Wastewater Aquaculture and Children Health Risk:

A Case analysis of mercury contamination in Ya-Er Lake in China

Hui Yang , Yang Fangxing, Xu Ying*

（ Institute of Hydrobiology, Chinese Academic of Science; State Key Laboratory of Freshwater Ecology and Biotechnology, Wuhan 430072, China ）

Abstract: Freshwater fish is important protein source for people, especially there is 22 carbon 6 alkenes fatty acid in fish muscle, which can activate nerve cell in cerebrum and prevent cardiovascular diseases, and now is regarded as a kind of healthy nutrient food. It has been more than 100 years for wastewater aquaculture in China and many south-east Asian countries. In recent years, with economy sustainable development and rapid growth of population, discharged volumes of industrial and domestic wastewater has grown greatly, wastewater aquaculture has become more and more popular. In order to assess the safety of wastewater aquaculture fishery products and children health risk, Ya-Er lake and Donghu Lake were chosen as experimental sites in this study, which was polluted by chlorine industrial wastewater and urban domestic wastewater, respectively. The concentrations of mercury in the main economic fishes (Silver Carp and Big Head) in the lakes, together with hair and teeth of school-age children surrounding the lakes were determined in Oct. in 2002. The results showed that the mean concentrations of mercury in silver carp fish muscle, big head carp muscle, hair and teeth of school-age children in Donghu Lake were 0.105±0.069 ug/g (n=10), 0.248±0.224 ug/g (n=10), 0.548±0.151 ug/g (n=10) and 1.081±1.233 ug/g (n=20), respectively. The mean concentrations of mercury in silver carp fish muscle, big head fish muscle, hair and teeth of school-age children in Ya-er Lake were 0.349±0.115 ug/g ( n=10 ， p<0.001), 0.521±0.098 ug/g ( n=10, p<0.01), 2.53±0.659 ug/g ( n=10, p<0.001)and 3.83±3.071 ug/g(n=36, p<0.001), respectively. Meanwhile, it was found that almost 10% of silver carp and big head were obviously abnormal, and the mean concentrations of mercury in abnormal silver carp and big head fish muscle were 0.572±0.118 ug/g (n=10, p<0.001) and 0.739±0.119 ug/g (n=10, p<0.001), respectively, both of them are above the food safety standards of mercury regulated by Ministry of health in China (0.3 ug/g). According to dietetic customs of local residents, uptake of fish for children in one week was about 860 -1290g , which exceeded the safe limit of FDA and EPA of USA ( 340g ) greatly. The mean mercury uptakes for children in one week surrounding Ya-Er Lake were about 10 － 22.4ug/kg; while the mean mercury uptakes for children in one week surrounding Donghu Lake were about 7 － 10.7ug/kg. Both of them exceeded the allowable mercury uptake standard in one week which suggested by WTO (5ug/kg). The above results showed that there was health risk for children to eat the fish from wastewater aquaculture. In order to prevent environmental contaminants to damage human health via food chain, especial for children, water quality and fishery products examination system are urgently needed in wastewater aquaculture areas.

Key words: mercury, silver carp, big head carp, human hair, children teeth