Distribution Of Perfluorooctanoic Acid Research Articles

Perfluorooctanoic acid in the sediment matrices of Arctic fjords, Svalbard

Per- and polyfluorinated chemicals (PFASs) are very toxic industrial compounds, and fewer studies have been conducted on their presence in the sedimentary environment of the polar region. The present study is a preliminary assessment of the concentration and distribution of PFOA (Perfluorooctanoic acid) in selected fjord systems of the Svalbard archipelago, Norwegian Arctic. The ∑PFOA observed for Smeerenburgfjorden, Krossfjorden, Kongsfjorden Hotmiltonbuktafjorden, Raudfjorden and Magdalenefjorden were 1.28 ng/g, 0.14 ng/g, 0.68 ng/g, 6.54 ng/g, 0.41 ng/g and BDL respectively. Of the twenty-three fjord samples studied, the sediments from Hotmiltonbuktafjorden exhibited the presence of a higher concentration of PFOA in the sediment matrices. More studies are needed to understand their fate in the sedimentary environment with respect to the physio-chemical properties of the sediments.

Binding of serum albumin to perfluorooctanoic acid reduced cytotoxicity

With the ubiquitous applications of perfluorinated compounds such as perfluorooctanoic acid (PFOA) in industrial and commercial products, the toxicity of these engineered materials in environmental and public health is received growing attention. As a typical organic pollutant, PFOA has been extensively found in wildlife and human bodies, and can preferentially bind to serum albumin in vivo. However, the importance of protein–PFOA interactions on the cytotoxicity of PFOA could not be stressed enough. In this study, we used both experimental and theoretical approaches, to investigate the interactions of PFOA with bovine serum albumin (BSA, the most abundant protein in blood). It was found that PFOA could mainly interact with Sudlow site I of BSA to form BSA-PFOA complex, in which van der Waals forces and hydrogen bonds played dominant roles. Moreover, the strong binding of BSA could greatly alter the cellular uptake and distribution of PFOA in human endothelial cells, and result in the decreases of reactive oxygen species formation and cytotoxicity for these BSA-coated PFOA. Consistently, the addition of fetal bovine serum into cell culture medium also significantly mitigated PFOA-induced cytotoxicity, which was attributed to the extracellular complexation between PFOA and serum proteins. Altogether, our study demonstrates that the binding of serum albumin to PFOA could reduce its toxicity by affecting the cellular responses.

Sorption and partitioning of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) onto sediments of Diep and Plankenburg river systems Western Cape, South Africa

Partitioning behaviour of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in sediments obtained from river systems were investigated in this study. The partitioning coefficient (log K OC ) and distribution coefficient (log K D ) of PFOA and PFOS between sediments and the aqueous solution were estimated from the sorption data. Levels of PFOA and PFOS in the sediment samples ranged between 30.01–191.96 ng/g dw and 0.50–248.14 ng/g dw, respectively. The kinetic study showed that the time required for equilibrium was <400 min for the compounds. Sediment samples SS-C provided the highest sorption capacities (0.11 and 0.13 mg/g) for both PFOA and PFOS. Sorption studies revealed that the removal kinetics fitted well into the Elovich rate equation (R 2 = 0 . 98 and 0.92) followed by the pseudo-second-order kinetic model (R 2 = 0 . 91 and 0.89) for PFOA and PFOS, respectively. Mean values for the partitioning coefficient (log K OC ) in the river systems were 1.04 ± 0.26 and 1.85 ± 0.65 (cm 3 /g) for PFOA and PFOS respectively. Partitioning coefficient (log K OC ) significantly (p < 0.05) increased over time. This study represents the first report on partitioning and distribution of PFOA and PFOS in sub-Sahara Africa, which provide data and a scientific base to understand the fate and sorption of PFOA and PFOS in an aquatic system. The findings showed that lower pH values and increasing ionic strength favours sorption and partitioning of perfluoroalkyl substances (PFAS) in aqueous solution onto sediments; hence, plays an important role in their availability in water. Presence of PFAS in the aquatic system sediments is a potential risk to organisms. • Maximum concentration of PFOA and PFOS in the sediments from the river systems were 191.9 and 248.1 ng/g dw, respectively. • Mean values for the log K OC in the river systems were 1.04 ± 0.2 and 1.85 ± 0.6 (cm 3 /g) for PFOA and PFOS respectively. • Sorption kinetics for PFOA and PFOS fitted well into the elovich rate equation for the investigated sediment samples. • Lower solution pH and increase in Ca 2 + concentration favours the sorption and partitioning behaviour of PFOA and PFOS.

