Binding of perfluorinated fatty acids to serum proteins

Fish consumption as a source of human exposure to perfluorinated alkyl substances in Sweden - analysis of edible fish from Lake Vättern and the Baltic Sea

Perfluorinated alkyl substances (PFAS) were analyzed in muscle tissue from edible fish species caught in the second largest freshwater lake in Sweden, Lake Vättern (LV), and in the brackish water Baltic Sea (BS). Perfluorooctane sulfonate (PFOS) was the predominant PFAS found. PFOS concentrations were higher in LV (medians 2.9-12 ng g(-1) fresh weight) than in BS fish (medians 1.0-2.5 ng g(-1) fresh weight). Moreover, LV fish was more contaminated with several other PFAS than BS fish. This may be due to anthropogenic discharges from urban areas around LV. The PFAS pattern differed between LV and BS fish, indicating different sources of contamination for the two study areas. Human exposure to PFOS via fish intake was calculated for three study groups, based on consumption data from literature. The groups consisted of individuals that reported moderate or high consumption of BS fish or high consumption of LV fish, respectively. The results showed that PFOS intake strongly depended on individual fish consumption as well as the fish catchment area. Median PFOS intakes were estimated to 0.15 and 0.62 ng kg(-1) body weight (bw) d(-1) for the consumers of moderate and high amounts of BS fish, respectively. For the group with high consumption of LV fish a median PFOS intake of 2.7 ng kg(-1)bw d(-1) was calculated. Fish consumption varied considerably within the consumer groups, with maximum PFOS intakes of 4.5 (BS fish) or 9.6 ng kg(-1)bw d(-1) (LV fish). Comparison of our results with literature data on PFOS intake from food suggests that fish from contaminated areas may be a significant source of dietary PFOS exposure.

Perfluorooctane sulfonate (PFOS) toxicity in domestic chicken (Gallus gallus domesticus) embryos in the absence of effects on peroxisome proliferator activated receptor alpha (PPARalpha)-regulated genes

Perfluorooctane sulfonate (PFOS) is a widely distributed industrial compound that has been detected in the eggs of various wild avian species. Laboratory studies have indicated that PFOS is embryotoxic to domestic chickens (Gallus gallus domesticus), but the mechanisms of toxicity in the developing avian embryo remain unknown. We recently demonstrated that PFOS acts as a peroxisome proliferator by causing increased expression of peroxisome proliferator activated receptor alpha (PPARalpha)-regulated genes in cultured primary chicken embryo hepatocytes. The present study examined whether PPARalpha-regulated genes were dose-dependently affected in chicken embryos exposed in ovo to PFOS. White leghorn chicken eggs were injected with 0.1, 5.0 or 100.0 microg PFOS/g egg into the air cell prior to incubation. Embryos were incubated until pipping, after which the expression of PPARalpha-regulated genes was measured in the liver tissue of surviving embryos using real-time reverse transcription polymerase chain reaction. A dose-dependent decrease in embryo pippability was observed with an LD50 of 93 microg/g (3.54 microg/g-672,910 microg/g, 95% confidence interval). Hepatic PFOS concentrations increased concomitantly with dose. The PPARalpha-regulated genes measured were peroxisomal acyl CoA oxidase, bifunctional enzyme, liver fatty acid binding protein and peroxisomal 3-ketoacyl thiolase. PFOS exposure via egg injection prior to incubation did not affect the transcriptional activity of any of the assayed PPARalpha-regulated genes at any of the doses examined in day 21 chicken embryos.

Total body burden and tissue distribution of polyfluorinated compounds in harbor seals (Phoca vitulina) from the German Bight

Total body burden and tissue distribution of polyfluorinated compounds (PFCs) were investigated in harbor seals (Phoca vitulina) from the German Bight in 2007. A total number of 18 individual PFCs from the following groups could be quantified in the different tissues: perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs) and their precursors perfluorinated sulfinates (PFSiAs), perfluorinated sulfonamides, and sulfonamido ethanols. Perfluorooctanesulfonate (PFOS) was the predominant compound in all measured seal tissues (up to 1665 ng g(-1) wet weight in liver tissue). The dominant PFCAs were perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), but their concentrations were much lower compared to PFOS. The mean whole body burden in harbor seals of all detected PFCs was estimated to be 2665+/-1207 microg absolute. The major amount of the total PFCs burden in the bodies was in blood (38%) and liver (36%), followed by muscle (13%), lung (8%), kidney (2%), blubber (2%), heart (1%), brain (1%), thymus (<0.01%) and thyroid (<0.01%). These data suggest large differences in body burden and accumulation pattern of PFCs in marine mammals.

Time trends and the influence of age and gender on serum concentrations of perfluorinated compounds in archived human samples

Fifty-seven pooled archived human serum samples were analyzed to assess the time trends as well as influence of age and gender on selected perfluorinated compounds (PFCs) in Norwegian residents. The study comprised determinations of 19 PFCs in serum samples pooled according to year of collection from 28 years in the period 1976 to 2007. A 9-fold increase in the serum concentrations of perfluorooctyl sulfonate, perfluorooctanoic acid, and perfluoroheptyl sulfonate was measured for men (40-50 years) from 1977 to the mid 1990s where the concentrations reached a plateau before starting to decrease around year 2000. A similar trend was also seen for perfluorohexyl sulfonate, perfluorononanoic acid, perfluorodecanoic acid, and perfluoroundecanoic acid, but no clear decline was observed for these PFCs in the recent years. No statistically significant difference was observed between the PFC levels in the male and female serum pools, though the statistical power is low due to few data points. For most PFCs, the concentrations in the human serum samples were found to increase with age in the pools from 2007, while the results for 1976, 1987, and 1998 were more varying. Several PFCs were significantly intercorrelated.

Computational approaches may underestimate pK(a) values of longer-chain perfluorinated carboxylic acids: Implications for assessing environmental and biological effects

Acidity constants were calculated using the semiempirical PM6 pK(a) estimation method for all C(2) through C(9) perfluoroalkyl carboxylate (PFCA) congeners and the straight-chain C(10) through C(13) isomers. According to the PM6 estimates, the linear congeners within each PFCA homologue group have the highest pK(a) values by up to 6 units depending on the degree of branching in the perfluoroalkyl chain. In general, the higher the degree of branching in the perfluoroalkyl chain within a homologue group, the lower the estimated pK(a) value. When the branching is closest to the terminal carboxylate group, the effect on the calculated pK(a) is greatest. Although the PM6 calculated pK(a) values agree well with previously reported estimates for selected linear PFCA congeners using the SPARC and COSMOtherm approaches, all computational approaches only show good agreement with reported experimental values for short chain PFCAs (C(2) through C(5)). Increasing divergences are observed between calculated and experimental results by up to several pK(a) units as the perfluoroalkyl chain length increases beyond C(5). The findings demonstrate a need for additional experimental pK(a) measurements for an expanded set of both linear and branched PFCA congeners to confirm previous experimental reports that are potentially in error, and upon which to calibrate existing computational methods and environmental, toxicological, and waste treatment method models.

