食物砷之攝取對職業性砷暴露評估之影響

Abstract

本研究目的在於探討攝食不同海產食 物及攝食後時間長短對於各種砷代謝產物 量測之干擾。十種海產食物經分析後顯示 有機砷含量最高的是花蟹219.4 ug/g ，最低 的是海沙蝦2.58 ug/g 。十二名志願者分組 參與後續的飲食控制實驗，使用的海產食 物包括茶葉菜、蛤、牡蠣及海沙蝦。在一 週實驗期間，由本計畫提供受試者每日三 餐以避免受試者暴露於含海產食物之飲 食。各組實驗指定之特定一種海產係在第 四天午餐及晚餐提供。自進食海產前一天 起至實驗結束前的另三天，受試者必須收 取其所有尿液樣本，分別存放在500 ml 塑 膠瓶。尿中砷代謝物種，包括三價砷、五 假砷、單甲基砷酸及雙甲基砷酸，係以高 效率液相層析儀結合原子吸收光譜進行分 析。結果顯示，雙甲基砷酸是最主要的尿中砷代謝物種，佔80 %左右。在進食茶葉 菜、蛤、牡蠣等三組，其攝食後第一天早 起第一泡尿液中的雙甲基砷酸濃度平均分別達到36.4 ±7.8 ug/L,48.6 ±15.1 ug/L, 26.6 ±5.2 ug/L 。一般而言，在正常飲食攝取 150g 的海產就有可能讓尿中砷濃度上升幅 度達30 ug/L ，顯示海產飲食會干擾對無機 砷暴露後的尿中砷代謝產物偵測。本研究 的發現也顯示不同人間對砷的代謝機制與 解毒能力有很大的變異情形。需進一步針 對個體易感受性對砷暴露的關係進行探 討，以瞭解攝食海產對尿中砷物種分佈， 甚至是砷相關疾病的綜合效應。

The present study was conducted to explore the potential confounding effects resulting from dietary arsenic intake from seafoods with the aims to delineate the effects of seafood items and time since seafood ingestion on the elevation of speciated urinary arsenic metabolite levels. Among the ten seafoods determined for arsenic species, the most common arsenic species was arsenobetaine, with the highest total arsenic content found in flower crab, 219.42 ug/g and the lowest observed in seasand shrimp, 2.58 ug/g. Twelve volunteers were invited to participate in the next step seafood-restrain study. The seafoods used for this study included brown seaweed, clam, oyster, and shrimp from the ten aforementioned seafoods. During the one-week study period, study subjects were provided with all meals for dietary control and restrained from any aquatic and seafoods, except the designated study seafoods aforementioned provided in the lunch meal and dinner meal on the fourth day. All the urine excretions of the study subjects were separately collected in 500 ml bottles for the day prior to seafood ingestion, and the following 3 consecutive days. Urinary arsenic metabolites were determined with high performance liquid chromatography - hydride generation - atomic absorption spectrometry, including arsenite(As 3+ ), arsenate (As 5+ ), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). DMA dominated the urinary arsenic metabolites, constituting about 80 % of the total arsenicals excreted. Average DMA concentrations in the first morning void samples after ingestion of the brown seaweeds, clam, oyster were 36.4±7.8 ug/L, 48.6±15.1 ug/L, 26.6±5.2 ug/L, respectively. In general, an elevation of urinary arsenic levels by 30 ug/L is possible by regular meals composed of 150 g seafoods, implying a critical confounding effect of seafood ingestion on the biological marker for inorganic arsenic exposure monitoring. The findings of the present study also shed light on the significant individual variation in the arsenic metabolism and/or the capability of arsenic detoxification. Further studies emphasizing on the individual susceptibility to arsenic exposure are warranted in order to explore the comprehensive effects of seafood intake on the distribution of urinary arsenic species, and even more on the arseniasis.