Characteristics of Neonicotinoids in Colostrum from Shanghai, China (2007–2019): Concentration Levels, Temporal Trends, and Potential Health Risk

Neonicotinoids (NEOs) are widely used neuroactive insecticides with several adverse effects on human health. This study examined 186 colostrum samples collected at three time points between 2007 and 2019 from Shanghai, China to investigate the distribution and temporal variations of NEOs. The median total concentration (ΣNEOs) was 136 ng/L, with the imidacloprid equivalent concentration (IMIeq) of 249 ng/L. N-desmethyl-acetamiprid (DM-ACE) had the highest median level at 49.6 ng/L, accounting for 43.9% of ΣNEOs, followed by imidacloprid (IMI) (20.1 ng/L and 22.1%). Thiamethoxam (THM), clothianidin, and acetamiprid were also identified as important parent compounds (p-NEOs). Temporal variations suggested a decrease in ΣNEOs, IMIeq, and DM-ACE concentrations from 2013 to 2019; however, the total concentrations of p-NEOs remained comparable. Distinct trends were also observed in the concentrations of dinotefuran and IMI. Maternal body mass index and weight changes, which reflect the dietary habits of mothers, appeared to influence IMI and THM levels. No statistically significant relationships were found between colostrum concentrations and birth parameters using full-term birth data in 2019. The estimated hazard quotients (≤0.003), which were far below the risk threshold of 1, generally indicated negligible health risks for breastfeeding neonates. Nevertheless, the substantial contribution from several p-NEOs warrants further investigation.