Binding of PFOS to serum albumin and DNA: insight into the molecular toxicity of perfluorochemicals

Background

Health risk from exposure of perfluorochemicals (PFCs) to wildlife and human has been a subject of great interest for understanding their molecular mechanism of toxicity. Although much work has been done, the toxigenicity of PFCs remains largely unknown. In this work, the non-covalent interactions between perfluorooctane sulfonate (PFOS) and serum albumin (SA) and DNA were investigated under normal physiological conditions, aiming to elucidate the toxigenicity of PFCs.

Results

In equilibrium dialysis assay, the bindings of PFOS to SA correspond to the Langmuir isothermal model with two-step sequence model. The saturation binding number of PFOS was 45 per molecule of SA and 1 per three base-pairs of DNA, respectively. ITC results showed that all the interactions were spontaneous driven by entropy change. Static quenching of the fluorescence of SA was observed when interacting with PFOS, indicating PFOS bound Trp residue of SA. CD spectra of SA and DNA changed obviously in the presence of PFOS. At normal physiological conditions, 1.2 mmol/l PFOS reduces the binding ratio of Vitamin B₂ to SA by more than 30%.

Conclusion

The ion bond, van der Waals force and hydrophobic interaction contributed to PFOS binding to peptide chain of SA and to the groove bases of DNA duplex. The non-covalent interactions of PFOS with SA and DNA alter their secondary conformations, with the physiological function of SA to transport Vitamin B₂ being inhibited consequently. This work provides a useful experimental method for further studying the toxigenicity of PFCs.

Alterations of cytokines and MAPK signaling pathways are related to the immunotoxic effect of perfluorononanoic acid

Perfluorononanoate (PFNA), a perfluorinated alkyl acid containing nine carbon chains, has been detected in abiotic and biotic matrices worldwide. Although a few studies have reported toxic effects of PFNA, little information of the mechanism has been offered. In this study, the effects of PFNA exposure on thymus and the related mechanisms were investigated. Male rats were orally dosed with 0, 1, 3, or 5 mg PFNA/kg/day for 14 days. A significant decrease of body weight and thymus weight were observed in the rats receiving 3 or 5 mg PFNA/kg/day. Histopathological examination revealed dose-dependent increases in thymocyte apoptosis. Rats receiving 3 or 5 mg PFNA/kg/day exhibited increased interleukin (IL)-1 and decreased IL-2 concentrations in sera, whereas elevated IL-4 and cortisol levels only occurred in the highest dose group. Quantitative real-time PCR indicated that expression of peroxisome proliferator-activated receptor alpha (PPAR-alpha) was increased in the thymi of all dosed rats, and a similar trend occurred for PPAR-gamma in the two highest dose groups. The mRNA levels of c-Jun NH(2)-terminal kinase (JNK), nuclear factor-kappa B, p65 subunit, and inhibitory protein IkappaBalpha were unchanged; however, increased and decreased mRNA levels of p38 kinase were found in rats exposed to 3 or 5 mg PFNA/kg/day, respectively. Decreased Bcl-2 mRNA levels were observed in rats receiving 5 mg PFNA/kg/day. A significant increase in protein levels of phospho-JNK was found in all PFNA-treated rats. Phospho-p38 was significantly enhanced in 1 and 3 mg PFNA/kg/day groups, whereas phospho-IkappaBalpha remained consistent in all rats studied. Together, these data suggested that apart from the activation of PPARs, PFNA exposure in rats lead to the alteration of serum cytokines, which subsequently activated mitogen-activated protein kinase signaling pathways and potentially modulated the immune system. Additionally, increased serum cortisol and decreased expression of Bcl-2 in thymus likely contributed to the PFNA-induced thymocyte apoptosis.

Chronic effects of water-borne PFOS exposure on growth, survival and hepatotoxicity in zebrafish: a partial life-cycle test

Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and wildlife. The main aim of this study was to investigate the impact of long-term exposure to low concentrations of PFOS in zebrafish. Zebrafish fry (F(0), 14 d post-fertilization, dpf) were exposed via the water for 70 d to 0 (control), 10, 50 and 250 microg L(-1) PFOS, followed by a further 30 d to assess recovery in clean water. The effects on survival and growth parameters and liver histopathology were assessed. Although growth suppression (weight and length) was observed in fish treated with high concentrations PFOS during the exposure period, no mortality was observed throughout the 70 d experiment. Embryos and larvae (F(1)) derived from maternal exposure suffered malformation and mortality. Exposure to 50 and 250 microg L(-1) PFOS could inhibit the growth of the gonads (GSI) in the female zebrafish. Histopathological alterations, primary with lipid droplets accumulation, were most prominently seen in the liver of males and the changes were not reversible, even after the fish were allowed to recover for 30 d in clean water. The triiodothyronine (T(3)) levels were not significantly changed in any of the exposure groups. Hepatic vitellogenin (VTG) gene expression was significantly up-regulated in both male and female zebrafish, but the sex ratio was not altered. The overall results suggested that lower concentrations of PFOS in maternal exposure could result in offspring deformation and mortality.

Environmental and biological monitoring of persistent fluorinated compounds in Japan and their toxicities

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) comprise a class of per- and poly-fluorinated compounds that have been detected in the environment as well as in humans. The aim of this review is to summarize several monitoring studies in Japan and characterize the toxicokinetics of these compounds. We found that the levels of contamination by these compounds had unique patterns in Japan. The levels of PFOA in serum from inhabitants of the Kansai region were higher than those of other regions. The PFOA levels in air and water samples from the Kansai region were also relatively high. The estimated intakes from these routes partly explain the differences in the serum levels. The toxicokinetics of these compounds have been investigated. Serum samples from male participants had significantly higher geometric means for PFOS and PFOA compared to samples from female participants. This sex-related difference was partly simulated by menstrual blood loss. There are large interspecies differences in the excretion pathways of these compounds. The serum clearances of PFOA via urine were 300-1,000-fold lower in humans than in Wistar rats and Japanese macaques. On the other hand, the biliary excretion of these compounds was comparable in rats and humans, and the long half-lives in humans may be attributable to the low levels of urinary excretion and high biliary reabsorption rates. These findings suggest that qualitative differences in the excretion routes exist between humans and other species. For risk assessment of these compounds, further information regarding sources of exposure and their toxicokinetics is needed.

