Mercury In Consumer Aquatic Production And Human Exposure Of Mercury Via Aquatic Production Consumption In Guangdong Province

Mercury contaminations have already been a hot issue in realm of Environmental Science, since Minamata disease happened in Japan in the early 1950s. Scientist studied sources, pollution degree, migration and transformation of mercury in different medium, recognized the biomagnifications and bioaccumulations through food chain in environments, especially in aquatic systems and risks to human health.Mercury concentrations in aquatic production are ultimately determined by methylmercury accumulation at the base of the food chain. The predominance of methylmercury in fish, however, is a consequence of the greater trophic transfer efficiency of methylmercury than inorganic mercury. Higher mercury concentrations in aquatic production are associated with higher trophic position, and generally increases with fish length and fish weight. Previous studies have demonstrated that methlymercury exposure via food consumption, especially fish with high mercury concentrations, predominated in population without occupational exposure. China (mainland) has been the largest fishery production in the world over last 12 years, and Guangdong province is a main aquatic production area, with an output of 6.95 million metric tons in 2005, accounting for 13.6% of the total national production. Based on above reasons, this study collected random samples from Guangdong province systematically, and determined total mercury concentration in muscle or parenchyma. Meanwhile, dietary exposure via seafood consumption was assessed based on the results of this study and our recent dietary survey. Consequently, realize the actuality of mercury contaminations in aquatic production in this area and associated health risk.The results showed that the median concentration of mercury in aquatic production from Guangdong province was 24.62ng·g^-1, which was lower than the mean concentration (37.18ng·g^-1), indicating that most samples have lower concentrations. Mercury concentrations ranged from 0.11 to 317.45ng·g^-1, and there was no one exceeded the corresponding maximum level established by the Chinese government, which is 500ng·g^-1 for methylmercury (GB2762-2005). Mercury concentrations in fish were significant higher than shrimp, crab and shell, and crab were higher than shrimp and shell. Gold thread (Nemipterus virgatus) had the highest mercury levels, while Giant freshwater prawn (Macrobrachium rosenbergii) was the lowest one. Results on Mercury distribution for cities showed that herbivorous and omnivorous fish by freshwater farmed were relatively higher in pearl river delta, but all of carnivorous fish were higher in western Guangdong area. Differences also existed in shrimp, crab and shell, however, no obvious laws were observed. Meanwhile, we found that mercury content had significant positive correlation with output of aquatic production for cities (P<0.01), but negative with the ratio of freshwater farmed (P<0.05), district was in the order of western Guangdong>eastern Guangdong>pearl river delta, which may be ascribed to sources of samples, ratio of freshwater farmed was lower in western Guangdong.Significant differences on kinds showed that mercury concentration in carnivorous fish were greater than herbivorous fish and omnivorous fish, similarly, mercury in wild marine fish and seawater farmed fish were higher than freshwater farmed. For Two omnivorous fish, wild marine fish (Common mullet) were slightly higher than freshwater farmed(Tilapia). Three herbivorous fish were farmed by freshwater, while mercury in Bighead carp and Bluntsnout bream were higher than Grass carp. For eight carnivorous fish, mercury in wild marine fish (Hairtail and Gold thread) were greater than seawater farmed fish (Red drum, Snubnose pompano and Crimson snapper) and freshwater farmed (Largemouth bass, Mandarin fish, Northern snakehead). We may concluded that mercury in wild were higher than farmed through biomagnifications and bioaccumulation for the same feeding behavior fish.The mercury concentrations of aquatic production in Guangdong province were comparable with other areas in China, slightly higher than Beijing and Shenyang, while lower than Songhua River, Hongkong and Taiwan. Compared with other countries or regions, mercury levels were lower in Guangdong province. But, several farmed fish have relative higher mercury concentration, exceeded 300ng·g^-1, indicated that some local aquaculture water and fish feed may be contaminated by mercury.Mean value of mercury dietary intake via aquatic production consumption in Guangdong province was 25.32ng·kg^-1·d^-1 90^th-value was 84.92ng·kg^-1·d^-1, lower than criterion established by USEPA and FAO/WHO. Dietary intake of senior citizen(≥60 years) were higher than other group owing to relative higher fish consumption, and the intake levels were lower when compared with other countries and regions.Mercury in aquatic production of Guangdong were transported to China's trading partners through fishery production exportation. Japan, Korea, and the U.S. were the top three countries receiving China's fishery products as well as mercury in them. But for dietary intake about human exposure, Macao was the highest one, ordinal by Hongkong, Korea and Japan, Africa and South America were at the end.