Health & Environmental Research Online (HERO)


PFOA (335-67-1) and PFOS (1763-23-1)


3,458 References Were Found:

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Effects of Perfluoralkyl Substances on a Multigenerational Scale: A Case Study with Chironomus riparius (Diptera, Chironomidae)

Authors: Marziali, L; Rosignoli, F; Valsecchi, S; Polesello, S; Stefani, F (2019) Environmental Toxicology and Chemistry 38:988-999. HERO ID: 5080194

[Less] A multigenerational test with Chironomus riparius was performed to assess long-term effects on life-traits . . . [More] A multigenerational test with Chironomus riparius was performed to assess long-term effects on life-traits of exposure to selected perfluoroalkyl compounds: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorobutane sulfonate (PFBS). These persistent contaminants are widespread in aquatic ecosystems at low concentrations, possibly exerting long-term toxicity. Larvae of C. riparius of a native population were exposed for 10 generations to 10 μg/L nominal concentrations of PFOS, PFOA, and PFBS, comparable with the maximum values found in European rivers. All treatments showed reduced growth at most/several generations. No effects on survival, development, and reproduction were found. A final tolerance-induction test was performed exposing the pre-exposed experimental cohorts to 100 µg/L PFOS and 150 µg/L PFOA for a whole life cycle. Factorial analysis of variance revealed no difference between treatments (i.e., PFOS vs PFOA), indicating no induced tolerance. Instead, organisms pre-exposed to PFBS were the most stressed, followed by those pre-exposed to PFOA and PFOS, with earlier emergence and reduced adult weight. The results may be related to general stress and genetic erosion induced by long-term laboratory culture, but also to long-term toxicant exposure. However, no effects at the population level (population growth rate) were proved, and thus a toxicity risk in real ecosystems at the tested concentrations seems unlikely. Environ Toxicol Chem 2019;00:1-12. © 2019 SETAC.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Effect of perfluorodecanoic acid on pig oocyte viability, intracellular calcium levels and gap junction intercellular communication during oocyte maturation in vitro

Authors: Domínguez, A; Salazar, Z; Betancourt, M; Ducolomb, Y; Casas, E; Fernández, F; Bahena, I; Salomón, A; Teteltitla, M; Martínez, R; Chaparro, A; Cuapio, P; Salazar-López, C; Bonilla, E (2019) HERO ID: 5080569

[Less] Perfluorodecanoic acid (PFDA) is a synthetic perfluorinated compound, which has been reported to exert . . . [More] Perfluorodecanoic acid (PFDA) is a synthetic perfluorinated compound, which has been reported to exert adverse effects on somatic cells. However, its effects on germ cells have not been studied to date. The aim of the present study was to analyze the effects of PFDA on the viability, intracellular calcium levels and gap junction intercellular communication (GJIC) during porcine oocyte maturation in vitro. PFDA negatively impacted oocyte viability (medium lethal concentration, LC50 = 7.8 μM) and maturation (medium inhibition of maturation, IM50 = 3.8 μM). Oocytes exposed to 3.8 μM PFDA showed higher levels of intracellular calcium relative to control oocytes. In addition, GJIC among the cumulus cells and the oocyte was disrupted. The effects of PFDA on oocyte calcium homeostasis and intercellular communication seem to be responsible for the inhibition of oocyte maturation and oocyte death. In addition, since the deleterious effects of PFDA on oocyte viability, maturation and GJIC are significantly stronger than the previously reported effects of another widely used perfluorinated compound (Perfluorooctane sulfonate) in the same model, the use of PFDA in consumer products is questioned.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Per- and polyfluorinated compounds in saleswomen's urine linked to indoor dust in clothing shops

Authors: Wu, N; Cai, D; Guo, M; Li, M; Li, X (2019) Science of the Total Environment 667:594-600. HERO ID: 5080616