Depuration kinetics and tissue disposition of PFOA and PFOS in white leghorn chickens (Gallus gallus) administered by subcutaneous implantation

Elimination kinetics and tissue disposition of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in male chickens (Gallus gallus) was determined following exposure by subcutaneous implantation. Chickens were exposed to two levels of PFOA or PFOS for 4wk and then allowed to depurate for an additional 4wk. These exposures did not cause any statistically significant changes in body index, clinical biochemistry or histology among treatments relative to the controls (p>0.05), except that concentrations of total cholesterol and phospholipids were less in chickens exposed to PFOS. The elimination rate constant for PFOA (0.150+/-0.010d(-1)) was approximately six-fold greater than that of PFOS (0.023+/-0.004d(-1)). The greatest concentrations of PFOA and PFOS were found in kidney and liver, respectively. The organ to blood ratio of PFOS concentration was increased after the whole experiment, indicating the importance of organ partitioning of PFOS in elimination kinetics. The depuration half-life of PFOA (t(1/2)=4.6d) and PFOS (t(1/2)=125d) in chickens was calculated.

Fractionation and bioaccumulation of perfluorooctane sulfonate (PFOS) isomers in a Lake Ontario food web

The environmental ubiquity of perfluorooctane sulfonate (PFOS) is well-known. However, little is known about the environmental fate of individual PFOS isomers. In this study, we investigated the fractionation and the bioaccumulation of PFOS isomers in water, sediment and biota collected from Lake Ontario. A total of six isomers, three perfluoro-monomethyl-substituted compounds, and three perfluoro-dimethyl isomers in addition to the linear PFOS (L-PFOS) were detected in water, sediment and biota. L-PFOS represented a much higher proportion of total PFOS (sum of linear and branched) in all organisms (>88%) compared to its proportion in technical PFOS (77%). The predominance of L-PFOS suggests a reduced uptake of branched isomers, a more rapid elimination of the branched isomers and/or a selective retention of the L-PFOS. The PFOS isomer profile found in biota was very similar to sediment, even for pelagic organisms such as zooplankton, suggesting greater partitioning of L-PFOS to biota and to sediment. The bioaccumulation factor (BAF) for L-PFOS between lake trout (whole fish) and water was estimated to be 3.4 x 10(4) L/kg compared with 2.9 x 10(3) L/kg for the monomethyl-substituted group (MM-PFOS). The remarkable difference between L-PFOS and branched isomer BAFs is due to an enrichment of branched isomers in water. The trophic magnification factor of L-PFOS (4.6 +/- 1.0) was greater than MM-PFOS isomers (1.3 +/- 0.17 to 2.6 +/- 0.51), whereas dimethyl-PFOS showed no biomagnification. The results illustrate the important influence of molecular structure on the bioaccumulation of perfluoroalkyl sulfonates.

Mechanism of cytotoxic action of perfluorinated acids. I. alteration in plasma membrane potential and intracellular pH level

Perfluorinated (aliphatic) acids (PFAs) and congeners have many applications in various industrial fields and household for decades. Years later they have been detected in wildlife and this has spurred interest in environmental occurrence as well as influencing living organisms. PFAs were established as peroxisome proliferators and hepatocarcinogens. Amphipatic structure suggests that they may alter cell membrane potential (mbDeltaPsi) and/or induce changes in cytosolic pH (pHi). The aim of this study was to examine the correlation between changes of above parameters and PFAs structure (CF(6)-CF(12)) in human colon carcinoma HCT116 cells. mbDeltaPsi and pHi were measured by flow cytometry using fluorescence polarization of the plasma membrane probe 3,3'-dipentyloxacarbocyanine (DiOC(5)(3)) and fluorescein diacetate (FDA), respectively. Dose- and time-dependent manner analysis revealed relatively fast depolarization of plasma membrane and acidification of cytosol both positively correlated with fluorocarbon chain length. mbDeltaPsi depletion after 4 h of incubation reached 8.01% and 30.08% for 50 muM PFOA and 50 muM PFDoDA, respectively. Prolonged treatment (72 h) led to dramatic dissipation of membrane potential up to 21.65% and 51.29% and strong acidification to pHi level at 6.92 and 6.03 at the presence of above compounds, respectively. The data demonstrate that PFAs can alter plasma membrane protonotrophy with the mode dependent on the compound hydrophobicity.

Cooking decreases observed perfluorinated compound concentrations in fish

Dietary intake is a major route of exposure to perfluorinated compounds (PFCs). Although fish and seafood contribute significantly to total dietary exposure to these compounds, there is uncertainty with respect to the effect of cooking on PFC concentrations in these foods. Eighteen fish species purchased from markets in Toronto, Mississauga, and Ottawa, Canada were analyzed for perfluorooctanesulfonamide (PFOSAs)-based fluorochemicals and perfluorinated acids (PFAs) in raw and cooked (baked, boiled, fried) samples. Of 17 analytes, perfluorooctanesulfonic acid (PFOS) was detected most frequently; concentrations ranged from 0.21 to 1.68 ng/g ww in raw and cooked samples. PFOSAs were detected only in scallops at concentrations ranging from 0.20 ng/g ww to 0.76 ng/g ww. Total concentrations of PFAs in samples were 0.21 to 9.20 ng/g ww, respectively, consistent with previous studies. All cooking methods reduced PFA concentrations. Baking appeared to be the most effective cooking method; after baking samples for 15 min at 163 C (325 degrees F), PFAs were not detected in any of the samples. The margin of exposures (MOE) between the toxicological points of reference and the dietary intake of perfluorocarboxylates (PFCAs) and PFOS in fish and seafood muscle tissue were greater than 4 orders of magnitude. This indicates that reducing consumption of fish muscle tissue is not warranted on the basis of PFC exposure concerns at the reported levels of contamination, even for high fish consuming populations.

Comparing single and repeated dosimetry data for perfluorooctane sulfonate in rats

Perfluorooctane sulfonate (PFOS) is a member of a class of perfluorinated chemicals used in a variety of consumer and industrial applications because of their oleophobic and hydrophobic properties. It has been shown to cause toxicity in adult and developing laboratory animals. Because PFOS has also been shown to be widely distributed throughout the environment, there have been concerns about its potential health risk to humans. Limited pharmacokinetic data for PFOS are available in rodents and humans, while epidemiological studies of workers and extensive toxicity studies in rodents have been performed. The existing pharmacokinetic and toxicity database in rodents can be useful in the cross-species extrapolations needed to evaluate and interpret internal dosimetry in humans. A mathematical model that describes the disposition of PFOS in adult rats following intravenous, oral, and chronic dietary exposures was developed to gain a better understanding of the pharmacokinetics of PFOS and to determine whether single-dose kinetics are predictive of repeated-dose kinetics. In order to characterize existing time-course data, time-dependent and concentration-dependent changes in the pharmacokinetic parameters for urinary and biliary clearance and liver distribution were needed. Whether these time-dependent changes represent inconsistencies across experiments, effects of aging in the rats, or chemically induced changes in pharmacokinetics remains to be determined.

