Bioaccumulation of perfluoroalkyl acids in dairy cows in a naturally contaminated environment
Bioaccumulation of perfluoroalkyl acids in dairy cows in a naturally contaminated environment
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DOI：
10.1007/s11356-013-1722-x
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发表时间：
2013-05
影响因子：
5.8
通讯作者：
R. Vestergren;F. Orata;U. Berger;I. Cousins
中科院分区：
文献类型：
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作者：
R. Vestergren;F. Orata;U. Berger;I. Cousins
牛肉和乳制品可能是人类接触全氟烷基酸(PFAA)的重要媒介，但对PFAA如何通过农业食物链积累和转移的了解非常有限。在这里，通过对典型瑞典奶牛场牛舍中的一群奶牛进行PFAA的质量平衡，研究了PFAA在接受自然污染的饲料和饮用水的奶牛体内的生物积累。据推测，奶牛能够通过饮食摄入PFAA达到稳定状态。在奶牛组织样本(肝脏、肌肉和血液)中检测到的全氟辛烷磺酸(PFOS)和全氟烷基羧酸(PFCA)含有8到12个碳，浓度高达130ngkg−1。质量平衡计算表明，总摄入量和排泄量在1.5倍以内，青贮料消费是所有PFAA的主要摄取途径。生物放大因子(BMF)具有高度的组织和同源特异性。全氟辛酸和含9个和10个氟化碳的全氟辛酸和全氟辛酸在肝脏中的BMF在10到20之间，而全氟辛酸( <； 1)在任何被调查的组织中都没有被生物放大。计算肌肉和牛奶的生物转移因子(BTF；定义为组织中的浓度除以每天的总摄入量)。对数全氟辛烷磺酸的BTF值在−1.95到−1.15之间，每天每千克−1，肌肉中全氟辛烷磺酸的BTF值最高。总体而言，这项研究的结果表明，长链PFAA有相对较高的潜力从奶牛的饮食转移到牛奶和牛肉。然而，通过大气沉积向陆地系统输入的PFAA较少，土壤中PFAA的生物有效性较低，限制了在背景污染环境中进入陆地农业食物链的PFAA数量，使这一途径不如水生暴露途径那么重要。这里估计的BTF为预测人类在不同污染情况下通过牛奶和牛肉接触PFAA提供了一个有用的工具。
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−1with 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.