Toxicological evaluation and bioavailability of 14C-fenitrothion bound residues on soybeans towards experimental animals

Under local practice of Egyptian conditions, the application of C-14-fenitrothion on soybeans at a dose of 10 mg insecticide/kg grains, led to the formation of 21% of C-14-bound residues (non-extractable) after 24 weeks of storage. The external residues were 20% and the internal extracts were 55% of the applied dose. Feeding studies on rats revealed that bound residues were bioavailable. After feeding rats for three days with bound C-14-fenitrothion residues, the main portion of radioactivity was eliminated via expired air (42%), urine (20%) and feces (11.5%). About 15% of the administered radioactivity was distributed among various organs as, liver, kidney, lung, fat, intestine, blood, heart, and brain. Toxicity of bound residues of C-14-fenitrothion in stored soybeans was studied in mice through feeding experiments for three months at a concentration of 1.9 mg/kg. The maximum inhibition in plasma and erythrocyte cholinesterase activity was observed 22.5%, 18.9% and 8.6%, 9% after one and seven days, respectively. The obtained results showed a slight significant elevation after three months in the activity of liver enzymes alanine amino transferase, aspartate amino transferase and alkaline phosphatase. A moderate increase in blood urea nitrogen and creatinine concentration was observed in the treated groups at the end of the experimental period. The detected levels of albumin and total protein showed no significant compared to the control values, of controlled animals, after three months. (C) 2008 Elsevier Ltd. All rights reserved.