A probabilistic assessment of dietary heavy metal exposure and its temporal trends in Chongqing China from 2012 to 2022.

Chongqing, a traditional industrial base and agricultural hub in inland Southwest China, exhibits dietary patterns representative of this rapidly developing region. This study employed a probabilistic risk assessment (Monte Carlo simulation) to evaluate the impact of early 21st-century environmental policies on population health from 2012 to 2022. Results revealed significant reductions in heavy metal (HM) concentrations in commercially available foods during 2018-2022 compared to 2012-2014. The mean concentrations of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) declined to 0.016-0.061, 0.002-0.092, 0.006-0.075, and 0.002-0.006 mg/kg respectively. These declines align with Chongqing's regulatory evolution and industrial transformation, driving progressive health risk reductions. The probabilistic assessment showed that hazard quotients (HQ) for Pb and Hg remained below 1.0, indicating negligible risks. In contrast, Cd and As posed sustained yet decreasing concerns, with 6.9% and 49.5% of residents, respectively, exceeding an HQ of 1 in the recent period. Cumulative exposure to the four HMs yielded hazard index values of 1.57-7.60, highlighting potential health implications from combined HM exposure. Sensitivity analysis identified rice and leafy vegetables as the primary exposure vectors, which should be prioritized for surveillance. This study establishes a robust evidence base for food safety policy optimization in Southwest China, with the probabilistic framework comprehensively characterizing exposure and its associated uncertainties across core food categories.