探討懷孕婦女胎盤戴奧辛及多氯聯苯之暴露與胎盤及臍帶血中n-3及n-6多元不飽和脂肪酸之相關性-一個對台灣中部懷孕婦女之橫斷面研究

Relationships between Placental Dioxin and Polychlorinated Biphenyls and Placental and Cord Blood n-3 and n-6 Polyunsaturated Fatty Acid Status-A Cross-Sectional Study among Pregnant Women from Central Taiwan

蘇郁婷(Yu-Ting Su)

指導教授 ： 黃孟娟

高雄醫學大學/醫學院/醫學研究所/碩士(2012年)

摘要

n-3及n-6 polyunsaturated fatty acids (PUFA)，docosahexaenoic acid (DHA; C22:6n3)及arachidonic acid (ARA; C20:4n6)，在胎兒成長發育扮演重要的角色。而脂肪酸及polychlorinated dibenzo-para-dioxins (PCDDs)、polychlorinated dibenzofurans (PCDFs)、dioxin-like polychlorinated biphenyls (PCBs)及indicator PCBs皆有類似親脂性化學特性及食物來源，但其暴露對嬰幼兒之大腦神經及視力發展具有負面的影響。目前較少研究探討dioxin/PCBs與胎盤或臍帶血n-3及n-6 PUFA之關係。先前研究曾探討34位孕婦胎盤dioxin/PCBs毒性當量與胎盤DHA及ARA之相關性研究(Huang, Brenna et al. 2011)，本研究接續前述研究擴大分析樣本數，以胎盤dioxin/PCBs毒性當量作為懷孕前後之累積暴露量指標(Chao, Wang et al. 2005)，探討來自97位台灣台中懷孕婦女胎盤dioxin/PCBs之暴露與胎盤及臍帶血中n-3及n-6 PUFA之相關性。當將胎盤dioxin/PCBs以33.3%及66.6%分為低、中、高三種暴露量，DHA weight% (2.78、3.15、3.55, p=0.197)及ARA weight% (11.83、12.75、13.62, p=0.431)在dioxin-like PCBs低、中、高三組有逐漸上升，但趨勢並無達到顯著相關(DHA: p=0.127, ARA: p=0.397)。進一步以多變量線性迴歸校正孕婦年齡及懷孕前BMI後，每增加一單位之dioxin-like PCBs毒性當量，則DHA增加0.34% (beta=0.34, SE=0.16, p=0.034)，而胎盤ARA與dioxin-like PCBs則無呈現顯著相關性(p=0.195)。胎盤DHA及ARA與PCDD/Fs及indicator PCBs亦無顯著相關性。臍帶血DHA及ARA在胎盤dioxin/PCBs低、中、高三組之分佈並無顯著不同，以多變量線性迴歸校正孕婦年齡及懷孕前BMI後，胎盤dioxin/PCB與臍帶血之DHA及ARA亦無顯著相關性。本研究結論，以胎盤之dioxin/PCBs毒性當量為暴露指標，胎盤DHA僅在dioxin-like PCBs低、中、高三組濃度逐漸上升，但無顯著差異。以多變量線性迴歸校正孕婦年齡及懷孕前BMI後，dioxin-like PCBs毒性當量與DHA wt%具顯著相關性(beta=0.34, SE=0.16, p=0.034)。而胎盤DHA與PCDDs、PCDFs及Indicator PCBs則無發現相關性，且胎盤及臍帶血ARA亦與dioxin/PCBs無顯著相關性。本研究胎盤ARA與臍帶血DHA及ARA之濃度分佈與胎盤dioxin/PCBs之高低無關，僅有胎盤DHA與dioxin-like PCBs具較弱之相關性。本研究孕婦及胎兒屬於dioxin/PCBs暴露較低的族群，海水魚類攝取對於本族群孕婦應予以鼓勵且無安全性的疑慮，但仍建議避免含有機氯化合物或重金屬較多之海水魚類。未來本世代研究須進一步了解dioxin/PCBs暴露及胎盤和臍帶血中脂肪酸濃度對於本研究族群之嬰幼兒在神經及智能發展之影響。除此之外，關於dioxin/PCBs暴露如何影響胎盤及臍帶血必需脂肪酸之運輸機制需要更進一步的探討及研究。

關鍵字

n-3 PUFA ； ARA ； DHA ； dioxin ； PCDD/Fs ； PCBs ； 孕婦 ； 胎盤 ； 臍帶血

並列摘要

n-3 and n-6 polyunsaturated fatty acids (PUFA), arachidonic acid (C20:4 n6; ARA) and docosahexaenoic acid (C22:6 n3; DHA), have positive effects, and environmental toxins, polychlorinated dibenzo-para-dioxins / dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (PCBs) and indicator PCBs, have negative effects on perinatal development. n-3 and n-6 PUFA, as well as dioxin/PCBs, have similar lipophilic properties and food origins, thus the relationship between transport n-3 and n-6 PUFA from placental to fetus and the impact and exposure of these harmful organo-chlorines may be of concern. Previous studies have showed that placental toxic equivalent (TEQ) levels of dioxin/PCBs correlated significantly with those of maternal blood, human milk, and cord blood in Taiwanese women, thus placental levels are considered indicators as perinatal accumulative exposure of dioxin/PCBs (Chao, Wang et al. 2005). In addition, weak and negative correlations between placental PCDFs and placental ARA and DHA were reported in the previous study with 34 pregnant women from central Taiwan (Huang, Brenna et al. 2011). This investigation aimed to examine the correlations between the placental TEQ levels of dioxin/PCBs and PUFA in both placental and cord blood (weight %) from the same cohort with expanded sample size of 97 pregnant women from central Taiwan. As we categorized placental TEQ of dioxin/PCBs into low, medium and high levels, accumulation of DHA (wt%) was increased as dioxin-like PCBs exposure increased, but the trend was only marginally significant (p=0.127). After adjustment for maternal age and pre-pregnancy body mass index, an one-unit placental dioxin-like PCBs TEQ increase was associated with 0.34% increase in placental DHA (beta=0.34, SE=0.16, p=0.034), and placental PCDDs, PCDFs, and indicator PCBs did not correlate with placental DHA. In addition, placental dioxin/PCBs did not correlate with neither placental ARA, cord blood ARA, nor cord blood DHA. In conclusion, placental ARA, cord blood DHA/ARA did not vary with placental dioxin/PCBs levels. Only placental DHA was found to correlate weakly with placental dioxin-like PCBs levels. Since the dioxin/PCBs exposure in this population is low, pregnant women should be encouraged to consume marine fish to obtain unique nutrients and avoid species with high environmental pollutants. Future study will be needed to examinate the effects of dioxin/PCBs exposure and long-chain PUFA concentration on postnatal neural and cognitive development in this cohort. Further, more explorations on the mechanisms of how dioxin/PCBs will affect the transport of n-3 and n-6 PUFA within the placenta and cord blood are also warranted investigation.

並列關鍵字

n-3 PUFA ； ARA ； DHA ； dioxin ； PCDD/Fs ； PCBs ； pregnancy ； placenta ； cord blood

參考文獻

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