整合空間資訊分析攝食烏腳病盛行地區養殖魚貝類人體健康風險評估及管理

• Main Authors: 梁菁萍, Liang, Ching-Ping
• Other Authors: 劉振宇, Liu, Chen-Wuing, 臺灣大學:生物環境系統工程學研究所
• Format: Thesis
• Language: English
• Published: 2008
• Subjects: 砷;烏腳病;標的致癌風險;地理資訊系統;逐步指標模擬法;不確定性;養殖魚貝類; Arsenic;Blackfoot disease;Target cancer risk;GIS;Sequential indicator simulation;Uncertainty;Aquaculture fish and shellfish; Crassostrea gigas
• Online Access: http://ntur.lib.ntu.edu.tw/handle/246246/181143; http://ntur.lib.ntu.edu.tw/bitstream/246246/181143/1/ntu-97-D94622002-1.pdf

海鮮食物中經常因含有高量的砷（As），造成人類健康的威脅並引起大眾之高度關切，砷之暴露途徑眾多包括食物、水、土壤及空氣等，其中藉由攝入海鮮類食物之砷暴露為最重要之途徑。本研究主要針對台灣烏腳病盛行地區，估算因攝食高砷污染地區之養殖魚貝類（包括吳郭魚、虱目魚、烏魚、文蛤及牡蠣）所致之潛在致癌風險；考量養殖魚貝類之無機砷濃度及合理之攝食量，本研究建構一以風險為基礎之合理攝食風險機率估算地圖，以地理資訊系統（GIS）地圖所提供之養殖資訊結合地下水砷濃度之機率分布，採用人體健康風險估算模式，評估食用受砷污染之養殖魚貝類之標的致癌風險（Target cancer risk）及合理攝食量之估算。由於受限於有限之實測資料，本研究使用蒙地卡羅（MC）模擬法及逐步指標模擬法（SIS）估算人體健康風險模式中所使用之參數並探討模式之不確定性。研究首先估算攝食養殖牡蠣之無機砷所造成的人體健康風險（Chapter 2），研究結果顯示四鄉鎮的養殖牡蠣中，平均無機砷濃度佔總砷濃度大約為1.64%。以95%的發生機率，每日攝取18.6-56公克的牡蠣，估算攝入無機砷之致癌風險為1.26×10-5 – 3.82×10-5。此外，每日攝取18.6-56公克的牡蠣，攝入無機砷之非致癌風險（危害商數，THQ）介於 0.071-0.214。以致癌風險模式估算，符合致癌風險為10-6建議之每日牡蠣攝取量為1.6公克。第三章（Chapter 3）探討文蛤、底泥和養殖池水之砷和物種砷含量，並針對在砷暴露環境中文蛤的生物累積效應進行估算，並採機率的方式估算攝入養殖文蛤所致砷之潛在致癌風險。結果指出文蛤體內無機砷含量佔總砷含量約為12.3%-14%，此值遠高於養殖牡蠣無機砷含量的比值，顯示攝取與牡蠣等量的文蛤將攝入更多的無機砷含量。風險評估結果顯示，攝取烏腳病地區文蛤之潛在致癌風險，介於 4.52×10-6 – 80.7×10-6 均超過可接受的目標風險値（10-6），根據致癌風險模式推估，人體每日攝食烏腳病地區的文蛤安全量建議為0.18公克。第四章（Chapter 4）提出以GIS為基礎之整合空間資訊分析方法，探討經由砷污染地下水地區養殖魚種之食物鏈暴露而攝入無機砷所造成之潛在致癌風險。分析結果顯示，西部沿海地區的養殖文蛤和養殖虱目魚對人體健康有較高的健康風險，而主要在內陸養殖的吳郭魚僅在第95百分位數致癌風險（TR）値為最高。建議在文蛤和虱目魚養殖區域，應減少使用含砷污染的地下水，而由於烏魚對人類呈現較低健康風險，因此砷汙染的地下水建議可繼續提供烏魚養殖用水之使用。最後在論文第五章（Chapter 5）中主要以訂定合理的海鮮攝取量的目標下，納入五種養殖於砷污染地區魚種(包括吳郭魚、虱目魚、烏魚、文蛤和牡蠣)，進行以風險為基礎之合理攝取量之估算。根據糧食與農業組織/世界衛生組織所提出之每週砷容許攝取量（每公斤體重15微克），換算為台灣每位成人經由魚貝類攝入砷容許攝取量，約為每日6.37微克。每日飲食攝入砷含量在第5、第25、第50、第75及第95百分位數分別是0.52、1.20、2.17、3.95及9.22微克。第95百分位數之每日攝入砷含量（9.22微克）高於每日容許攝取量（PTDI）。合理的魚貝類攝取量是以人一生所能接受最大風險進行估算，根據無機砷的濃度（Cinorg）與風險為基礎之每日攝取量（RBIRf）之關係，研究中建構圖解法建立風險値介於1×10-5 至6.07×10-5之可接受風險區（acceptable risk zone）訂定合理的魚貝類攝食量。研究提出一整合空間資訊分析攝食高砷地區養殖魚貝類之人體健康風險評估方法，並建構一合理攝食風險估算方法以進行快速有效之合理攝食量之估算。研究結果建議可降低高砷污染地區用於養殖魚貝類地下水之使用量，並以提出之合理攝食量之估算法，提供公共衛生決策者進行砷之潛在致癌風險評估、進行養殖區域之風險等級劃分、改變養殖魚貝類之種類，以及針對消費大眾能提供更多資訊以正確選擇海鮮食物，降低因高砷地下水砷用於養殖所致之潛在致癌風險。 Arsenic (As) in seafood receives public attention because it is potential hazardous to human health and frequently presents at high concentration levels. Humans are exposed to various sources of As (food, water, soil and air), but exposure via ingesting seafood is by far the most important one. This study estimates the potential carcinogenic risk of ingesting inorganic As in aquacultural fish and shellfish in the blackfoot disease (BFD) hyperendemic areas of Taiwan, using geostatistical methods and geographic information systems. Five aquacultural species, tilapia (Oreochromis mossambicus), milkfish (Chanos chanos), mullet (Mugil cephalus), clams (Meretrix lusoria) and oysters (Crassostrea gigas), are taken into account. We herein construct a rational ingestion risk diagram with considering the concentration of inorganic As and risk-based daily ingestion rate of aquaculture