Human exposure to mercury and other elements in Eastern China
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Mercury contamination is a global issue due to its neurotoxicity, and China is not an exception due to its increasing industrialization. Fish is of the most concern, in respect to human exposure to mercury, because fish accumulates methylmercury through food chain in aquatic systems. The province of Zhejiang is renowned for its cuisine that incorporates freshwater fish. Qiandao Lake, in Zheijang, was the site of a case study examining the link between the total mercury (THg) concentration in hair samples and fish consumption. A questionnaire survey and hair sampling were carried out on women of childbearing age (17-46 years) from a fishing town by Qiandao Lake. The average hair THg concentration was 0.76±0.51μg/g dw. The most-frequently consumed species included four species of carp (golden, bighead, silver and predatory) and the Mongolian redfin. Hair THg concentrations accumulated rapidly during younger years, reaching a plateau around age 25, implying that the hair mercury concentrations in adult females >25 years can be interpreted by environmental exposure. Hair THg concentrations were positively correlated both with the frequency and the average weekly amount of fish consumption. This indicates that fish consumption is an important contributor to hair mercury concentrations in the absence of occupational or environmental mercury sources. A positive correlation between selenium and mercury in hair samples was also observed, suggesting a possible antagonistic relationship. This is the first study to look at mercury exposure in an eastern China community dependent on freshwater fish. This study also compared element trends (Mg, Ca, Cr, Mn, Cu, Zn, As, Se, Pb) in hair samples from three groups: 50 residents by Qiandao Lake (QD), 17 people from Fudan University, China (FU), and 20 people from Queen’s University, Canada (KI). Trends of mean Mg, Cu, Ca, As concentrations among groups are the same (KI>FU>QD). Mn, Cr, and Hg share the same trends of QD>FU>KI. Se concentrations follow the trend of QD>KI>FU. Strong correlations between Ca and Mg were observed within each group. Relationships between Se and Hg are clear in QD but not in FU and KI, probably due to the different dietary proportion of fish.