China’s municipal wastewater policies enhanced seafood safety and offset health risks from atmospheric mercury emissions in the past four decades

Abstract

The neurotoxin methylmercury in seafood threatens food safety worldwide. China has implemented stringent wastewater policies, established numerous treatment facilities and enforced rigorous water quality standards to address pollution in its waterways. However, the impact of these policies on seafood safety and methylmercury exposure remains unknown. Here we developed a process-based model showing that, although mercury reductions from municipal wastewater policies accounted for only 9% of atmospheric mercury emissions during 1980–2022, these measures unexpectedly prevented $${\mathrm{102,000}}_{-\mathrm{6,600}}^{+\mathrm{11,000}}$$ mercury-related deaths and counteracted nearly two thirds of potential deaths from those emissions. Furthermore, these policies ensured that $${146}_{-9}^{+8}$$ megatonnes of freshwater seafood met the World Health Organization and China’s mercury-safety standards, preventing $${\mathrm{US}}\${498}_{-29}^{+32}$$ billion in economic losses. Finally, we explore how China, as the primary global seafood producer and exporter, could develop municipal wastewater policies at the regional level to reduce aquatic pollutants and unlock the health benefits of seafood consumption. Seafood methylmercury contamination is a global food safety issue. A model is developed to explore the impact of China’s municipal wastewater policies on seafood safety and reductions in methylmercury exposure.