species. Moreover, the rational consumption rates of fish and shellfish farmed in As-affected groundwater areas are evaluated. Target cancer risks (TRs) of ingesting As contents in aquaculture fish and shellfish are spatially mapped to assess potential risks to human health and to elucidate the safety of As-polluted groundwater use in fish ponds. Owing to sparse measured data, Monte Carlo simulation and sequential indicator simulation are used to propagate the uncertainty and assessed parameters. For the first assessment (Chapter 2), the human health risk associated with ingesting inorganic As through consumption of farmed oysters in Taiwan is estimated. The results reveal that the ratio of mean concentration among the four townships of inorganic As to total concentration of As in oysters is approximately 1.64%. The estimated target cancer risks (TR), based on a 95% occurrence probability from ingesting inorganic As by consuming oysters at a rate of 18.6–56 g/day, range from 1.26×10-5 to 3.82×10-5. Moreover, a target hazard quotient (THQ) associated with ingesting inorganic As through oyster consumption at a rate of 18.6–56 g/day range from 0.071 to 0.214. Based on the estimation of the TR model, an ingestion rate of 1.6 g/day is recommended to meet the 95th percentile of carcinogenic risk, 10-6, for exposure to inorganic As through the consumption of oysters in Taiwan. Furthermore, this study investigated the relationship between As content in clams and their environment, including sediment and pond water (Chapter 3). The bioaccumulation of As in clams in their exposure environment and the potential carcinogenic risks associated with the ingestion of As in aquaculture clams are probabilistically evaluated. The average ratios of inorganic As contents to total As contents in clams ranged from 12.3% to 14.0% which are much higher than that found in the farmed oysters, indicating that humans may expose to larger quantities of inorganic As by ingesting the same amount of clams as oysters. The results of the risk assessment indicate that potential carcinogenic risks associated with consumption of clams from the BFD area rangs from slightly (4.52×10-6) to largely (80.7×10-6) exceeding the acceptable target risk. Based on the estimation of the TR model, a 0.18 g/day-person of the safe ingestion rate of clams in the BFD region is recommended. For integration of spatial information, an integrated GIS-based approach for assessing potential carcinogenic risks via food-chain exposure of ingesting inorganic As in aquaculture species in the As-affected groundwater areas is presented (Chpater 4). The analyzed results reveal that clams farmed in the western coastal ponds and milkfish farmed in the southwestern coastal ponds have the high risks to human health and tilapia cultivated mainly in the inland ponds only has high risks at the 95th percentile of TR. As-contaminated groundwater used for clams and milkfish ponds should be significantly reduced. The fact that mullet has low risks to human health revealed that As-affected groundwater can be used