Department of Applied Environmental Science (ITM), Stockholm University, 106 91, Stockholm, Sweden,
Environ Sci Pollut Res Int. 2013 Nov;20(11):7959-69. doi: 10.1007/s11356-013-1722-x. Epub 2013 May 4.
Beef and dairy products may be important vectors of human exposure to perfluoroalkyl acids (PFAAs), but the understanding of how PFAAs are accumulated and transferred through agricultural food chains is very limited. Here, the bioaccumulation of PFAAs in dairy cows receiving naturally contaminated feed and drinking water was investigated by conducting a mass balance of PFAAs for a herd of dairy cows in a barn on a typical Swedish dairy farm. It was assumed that the cows were able to reach steady state with their dietary intake of PFAAs. Perfluorooctane sulfonic acid (PFOS) and perfluoroalkyl carboxylic acids (PFCAs) with 8 to 12 carbons were detected in cow tissue samples (liver, muscle, and blood) at concentrations up to 130 ng kg(-1). Mass balance calculations demonstrated an agreement between total intake and excretion within a factor of 1.5 and consumption of silage was identified as the dominant intake pathway for all PFAAs. Biomagnification factors (BMFs) were highly tissue and homologue specific. While BMFs of PFOS and PFCAs with 9 and 10 fluorinated carbons in liver ranged from 10 to 20, perfluorooctanoic acid (PFOA) was not biomagnified (BMF<1) in any of the investigated tissues. Biotransfer factors (BTFs; defined as the concentration in tissue divided by the total daily intake) were calculated for muscle and milk. Log BTFs ranged from -1.95 to -1.15 day kg(-1) with the highest BTF observed for PFOS in muscle. Overall, the results of this study suggest that long-chain PFAAs have a relatively high potential for transfer to milk and beef from the diet of dairy cows. However, a low input of PFAAs to terrestrial systems via atmospheric deposition and low bioavailability of PFAAs in soil limits the amount of PFAAs that enter terrestrial agricultural food chains in background contaminated environments and makes this pathway less important than aquatic exposure pathways. The BTFs estimated here provide a useful tool for predicting human exposure to PFAAs via milk and beef under different contamination scenarios.
牛肉和奶制品可能是人类接触全氟烷基酸 (PFAAs) 的重要载体，但人们对 PFAAs 如何通过农业食物链积累和转移知之甚少。在这里，通过对瑞典典型奶牛场牛舍中一群奶牛的 PFAAs 进行质量平衡，研究了摄入受污染饲料和饮用水的奶牛对 PFAAs 的生物积累情况。假设奶牛通过饮食摄入 PFAAs 能够达到稳定状态。在奶牛组织样本（肝脏、肌肉和血液）中检测到全氟辛烷磺酸 (PFOS) 和 8 到 12 个碳原子的全氟烷基羧酸 (PFCAs)，浓度高达 130 ng kg(-1)。质量平衡计算表明，总摄入量和排泄量之间的差异在 1.5 倍以内，青贮饲料的消耗被确定为所有 PFAAs 的主要摄入途径。生物放大因子 (BMF) 高度组织和同系物特异性。虽然肝脏中 9 个和 10 个氟化碳原子的 PFOS 和 PFCAs 的 BMF 范围在 10 到 20 之间，但在任何研究的组织中，全氟辛酸 (PFOA) 都没有被生物放大 (BMF<1)。生物转移因子 (BTF；定义为组织中的浓度除以每日总摄入量) 被计算用于肌肉和牛奶。肌肉中 PFOS 的对数 BTF 范围为-1.95 至-1.15 天 kg(-1)，BTF 最高。总的来说，这项研究的结果表明，长链 PFAAs 从奶牛的饮食中向牛奶和牛肉转移的潜力相对较高。然而，大气沉积向陆地系统输入的 PFAAs 较少，以及土壤中 PFAAs 的生物利用度较低，限制了背景污染环境中进入陆地农业食物链的 PFAAs 数量，使这一途径不如水生暴露途径重要。这里估计的 BTF 为预测不同污染情况下人类通过牛奶和牛肉接触 PFAAs 提供了有用的工具。