Acute enhancement of synaptic transmission and chronic inhibition of synaptogenesis induced by perfluorooctane sulfonate through mediation of voltage-dependent calcium channel

Perfluorooctane sulfonate (PFOS) is a persistent and bioaccumulative pollutant ubiquitous in wildlife and humans. Although the distribution and fate of PFOS have been widely studied, its potential neurotoxicity remains largely unknown. In the present study, the acute and chronic effects of PFOS on the development and synaptic transmission of hippocampal neurons was examined. Perfusion with PFOS markedly increased the frequency of miniature postsynaptic currents (mPSCs) and slightly elevated the amplitude of mPSCs in cultured hippocampal neurons. Perfusion with PFOS also increased the amplitude of field excitatory postsynaptic potentials (fEPSPs) recorded in the CA1 region of hippocampal slices. Both of these effects were largely blocked by the L-type Ca2+ channel antagonist nifedipine. Further studies showed that PFOS enhanced inward Ca2+ currents and increased intracellular Ca2+ in cultured neurons; these effects were also substantially inhibited by nifedipine. Moreover, prolonged treatment with PFOS moderately inhibited neurite growth and dramatically suppressed synaptogenesis in cultured neurons in a nifedipine-sensitive manner. Thus, through enhancement of Ca2+ channels, PFOS may exhibit both acute excitotoxic effects on synaptic function and chronically inhibit synaptogenesis in the brain.

Transcriptional effects of PFOS in isolated hepatocytes from Atlantic salmon Salmo salar L

The main aim of the current in vitro experiment was to search for makers for PFOS exposure in isolated hepatocytes from Atlantic salmon Salmo salar, based on genes responding to PFOS exposure in other animals. Primary cell cultures of hepatocytes were exposed to four concentrations of PFOS (2.1-6.2-15.1-25.0 mg/L) for 24 and 48 h and the transcriptional levels of 12 genes encoding proteins known to respond to PFOS were quantified with real-time RT-PCR. The 12 examined genes were caspase 3B (apoptosis), GSH-Px and HSP70 (cellular stress), CYP1A, CYP3A, GST and UGT (P450 and phase II enzymes), acyl-CoA oxidase, PPARalpha, PPARbeta and PPARgamma (lipid metabolism) and Na(+)-K(+)-ATPase (ion regulation). Most of the studied genes responded in a dose-dependent manner to PFOS exposure, although the transcriptional differences in general where small with regard to fold change. Our results clearly suggest that PFOS exposure enhanced cellular stress in the examined cells, even though the exact mechanisms behind this stress remain unknown. The results from this in vitro experiment showed that genes known to be affected by PFOS exposure in other species also were induced in hepatocytes of Atlantic salmon, giving us the rationale to expand to testing the actual in vivo magnitude of effect in Atlantic salmon exposed to PFOS at doses usually seen in nature/diets.

Perfluorinated compounds in human milk from Massachusetts, U.S.A

Perfluorinated compounds (PFCs), notably perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been reported in human blood. Furthermore, the occurrence of PFCs in the blood of newborn babies, coupled with the need to study the potential association of PFC exposure with birth outcomes in neonates, suggests the need for determining the sources and magnitude of exposure in infants. In this study, nine PFCs were measured in 45 human breast milk samples collected in 2004 from Massachusetts, U.S.A. PFOS and PFOA were the predominant PFCs found at mean concentrations of 131 and 43.8 pg/mL, respectively. Comparison of the ratio of PFOS to PFOA in human milk with the ratios published for human serum from the U.S. female population suggested preferential partitioning of PFOA to milk. Concentrations of PFOA were significantly higher in the milk of mothers nursing for the first time (n = 34) than in the milk of mothers who have previously nursed (n = 8). Based on the estimated body weight and milk intake, the average and highest daily intakes of total PFCs by infants were 23.5 and 87.1 ng/kg bw, respectively. We found that the daily ingestion rates of PFOS and PFOA did not exceed the tolerable daily intake recommended by the U.K. Food Standards Agency. This is the first study to measure the occurrence of PFCs in human milk from the U.S.A.

Are PFCAs bioaccumulative? A critical review and comparison with regulatory criteria and persistent lipophilic compounds

Perfluorinated acids, including perfluorinated carboxylates (PFCAs), and perfluorinated sulfonates (PFASs), are environmentally persistent and have been detected in a variety of wildlife across the globe. The most commonly detected PFAS, perfluorooctane sulfonate (PFOS), has been classified as a persistent and bioaccumulative substance. Similarities in chemical structure and environmental behavior of PFOS and the PFCAs that have been detected in wildlife have generated concerns about the bioaccumulation potential of PFCAs. Differences between partitioning behavior of perfluorinated acids and persistent lipophilic compounds complicate the understanding of PFCA bioaccumulation and the subsequent classification of the bioaccumulation potential of PFCAs according to existing regulatory criteria. Based on available research on the bioaccumulation of perfluorinated acids, five key points are highlighted in this review: (1) bioconcentration and bioaccumulation of perfluorinated acids are directly related to the length of each compound's fluorinated carbon chain; (2) PFASs are more bioaccumulative than PFCAs of the same fluorinated carbon chain length; (3) PFCAs with seven fluorinated carbons or less (perfluorooctanoate (PFO) and shorter PFCAs) are not considered bioaccumulative according to the range of promulgated bioaccumulation,"B", regulatory criteria of 1000-5000 L/kg; (4) PFCAs with seven fluorinated carbons or less have low biomagnification potential in food webs, and (5) more research is necessary to fully characterize the bioaccumulation potential of PFCAs with longer fluorinated carbon chains (>7 fluorinated carbons), as PFCAs with longer fluorinated carbon chains may exhibit partitioning behavior similar to or greater than PFOS. The bioaccumulation potential of perfluorinated acids with seven fluorinated carbons or less appears to be several orders of magnitude lower than "legacy" persistent lipophilic compounds classified as bioaccumulative. Thus, although many PFCAs are environmentally persistent and can be present at detectable concentrations in wildlife, it is clear that PFCAs with seven fluorinated carbons or less (including PFO) are not bioaccumulative according to regulatory criteria.

