Longitudinal study and predictive modelling of urinary pesticide metabolite concentrations in residents of Guangzhou, China.

Continuous human biomonitoring and predictive modelling of urinary pesticide metabolites are critical for evaluating pesticide exposure trends and associated health risks. We conducted repeat cross-sectional surveys to determine the urinary concentrations of eight pesticide metabolites in the residents of Guangzhou, China, from 2018 to 2022. We longitudinally analyzed the changes in these metabolite concentrations over the years and assessed the potential non-carcinogenic risks by calculating the hazard quotient and hazard index. No significant differences were observed in the total urinary pesticide metabolite concentrations over the 5 years (9.16-12.99 μg/L). The urinary concentrations of 3,5,6-trichloro-2-pyridinol and 2,4-dichlorophenoxyacetic acid reached their lowest levels in 2020 (1.47 and 0.11 μg/L). Conversely, urinary para-nitrophenol concentrations exhibited an inverse trend, peaking in 2020 (6.16 μg/L). The composition profiles of urinary pesticide metabolites showed that para-nitrophenol consistently constituted the largest proportion each year. Males consistently showed higher median concentrations of total urinary pesticide metabolites and individual metabolites of 3,5,6-trichloro-2-pyridinol, trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and para-nitrophenol than females. The concentrations of cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid in adults' urine were significantly higher than those in minors' urine each year. The total pesticide metabolite concentrations in adults' urine were significantly higher than those in minors' urine in 2018 and 2020, whereas no significant differences were observed in other years. No significant differences in urinary pesticide metabolite concentrations were observed among different BMI groups. Results showed that 14.17% of the population had hazard index values above 1, indicating a higher risk of health hazards. Three predictive models were employed to predict urinary pesticide metabolite concentrations for 2023-2024, revealing an increasing trend in 3,5,6-trichloro-2-pyridinol concentrations while other metabolites are expected to decrease. The study showed the concentration of para-nitrophenol peaked in 2020 while 3,5,6-trichloro-2-pyridinol and 2,4-dichlorophenoxyacetic acid reached their lowest levels, suggests that the COVID-19 pandemic may have influenced pesticide exposure patterns.