The burden of mild intellectual disability attributed to prenatal exposure to methylmercury in China, 2017

Methylmercury (MeHg) is a neurodevelopmental toxicant that is widespread in the environment and food. Considering the presence of multiple sources of MeHg exposure in the environment, the burden attributable to different exposure sources needs to be determined. This study aimed to estimate the burden of mild intellectual disability (MID) caused by in-utero exposure to MeHg and identify the attributable burden related to MeHg exposure from different sources in China. We applied the hair mercury concentrations from studies to evaluate the burden of MID associated with maternal MeHg exposure and quantify it by disability-adjusted life years (DALYs). The DALYs attributable to MeHg exposure sources were calculated by combining the total DALYs and the contribution rates of various sources of MeHg exposure. The maternal MeHg exposure resulted in 6504 MID cases and a loss of 63,354 DALYs in China in 2017. The contribution rates of aquatic products and rice were 52.2% and 27.1%, respectively, leading to health losses of 28,115 and 18,011 DALYs. The burden of MeHg-induced MID associated with aquatic products was high in coastal areas. Several sites such as Zhejiang, Hunan, and Guangxi had high DALYs caused by rice MeHg exposure. Regions with high DALYs of MID related to MeHg exposure require more attention. Local governments should establish targeted measures to reduce MeHg exposure, thus preventing health loss.