Evaluation of estrogenic activities and mechanism of action of perfluorinated chemicals determined by vitellogenin induction in primary cultured tilapia hepatocytes

Perfluorochemicals (PFCs) are emerging persistent organic pollutants (POPs) and are widely present in the environment, wildlife and humans. Recently, reports have suggested that PFCs may have endocrine-disrupting activities. In the present study, we have developed a non-competitive enzyme-linked immunosorbent assay (ELISA) method to investigate estrogenic activities of selected PFCs using vitellogenin (VTG) induction in primary cultured hepatocytes of freshwater male tilapia (Oreochromis niloticus). Cultured hepatocytes were exposed to various concentrations of perfluorooctanyl sulfonate (PFOS), pentadecafluorooctanoic acid (PFOA), 1H, 1H, 2H, 2H-nonafluoro-1-hexanol (4:2 FTOH), 1H, 1H, 2H, 2H-perfluorooctanol (6:2 FTOH) and 1H, 1H, 2H, 2H-perfluoro-1-decanol (8:2 FTOH) for 48 h, while 17beta-estradiol (E2) and 4-nonylphenol (4-NP) were used as positive controls. A dose-dependent induction of VTG was observed in E2-, 4-NP-, PFOS-, PFOA- and 6:2 FTOH-treated cells, whereas VTG levels remained unchanged in the 4:2 FTOH and 8:2 FTOH exposure groups at the concentrations tested. The estimated 48-h EC(50) values for E2, 4-NP, PFOS, PFOA and 6:2 FTOH were 4.7 x 10(-7), 7.1 x 10(-6), 1.5 x 10(-5), 2.9 x 10(-5) and 2.8 x 10(-5)M, respectively. In the time-course study, significant VTG induction took place at 24 h (E2), 6 h (4-NP), 48 h (PFOS), 48 h (PFOA), 72 h (4:2 FTOH), 12 h (6:2 FTOH), 72 h (8:2 FTOH), and increased further after 96 h of exposure. Co-exposure to binary mixtures of individual PFCs and E2 for 48 h significantly inhibited E2-induced hepatocellular VTG production in a dose-dependent manner except for 4:2 FTOH. The estimated 48-h IC(50) (concentration of a compound that elicits 50% inhibition of maximally E2-induced VTG) values for PFOS, PFOA, 6:2 FTOH and 8:2 FTOH were 3.1 x 10(-7), 5.1 x 10(-7), 1.1 x 10(-6) and 7.5 x 10(-7)M, respectively. In order to further investigate the estrogenic mechanism of PFCs, the hepatocytes were co-exposed to binary mixtures of individual chemicals (E2, 4-NP, PFOS, PFOA and 6:2 FTOH) and the known estrogen receptor inhibitor tamoxifen for 48 h; tamoxifen significantly inhibited the ability of these chemicals to stimulate vitellogenesis. The overall results demonstrated that PFOS, PFOA and FTOHs have estrogenic activities and that exposure to a combination of E2 and PFCs produced anti-estrogenic effects. The results of the estrogen receptor inhibition assay further suggested that the estrogenic effect of PFCs may be mediated by the estrogen receptor pathway in primary cultured tilapia hepatocytes.

Cord serum concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in relation to weight and size at birth

BACKGROUND

Recent studies have reported developmental toxicity among rodents dosed with perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA).

OBJECTIVES

We examined the relationship between concentrations of PFOS and PFOA in cord serum (surrogates for in utero exposures) and gestational age, birth weight, and birth size in humans.

METHODS

We conducted a hospital-based cross-sectional epidemiologic study of singleton deliveries in Baltimore, Maryland. Cord serum samples (n = 293) were analyzed for PFOS and PFOA by online solid-phase extraction, coupled with reversed-phase high-performance liquid chromatography-isotope dilution tandem mass spectrometry. Maternal characteristics and anthropometric measures were obtained from medical charts.

RESULTS

After adjusting for potential confounders, both PFOS and PFOA were negatively associated with birth weight [per ln-unit: beta = -69 g, 95% confidence interval (CI), -149 to 10 for PFOS; beta = -104 g, 95% CI, -213 to 5 for PFOA], ponderal index (per ln-unit: beta = -0.074 g/cm(3) x 100, 95% CI, -0.123 to -0.025 for PFOS; beta = -0.070 g/cm(3) x 100, 95% CI, -0.138 to -0.001 for PFOA), and head circumference (per ln-unit: beta = -0.32 cm, 95% CI, -0.56 to -0.07 for PFOS; beta = -0.41 cm, 95% CI, -0.76 to -0.07 for PFOA). No associations were observed between either PFOS or PFOA concentrations and newborn length or gestational age. All associations were independent of cord serum lipid concentrations.

CONCLUSIONS

Despite relatively low cord serum concentrations, we observed small negative associations between both PFOS and PFOA concentrations and birth weight and size. Future studies should attempt to replicate these findings in other populations.

Trends of perfluorinated alkyl substances in herring gull eggs from two coastal colonies in northern Norway: 1983-2003

The present study reports on concentrations, patterns, and temporal trends (1983, 1993, and 2003) of 16 perfluorinated alkyl substances (PFAS) in whole eggs of herring gulls (Larus argentatus) from two geographically isolated colonies in northern Norway. Perfluorooctane sulfonate (PFOS) was the predominant PFAS in all eggs with mean concentrations up to 42 ng/g wet weight (ww) in samples from 2003. Perfluorohexane sulfonate (PFHxS) and perfluorodecane sulfonate (PFDcS) were found at concentrations several orders of magnitude lower than PFOS. The general accumulation profile of perfluorocarboxylates (PFCAs) in herring gull eggs was characterized by high proportions of odd and long carbon (C) chain length compounds in which perfluoroundecanoate (C11) and perfluorotridecanoate (C13) dominated with mean concentrations up to 4.2 and 2.8 ng/g ww, respectively. In both colonies PFOS concentrations in eggs showed a nearly 2-fold significant increase from 1983 to 1993, followed by a leveling off up to 2003. A comparable trend was found for PFHxS, whereas PFDcS was found to increase also between 1993 and 2003. PFCA concentrations showed marked significant increases during 1983-1993 associated with either a weak rise post-1993 (C8- to C11-PFCAs), although nonsignificant, or leveling off (C12- and C13-PFCAs). However, the composition of individual PFCAs (C8 to C15) to the summed concentrations of those eight PFCAs highly differed between the colonies and sampling years investigated. Present results suggest that direct and indirect local- and/or remote-sourced inputs (atmospheric and waterborne) of PFCAs have changed over the last two decades in these two coastal areas of Northern Norway.

Bioaccumulation of per- and polyfluorinated alkyl substances (PFAS) in selected species from the Barents Sea food web

The present study reports concentrations and biomagnification potential of per- and polyfluorinated alkyl substances (PFAS) in species from the Barents Sea food web. The examined species included sea ice amphipod (Gammarus wilkitzkii), polar cod (Boreogadus saida), black guillemot (Cepphus grylle) and glaucous gull (Larus hyperboreus). These were analyzed for PFAS, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs). Perfluorooctane sulfonate (PFOS) was the predominant of the detected PFAS. Trophic levels and food web transfer of PFAS were determined using stable nitrogen isotopes (delta(15)N). No correlation was found between PFOS concentrations and trophic level within species. However, a non-linear relationship was established when the entire food web was analyzed. Biomagnification factors displayed values >1 for perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), PFOS and SigmaPFAS(7). Multivariate analyses showed that the degree of trophic transfer of PFAS is similar to that of PCB, DDT and PBDE, despite their accumulation through different pathways.

