臺灣學齡前孩童血中金屬濃度分布與相關影響因素探討

Distributions of Metal Levels in the Blood of Preschool Children in Taiwan and the Relevant Affecting Factors

林宜萱(Yi-Hsuan Lin)

指導教授 ： 黃耀輝

共同指導教授 ： 張靜文

國立臺灣大學/公共衛生學院/環境衛生研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01003

摘要

人體血液中的金屬元素濃度，可用來當作人體受到環境金屬暴露的生物指標。本研究目的在於建立臺灣學齡前孩童血中金屬濃度之常模，並探討主要的影響因素，做為日後有害金屬暴露防治的參考。

本研究收樣期間自2011年4月到2011年11月，以行政等級為單位做分層抽樣，隨機選取了全台44個區、市、鎮、鄉，依序邀請其轄內幼稚園參與本計劃，最後共有85所幼稚園同意參與本計畫。所有幼稚園受邀孩童家長會先被告知研究目的與流程，並請其同意後簽署參與計畫同意書。問卷資料由幼稚園老師協助孩童家長完成，血液樣本則由小兒科護士或醫生至幼稚園進行採樣。總共收集932個血液樣本，儲存於4℃冰箱，後以感應耦合電漿質譜儀進行18種金屬元素的分析，包括鈹(Be)、鉛(Pb)、鍶(Sr)、鉬(Mo)、鎘(Cd)、銻(Sb)、銫(Cs)、鈾(U)、釩(V)、錳(Mn)、鈷(Co)、銅(Cu)、鋅(Zn)、砷(As)、硒(Se)、銣(Rb)、錫(Sn)、汞(Hg)等元素。

若以各血中金屬濃度平均值正負兩個標準差範圍內為常模，本研究結果顯示臺灣地區學齡前孩童血中金屬濃度常模分布範圍分別為：鉛0.774~4.47 μg/dL、鈹<1.47μg/L、鍶7.75~38.0 μg/L、鉬<2.47 μg/L、鎘<0.340 μg/L、銻1.49~6.24 μg/L、銫0.752 ~4.12μg/L、鈾<0.0170 μg/L、釩<0.674μg/L、錳6.00~22.1 μg/L、鈷0.0481~0.917μg/L、銅674~1397 μg/L、鋅2623~6315 μg/L、砷0.745~11.4 μg/L、硒79.7~154 μg/L、銣1140~3059μg/L、錫<1.44 μg/L、汞1.04~17.7 μg/L。

　　以北、中、南、東、離島等地理區域別來看，研究個案血中18 種金屬濃度除了鎘和銻之外，其他金屬濃度都呈現與研究個案居住之地理區域有顯著差異(p<0.025)。其中血中鉛和錫濃度都是離島區域最高，而血中鈹、鉬、銫、錳、砷、銣、汞等金屬濃度都是東部區域最高，血中鍶濃度是中部區域最高，血中釩、鈷、銅、鋅、硒等金屬濃度都是南部區域最高。血中鉛、錳、鋅、銣、汞等金屬濃度都是居住在北部區域的研究個案最低，而血中鈹、鍶、銫、釩、銅、硒等金屬濃度都是離島區域最低，血中鈷、錫等金屬濃度則是東部區域最低，血中砷濃度則是南部區域最低。

　　全台灣學齡前孩童血中鉛濃度分布曲線呈現右偏，血中鉛值最多分布在1~2μg/dL 之間。與美國4 到7 歲孩童比較，台灣學齡前孩童血中鉛的累積分佈圖形與美國2003-2004 年和2005-2006 年最為類似；預期再過4 至6 年，台灣學齡前孩童血中鉛可以更接近美國當代的學齡前孩童血中鉛濃度分布。

　　本研究發現家中是否燒香拜拜，與孩童血中的砷、汞、鉛濃度有正相關。特別是家中燒香拜拜的頻率，與孩童的血中鉛濃度有劑量效應關係，顯示燒香拜拜可能是孩童的鉛暴露來源之一。研究個案居住地附近是否有工廠與其血中鉛濃度呈正相關。血中銻濃度則與居住地附近是否常聞到異味呈正相關。血中鉛與家庭平均月收入呈負相關，而血中鍶與錫都與父親教育程度呈現負相關。這些金屬都是在製造業或工業會使用到的材料，像是錫常被使用於金屬零件的焊接、電鍍上，因此父母的職業暴露可能間接導致孩童的金屬暴露。

　　此外，以2 μg/dL 和3 μg/dL 為高低血鉛濃度之切分點的羅吉斯回歸模式分析結果顯示，主要的顯著影響因素是孩童家庭背景資料相關的變項。以4 或5μg/dL 為高低血鉛濃度之切分點的羅吉斯回歸模式分析結果則顯示主要的顯著影響因素是與父親職業與居住環境相關的變項。以衛生單位的角度來看，考量台灣孩童血中鉛常模值分布範圍，以及有限的行政資源，孩童血中鉛警戒值可訂在5μg/dL，以便能針對少部分高血中鉛濃度孩童進行重點式鉛暴露防治工作。

　　相較於傳統較高濃度、有明顯汙染源的有害金屬暴露環境，現今的有害金屬暴露已轉變為來源不明確之多金屬元素低濃度暴露為主，常以低社經地位、低教育程度、文化差異等健康不平等因素反映出高金屬暴露族群，顯示未來的金屬暴露防治應多著眼於這些社會上的弱勢族群。

關鍵字

血液 ； 鉛 ； 砷 ； 汞 ； 生物偵測 ； 微量金屬 ； 學齡前孩童 ； 感應耦合電漿質譜儀

並列摘要

Biological monitoring of metals in blood is important in characterizing human’s exposure to metals. The aim of this study was set to establish the norm of metal levels in blood of the preschool children in Taiwan as well as to explore their determinants in order to set forth the benchmarks for further toxic metal exposure prevention.

