Temporal Distribution of Imidacloprid and Its Metabolites in Laying Hens: An Evaluation of the Potential Impact on Food Safety

Imidacloprid (IMI) is widely used in poultry houses in the United States to control darkling beetles. However, there is limited knowledge regarding the persistence and distribution of IMI and its metabolites in poultry products following acute exposure to subclinical concentrations. In this study, mature hens received a dose of imidacloprid (placebo, 1 mg/kg, or 10 mg/kg), and liquid chromatography tandem mass spectrometry was used to quantify IMI and its metabolites in tissues. IMI was below the limit of quantitation in plasma within 24 (1 mg/kg) and 48 h (10 mg/kg). At 10 mg/kg, IMI equivalents (sum of IMI and its metabolites) exceeded the regulatory threshold as established by the United States Code of Federal Regulations for pectoral and thigh muscle, brain, liver, spleen, kidney, fat, and eggs after 24 h. At 1 mg/kg, IMI equivalents surpassed the threshold for liver, spleen, and eggs after 24 h. These results suggest that low dose exposure to IMI may cause poultry products destined for human consumption to violate federal regulations.