Residues in tissues of sheep following oral dosing and tip spraying with 32 p‐labelled ronnel

Abstract Following oral dosing at a rate of 100 mg/kg live weight, ronnel appeared rapidly in the blood of sheep. The highest concentrations found were attained four hours after treatment. After 21 days, 70 per cent of the administered dose had been detected in the urine and 7 per cent in the faeces, largely as a‐methyl, a‐hydrogen, 0‐(2, 4, 5, trichlorophenyl) phosphorothioate, and dimethyl phosphorothioic and phosphoric acids. Ronnel was not stored in the fat in appreciable quantities. Residues in subcutaneous fat taken from sheep sprayed with 600 ml of 0.2 per cent and 0.4 per cent solutions of ronnel were negligible, the maximal concentration found being 0.35 μg/g (wet weight) one week after treatment. No ronnel could be detected in the fat three weeks after spraying.