successively in mullet ponds. Finally, with the goal to propose the suitable consumption rates of seafood, five aquacultural species, tilapia, milkfish, mullet, clams and oysters farmed in As-affected groundwater areas are taken into account to estimate the risk-based rational consumption rates (Chapter 5). Based on the provisional tolerable weekly intake (PTWI) of 15 μg inorganic As/kg body weight suggested by the Food and Agriculture Organization/World Health Organization (FAO/WHO), the daily basis of inorganic As intake of 6.37 μg/day for provisional tolerable daily intake for fish and shellfish (PTDI ) for an adult Taiwanese is transformed. The total dietary intakes estimate for inorganic As in fish and shellfish are 0.52, 1.20, 2.17, 3.95 and 9.22 μg/day, respectively, for 5th, 25th, 50th, 75th and 95th percentiles.The 95th percentile of 9.22 μg/day is higher than PTDI. The rational consumption rate of fish and shellfish is evaluated based on the maximum acceptable lifetime risk. According to the relationship between concentrations of inorganic As (Cinorg) and risk based daily ingestion rate (RBIRf), a tolerance zone with risk range from 1×10-5 to 6.07×10-5 is graphically constructed to define the rational consumption rate of fish and shellfish for general public in Taiwanhe study concludes that the integration of spatial information in assessing and managing potential carcinogenic health risk via ingestion of farmed fish and shellfish in blackfoot disease hyperendemic areas has been proposed. It suggests an effective framework for public health officials in Taiwan in assessing potential carcinogenic risks and informs consumers to wisely choose aquacultural products from As-affected groundwater areas. TABLE OF CONTENTSbstract…….…………….…………………………………….……………………………I要………….…………….……………………………………………….………………IVable of contents.…….………………………………………………………….………VIIist of Tables.…….………………………………………………………….………….VIIIist of Figures.…….………………………………………………………….……….…Χomenclature…….………………………………………………………….………. ΧIIhapter 1 Introduction……….………….……………………………………………………1.1 Background….…….….……………………….……………………………….1.2 Research objectives…….…………………….………….……………………….10eferences…………………………………………………………………….….11hapter 2 Assessing the human health risks from exposure of inorganic arsenic through oyster (Crassostrea gigas) consumption in Taiwan………………………….…………………….16published in Science of the Total Environment)hapter 3 Bioaccumulation of arsenic compounds in aquacultural clams (Meretrix lusoria) and assessment of potential carcinogenic risks to human health by ingestion……………….27published in Chemosphere)hapter 4 An integrated GIS-based approach in assessing carcinogenic risks via food-chain exposure in arsenic-affected groundwater areas………….…………………….…………….35submitted to Environmental Toxicology) hapter 5 Rational consumption rates of fish and shellfish farmed in arsenic-affected groundwater areas………….………………………………………………………….…….69submitted to Environmental Research)hapter 6 Conclusions and Suggestion .1 Conclusions…….………………………………….……………………….……108.2 Suggestion…….………………………………….…………………….……….110