivity were found in the hepatopancreas and stomach. The metabolites which were detected in the water and liver indicate that Callinectes metabolize fenitrothion by oxidation of the phosphorothioate to a phosphate to yield fenitrooxon. The presence of aminofenitrothion and 3-methyl-4-aminophenol shows that reduction of the nitro group to an amino group also occurs. The isolation of desmethyl forms of fenitrooxon and fenitrothion as well as 3-methyl-4-nitrophenol indicates that hydrolysis of both the P-O-aryl and P-O-alkyl bonds occurred. Glycoside and sulfate conjugates of both phenols were inferred in the hepatopancreas. Higher levels of fenitrooxon and lower levels of desmethyl fenitrothion were detected in the 34 ppt seawater than in the 17 ppt seawater. The 5 degrees C differential had no significant effect on the nature and concentrations of metabolites detected in the seawater.