Uncovering Urinary Neonicotinoid Exposure Signatures Among Older Adults in South China: A Multicenter Biomonitoring Study

Neonicotinoid insecticides (NEOs) are widely used neuroactive pesticides, but biomonitoring evidence among older adults remains limited. This multicenter cross-sectional study characterized urinary exposure profiles of NEOs and their metabolites among 419 older adults from South China. Ten urinary NEO biomarkers, including six parent compounds and four metabolites, were measured using high-performance liquid chromatography coupled with tandem mass spectrometry. NEOs were frequently detected in urine samples; except for thiacloprid and acetamiprid, with detection frequencies of 81.67% and 65.48%, respectively, all other compounds were detected in more than 90% of participants. Among the parent NEOs, clothianidin had the highest median concentration (1.402 μg/L), followed by dinotefuran (1.240 μg/L) and thiamethoxam (0.888 μg/L). The main metabolite was N-desmethyl-acetamiprid (1.643 μg/L). Looking at the overall composition, dinotefuran, clothianidin, thiamethoxam, and N-desmethyl-acetamiprid were the biggest contributors to the total urinary NEO burden, though their shares varied by region and recruitment center. Correlation analysis pointed to common co-exposure patterns, especially between thiamethoxam and clothianidin, and between imidacloprid and its metabolites. In exploratory analyses, N-desmethyl-thiamethoxam showed a positive correlation pattern, with significant positive correlations with glucose, glycated hemoglobin, triglycerides, and alanine aminotransferase (all q < 0.01). CLO was positively correlated with high-density lipoprotein cholesterol (q < 0.05). These findings indicate widespread co-exposure to multiple NEOs among older adults in South China and highlight the need for longitudinal studies to clarify exposure sources, temporal variability, and potential health implications.