Stratum random sampling was adopted based on administrative area and in total 44 districts, cities, towns, and villages were selected. Within these areas, after being invited in sequence, 85 kindergartens agreed to participate in this study. All the parents of children of the participating kindergarten were informed the study goals and processes, and asked to sign a statement of consent once they agreed to take part in this study. Questionnaires were administrated through help of the kindergarten teachers, while blood samples were collected by pediatric nurses or doctors. From April to October 2011, in total, 932 blood samples were collected from the volunteering kindergarten children, and stored in tubes with heparin at 4℃ until laboratory analysis with inductively coupled plasma mass spectrometry for 18 trace metals, including beryllium, lead, strontium, molybdenum, cadmium, antimony, cesium, uranium, vanadium, manganese, cobalt, copper, zinc, arsenic, selenium, rubidium, tin, mercury.

As being defined as mean plus/minus two times the standard deviation, the norms of metal levels in blood of preschool children were set as 0.774 to 4.47 μg/dL for lead, less than 1.47μg/L for beryllium, 7.75 to 38.0 μg/L for strontium, less than 2.47μg/L for molybdenum, less than 0.340μg/L for cadmium, 1.49 to 6.24 μg/L for antimony, 0.752 to 4.12 μg/L for cesium, less than 0.0170 μg/L for uranium, less than 0.674 μg/L for vanadium, 6.00 to 22.1μg/L for manganese, 0.0481 to 0.917 μg/L for cobalt, 674 to 1397 μg/L for copper, 2623 to 6315 μg/L for zinc, 0.745 to 11.4 μg/L for arsenic, 79.7 to 154 μg/L for selenium, 1140 to 3059 μg/L for rubidium, less than 1.44 μg/L for tin and 1.04 to 17.7 μg/L for mercury, respectively.

Except for cadmium and antimony, levels of all study metals in children’s blood were significantly different among geographical zones, i.e. northern, central, southern, eastern Taiwan, and off-shore islands (p<0.025). The highest levels of lead and tin in children’s blood were found in off-shore islands; the highest levels of beryllium, molybdenum, cesium, manganese, arsenic, rubidium and mercury were found in eastern Taiwan; the highest level of strontium was found in central Taiwan; the highest levels of vanadium, cobalt, copper, zinc and selenium were found in southern Taiwan. The lowest levels of lead, manganese, zinc, rubidium and mercury in children’s blood were found in northern Taiwan; the lowest levels of beryllium, strontium, cesium, vanadium, copper and selenium were found in off-shore islands; the lowest levels of cobalt and tin in children’s blood were found in eastern Taiwan; the lowest level of arsenic was found in southern Taiwan.

The distribution of blood lead level of the preschool children in Taiwan was skewed to right with most blood lead levels ranging from 1 to 2 μg/dL. Such a distribution was similar to the findings in the surveys on American children aged 4-7 years in 2003-2004 and 2005-2006, respectively. It is expected that the blood lead level distribution of the preschool children in Taiwan will get close to the contemporary blood lead level of same age children of the United States in the upcoming four to six years.

It was found that incense burning at home was associated with arsenic, mercury and lead levels in children’s blood samples. Especially, there was a dose-response relationship between frequency of incense burning at home and lead level in children’s blood samples, indicating incense burning probably a lead exposure source for children. Besides, factories located in the vicinity of the study subject’s residence is positively correlated with lead level in children’s blood samples; smell of odor in the vicinity of study subject’s residence was also positively correlated with antimony level in children’s blood samples. Lead level in children’s blood samples was negatively correlated to family income, and blood strontium and tin levels in children’s blood samples were also negatively correlated to parental education levels. These relevant metals are generally used in the manufacturing industry, implying parental occupational exposure could indirectly lead to children’s metal exposure.

With different cut-points applied in categoring high-low blood lead level groups, results of logistic regression model showed that the major variables for high blood lead level group were demographic related factors as cut-point set at 2 or 3 μg/dL, while the major affecting factors for high blood lead level group were parental occupation and general living environmental related factors as cut-point set at 4 or 5 μg/dL. Therefore, from the viewpoint of health administration, considering the norm of blood lead level of preschool children and limited administrative resources, the alert for blood lead level of preschool children could be set at 5 μg/dL, in order to launch lead exposure prevention by focusing on the small part of children with relatively high level of lead in blood.

As compared to the traditional hazardous metal exposure environment with conspicuous pollution sources and high levels of pollutant contents, the hazardous metal exposure nowadays becomes low level multi-elements exposure with obscure sources, and was reflected by low social economic status, low educational level and culture heritage. This phenomenon suggested that the exposure prevention for hazardous metals in the future should focus on the disadvantaged minority.

並列關鍵字

blood ； lead ； arsenic ； mercury ； biological monitoring ； trace metal ； inductively coupled plasma-mass spectrometry

參考文獻

劉俊宏。台灣臍帶血中微量元素與重金屬濃度分布情形，2009。[碩士論文]台灣大學職業醫學與工業衛生研究所。

Kuo CY, Wang JY, Yeh CJ, Chen MC, Kuo CW, Chiang CY, Chou HL. Metal exposure for residents near diesel transport routes. Journal of Environmental Science and Health 2010;28:22-38.

勞工安全衛生研究所。作業環境中有害物勞工暴露生物偵測分析方法驗證程序。

行政院勞工委員會勞工安全衛生研究所，台北，民國八十九年。

US CDC. Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables. Department of Health and Human Services Centers for Disease Control and Prevention, Atlanta, Georgia, 2010.