鄰近燃煤火力發電廠居民紅血球中汞物種與代謝物質的影響

The Exposure of Mercury Species in Red Blood Cell and the Effects on Metabolites of Residents Living Near Coal-Fired Power Plants

施蓓婷(Bei-Ting Shih)

指導教授 ： 詹長權

共同指導教授 ： 吳涵涵(Charlene Wu)

國立臺灣大學/公共衛生學院/環境與職業健康科學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003099

摘要

背景
位在台灣中部的雲林縣麥寮燃煤電廠，是雲林石化工業區中的一家私人電廠，每年約可發電1800兆瓦。先前的研究指出了該地區中在距離燃煤火力發電廠的居民有較高的汞暴露，並且透過代謝體學及氧化壓力指標，發現汞可能是造成當地居民有不良健康影響的原因之一。然而過去的研究並未針對不同汞物種的暴露進行分析，例如毒性較強的甲基汞及與燃煤火力發電廠較相關的無機汞。
目的
本研究目標是希望透過分析居住在燃煤電廠周遭成人紅血球中汞物種的濃度，以釐清汞的暴露並結合代謝體資料進一步了解當地居民紅血球中汞物種濃度對其體內代謝物質的影響。
方法
研究團隊過去在此燃煤電廠附近，於2009年到2012年間建立一個由3230位長期在地的居民所組成的世代研究，此世代除透過問卷調查基本人口學資料及生活習慣，並收集血液及尿液生物檢體。本研究對象為此世代研究族群中，年齡大於55歲的居民，並且根據先前世代研究建立之生物暴露指標濃度的高低及居住地距離燃煤電廠的遠近，作為高低暴露組的分組依據，最後研究對象共152位，包含高暴露組76位及低暴露組76位。
為了暸解研究對象對汞物種的暴露情況，使用HPLC串聯ICPMS分析紅血球中的無機汞及甲基汞濃度。並為了瞭解高低暴露組間之差異，使用變異數分析和卡方檢驗進行人口學基本資料及生活習慣差異的分析。為了解紅血球中汞物種與總汞濃度能顯示當地居民的環境汞暴露，使用皮爾森相關性分析，釐清研究對象過去之尿液與血清總汞濃度與本研究紅血球中汞物種及總汞濃度的相關性。
依據研究對象紅血球中無機汞濃度及甲基汞整體濃度分布的60百分位及40百分位重新分為無機汞高低濃度組及甲基汞高低濃度組，與尿液及血清代謝體資料結合後，使用線上統計軟體MetaboAnalyst 4.0以偏最小平方判別分析( PLS-DA)探討高低濃度組別之間代謝體的差異，來連結紅血球中汞物種高低濃度與汞代謝反應有關的特定代謝物質，並以熱圖( Heatmap)呈現代謝物質在高低濃度組別間的表現量差異。
結果
高暴露組居民的紅血球中無機汞的濃度為2.48 ± 0.48µg / L，且在統計上顯著高於低暴露組居民的1.13 ± 0.60 µg / L。但紅血球中的甲基汞濃度在高低暴露組別中並未有顯著差異。在高暴露組別中，無機汞佔紅血球總汞濃度的12± 13％，低暴露組中無機汞佔紅血球總汞濃度7± 6 %。紅血球中無機汞濃度與甲基汞濃度加總後與血清和尿液中的總汞濃度皆呈顯著正相關，且紅血球中無機汞濃度亦與血清和尿液中的總汞濃度呈顯著正相關。
以紅血球中汞物種濃度將研究對象再分為無機汞高低濃度組及甲基汞高低濃度組，結合尿液及血清代謝體資料進行分析，結果顯示以紅血球中無機汞濃度分組，高底濃度組之間的尿液及血清代謝體皆有顯著差異。無機汞濃度分組的的尿液代謝物質中1,3-Butanediol、Dimethyl sulfone、Cyclohexanone、Serine、Hexadecanoic acid 及2-Hydroxyglutaric acid在高濃度組中相對低濃度組上調；Phenol acid 、Octadecanoic及Phosphoric acid在高濃度組中則相對低濃度組下調。無機汞分組的血清代謝物中，只有Ketoleucine在高濃度組中相對低濃度組下調，其餘代謝物 D-Glucurono-6,3-lactone、Pyruvic acid、2-Oxoglutarate以及2-Ketohexanoic acid則在高暴露組相對低暴露組上調。但以紅血球中甲基汞濃度作為分組依據的組別在尿液代謝體或血清代謝體皆未有顯著差異。
結論
紅血球中的無機汞濃度在距離燃煤火力發電廠較近居民中有顯著較高的濃度，且較高的無機汞暴露會影響與體內氧化壓力反應相關代謝物質表現。未來應該在當地建立環境中無機汞濃度的監測資料，並對當地居民與無機汞暴露相關的健康效應進行長期追蹤。
關鍵字：燃煤火力發電廠、無機汞、甲基汞、代謝體學