Determinants of fetal exposure to polyfluoroalkyl compounds in Baltimore, Maryland

Polyfluoroalkyl compounds (PFCs), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), are ubiquitous, man-made chemicals. Human data suggest that in utero exposures to these chemicals occur and some evidence of developmental toxicity in animals exists. To assess the distribution and determinants of fetal exposure to PFCs, we analyzed cord serum samples from 299 singleton newborns delivered between 2004 and 2005 in Baltimore, MD for 10 PFCs by employing on-line solid-phase extraction coupled with reversed-phase high-performance liquid chromatography-tandem mass spectrometry. PFOS and PFOA were detected in 99 and 100% of umbilical cord sera, with geometric mean concentrations of 4.9 and 1.6 ng/mL, respectively. PFOS and PFOA concentrations were highly correlated (Pearson's r = 0.64 after natural log transformation, p < 0.01). Eight other PFCs were detected less frequently and at lower concentrations than PFOS and PFOA. Geometric mean concentrations of PFOS for Asians (6.0 ng/mL) and Blacks (5.1 ng/mL) were higher than those for Whites (4.2 ng/mL), while PFOA levels were more evenly distributed by race. Other maternal demographic and socioeconomic characteristics, including age, education, marital status, and living in the city limits were not significantly associated with cord concentrations. Our findings suggest that in utero exposure to PFOS and PFOA is ubiquitous in a population of babies born in Baltimore, MD.

Perfluoroalkyl Acids: A Review of Monitoring and Toxicological Findings

In recent years, human and wildlife monitoring studies have identified perfluoroalkyl acids (PFAA) worldwide. This has led to efforts to better understand the hazards that may be inherent in these compounds, as well as the global distribution of the PFAAs. Much attention has focused on understanding the toxicology of the two most widely known PFAAs, perfluorooctanoic acid, and perfluorooctane sulfate. More recently, research was extended to other PFAAs. There has been substantial progress in understanding additional aspects of the toxicology of these compounds, particularly related to the developmental toxicity, immunotoxicity, hepatotoxicity, and the potential modes of action. This review provides an overview of the recent advances in the toxicology and mode of action for PFAAs, and of the monitoring data now available for the environment, wildlife, and humans. Several avenues of research are proposed that would further our understanding of this class of compounds.

Evaluation of the acute toxicity of perfluorinated carboxylic acids using eukaryotic cell lines, bacteria and enzymatic assays

The acute biological activity of a homologous series of perfluorinated carboxylic acids - perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) - was studied. To analyze the potential risk of the perfluorinated acids to humans and the environment, different in vitro toxicity test systems were employed. The cytotoxicity of the chemicals towards two different types of mammalian cell lines and one marine bacteria was investigated. The viability of cells from the promyelocytic leukemia rat cell line (IPC-81) and the rat glioma cell line (C6) was assayed calorimetrically with WST-1 reagent. The evaluation was combined with the Vibrio fischeri acute bioluminescence inhibition assay. The biological activity of the compounds was also determined at the molecular level with acetylcholinesterase and glutathione reductase inhibition assays. This is the first report of the effects of perfluorinated acids on the activity of purified enzymes. The results show these compounds have a very low acute biological activity. The observed effective concentrations lie in the millimole range, which is well above probable intracellular concentrations. A relationship was found between the toxicity of the perfluorinated carboxylic acids and the perfluorocarbon chain length: in every test system applied, the longer the perfluorocarbon chain, the more toxic was the acid. The lowest effective concentrations were thus recorded for perfluorononanoic and perfluorodecanoic acids.

Exposure of perfluorinated chemicals through lactation: levels of matched human milk and serum and a temporal trend, 1996-2004, in Sweden

BACKGROUND

Only limited data exist on lactation as an exposure source of persistent perfluorinated chemicals (PFCs) for children.

OBJECTIVES

We studied occurrence and levels of PFCs in human milk in relation to maternal serum together with the temporal trend in milk levels between 1996 and 2004 in Sweden. Matched, individual human milk and serum samples from 12 primiparous women in Sweden were analyzed together with composite milk samples (25-90 women/year) from 1996 to 2004.

RESULTS

Eight PFCs were detected in the serum samples, and five of them were also above the detection limits in the milk samples. Perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonate (PFHxS) were detected in all milk samples at mean concentrations of 0.201 ng/mL and 0.085 ng/mL, respectively. Perfluorooctanesulfonamide (PFOSA), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected less frequently.

DISCUSSION

The total PFC concentration in maternal serum was 32 ng/mL, and the corresponding milk concentration was 0.34 ng/mL. The PFOS milk level was on average 1% of the corresponding serum level. There was a strong association between increasing serum concentration and increasing milk concentration for PFOS (r(2) = 0.7) and PFHxS (r(2) = 0.8). PFOS and PFHxS levels in composite milk samples were relatively unchanged between 1996 and 2004, with a total variation of 20 and 32% coefficient of variation, respectively.

CONCLUSION

The calculated total amount of PFCs transferred by lactation to a breast-fed infant in this study was approximately 200 ng/day. Lactation is a considerable source of exposure for infants, and reference concentrations for hazard assessments are needed.

Effects of perfluorooctane sulfonate on mallard and northern bobwhite quail exposed chronically via the diet

Adult mallard ducks and northern bobwhite quail were exposed to 0, 10, 50, or 150mg perfluorooctane sulfonate (PFOS)/kg in the diet for up to 21 weeks. Adult health, body and liver weight, feed consumption, gross morphology and histology of body organs, and reproduction were examined. Due to mortality, birds exposed to 50 or 150mg PFOS/kg feed were terminated by Week 7. In quail, the lowest observable adverse effect level (LOAEL) was 10mg PFOS/kg feed based on decreased survivorship of 14-day-old quail offspring. For adult female quail fed 10mg/kg feed, there was a slight but statistically significantly PFOS-related increase in liver weight when compared to controls. When liver weight was normalized to body weight, the statistically significant differences were still observed indicating that PFOS affected liver size. However, no other pathological effects were observed livers of quail from this treatment group which suggests that this enlargement may have been an adaptive response. For adult mallards, no treatment-related effects on feed consumption, body or liver weight, growth, or reproductive performance were observed. There was a slightly greater incidence of small testes (length) in adult male mallards and quail exposed to 10mg PFOS/kg, feed when compared to controls. However, spermatogenesis was not affected and there was no effect on the rates of egg fertilization. Due to transfer to eggs, concentrations of PFOS measured in the liver and blood at study termination were greater in male birds than female birds.

