Percutaneous absorption and excretion of alachlor in rhesus monkeys.

The percutaneous absorption and excretion profile of alachlor were evaluated in rhesus monkeys. A preliminary study demonstrated that an average of 86.7 and 9.7% of the administered dose was recovered in the urine and feces, respectively, following intravenous administration of radiolabeled alachlor to rhesus monkeys. In subsequent studies, diluted and undiluted emulsifiable concentrate (EC) and microencapsulated (ME) formulations of radiolabeled alachlor were applied to a 40-cm2 shaved abdominal area and allowed to remain on the skin for 12 hr. The radioactivity excretion profiles in all animals were comparable. In all cases, approximately 88% of the absorbed dose was eliminated via the urine, primarily within the first 48 hr. Comparison of the amount of radiolabel recovered in the topical studies with that recovered following intravenous administration indicated that an average of 8.5 and 3.7% of the alachlor in the topically applied EC and ME formulations, respectively, was absorbed.

Binding of (14C) parathion in soil: a reassessment of pesticide persistence.

A steady decrease of extractable [14C] parathion residues in soils over a 1-month incubation period was accompanied by an increase of unextractable, bound 14C-labeled residues, resulting finally in total recoveries of extracted plus bound residues of 80 to 87 percent of the applied radiocarbon. Soils containing bound residues were nontoxic to fruit flies. Binding of 14C-labeled residues was related to the activity of soil microorganisms; soil sterilization resulted in a reduction of binding by 58 to 84 percent. Under flooded (anaerobic) conditions, the binding of compounds labeled with 14C doubled, and parathion was reduced to aminoparathion. Reinoculation of sterilized flooded soil fully reinstated the binding capacity. [14C] Aminoparathion was preferentially bound to soil, since its binding within 2 hours was 30 times greater than that of [14C] parathion. Because of the existence of formerly "unseen," unextractable residues, the concept of "persistent" and "nonpersistent" pesticide residues might have to be reconsidered.

Activity of an NADPH-dependent nitroreductase in houseflies.

A nitroreductase, reducing parathion to aminoparathion, was found in the soluble fraction that was obtained from abdomens of female houseflies. The reaction required reduced nicotinamide adenine dinucleotide phosphate (NADPH), but was not affected by the presence or absence of oxygen. Further degradation of aminoparathion into water-soluble compounds occurred in NADPH-fortified incubation mixtures over prolonged incubation periods. The effect of sesamex or SKF 525-A on these reactions is described.

Aldrin and dieldrin: loss under sterile conditions.

After their application to sterile nutrient agar, both aldrin and dieldrin disappeared rather rapidly from the agar in glass-covered petri dishes. In most instances this disappearance was considerably retarded from agar inoculated with either fungi or bacteria. In the presence of microorganisms, aldrin was also epoxidized into dieldrin. Half of the applied aldrin volatilized from the agar during the first day of incubation; dieldrin volatilized more slowly and at a constant rate.