關鍵字

燃煤火力發電廠 ； 無機汞 ； 甲基汞 ； 代謝體學

並列摘要

Background
Mailiao coal-fired power plant, which can produce 1800MW electricity, is a private power plant in the No. 6 Naphtha Cracker Complex in Yunlin of central Taiwan. Previous studies reported that residents living away from coal-fired power plants had higher mercury exposure, which were associated with adverse health effects via the mercury -related metabolomics and oxidative stress. It is, however, not clear whether such effects are related to mercury species of different exposure sources and routes, such as methylmercury and inorganic mercury.
Objectives
This study has two objectives: to assess the elder residents’ exposures of mercury species in red blood cells by their living distance to coal-fired power plants of the Complex; and to understand the elder residents’ metabolite profiles related to exposures of different mercury species.
Materials and methods
The 152 residents, who were older than 55 years old, in my research were selected from a cohort of 3,230 residents in the vicinity of the coal-fired power plants which were established between 2009 and 2012. We used red blood cells to analyze mercury species as well as basic demographic information and living habits of each study subject in questionnaires to perform further data analysis. Based on previously-analyzed biomonitoring data in urine and the distance of their residence to coal-fired power plants, we divided our study subjects equally into a high-exposure group (HE) and a low-exposure group (LE).
Study subject’s exposure to mercury species, inorganic mercury, and methylmercury in red blood cells were analyzed by HPLC- ICPMS. The statistical methods of t test and chi-square test were used to compare differences in basic demographic data and living habits between high and low exposure groups. Pearson correlation analysis was used to assess the associations of total and speculated mercury concentrations in red blood cells of this study with total mercury concentrations in urine and serum reported in previous studies.
We further classified our study subjects as a high inorganic mercury group (HHg2+) for those with concentration above the 60th percentile and a low inorganic mercury group (LHg2+) for those below the 40th percentile of all in organic mercury measurements among all study subjects. We used the same criteria to classify a high methylmercury group (HMeHg) and a low methylmercury group (LMeHg) for our study subjects. An online statistical software MetaboAnalyst 4.0 was used to perform partial least square discriminant analysis (PLS-DA) in order to separate metabolite profiles between high and low concentration groups, establish the link between concentration of mercury species in the red blood cells and specific metabolites related to mercury metabolism pathways. Heatmap was used to visualize the differences in the expression levels of metabolites between high and low concentration groups.
Results
The concentration of inorganic mercury in red blood cells of the residents of the HE group was 2.48 ± 0.48 µg / L, which was significantly higher than that of the residents of the LE group of 1.13 ± 0.60 µg / L. Methylmercury concentration in residents’ red blood cells didn’t show significant difference between HE and LE groups. Inorganic mercury concentrations accounted for 12±13% of total mercury concentrations in red blood cell for the HE group, and accounted for 7± 6% for the LE group. The concentrations of sum of inorganic mercury and methylmercury in red blood cells was positively correlated with the concentrations of total mercury in serum and urine. And the concentrations of inorganic mercury was positively correlated with the concentrations of total mercury in serum and urine. Urine metabolite profiles showed that 1,3-Butanediol, Dimethyl sulfone, Cyclohexanone, Serine, Hexadecanoic acid, and 2-Hydroxyglutaric acid in the HHg2+group were up-regulated compared to the LHg2+ group. Phenol acid, Octadecanoic, and Phosphoric acid in the HHg2+ group were down-regulated compared to the LHg2+ group. Serum metabolites showed that D-Glucurono-6,3-lactone, Pyruvic acid, 2-Oxoglutarate, and 2-Ketohexanoic acid in the HHg2+ group were up-regulated compared to the LHg2+ group. Only Ketoleucine in the HHg2+ group were down-regulated compared to the LHg2+ group. No significant separation were found for urine and serum metabolite profiles between the HMeHg group and the LMeHg group.
Conclusion
The concentrations of inorganic mercury in red blood cells were significantly higher among the elder residents living closer to the coal-fired power plants. Higher exposure of inorganic mercury influenced the expression of metabolites related to oxidative stress. Our findings suggest that we need environmental monitoring of inorganic mercury in the vicinity of the Complex for better environmental impact assessments on emissions from coal-fired power plants. We also need perform bio-monitoring of inorganic mercury health to improve health impact assessments for residents living surrounding coal-fired power plants.
Key words: Coal-fired power plant, Inorganic mercury, Methylmercury, Metabolomics

並列關鍵字

Coal-fired power plants ； Inorganic mercury ； Methylmercury ； Metabolomics

參考文獻

陳其欣. (2019). 六輕石化工業區附近居民多重污染暴露與代謝體關係之暴露體學研究. (未發表之博士論文). 國立臺灣大學

陳怡伶. (2013). 固定汙染源戴奧辛及重金屬排放調查及管制計畫 (EPA-102-FA12-03-A096). Retrieved from 行政院環境保護署

孫稚翔. (2017). 鄰近六輕工業區成人血清中重金屬濃度與高血脂症、慢性腎臟病相關性之研究. (未發表之碩士論文). 國立臺灣大學

Agency for Toxic Substances and Disease Registry(ATSDR). (1999). Toxicological Profile for Mercury.

AgilentTechnologies. (2011). https://www.chem-agilent.com/cimg/00000124.pdf.