Effect of the commercial processing procedures on [14]C chlorpyrifos residues in soybean oil

Crude soybean oil extracted from grains treated with chlorpyrifos at a dose of 15 mg insecticide/kg seeds and stored for 30 weeks was subjected to different refining processes such as alkali treatment, bleaching, winterization and deodorization. The effect of the refining processes on the nature and magnitude of the originally present residues was investigated. The radioactive insecticide residues in crude oil and cake amounted to 9% and 65%, respectively, of original radioactive residues inside the seeds. A high percentage of the residues [50-55%] were removed during alkali treatment and bleaching steps. The C-activity in the crude stored soybean oil could be reduced by about 85% of radioactivity originally present in crude oil through simulated commercial processes locally used for oil refining. Refined soybean oil fortified with [14]C-chlorpyrifos had only 20% of the radioactivity originally present, mainly in the form of chlorpyrifos, and 3,5,6-trichloropyridinol in addition to desethylchlorpyrifos [in oil with aged residues]

Mineralization of 14C-carbofuran in soil under aerobic and anaerobic conditions

The mineralization of 14C-carbofuran in clay loam soil was determined during a three months laboratory incubation period under anaerobic and aerobic conditions. 14C-activity in solution was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion. Evolution of 14CO2 increased with time and reached to 7.5% and 12.0% of the initial 14C-concentration, within 90 days in case of anaerobic and aerobic conditions, respectively. At that time, soil contained about 58% of the applied dose as extractable residues under anaerobic conditions and 59% under aerobic conditions. The unextractable pesticide residues were gradually increased with time and the highest binding capacity of about 5.3% and 13% in case of anaerobic and aerobic conditions, respectively were observed after 90 days of incubation. Chromatographic analysis of methanolic extracts revealed the presence of labelled carbofuran, carbofuran phenol and 3-hydroxycarbofuran as main products. Radiorespirometiy was used to evaluate the effect of carbofuran on soil microbial activity for 14 days. Both 3 and 9 mg carbofuran/kg soil depressed 14CO2 evolution from 14C-glucose and microbial activity was significantly inhibited especially in case of the high dose

Bioavailability to rat and toxicity of bound 14 C - pirimiphos-methyl residues in stored soybeans

The amount of bound residues of 14C-pirimiphos-methyl in stored soybeans was determined to examine their bioavailability and toxicological potential in the experimental animals. Whole seeds of soybeans were treated with 14C-pirimiphos-methyl insecticides at a dose of 30 mg/kg and stored for 24 weeks. The level of total internal and bound insecticide residues represented 60% and 4-5% of the actual dose, respectively. Feeding rats with the soybeans-bound residues for 72 hours, revealed that these residues were bioavailable. The main excretion route was the urine [40%] and feces [108%], while a small amount [6%] could be detected in the expired air. About 25% of the administered radioactivity was detected among various organs of the rat. Chromatographic analysis of urine showed the presence of some free as well as conjugated metabolites of pirimiphos-methyl. Subchronic feeding experiments on mice for 90 days with a diet containing the bound pesticide residues at a dose of 1.6 ppm/day/mouse caused no significant symptoms of toxicity during the period of the experiment. Both plasma and erythrocyte cholinesterases suffered a slight inhibition during the first 15 days. The blood picture and liver function enzymes showed no significant differences from control values. A significant increase in the level of blood urea nitrogen was observed; Whereas, creatinine clearance showed only a slight increase as compared with controls