唾液中砷物種與多種金屬元素作為無機砷與重金屬暴露指標可行性評估

Abstract

生物偵測是指藉由生物檢體之採樣，分析其中某化學物質或者是其代謝物的濃度，以評估人員的暴露或是健康效應，生物偵測常用的檢體類型包含血液、尿液、頭髮、指甲、唾液等。在重金屬暴露之生物偵測上，通常以血液、尿液為主，也有部分是以頭髮、指甲作為評估工具，僅有少數研究以唾液作為重金屬暴露之生物偵測指標。以砷為例，過去的研究通常以尿中砷濃度作為無機砷暴露之評估工具，然而尿中砷濃度容易受到受試者食用海鮮食品而造成無機砷暴露評估上的干擾，若有一生物偵測方式不受食用海鮮食品之影響，又可以反映出無機砷暴露，對於砷暴露之評估將是一項有力的評估方式。唾液作為生物偵測之工具的優點為採集簡單且非侵入性，受試者提供檢體之意願較高。本研究分析唾液中的多元素以及砷物種濃度，一方面研究唾液中多元素濃度以及尿液中濃度之相關性，並且探討影響唾液中元素濃度之因子，藉此評估唾液是否可作為暴露指標；另一方面則是評估唾液中的砷濃度是否會受到海鮮食品攝取之影響。 本研究分兩部分，第一部分分析34名受試者唾液與尿液中的多種元素以及砷物種，其中17人為台大醫院腎臟科之病患，17人為無泌尿系統相關疾病之受試者，此部分實驗探討：（1）唾液與尿液中之元素濃度之間是否有相關性，（2）比較健康受試者與泌尿系統相關疾病受試者之唾液中金屬元素濃度與砷物種濃度之間是否有差異，（3）藉由問卷調查分析不同的人口學變項是否會影響唾液中多元素以及砷物種之濃度。以感應耦合電漿質譜儀（ICP-MS）分析砷、鋇、鉻、鈷、鎘、鎵、銦、錳、鎳、鉛、鈀、硒、鍶、釩、鎢，並且以高效能液相層析儀串聯感應耦合電漿質譜儀（HPLC-ICP-MS）分析三價無機砷（arsenite）、五價無機砷 （arsenate）、單甲機砷酸（monomethylarsonic acid）、雙甲機砷酸（dimethylarsinic acid）、砷酸甜菜鹼（arsenobetaine）。結果發現，唾液中鎳濃度與尿液中鎳濃度之Spearman相關係數為0.503（p < 0.05），唾液中鎢濃度與尿液中鎢濃度之Spearman相關係數為0.703（p < 0.05），皆達到統計上顯著差異。唾液中的砷、鈷、鉻、錳、鎳、鉛、硒、釩等元素在不同年齡層中平均濃度有顯著差異；目前仍配戴口腔矯正器或假牙之受試者唾液中鉻濃度顯著較從未配戴之受試者高。有泌尿系統相關疾病之受試者，唾液中的五價無機砷濃度顯著較無疾病者高。本研究第二部分則是讓16名健康受試者食用海鮮食品，比較食用前後兩天尿液及唾液中的砷及其物種濃度變化，以評估海鮮攝取是否會對唾液中的砷濃度造成影響。結果顯示，尿中的砷濃度明顯會受到飲食海鮮食品而改變，但是唾液中的砷濃度在食用海鮮食品前後變化不大，表示唾液中砷濃度不受食用海鮮食品之影響。本研究之結果顯示，唾液中的鎢在唾液中的濃度與尿液中的濃度相關性高，表示可能可以作為鎢暴露的生物偵測指標。唾液中的砷濃度不受食用海鮮食品之影響，為避免食用海鮮食品對於尿中砷及砷物種濃度之影響，未來唾液中砷濃度可望作為評估無機砷暴露之工具之一。

Biomonitoring is the measurement of chemicals or their metabolites in body fluids or tissues, such as blood, urine, hairs, nails, and saliva. Blood and urine samples are the most widely accepted matrices for the biomonitoring of trace metal exposure, and there is less research on trace elements in saliva. Collection of saliva is simple and non-invasive, and saliva is much more accessible as compared to other sample mediums. In addition, dietary arsenic from seafood intake would be significant interference for the assessment of exposure to inorganic arsenic using urine arsenic levels as biological marker. Therefore, the purpose of this study was to determine the levels of trace elements in saliva and urine, including arsenic, barium, chromium, cobalt, cadmium, gallium, indium, lead, manganese, nickel, palladium, selenium, strontium, vanadium, and tungsten and arsenic species, i.e., arsenite (AsIII), arsenate (AsV), methylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine (AsB), and to evaluate the usability of saliva as biomonitoring medium. Mean while, fluctuation of salivary arsenic species levels after seafood intake was also examined to evaluate the effect of dietary arsenic intake on the inorganic metabolites in saliva. There are two parts in this study. In the first part, the levels of arsenic species and trace elements were determined in 34 saliva and urine samples, respectively, from 17 healthy volunteers and 17 patients from the Division of Nephrology in National Taiwan University Hospital. The levels of trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the arsenic species were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). There were positive correlations between salivary nickel level and urinary nickel level (rs = 0.503, p < 0.05), and between salivary tungsten level and urinary tungsten level (rs = 0.703, p < 0.05). There were significant differences in the saliva levels of arsenic, chromium, cobalt, lead, manganese, nickel, selenium, and vanadium among various age groups. The mean chromium level in saliva samples of volunteers with fixed orthodontic appliances or dentures was higher than that of volunteers without them. Higher salivary arsenate levels were observed in volunteers with kidney diseases. In the second part of this study, 16 volunteers were asked to eat about 100 g oyster or cuttlefish in one meal, and their saliva and urine samples were collected before and after the seafood intake for the determination of arsenic species levels. Results showed that the levels of arsenic in urine samples increased significantly after the intake of seafood, while there was no difference between arsenic levels in saliva before and after the seafood intake. In conclusion, tungsten in human saliva could be a useful biomarker to assess human exposure to tungsten. So were saliva arsenic species for the evaluation of inorganic arsenic exposure since they would not be affected by seafood arsenic intake.