臺灣野生及圈養亞洲黑熊之重金屬鉛暴露分析—以血液及毛髮為生物指標

Analysis of lead (Pb) exposure in free-ranging and captive Asiatic black bears (Ursus thibetanus) in Taiwan — Using blood and hair samples as biomarkers

黃立心(Li-Hsin Huang)

指導教授 ： 余品奐

國立臺灣大學/獸醫專業學院/臨床動物醫學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104460

摘要

金屬鉛為自然環境中的微量元素之一，既是生物體的非必須元素，亦同時是具有生物毒性的重金屬物質。在過去的研究當中，發現台灣的野生動物有暴露於鉛危害之可能。而依據生物放大作用及生物累積作用之原理，體型越大之動物，可能面臨越大的毒物暴露及中毒風險。換言之，台灣最大的食肉目動物——亞洲黑熊，可能面臨了較高的金屬鉛暴露風險。微量元素研究當中常使用生物指標來評估環境、動物及人類的暴露情形，相較於其他生物性檢體，毛髮具有不需麻醉即可取得、採樣過程對動物造成之緊迫較少，以及容易保存的優點，因此廣泛地被使用於此類研究之中。本研究之目的在於分析臺灣的亞洲黑熊所面臨之金屬鉛暴露及中毒情形，除了血液之外，亦選用毛髮做為評估臺灣黑熊之金屬鉛暴露情形的檢體。此外，本研究也將建立亞洲黑熊血液及毛髮鉛濃度之參考值，並評估鉛對於這些黑熊的影響，包含血液學、血液生化肝指數及腎指數。最後，評估使用毛髮對亞洲黑熊進行鉛暴露調查之可行性。

本研究一共取得有效血液檢體32份，其中16份來自野生亞洲黑熊，另16份來自圈養亞洲黑熊；毛髮檢體方面共有31份有效檢體，15份來自野生個體，剩餘16份則來自圈養個體。血液及毛髮檢體皆以感應耦合電漿質譜儀(ICP-MS)對檢體進行鉛含量之分析，在本研究的亞洲黑熊個體中，血液鉛濃度中位數為4.1 μg/dL，而毛髮中鉛濃度中位數為0.44 ppm，參考值上限則分別為9.39 μg/dL及1.46 ppm。在評估鉛的可能影響方面，MCV和血液鉛濃度呈正相關(ρ= 0.6279, p < 0.001)，ALT及AST則與血液鉛濃度呈負相關(ρ= -0.5124, p < 0.01；ρ= -0.5201, p < 0.01)；至於毛髮鉛濃度則未與任何血液檢查數值呈顯著相關。在毛髮作為評估亞洲黑熊鉛暴露情形之生物指標方面，毛髮鉛濃度與血液之鉛濃度呈現顯著之正向弱相關(ρ= 0.3929, p < 0.05)，然而毛髮鉛濃度對於血液鉛濃度之預測程度僅中等，其敏感性只有60%，並伴隨40%之偽陰性。因此，本研究建議，在評估亞洲黑熊金屬鉛之暴露情形時，相較於僅以毛髮作為評估工具，以血液檢體評估急性鉛暴露並搭配毛髮檢體評估慢性暴露將提供較為精確之結果。

關鍵字

亞洲黑熊 ； 鉛 ； 毛髮 ； 血液 ； 參考值

並列摘要

Lead (Pb), as a non-essential trace metal to the body, is a notable pollutant while overexposed which could result in various disorders in human and animals. Previous studies have found that wildlife in Taiwan may expose to Pb pollution. Besides, larger animals may be more prone to accumulate this toxic element in their body due to the effect of biomagnification. Thus, it is suspected that Asiatic black bears (Ursus thibetanus), the largest wild carnivores in Taiwan, may face a higher risk of lead toxicity. Beside blood, animal hair has been used as bioindicator material for trace-metal contamination due to potential stress/anesthetic free collection process for wild animals and hair can be stored at ambient temperature for long periods of time without degradation, making them suitable for long-term and consecutive studies. The aim of the study was to assess situation of Pb exposure, evaluate the correlation between tissue (blood and hair) Pb level between hematological values, hepatic and renal biochemical parameters, and discuss the potential of using hair as a bioindicator in the monitoring of lead toxicity in Asiatic Black Bears. This study included 32 valid blood samples (16 from free-ranging bears and 16 from captive bears) and 31 valid hair samples (15 from free-ranging bears and 16 from captive bears). All samples were submitted for ICP-MS analysis to determine their Pb concentration. Median of blood Pb level and hair Pb level was 4.1 μg/dL and 0.44 ppm, respectively. The upper limit of reference interval for blood Pb and hair Pb level derived from healthy individuals were 9.39 μg/dL and 1.46 ppm. Significant positive correlation was found between blood Pb level and MCV (ρ= 0.6279, p < 0.001). On the other hand, blood Pb level had significant negative correlations with ALT (ρ= -0.5124, p < 0.01) and AST (ρ= -0.5201, p < 0.01). On the contrast, significance for hair Pb level and both hematological and biochemical parameters was not evidenced. A weak but significant positive correlation (ρ= 0.3929, p < 0.05) between blood Pb and hair Pb level and a 60% sensitivity with 40% false negative for hair to predict blood Pb level indicated that it would be better to combine hair Pb with blood Pb to evaluate Pb exposure status rather than using hair alone.

並列關鍵字

Asiatic black bears (Ursus thibetanus) ； lead ； blood ； hair ； reference interval

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