[Less] This study aims to investigate the characteristics of typical per- and polyfluorinated compounds (PFCs) . . . [More] This study aims to investigate the characteristics of typical per- and polyfluorinated compounds (PFCs) in indoor dust from clothing shops and urine sampled from saleswomen. A total of 58 indoor dust samples and 73 urine samples from saleswomen were collected from clothing shops in Shanghai, China. All samples were analyzed for PFCs using high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS). The mean PFC concentrations in indoor dust ranged from 0.42 (PFDA) to 5.04 ng g-1 (PFDoA). PFDoA and PFHxS were the most prominent PFCs, with median concentrations of 2.95 ng g-1 and 1.49 ng g-1, respectively. The median PFC concentrations in urine ranged from 10.15 (PFDS) to 666.1 ng l-1 (PFOA) and PFOA was the most abundant chemical with concentrations ranging from 207 to 907 ng l-1. A significant positive correlation was obtained between long-chain PFCs in dust and in urine (p < 0.01). Daily intake values of PFCs via dust ingestion were also calculated, and even under high-end exposure scenarios, the intake of PFOA (36.5 pg day-1) and PFOS (56.7 pg day-1) were well within the tolerable daily intake values. These results are important to both characterize PFC levels and estimate the saleswomen's exposure to PFCs from indoor dust.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Limited reproductive impairment in a passerine bird species exposed along a perfluoroalkyl acid (PFAA) pollution gradient

Authors: Groffen, T; Lasters, R; Lopez-Antia, A; Prinsen, E; Bervoets, L; Eens, M (2019) Science of the Total Environment 652:718-728. HERO ID: 5080648

[Less] Although bird eggs have been used in biomonitoring studies on perfluoroalkyl acids (PFAAs), effects . . . [More] Although bird eggs have been used in biomonitoring studies on perfluoroalkyl acids (PFAAs), effects of environmental concentrations on reproduction remain largely unknown in wild birds. In the present study we examined the associations between the concentrations of 4 perfluoroalkyl sulfonic acids (PFSAs) and 11 perfluoroalkyl carboxylic acids (PFCAs) in the eggs of great tits (Parus major), collected along a distance gradient from a pollution source, and multiple reproductive parameters (including the start of egg laying, clutch size, hatching success, fledging success and total breeding success) along with egg shell thickness and body condition of the nestlings. The PFAA concentrations measured at the plant site were among the highest ever reported in wild bird eggs. PFAA concentrations decreased sharply with increasing distance (0-11 km) from the plant, but remained relatively elevated in the adjacent sites. PFAAs were grouped into principal components (PCs) to prevent collinearity. High concentrations of PFOS, PFDS, PFDoDA, PFTrDA and PFTeDA (grouped as PC1) were associated with a reduced hatching success of nests where at least one egg hatched, thinner egg shells and increased survival of the hatched chicks. High concentrations of PFDA (PC2) were associated with a reduced hatching success, especially in nests where no eggs hatched, an earlier start of egg laying and a reduction of total breeding success, mainly caused by the failure in hatching. Although the major manufacturer of PFAAs phased out the production of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and related products in 2002, concentrations appear to have increased since previous measurements. Surprisingly, despite the very high concentrations close to the fluorochemical plant, there was no clear evidence for reproductive impairment as the observed associations between PFAA concentrations and reproductive parameters were rather limited compared to previous studies in songbirds. These findings also suggest potential differences in sensitivity between species. CAPSULE: Despite the very high PFAA concentrations at the perfluorochemical hotspot, correlations with reproductive parameters were limited.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Destabilizing effect of perfluorodecanoic acid on simple membrane models

Authors: Viada, B; Cámara, CI; Yudi, LM (2019) HERO ID: 5082178

[Less] Perfluoroalkyl acids (PFA) are amphiphilic surfactants widely used in industry with several commercial . . . [More] Perfluoroalkyl acids (PFA) are amphiphilic surfactants widely used in industry with several commercial applications. An important feature of these compounds is their non-biodegradability and their tendency to bio-accumulate in the environment, which has led to these compounds being considered among the most persistent pollutants worldwide. Many studies have provided evidence of their toxic effect on humans and wildlife. For this reason, more and more efforts have been made to better understand the effect of these compounds on living organisms. The aim of the present study is to understand how the electrostatic interactions and film compactness of biological membrane models modulate their interaction with PFA, more specifically with perfluorodecanoic acid (PFD). Langmuir isotherms and Brewster angle microscopy (BAM) are used to evaluate the effect of PFD on lipid membrane models (air/water monolayers and vesicles), analyzing the behavior of PFD : lipid mixtures. The lipids used in this study are distearoyl phosphatidic acid (DSPA), dilauroyl phosphatidic acid (DLPA) and distearoyl phosphatidylethanolamine (DSPE). PFD induces an increase in the mean molecular area per lipid in monolayers, mainly at lower surface pressures. BAM images demonstrate that PFD mixes with DLPA, inducing a decrease in gray level, while it forms a non-miscible mixture with DSPA, segregating PFD domains. Insertion studies of PFD within monolayers and dynamic light scattering experiments demonstrate that PFD can penetrate into monolayers and bilayers above 30 mN m-1, which is the lateral pressure value accepted for a cellular bilayer.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Contaminants in bald eagles of the upper Midwestern U.S.: A framework for prioritizing future research based on in-vitro bioassays

