Modeling Drug Residue Uptake by Eggs: Evidence of a Consistent Daily Pattern of Contaminant Transfer into Developing Preovulatory Yolks

Abstract

A study was conducted to determine if the chicken ovary deposits the pesticide lindane into preovulatory egg yolks in a daily pattern similar to that previously reported for both of the antibiotics ampicillin and oxytetracycline. Our laboratory has proposed that a variety of drugs or contaminants are deposited into preovulatory yolks in a consistent manner. This possibility of a consistent pattern of drug deposition in preovulatory yolks has been used as a foundation for a model which predicts the pattern of residues contained in laid eggs. In two separate experiments, 16 hens were dosed with 3 mg of lindane per kg of body weight orally approximately 1 h after oviposition (8 hens per experiment). Twenty-four hours following dosing, hens were sacrificed and the ovaries were collected. Yolks were dissected free from the individual follicles with a blunt probe. Individual large (≥0.2 g) yellow yolks and a pool of 5 small (<0.2 g) yellow yolks were collected for determination of lindane content. Samples were prepared and assayed by using a gas chromatography method. Results indicate the pattern of incorporation of lindane residues in developing yolks is similar to the previous pattern obtained for both ampicillin and oxytetracycline. These data confirm the possibility that diverse chemical compounds may be incorporated into preovulatory yolks in a similar pattern, supporting a key component of our model, which predicts the pattern of incurred residues in laid eggs for a variety of drugs or contaminants.