Bound Residues of 14C-Fenitrothion in Stored Faba Beans. Their Bioavailability and Toxicity to Experimental Animals

Seeds of faba beans treated with 14C-fenitrothion at a dose of 10 mg/kg seeds and stored for 24 Weeks were extracted with 95% methanol for 24 hours. About 48% of the applied 14C-activity was recovered in the extract (extractable residues), and the amount of 14C-residues bound to the grains (non-extractable residues) amounted to about 18% of the applied radioactivity. After feeding rats with bound 14C-fenitrothion residues (69μg equivalent / rat) for 3 days, a substantial amount of administered 14C-activity), (about 45%) was eliminated via the expired air while urine and feces contained 15% and 8%, respectively. About 23.5 % of the administered radioactivity was found to be distributed among various organs of the rat. Chromatographic analysis of urine showed the presence of dimethyl phosphorothioate and dimethyl phosphate as the radiolabelled products detected in urine together with traces of nonlabelled 3-methyl-4,nitrophenol. Feeding mice for 90 days with a diet mixed with bound fenitrothion residues in stored faba beans (1.54 ppm insecticide/ mouse) led to a reduction in body weight gain and an appreciable decrease in cholinesterase activity that amounted to 21.5 % for plasma and about 16 % for red blood cells at the end of the feeding experiment. Also, a significant decrease was observed in both total protein and albumin concentrations, while liver and kidney functions, as well as lipid profile of treated mice were significantly increased at the end of feeding period. After one month of recovery period, all the examined blood parameters did not return to the control values.