Authors: Elliott, SM; Route, WT; Decicco, LA; Vandermeulen, DD; Corsi, , SR; Blackwell, BR (2019) Environmental Pollution 244:861-870. HERO ID: 5080644

[Less] Several organic contaminants (OCs) have been detected in bald eagle (Haliaeetus leucocephalus) nestling . . . [More] Several organic contaminants (OCs) have been detected in bald eagle (Haliaeetus leucocephalus) nestling (eaglet) plasma in the upper Midwestern United States. Despite frequent and relatively high concentrations of OCs in eaglets, little is understood about potential biological effects associated with exposure. We screened an existing database of OC concentrations in eaglet plasma collected from the Midwestern United States against bioactivity information from the ToxCast database. ToxCast bioactivity information consists of concentrations expected to elicit responses across a range of biological space (e.g. cellular, developmental, etc.) obtained from a series of high throughput assays. We calculated exposure-activity ratios (EAR) by calculating the ratio of plasma concentrations to concentrations available in ToxCast. Bioactivity data were not available for all detected OCs. Therefore, our analysis provides estimates of potential bioactivity for 19 of the detected OCs in eaglet plasma. Perfluorooctanesulfonic acid (PFOS) EAR values were consistently the highest among all study areas. Maximum EAR values were ≥1 for PFOS, perfluorononanoic acid, and bisphenol A in 99.7, 0.53 and 0.26% of samples, indicating that some plasma concentrations were greater than what may be expected to elicit biological responses. About 125 gene targets, indicative of specific biological pathways, were identified as potentially being affected. Inhibition of several CYP genes, involved in xenobiotic metabolism, were most consistently identified. Other identified biological responses have potential implications for motor coordination, cardiac functions, behavior, and blood circulation. However, it is unclear what these results mean for bald eagles, given that ToxCast data are generated using mammalian-based endpoints. Despite uncertainties and limitations, this method of screening environmental data can be useful for informing future monitoring or research focused on understanding the occurrence and effects of OCs in bald eagles and other similarly-positioned trophic species.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

In vitro and in silico evaluations of binding affinities of perfluoroalkyl substances to baikal seal and human peroxisome proliferator-activated receptor α

Authors: Ishibashi, H; Hirano, M; Kim, EY; Iwata, H (2019) Environmental Science and Technology 53:2181-2188. HERO ID: 5024210

[Less] In this study, we assessed the binding affinities of perfluoroalkyl substances (PFASs), including perfluoroalkyl . . . [More] In this study, we assessed the binding affinities of perfluoroalkyl substances (PFASs), including perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), to the ligand-binding domains (LBDs) of Baikal seal ( Pusa sibirica; bs) and human (h) peroxisome proliferator-activated receptor alpha (PPARα). An in vitro competitive binding assay showed that six PFCAs and two PFSAs could bind to recombinant bs and hPPARα LBD proteins in a dose-dependent manner. The relative binding affinities (RBAs) of PFASs to bsPPARα were as follows: PFOS > PFDA > PFNA > PFUnDA > PFOA > PFHxS > PFHpA > PFHxA. The RBAs to bsPPARα showed a significant positive correlation with those to hPPARα. In silico PPARα homology modeling predicted that there were two ligand-binding pockets (LBPs) in the bsPPARα and hPPARα LBDs. Structure-activity relationship analyses suggested that the binding potencies of PFASs to PPARα might depend on LBP binding cavity volume, hydrogen bond interactions, the number of perfluorinated carbons, and the hydrophobicity of PFASs. Interspecies comparison of the in vitro binding affinities revealed that bsPPARα had higher preference for PFASs with long carbon chains than hPPARα. The in silico docking simulations suggested that the first LBP of bsPPARα had higher affinities than that of hPPARα; however, the second LBP of bsPPARα had lower affinities than that of hPPARα. To our knowledge, this is the first evidence showing interspecies differences in the binding of PFASs to PPARαs and their structure-activity relationships.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Leaching and bioavailability of selected perfluoroalkyl acids (PFAAs) from soil contaminated by firefighting activities

Authors: Bräunig, J; Baduel, C; Barnes, CM; Mueller, JF (2019) Science of the Total Environment 646:471-479. HERO ID: 5079692