Occurrence of perfluorooctane sulfonate and other perfluorinated alkylated substances in harbor porpoises from the Black Sea

Perfluorooctane sulfonate (PFOS) and other perfluorinated alkylated substances (PFAS) were determined in liver, kidney, muscle, brain, and blubber samples of 31 harbor porpoises (Phocoena phocoena relicta) of different age and sex stranded along the Ukrainian coast of the Black Sea. In all individuals and in all tissues, PFOS was the predominant PFAS, accounting for on average 90% of the measured PFAS load. PFOS concentrations were the highest in liver (327+/-351 ng/g wet wt) and kidney (147 +/-262 ng/g wet wt) tissue, and lower in blubber (18+/-8 ng/g wet wt), muscle (41+/-50 ng/g wet wt), and brain (24 +/-23 ng/g wetwt). No significant differences could be determined between males and females, nor between juvenile and adult animals (p > 0.05). Perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanoic acid could be detected in liver tissue of approximately 25% of the individuals. Perfluorobutane sulfonate, perfluorobutanoic acid, and perfluorooctanoic acid were not detected in any of the porpoise livers. Although we investigated a potential intraspecies segregation according to the source of prey, using stable isotopes, no statistically significant correlation between PFOS concentrations and stable isotopes could be determined. It is, however, noteworthy that the contamination by PFOS in the Black Sea harbor porpoises is comparable to levels found in porpoises from the German Baltic Sea and from coastal areas near Denmark and, therefore, might pose a threat to this population.

The applicability of biomonitoring data for perfluorooctanesulfonate to the environmental public health continuum

Perfluorooctanesulfonate and its salts (PFOS) are derived from perfluorooctanesulfonyl fluoride, the basic chemical building block for many sulfonyl-based fluorochemicals used as surfactants and for their repellent properties. PFOS is highly persistent in the environment and has a long serum elimination half-life in both animals and humans. PFOS has been detected globally in the environment and in blood serum in various populations throughout the world, with the majority of human sampling done in the United States and Japan. The mechanisms and pathways leading to the presence of PFOS in human blood are not well characterized but likely involve both direct exposures to PFOS or chemicals and materials that can degrade to PFOS, either in the environment or from industrial and commercial uses. In 2000 the 3M Company, a major manufacturer, announced a phaseout of PFOS-related materials. Animal studies indicate that PFOS is well absorbed orally and distributes mainly in blood serum and the liver. Several repeat-dose toxicology studies in animals consistently demonstrated that the liver is the primary target organ. In addition there is a steep dose response for mortality in sexually mature rats and primates as well as in neonatal rats and mice exposed in utero. Several biomonitoring research needs that have been identified on PFOS include additional data from general populations pertaining to other matrices besides blood; matched serum and urine samples from humans and research animals; and comparison of whole blood, serum, and plasma concentrations from the same individuals.

New perspectives on perfluorochemical ecotoxicology: inhibition and induction of an efflux transporter in the marine mussel, Mytilus californianus

The toxicological effects of perfluoroalkyl acids on the p-glycoprotein (p-gp) cellular efflux transporter were investigated using the marine mussel Mytilus californianus as a model system. Four of the perfluoroalkyl acids studied exhibit chemosensitizing behavior, significantly inhibiting p-gp transporter activity. The inhibitory potency is maximal for the longer chain acids perfluorononanoate (PFNA) and perfluorodecanoate (PFDA), with average IC50 values of 4.8 and 7.1 microM, respectively. Results indicate that PFNA inhibits p-gp by an indirect mechanism, and this inhibition is reversible and accompanied by a rapid loss of PFNA from the tissue. In addition, PFNA induces expression of the p-gp transporter after a 2-h exposure, a stress response that may result in a metabolic cost to the organism. Given that most organisms, including humans, share efflux transporters as a first line of defense against toxicants, the results of this study may have broader implications for the ecotoxicology of perfluoroalkyl acids.

Perfluorinated chemicals in relation to other persistent organic pollutants in human blood

In order to evaluate blood levels of some perfluorinated chemicals (PFCs) and compare them to current levels of classical persistent organic pollutants (POPs) whole blood samples from Sweden were analyzed with respect to 12 PFCs, 37 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene (DDE), hexachlorobenzene (HCB), six chlordanes and three polybrominated diphenyl ethers (PBDEs). The median concentration, on whole blood basis, of the sum of PFCs was 20-50 times higher compared to the sum of PCBs and p,p'-DDE, 300-450 times higher than HCB, sum of chlordanes and sum of PBDEs. Estimations of the total body amount of PFCs and lipophilic POPs point at similar body burdens. While levels of for example PCBs and PBDEs are normalized to the lipid content of blood, there is no such general procedure for PFCs in blood. The distributions of a number of perfluorinated compounds between whole blood and plasma were therefore studied. Plasma concentrations were higher than whole blood concentrations for four perfluoroalkylated acids with plasma/whole blood ratios between 1.1 and 1.4, whereas the ratio for perflurooctanesulfonamide (PFOSA) was considerably lower (0.2). This suggests that the comparison of levels of PFCs determined in plasma with levels determined in whole blood should be made with caution. We also conclude that Swedish residents are exposed to a large number of PFCs to the same extent as in USA, Japan, Colombia and the few other countries from which data is available today.

Levels of 12 perfluorinated chemicals in pooled australian serum, collected 2002-2003, in relation to age, gender, and region

Pooled serum samples from 3802 Australian residents were analyzed for four perfluoroalkylsulfonates, seven perfluoroalkylcarboxylates, and perfluorooctanesulfonamide (PFOSA). Serum was collected from men and women of five different age groups and from rural and urban regions in Australia. The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 20.8 ng/mL) followed by perfluorooctanoic acid (PFOA, 7.6 ng/mL), perfluorohexane sulfonate (PFHxS, 6.2 ng/mL), perfluorononanoic acid (PFNA, 1.1 ng/mL), and PFOSA (0.71 ng/mL). Additional four PFCs were detected in 5-18% of the samples at concentrations near the detection limits (0.1-0.5 ng/mL). An increase in PFOS concentration with increasing age in both regions and genders was observed. The male pool levels of some of the age groups compared to females were higherfor PFOS, PFOA, and PFHxS. In contrast, PFNA concentrations were higher in the female pools. No substantial difference was found in levels of PFCs between the urban and rural regions. The levels are equal or higher than previously reported serum levels in Europe and Asia but lower compared to the U.S.A. These results suggest that emissions from production in the Northern Hemisphere are of less importance for human exposure.

Persistent perfluorinated acids in seafood collected from two cities of China

As an initial survey of human exposure to perfluorinated acids through food consumption in China, seven types of seafood collected from fish markets in two coastal cities were analyzed. Nine perfluorinated compounds were determined using HPLC coupled with ESI-MS/MS. Perfluorooctane sulfonate (PFOS) was the predominant fluorochemical and was found in all 27 seafood samples, including fish, molluscs, crabs, shrimp, oysters, mussels, and clams. Concentrations of PFOS in seafood samples ranged from 0.3 to 13.9 ng/g wet weight, with the highest concentration in mantis shrimp. The hazard ratios of noncancer risk through seafood consumption based on PFOS and perfluorooctanoic acid concentrations were calculated and were less than unity.

