Plasma mercury levels in Hong Kong residents: in relation to fish consumption

Mercury exposure is of particular concern since mercury is a neurotoxin and the developing fetus is most sensitive to its adverse effect. Human blood is routinely used as an indicator for the evaluation of human exposure to Hg. To investigate Hg species in human plasma for Hong Kong residents and the relationship between fish consumption and Hg species in plasma, 151 plasma samples were analyzed for Hg species. The mean values of total Hg (THg) and methyl-mercury (MeHg) concentration in plasma were 0.62 and 0.28 μg/L, respectively. No significant differences were observed between females and males as well as among age groups. Fish consumption rate was significantly positively correlated with MeHg concentrations in plasma, which demonstrated that plasma could be a biomarker for human MeHg exposure. Two methods were used to estimate human MeHg exposure. One was based on fish MeHg content and fish consumption rate (EDI(Fish)), another was employed by converting MeHg concentration in blood to MeHg exposure amount (EDI(Blood)). A significant positive correlation was observed between EDI(Blood) and EDI(Fish), and no significant difference was found between EDI(Blood) and EDI(Fish). These results demonstrated that fish consumption was the major source of MeHg for humans.