食品中全氟碳化合物濃度調查

Abstract

全氟碳化合物為新興持久性有機汙染物，由於其穩定的物化性質，以及具有抗油、抗水之特性，使得這一類的化合物用途廣泛。然而因為其具有持久性與累積性，目前在許多環境基質、生物體以及人體中都可以偵測到各類全氟碳化合物的存在。全氟碳化合物對於生物體具有肝毒性，長期暴露可能對於生物體之生長發育造成影響。人體可經由飲用水、灰塵與食物攝取暴露到全氟碳化合物，其中飲食更被認為是最重要的暴露途徑之一。 本研究分析十四種食物中（稻米、麵粉、豬肉、牛肉、雞肉、豬肝、鮭魚、草魚、蝦子、牡蠣、蛤蠣、透抽、雞蛋、牛奶）所含的八種全氟碳化合物（全氟羧酸類：全氟己酸(PFHxA)、全氟辛烷酸(PFOA)、全氟壬酸(PFNA)、全氟癸酸(PFDA)、全氟十一烷酸(PFUnDA)、全氟十二烷酸(PFDoDA)，以及全氟磺酸類：全氟己烷磺酸(PFHxS)、全氟辛烷磺酸(PFOS)），以了解各類食物中全氟碳化合物的濃度分佈概況，並利用農委會每人每日糧食攝取量之統計資料，推估每日可能由食物攝取暴露到全氟碳化合物的量。 各類食物從台北市兩傳統市場隨機購買後進行分析。固體樣本在初步均質後，取一克置於均質管中，並加入同位素標定內標準品以及氫氧化鉀甲醇溶液後，均質兩分鐘並消化兩個小時，而後再離心30分鐘，並取出5 mL上清液以500 mL milli-Q water稀釋，調整pH值至3.5；稀釋液以0.45 μm玻璃纖維濾紙過濾後，使用Atlantic HLB disk搭配自動化固相萃取器進行萃取。牛奶樣本則取25 mL，加入同位素標定內標準品，並加入450 mL的0.5 N氫氧化鉀水溶液消化，再經過調整pH值至3.5以及過濾後，同樣以Atlantic HLB disk搭配自動化固相萃取器進行萃取。萃取後的樣本皆再經過濃縮至1 mL後，以極致液相層析/串聯式質譜儀使用電灑游離負離子模式(ESI-)與選擇性反應偵測模式(SRM)分析待測物。 結果顯示在大部分的食物樣本中都可以分析到五種全氟羧酸類碳化合物，包括PFHxA、PFOA、PFDA、PFUnDA以及PFDoDA。各類全氟碳化合物在植物樣本稻米和麵粉中的濃度（幾何平均濃度範圍分別為0.04~8.90 ng/g和0.02~8.84 ng/g）低於肉類和海鮮類樣本中所含的濃度（幾何平均濃度範圍分別為0.08~12.1 ng/g和0.04~12.3 ng/g）；海鮮類食物中所含的八種全氟碳化合物濃度又高於肉類樣本中所含的量。在所有樣本中，豬肝樣本所含八種全氟碳化合物的濃度有最高總量（幾何平均濃度為52.8 ng/g）。以化合物來看，PFOA、PFDA以及PFDoDA為最常被偵測到，且濃度有較高傾向的全氟碳化合物，三種化合物在各食物樣本中所含的幾何平均濃度範圍分別為1.44~12.1 ng/g、0.84~20.9 ng/g以及1.19~15.1 ng/g；其次較易被偵測到的化合物為PFUnDA以及PFHxA，幾何平均濃度分別為0.06~2.10 ng/g和0.03~1.33 ng/g；而其餘三個化合物PFNA、PFHxS以及PFOS在大多數的樣本中則是沒有被偵測到的情形。PFOA在食物中廣泛被測得且具有相對較高濃度之原因，可能與PFOA相關前驅物質仍持續使用於許多產品有關。除此之外，從結果也可以發現，烷基長度越長之全氟碳化合物的確在食物中有較高的累積情形。 本研究分析了8種全氟碳化合物在14樣不同食物當中的情形，可以了解目前臺灣全氟碳化合物於食物當中濃度的分布概況，並可提供未來在進行全氟碳化合物相關的暴露評估或風險評估之重要依據。