Biological monitoring of polyfluoroalkyl substances: A review

Polyfluoroalkyl substances (PFSs) are used in industrial and commercial products and can degrade to persistent perfluorocarboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs). Temporal trend studies using human, fish, bird, and marine mammal samples indicate that exposure to PFSs has increased significantly over the past 15-25 years. This review summarizes the biological monitoring of PFCAs, PFSAs, and related PFSs in wildlife and humans, compares concentrations and contamination profiles among species and locations, evaluatesthe bioaccumulation/biomagnification in the environment, discusses possible sources, and identifies knowledge gaps. PFSs can reach elevated concentrations in humans and wildlife inhabiting industrialized areas of North America, Europe, and Asia (2-30,000 ng/ mL or ng/g of wet weight (ww)). PFSs have also been detected in organisms from the Arctic and mid-ocean islands (< or = 3000 ng/g ww). In humans, PFSAs and PFCAs have been shown to vary among ethnic groups and PFCA/PFSA profiles differ from those in wildlife with high proportions of perfluorooctanoic acid and perfluorooctane sulfonate. The pattern of contamination in wildlife varied among species and locations suggesting multiple emission sources. Food web analyses have shown that PFCAs and PFSAs can bioaccumulate and biomagnify in marine and freshwater ecosystems. Knowledge gaps with respect to the transport, accumulation, biodegradation, temporal/spatial trends and PFS precursors have been identified. Continuous monitoring with key sentinel species and standardization of analytical methods are recommended.

Environmental analysis of fluorinated alkyl substances by liquid chromatography–(tandem) mass spectrometry: a review

Fluorinated alkyl substances (FASs) are widely distributed contaminants that have been found in many environmental, human and biological samples throughout the world. Perfluorochemicals are used in many industry and consumer products, such as polymers and surfactants, because they have unique and useful properties (they are stable, chemically inert and generally unreactive). However, these compounds have also been found to be toxic, persistent and bioaccumulative. In recent years various analytical methods have been developed for the analysis of FASs in environmental samples. Most of these methods are based on liquid chromatography coupled to mass spectrometry (LC-MS) or tandem mass spectrometry (LC-MS/MS), since this is considered to be the technique of choice. This article reviews the various LC-(tandem)MS methods described so far for the analysis of FASs in water, sediment, sludge and biota samples. It discusses the main experimental conditions used for sample pretreatment and for analysis as well as the most relevant problems encountered and the limits of detection achieved.

Isomer distribution of perfluorocarboxylates in human blood: potential correlation to source

Detection of perfluorocarboxylate anions (PFCAs), such as perfluorooctanoate (C7F15COO-, PFOA), at ng/g levels in human tissues has engendered public scrutiny of industrial fluorochemicals. Routes of PFCA exposure for the general human population are likely diverse given direct (industrially produced) and indirect (production from precursor organofluorines) sources. Major industrial production of organofluorines, including PFCAs, stems from either electrochemical fluorination (ECF) or telomerization. ECF products are a mixture of structural isomers (linear and branched perfluoroalkyls) and telomerization products are assumed to have one perfluorocarbon arrangement, typically linear. The objective of this research was to investigate structural isomer patterns of PFCAs in human blood. Volatile derivatives of PFCAs in human blood were analyzed by GC-(NCI)-MS for quantitation and isomers. PFOA was the dominant PFCA (mean 4.4 ng/g). Blood serum isomer profiles consisted of predominantly (mean approximately 98%) the linear isomer for each PFCA (C8-C11). There were similarities in branched isomer patterns of an ECF PFOA standard with both PFOA and PFNA in blood. Direct exposure to ECF PFOA, which has a legacy of production for uses in fluoropolymer industries, is postulated to be a source of the observed branched isomer pattern. Predominance of linear PFCA isomers and the [even PFCA] > [odd PFCA] concentration trend in blood is suggestive of additional input from a strictly linear perfluoroalkyl source.

Human exposure assessment to environmental chemicals using biomonitoring

In modern societies, humans may be exposed to a wide spectrum of environmental chemicals. Although the health significance of this exposure for many chemicals is unknown, studies to investigate the prevalence of exposure are warranted because of the chemicals' potential harmful health effects, as often indicated in animal studies. Three tools have been used to assess exposure: exposure history/questionnaire information, environmental monitoring, and biomonitoring (i.e. measuring concentrations of the chemicals, their metabolites, or their adducts in human specimens). We present an overview on the use of biomonitoring in exposure assessment using phthalates, bisphenol A and other environmental phenols, and perfluorinated chemicals as examples. We discuss some factors relevant for interpreting and understanding biomonitoring data, including selection of both biomarkers of exposure and human matrices, and toxicokinetic information. The use of biomonitoring in human risk assessment is not discussed.

Pharmacokinetics and acute lethality of perfluorooctanesulfonate (PFOS) to juvenile mallard and northern bobwhite

Ten-day-old mallards (Anas platyrhynchos) and northern bobwhite quail (Colinus virginianus) were fed perfluorooctanesulfonate (PFOS) in their diet for 5 days. The birds were then observed for 3 days while being given uncontaminated feed, and half of the birds were sacrificed on Day 8 of the trial. The remaining birds were maintained for an additional two weeks prior to being euthanized on Day 22 of the trial. Birds were assessed for growth, rate of feed consumption, behavior, physical injury, mortality, and gross abnormalities. Liver weight and concentrations of PFOS in blood serum and liver were also assessed. Based on the average daily intake (ADI) of PFOS calculated over the 5-day exposure period, the LD50 for juvenile mallards was determined to be 150 mg PFOS/kg body weight (bw)/day, equivalent to a total cumulative dose of 750 mg PFOS/kg bw calculated over a 5-day period. For juvenile quail, the LD50 based on the ADI was 61 mg PFOS/kg bw/day, equivalent to a total cumulative dose of 305 mg PFOS/kg bw. Reductions in weight gain and body weight were observed in quail from the 141 mg PFOS/kg treatment, but these measures returned to control levels by Day 22. The no-mortality dietary treatments were 70.3 and 141 mg PFOS/kg feed for quail and mallards, respectively. Both mallards and quail accumulated PFOS in blood serum and liver in a dose-dependent manner. The half-lives of PFOS in mallard blood serum and liver were estimated to be 6.86 and 17.5 days, respectively. In quail, the half-life of PFOS in liver was estimated to be 12.8 days, while the half-life of PFOS in quail blood serum could not be estimated. Concentrations of PFOS in juvenile mallard and quail liver associated with mortality are at least 50-fold greater than the single maximum PFOS concentration that has been measured in livers of avian wildlife.