Risk assessment of methylmercury and species identification in shark meats ingested by Taiwan children

Human exposure to methylmercury (MeHg) is through consumption of carnivorous fish and seafood to cause neurotoxicity. Carnivorous fish, especially fresh shark meat and its product are often used in Taiwan. This study is first to determine the shark species from fresh shark meats and smoked shark meats using genome sequencing. Additionally, the level of MeHg in a part of these shark meats was measured by using liquid chromatography/ inductively coupled plasma mass spectrometry (LC/ICP-MS). Based on these MeHg levels, the risk of MeHg exposure of the shark meat consumption was assayed by utilizing the estimated weekly intake (EWI) and hazard quotient (HQ) of MeHg for the children of 3-18 ages. The results indicate the major species of fresh shark meats is Prionace glauca , and the minor species includes critically endangered species Rhynchobatus australiae and vulnerable species Alopias superciliosus. The level of MeHg was below 2 mg/kg in most shark meats, which is consistent with the Taiwan standard limit. However, the level of MeHg in some samples of shark meats was more than 2 mg/kg. Importantly, higher level of MeHg was found in smoked shark meat than that in fresh shark meat. Another, the level of HQ was more than 1, which is a criterial risk point, for children to ingest a little shark meat for children of 3-12 ages. The results indicate that the dietary intake of shark meat or smoked shark meat is danger for 3-12 years old children.