Organochlorine Pesticides in Dairy Cows’ Diet and the Carryover into Milk in NW Romania

Since modern agriculture relies on high volumes of chemical pesticides, monitoring the exposure to these dangerous substances in feed and the food chain is crucial. This study investigates the transfer of organochlorine pesticide (OCP) from water, soil, and feed to milk in free-range dairy cows using the carryover rates (CORs) and biotransfer factors (BTFs) from feed to milk as tools that can be used for human and animal risk assessments. BTFs can predict the transfer of OCPs into milk due to cows’ ingestion of contaminated feed. Samples were collected from ten small-scale dairy cow farms located near Baia Mare city, NW Romania, identified for distributing fresh milk in the local market. After the appropriate extraction was performed, the OCP concentrations were measured by gas chromatography equipped with an electron capture detector and randomly confirmed using mass spectrometry. The most prominent compounds in the soil, feed, and milk samples were hexachlorocyclohexane (HCH) isomers and dichlorodiphenyltrichloroethane (DDT) and its metabolites. The concentrations of OCPs were lower than the maximum admissible values in feed, water, soil, and milk. The CORs of OCPs varied over four orders of magnitudes, from 0.10% (2,4′–dichlorodiphenylchloroethylene, 2,4′–DDE) to 250% (4,4′–dichlorodiphenyltrichloroethane, 4,4′–DDT). Similar to CORs, the values of BTFs varied largely, from 0.0001 to 1.408. Additionally, the values higher than the unit for some BTFs could be due to the accumulation and biomagnification of these organochlorine compounds in the animal body. The cows’ dietary exposure was evaluated by the estimated daily intake (EDI), considering the three components of ingestion (feed, water, and soil), and varied in the range of 0.0008–0.3509 µg/day/body weight (bw).