Analysis And Evaluation The Pollution Of Tetrodotoxin (TTX) From Marketed Fresh Seafood In Ningbo

Background:Tetrodotoxin (TTX) is a highly toxic marine bioactive substance, typical of nerve Na+channel blocker, which was considered to be the most toxic nature of non-protein toxin once. Study found that TTX not only exist in the dolphin fishes but also in the various types of marine vertebrates and invertebrates, and found that many bacteria can produce TTX. In daily cooking activities, TTX is not easy to damage, so cause food poisoning often, there is a serious threat to people’s lives. TTX poisoning occurs because eating seafood in China’s coastal areas, in addition to puffer fish poisoning, some snails, grilled fish poisoning is also related with the TTX. The studies were reported which focused on human and animal physiological effects and mechanism by TTX in domestic and foreign, and the TTX content and distribution in puffer fish, snails. While the study of dynamic monitoring and long-term safety assessment has not been reported what about the TTX content in a coastal city mainly sold fresh seafood daily.Objective:To analyze the content and variation of the TTX in the fresh seafood from Ningbo market, assess its risk, in order to reduce the TTX poisoning. Methods:Select28markets or supermarkets in Ningbo’s six administrative districts as a monitoring point, taken a large quantity of fresh seafood public consumption100to120parts per month to measure the TTX content in order to analyze the TTX seasonal variations, regional characteristics, types’different. The TTX is detected by indirect competitive ELISA. Food safety risk assessment uses the method of single quality index.Results:1055fresh seafood from five categories from Ningbo markets are sampled in12consecutive months, the TTX positive rate is20.19%, the highest TTX concentration is275.00μg/kg, and the average TTX concentration is10.46μg/kg, the concentration of P25, P50and P75are low than the detection limit what is5μg/kg. The213fresh seafood which are detected TTX, the average concentration is51.81μg/kg, the P25is25.25μg/kg, the P50is36.25μg/kg. the P75is63.20μg/kg. According to the season, from January to December, the fresh seafood TTX positive rate from7.14%to35.56%, χ2=79.54, P<0.01, showing the beginning and end of the year are higher and lower in midyear; there is a small peak in July and August. The TTX positive rate is from9.06%to33.96%by four seasons, χ2=65.48, P<0.01, the TTX positive rate of annual spring and winter is higher than in summer and autumn. The average concentrations of the TTX are from1.64μg/kg to21.32μg/kg in January to December,χ2=85.54, P<0.01, the trend of the monthly average concentration of the TTX which is higher in the beginning or end, lower in the midyear, there is a small peak in July and August. The trend of the TTX positive rate and average concentration are more consistent. By category, five categories seafood TTX positive rate are from7.32%to45.45%,χ2=156.30, P<0.01. The highest is shellfish which rate is45.45%, the second is the crab which rate is28.31%, and the lowest is cephalopods which rate is7.32%. The rate of marine fish is8.73%and shrimp is9.59%. The TTX annual average concentration of5categories seafood are from3.46μg/kg to25.04μg/kg,χ2=153.91, P<0.01, the highest is the shellfish which concentration is25.04μg/kg, the lowest is the cephalopods which concentration is3.46,μg/kg. The crab is12.71μg/kg, the saltwater fish is4.78μg/kg, and the shrimp is4.33μg/kg. Analysis by region, the TTX positive rate from16.05%to 23.04%in the six administrative,χ2=3.48, P>0.05, the TTX mean concentrations are from7.50μg/kg to12.44μg/kg in the six administrative,χ2=3.62, P>0.05, the TTX positive rate and mean concentration are not statistically different among every consumption area. The highest risk of TTX poisoning is shellfish, especially in the first and fourth quarters. Seafood TTX content quality assessment shows that the quality is safe.Conclusion:Ningbo marketed fresh seafood TTX-positive rate is higher, but the TTX content is lower. Seafood TTX positive rate and concentration there is seasonal, population differences, but the consumption area difference is not significant. Seafood TTX content quality assessment shows that the quality is safe. The highest risk of TTX poisoning is shellfish, especially in the first and fourth quarters, so in this time effective prevention the TTX poisoning of shellfish is the focal point of TTX poisoning prevention. But there is still some food safety risks in extreme conditions, because the fresh seafood daily consumption of the Ningbo citizen which containing a variety of marine toxins, and the Ningbo citizen in the same meal also eat a variety of seafood.