Research On Optimization Of Detection Method In Fish Methylmercury And Risk Assessment Of Fish Mercury Ingestion By Students In Campus

Mercury is a toxic heavy metal elements and the only metal with evaporation characteristics that is liquid at room temperature, Which can form a mercury vapor at room temperature. There are three mercury forms of elemental mercury, Hg and two price of alkyl mercury compounds in the medium of atmospheric environment and food. Mercury will cause serious damage to the body and chronic mercurialism will destroy nervous system if people stay in the mercury exposure for a long time, The main symptoms were movement disorder and aphasia. Organic mercury is much more toxic than inorganic mercury and it is hard to eliminate because it mainly store in the body’s vital organs of the brain, kidney and liver. In the last century 50’s, The "Minamata disease in japan" is caused by long term edible marine fish polluted by methylmercury pollution. Additionally, Methylmercury easily transfer from the placenta of pregnant maternal to fetal causing congenital mercury poisoning and idiot fetus.Fish which is one of main aquatic products plays an important status in people’s daily diet. Industrial wastewater pollutants in coastal areas and entering the water from other ways bring great harm to the aquatic ecosystem with the development of our economy in recent years. So it is necessary to evaluate the risk of fish heavy metal mercury to guide for health food fishes. This paper was divided into three parts of the research of fish methylmercury detection method, residues of heavy metals mercury content in fish and exposure assessment and risk characterization of feeding fish by the heavy metal mercury in the school through students’ dietary survey. The main results were as follows:Determination of methylmercury in aquatic products was measured by HPLC-AFS. Ultrasonic assisted extraction and extraction methods were taken to compare two pretreatment methods. Both methods could be used to determinate methylmercury in fish processing by HPLC-AFS. The limit of detection of ultrasonic assisted extraction and extraction method were 13.4μg/kg and 33.5μg/kg, percent recoveries were 84%~95% and 82%~101%, and precision were 3.83%~4.1% and 3.7%~6.82%, respectively. Through the comparison of two pretreatment methods, Wave assisted extraction method was more simple and economic than extraction method. However, extraction method cost less test time and lower detection limit than ultrasonic assisted extraction. Extraction method of ultrasonic assisted extraction was relatively more reliable under the measure of the unknown concentration of methylmercury(trace).the total average mercury content of 13 kinds of consumption fish sample which in detected one college is 0.0214mg/kg, we found that in different waters, mercury content in sea fish > mercury conten in freshwater fish, sea fish average total mercury is 0.0264mg/kg, freshwater fish average total mercury 0.0098mg/kg; After comparing different feeding habits, we found that carnivorous mercury > omnivorous mercury > erbivore herds mercury; and for different growth environment we found that lower fish mercury content > pelagics mercury content.There were 1090 dietary questionnaires collected in this research, The test of the mercury in the fish’s average monthly exposure were assessed combined with the diet ary survey data, the average and median value of edible fish exposure in the college st udents monthly were 8.07E-005mg/(kg?m) and 6.157E-005mg/(kg?m). The average a nd median values of edible fish exposure in the boy and girl students were 4.65E-05 m g/(kg?m) and 3.44E-05 mg/(kg?m), 3.556E-005 mg/(kg?m) and 2.648E-005mg/(kg?m), respectively. The average value and median values of edible marine fish mercury ex posure in the college were 4.58E-005mg/(kg?m) and 3.88 mg/(kg?m), and the values o f edible fish were 2.15E-05 mg/(kg?m) and 1.7 E-005mg/(kg?m). The follow values w ere lower than PTMI value of Mercury recommended by JECFA.The risk of mercury of fish in the college were described in this study, the results reflected that the hazard quotient of intake of heavy metals mercury through the consumption of fish was less than 1, Which showed the risk of mercury of fish in the stude nts of the school was very low even without risk.Risk assessment still existed uncertainty in this experiment, risk assessment para meters which were suitable for our country need to be improved to further establish p erfect risk assessment model and improve the reliability of the risk assessment.