Occurrence and distribution of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in natural forest soils: A nationwide study in China

Forests serve as the primary reservoir for organic carbon above ground. Previous studies have revealed that forest soils play key roles in the retention of persistent organic pollutants (POPs). In this study, the occurrence and distribution of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were investigated in 54 surface soil samples from 28 natural forested mountain sites across China between 2012 and 2013. The detection frequency of PFOA (70%) was significantly higher than that of PFOS (4%). PFOA levels ranged from <0.9 to 9.0 pg·g−1 dry weight (dw). Levels of PFOA and PFOS in forest soils were significantly lower than those in agricultural, urban and rural areas in China. Relatively high levels of PFOA were detected in Hubei Province (Jiugong Mountain, average: 3.4 pg·g−1 dw) and Jiangxi Province (Wugong Mountain, average: 4.4 pg·g−1 dw), where many domestic fluoropolymer manufacturers are located. PFOS was only detected in these two provinces (2.2 pg·g−1 dw and 2.7 pg·g−1 dw, respectively). From most of the surveyed mountains, the concentrations of PFOA increased with elevation. The lower temperature and greater precipitation probably made PFOA and its precursors available to transport and degrade more readily at higher altitude sites. A relatively higher level (1.9 ± 1.3 pg·g−1 dw) of PFOA was found in the broadleaf evergreen forest area, mainly due to the high industrial emissions, plant retention, and precipitation rate in this area. Source were the dominant factor controlling the spatial distribution of PFOA in natural forest soils in China.

PBPK modeling for PFOS and PFOA: Validation with human experimental data

In recent years, because of the potential human toxicity, concern on perfluoroalkyl substances (PFASs) has increased notably with special attention to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Unfortunately, there is currently an important knowledge gap on the burdens of these chemicals in most human tissues, as the reported studies have been mainly focused on plasma. In order to overcome these limitations, the use of physiologically-based pharmacokinetic (PBPK) models has been extended. The present study was aimed at testing an existing PBPK model for their predictability of PFOS and PFOA in a new case-study, and also to adapt it to estimate the PFAS content in human tissue compartments. Model validation was conducted by means of PFOA and PFOS concentrations in food and human drinking water from Tarragona County (Catalonia, Spain), and being the predicted results compared with those experimentally found in human tissues (blood, liver, kidney, liver and brain) of subjects from the same area of study. The use of human-derived partition coefficient (Pk) data was proven as more suitable for application to this PBPK model than rat-based Pk values. However, the uncertainty and variability of the data are still too high to get conclusive results. Consequently, further efforts should be carried out to reduce parametric uncertainty of PBPK models. More specifically, a deeper knowledge on the distribution of PFOA and PFOS within the human body should be obtained by enlarging the number of biological monitoring studies on PFASs.

Subcellular Distribution and Protein Binding of Perfluorooctanoic Acid in Rat Liver and Kidney

Perfluorooctanoic acid (PFOA) is an organic fluorochemical, and its elimination in rats is markedly sex-dependent. Liver and kidney are two primary tissues of distribution of PFOA in rats. In this study, the subcellular distribution of PFOA in male and female rat liver and kidney was examined. The results demonstrated that PFOA content in the liver cytosol of the female rat was significantly higher (49 ± 6% of total radioactive residues, TRR) than in the male liver (26 ± 5% TRR), whereas PFOA distribution in the heavier subcellular fractions, especially the nuclei and cell debris fraction, was marginally higher in male rat liver. In rat kidney, more than 70% of PFOA was distributed in the cytosolic fraction, with no significant difference between sexes. The degree of protein binding of PFOA in rat liver and kidney cytosol was analyzed by two different chromatographic methods. The percentage of protein-bound PFOA in the liver cytosol was found to be approximately 55% in both male and female rats. In contrast, significantly more PFOA was bound to cytosolic proteins in the kidney of male rats (42 ± 6% TRR) than in females (17 ± 5% TRR). Ligand blotting analysis revealed that multiple proteins from the liver cytosol, nuclei, and mitochondria fractions were capable of specific binding to PFOA.