Perfluorochemicals (PFCs) are emerging persistent pollutants. They are widely used in various products because of their stability and unique physicochemical properties. However, their persistence and bioaccumulation have resulted in the spread of these compounds in the environment, organisms and humans. PFCs have caused concerns because they are hepatoxic and are also potentially harmful to the development and reproduction of organisms. Human would expose to PFCs via drinking water, food intake and dust; food ingestion may be the primarily exposure route. This study measured eight PFCs (perfluorohexanoic acid, PFHxA)、(perfluorooctanoic acid, PFOA)、(perfluorononanoic acid, PFNA)、(perfluorodecanoic acid, PFDA)、(perfluoroundecanoic acid, PFUnDA)、(perfluorododecanoic acid, PFDoDA)、(perfluorohexane sulfonate, PFHxS)and (perfluorooctane sulfonate, PFOS) in 14 different types of foods, which were randomly purchased from two traditional markets in Taipei City, including rice, flour, pork, beef, chicken, salmon (sea fish), Grass carp (freshwater fish), oysters, shrimp, clams, squid, pig liver, chicken eggs, and whole milk. Combining the levels of PFCs in foods we detected and the data from the Council of Agriculture of Taiwan, we evaluated the PFCs exposure from food intake. Solid samples were homogenized and one-gram wet samples were further homogenized with 10 mL of 0.5 N potassium hydroxide (KOH) in methanol for 2 minutes and then were sonicated for 2 hours. After centrifugation, 5 mL supernatant of the samples were diluted with 500-mL Milli-Q water then were adjusted to pH 3.5 by formic acid. 25-mL whole milk samples were added with six stable isotope-labeled standards and then were mixed with 450 mL 0.5 N potassium hydroxide (KOH) in Milli-Q water for digestion then adjusted to pH 3.5 by formic acid. All samples were filtrated through 90-mm glass filter before undergoing solid-phase extractions. Digested samples after the dilution were further extracted with Atlantic HLB disk by automated solid-phase extraction. The 20-mL methanol containing 0.1% ammonium hydroxide (v/v) eluents were concentrated by a SpeedVac concentrator and finally were analyzed by ultra-high performance liquid chromatography/tandem mass spectrometry at negative electrospray ionization. Five PFCs (PFHxA、PFOA、PFDA、PFUnDA、PFDoDA) can be detected in most samples. Two types of cereal samples, rice and flour, with geometric means of PFCs ranged from 0.04 to 8.90 ng/g and 0.02 to 8.84 ng/g, respectively, contained relatively lower concentrations of PFCs than those in meat and sea food samples, with the geometric means ranged from 0.08 to 12.1 ng/g and from 0.04 to 12.3 ng/g, respectively). The concentrations of PFCs were often higher in sea food than in meat samples. The highest concentrations were found in pork liver (the geometric mean of the total eight PFC concentrations were 52.8 ng/g.) PFOA (geometric mean 1.44-12.1 ng/g), PFDA (geometric mean 0.84-20.9 ng/g), and PFDoDA (geometric mean 1.19-15.1 ng/g) were the most commonly detected compounds and the levels were mostly higher than others. PFUnDA (geometric mean 0.06-2.10 ng/g) and PFHxA (geometric mean 0.03-1.33 ng/g) were also detected frequently. However, PFNA、PFHxS and PFOS were not detected in most food samples. The higher concentrations of PFOA were than others would relate to the continuous use of the precursors in several products. Furthermore, PFCs with longer alkyl chains were often found in higher levels in most samples. In this study, we detected eight PFCs in different types of foods, and provide invaluable information on the concentrations of PFCs in foods, which are essential for the exposure of PFCs from diet.