Mercury levels in freshwater aquatic products across China: Spatial distribution, species differences, and health risk assessment

Abstract

Freshwater product consumption is a major source of mercury (Hg) exposure in China. This study analyzed Hg concentrations in 12,560 samples from 29 provinces across China (2010−2021) and conducted probabilistic health risk assessments across various life stages. The average Hg concentration in China's freshwater products was 40.9 ± 32.3 ng/g (wet weight), lower than global averages. However, certain species, Gymnocypris and Schizothoracids from Tibet, exhibited elevated levels (216.2 ± 84.2 ng/g and 156.7 ± 89.9 ng/g, respectively). The estimated dietary intakes (EDIs) of MeHg for all age groups were well below the JECFA threshold of 1.6 μg/kg BW, even at the P95 exposure level. However, long-term exposure assessments revealed elevated risks for children aged 2–12, with Target hazard quotients (THQ) values exceeding 1 at the P95 exposure level, particularly among younger children aged 2–7. Spatially, elevated Hg exposure risks were identified in Hong Kong, Zhejiang, Guizhou, and the Songhua River regions, with contamination in Zhejiang tied to the compact fluorescent lamp industry. Furthermore, prenatal MeHg exposure through freshwater product consumption was estimated to result in Intelligence Quotient (IQ) losses of 0.00548–0.193 points in infants. These findings underscore the need for targeted interventions to mitigate Hg exposure and provides recommendations for safer freshwater fish selection in the Chinese market.