Temporal Trends and Generation-Specific Shifts in Urinary Neonicotinoid Exposure in Southern China (2018-2024)

Despite the rapid generational turnover and global market expansion of neonicotinoid insecticides, long-term temporal shifts in human internal exposure remain largely unexplored. This study characterized temporal trends in urinary neonicotinoid exposure among 3077 participants in Guangzhou, China, from 2018 to 2024 using repeated cross-sectional biomonitoring. We quantified urinary concentrations of first-generation neonicotinoids (imidacloprid, acetamiprid, and thiacloprid) and their metabolites, second-generation neonicotinoids (thiamethoxam and clothianidin), and the third-generation neonicotinoid dinotefuran. Urinary concentrations of thiacloprid, imidacloprid, and acetamiprid showed upward trends, with annual percentage changes of 3.4, 4.6, and 5.0%, respectively. Urinary concentrations of the second-generation thiamethoxam and clothianidin showed greater increases, with annual percentage changes of 32.2 and 39.9%, respectively. Notably, the concentrations of third-generation dinotefuran exhibited a rapid increase, with an annual percentage change of 95.1%. Age was a significant determinant of neonicotinoid exposure, with most compounds showing positive age-related trends, with concentrations increasing from childhood to middle adulthood and then declining in older age groups. In contrast, thiacloprid exhibited a negative association with age. Sex-specific patterns were also observed for thiacloprid and dinotefuran. These findings suggest increasing urinary exposure to newer-generation neonicotinoids in southern China and highlight the need for long-term health risk assessment.