Determination and health-risk evaluation of nitroxynil residues in the edible tissue of cattle.

A specific Polarographic method with a sensitivity of ≥ 2 jig/kg (ppb) has been used to determine the plasma and tissue concentrations of nitroxynil (NTX), which is used against Parafilaria bovicola in cattle. After treatment with the therapeutic dose on NTX (2 × 20 mg/kg b.w., s,c), there was an initial rapid decrease in the plasma concentration followed by a slower elimination phase. The plasma levels of NTX were 8 mg/kg (ppm) and 3 mg/kg after 6 weeks and 2 months, respectively. The muscle and other edible tissue from treated cattle contained 0.1–0.3 mg/kg NTX after 2 months, and jxg/kg amounts were still detectable 3 months after the injection. Based on available pharmacological and toxicological data, a 3-months withdrawal time for NTX in cattle is proposed.