Neonicotinoids residues in cow milk and health risks to the Chinese general population

The application of neonicotinoid insecticides (NEOs) has increased dramatically in the world since being introduced in 1990s, yet the extent of human exposure and potential health risk is not fully unraveled. In this study, the residues were analyzed of 16 NEOs and their metabolites in 205 commercial cow milk samples circulating in Chinese market. All the milk samples contained at least one quantified NEO, and over 90% of samples contained a cocktail of NEOs. Acetamiprid, N -desmethyl acetamiprid, thiamethoxam, clothianidin and imidaclothiz were the most commonly detected analytes with detection frequencies of 50–88% and medians of 0.011–0.038 ng/mL in milk. Geographical origin was an important factor to influence abundances and levels of NEOs contamination in milk. Chinese local milk bore a significant higher risk from NEOs contamination than the imported milk. In China, the northwest presented the greatest concentrations of the insecticides relative to the north or south. Organic farming, ultra heat treatment and skimming could significantly reduce levels of NEOs contamination in milk. A relative potency factor method was used to evaluate estimated daily intake of NEO insecticides, and found the children had 3.5–5 times higher exposed risk via milk ingestion than the adults. The high frequency of NEOs detection in milk offers us a snapshot of the ubiquity of NEOs in milk, with possible health implications especially for children.