孩童及青少年飲食習慣與其血液及尿中金屬濃度分布關係之探討

Abstract

孩童及青少年是環境中金屬汙染物暴露的易感受族群，金屬暴露會對孩童及青少年產生負面健康效應。飲食為一般民眾暴露金屬的主要途徑之一，因食物可能被環境中金屬所污染，如海鮮體內可能含有高濃度的砷及汞，米飯中則含有無機砷。臺灣目前雖有國民營養健康狀況變遷調查，但尚無本土化研究討論飲食習慣與人體內金屬濃度的相關性。因此，本研究的目的為調查孩童及青少年之飲食習慣，並分析其血液中十種金屬元素及尿液中四種金屬元素，以探討飲食習慣與血液及尿中金屬元素濃度分布之關係。 本研究收樣期間自2018年1月至2018年5月，邀請來自於2009年至2012年間在台大醫院兒童醫院建立的Taiwan Birth Panel Study II (TBPS II)中324位年齡為4 – 14歲之孩童及青少年作為本次研究的受試者，並收集其尿液及血液樣本，使用感應耦合電漿質譜儀(ICP-MS)分析尿液中之砷、鎘、鉛、汞及血液中砷、鎘、鉛、汞、錳、鋅、鉬、銻、銫、鎢等金屬元素濃度。同時利用問卷收集人口學資料及居住環境暴露資料，而孩童及青少年的飲食習慣則使用飲食頻率問卷(FFQ)進行調查。 尿液中金屬元素濃度分析結果顯示，尿中濃度最高的金屬元素為砷，平均濃度值為109.5 mug/g creatinine。其次為汞、鉛，其平均濃度值分別為1.84、1.03 mug/g creatinine。尿中鎘平均濃度值則最低，為0.37 mug/g creatinine。至於血液中金屬元素濃度方面，以血中鋅平均濃度值最高，為4,278 mug/L。其次為錳、鉛、汞，平均濃度值分別為19.8、7.78、6.36 mug/L。再其次為砷、銫，其平均濃度值分別為3.37、2.61 mug/L。而血中鉬、銻、鎘、鎢之平均濃度值則較低，為0.72、0.32、0.15、0.05 mug/L。 多變項線性迴歸模型分析結果顯示，孩童及青少年尿中及血液中多種金屬元素濃度與飲食習慣具有相關性。米飯攝食份量與血中砷濃度呈現正相關p=0.002)。海鮮類攝食份量和尿中砷濃度(p=0.001)、血中砷濃度(p<0.001)、血中汞濃度(p<0.001)均為強烈正相關。此外，食用營養補充劑也可能影響孩童及青少年的尿中及血中金屬濃度分布情形。本研究發現，有無食用鈣補充劑與尿中鎘濃度呈強烈負相關(p=0.001)。有無服用中、草藥湯劑補品則和血中鎘(p=0.002)、鉛(p=0.016)、汞濃度(p=0.028)均有顯著負相關關係。 目前環境金屬危害暴露型態已逐漸轉變成長期、低劑量之暴露，而本研究發現了飲食習慣、食用營養補充劑等因素對人體內微量金屬暴露的影響。這些金屬暴露程度雖是低濃度範疇，但長期經飲食食入金屬可能造成的健康效應仍值得後續研究持續關注。

Children and adolescents are vulnerable to heavy metal exposure, with a number of adverse health effects. For the general population, food consumption is considered one of the predominant exposure pathways for toxic heavy metals, like mercury and arsenic in seafood and inorganic arsenic in rice. Although the Health Promotion Administration (HPA) has conducted several times the Nutrition and Health Surveys in Taiwan (NAHSIT) in the past years, there has been a growing concern on the relationship between dietary intake and human biomarker metal levels. Therefore, the objective of this study was set to discern the associations of dietary intake and blood and urinary metal levels of children and adolescents. From January 2018 to May 2018, in total, 324 participants, aged 4 – 14 years old, were recruited from the Taiwan Birth Panel Study II, which was conducted during 2009 – 2012. All participants completed questionnaires for the collection of information on demographic characteristics, living environment etc. Dietary intake by food category was assessed through Food Frequency Questionnaire administration. Urine and whole blood samples were collected from all participants for metal analysis using ICP-MS. Urine samples were analyzed for As, Cd, Pb and Hg, and whole blood samples were analyzed for As, Cd, Pb, Hg, Mn, Zn, Mo, Sb, Cs and W. The highest concentration of metal in urine was found for arsenic with a mean of 109.5 mug/g creatinine, followed by mercury and lead with means of 1.84 and 1.03 mug/g creatinine, respectively, and by cadmium with a mean of 0.37 mug/g creatinine. On the other hand, the highest concentration of metal in blood was found for zinc with a mean of 4,278 mug/L, followed by manganese, lead, mercury with means of 19.8、7.78、6.36 mug/L, respectively, and by arsenic and cesium, with means of 3.37、2.61 mug/L, respectively. The means of molybdenum, antimony, cadmium and tungsten levels in blood were 0.72、0.32、0.15、0.05 mug/L, respectively. Results of multivariate linear regression suggested that there were significantly associations of dietary intake with blood and urinary metal levels of children and adolescents. Positive correlation was found between rice consumption and blood arsenic level (p=0.002). Seafood consumption has strongly positive correlations with urinary arsenic level (p=0.001), blood arsenic level (p<0.001) and blood mercury level (p<0.001), respectively. Furthermore, taking nutritional supplements may also affect the distributions of metal levels in urine and blood. We found an inverse correlation between taking calcium supplements and urinary cadmium level (p=0.001). Meanwhile, negative correlations were also present between taking Chinese herbal medicine and blood cadmium, lead and mercury levels with p=0.002, p=0.016 and p=0.028, respectively. Nowadays, with relatively low background levels of metal exposure, dietary intake and taking nutritional supplements have been emerging as one of the prominent pathways for human metal exposure. Future studies are warranted to illustrate potential adverse health impacts, if any, through dietary metal intake.