[Less] Historical usage of aqueous film-forming foam (AFFF) at firefighting training grounds (FTGs) is a potential . . . [More] Historical usage of aqueous film-forming foam (AFFF) at firefighting training grounds (FTGs) is a potential source of perfluoroalkyl acids (PFAAs) to the surrounding environment. In this study the leaching of PFAAs from field contaminated soil and their uptake into biota was investigated. Soil was sampled from FTGs at two airports and the total as well as the leachable concentration of 12 PFAAs was determined. A greenhouse study was carried out to investigate the uptake of PFAAs from soils into earthworms (Eisenia fetida) and wheat grass (Elymus scaber). Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) were the most dominant PFAAs in all soils samples, with concentrations of PFOS reaching 13,400 ng/g. Leachable concentrations of PFOS and PFHxS reached up to 550 μg/L and 22 μg/L, respectively. In earthworms concentrations of PFOS reached 65,100 ng/g after a 28-day exposure period, while in wheat grass the highest concentration was measured for uptake of PFHxS (2,800 ng/g) after a 10-week growth-period. Bioaccumulation factors (BAFs) for earthworms ranged from 0.1 for perfluorohexanoic acid (PFHxA) to 23 for perfluorododecanoic acid (PFDoA) and initially showed a decreasing trend with increasing perfluoroalkyl chain length, followed by an increase with increasing perfluoroalkyl chain length for perfluoroalkyl carboxylic acids (PFCAs). In wheat grass the highest BAF was found for perfluorobutanoic acid (BAF = 70), while the lowest was observed for perfluorononanoic acid (BAF = 0.06). BAFs in wheat grass decreased with increasing perfluoroalkyl chain length for both PFCAs and perfluoroalkyl sulfonic acids (PFSAs). The results show that PFAAs readily leach from impacted soils and are bioaccumulated into earthworms and plants in an analyte dependent way. This shows considerable potential for PFAAs to move away from the original source either by leaching or uptake into ecological receptors, which may be a potential entry route into the terrestrial foodweb.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Factors associated with exposure of pregnant women to perfluoroalkyl acids in North China and health risk assessment

Authors: Yang, J; Wang, H; Du, H; Xu, L; Liu, S; Yi, J; Qian, X; Chen, Y; Jiang, Q; He, G (2019) Science of the Total Environment 655:356-362. HERO ID: 5080660

[Less] Perfluoroalkyl acids (PFAAs) have been frequently found in blood of pregnant women, but the predictors . . . [More] Perfluoroalkyl acids (PFAAs) have been frequently found in blood of pregnant women, but the predictors and potential health risk have not been well studied in China. We recruited 534 pregnant women in Tangshan City of Hebei Province in North China between 2013 and 2014 and measured five PFAAs in serum during their early term of pregnancy, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluoro‑n‑undecanoic acid (PFUdA), and perfluorononanoic acid (PFNA). We explored the factors associated with the levels of serum PFAAs and assessed associated health risks. Food consumption information was obtained by food frequency questionnaire covering 100 items. Multiple linear regression model was used to determine the associations of sociodemographic, anthropometric, and food factors with the concentrations of serum PFAAs. Some PFAAs in serum were positively associated with age and body mass index (BMI). Consumption of beans, aquatic products, and eggs was positively associated with the concentrations of several PFAAs after adjusting for important covariates. Pregnant women who ate more cereal, vegetables, mushrooms and alga tended to have lower levels of serum PFOA, PFOS and PFNA. The Hazard index (HI) for reproductive toxicity and developmental toxicity was below 0.8, and the HI for hepatotoxicity beyond 1 was found in 0.37% of pregnant women. These results suggested that age, BMI, and some food consumption were predictors for the exposure to PFAAs in Chinese pregnant women. More attention should be paid to the hepatotoxicity for these exposures.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Lipid accumulation responses in the liver of Rana nigromaculata induced by perfluorooctanoic acid (PFOA)

Authors: Zhang, H; He, J; Li, N; Gao, N; Du, Q; Chen, B; Chen, F; Shan, X; Ding, Y; Zhu, W; Wu, Y; Tang, J; Jia, X (2019) Ecotoxicology and Environmental Safety 167:29-35. HERO ID: 5080402

[Less] Perfluorooctanoic acid (PFOA) is a perfluorinated compound that is widely distributed, is persistent . . . [More] Perfluorooctanoic acid (PFOA) is a perfluorinated compound that is widely distributed, is persistent in the environment, and has a low-level chronic exposure effect on human health. The aim of this study was to investigate the peroxisome proliferator activated receptors γ (PPARγ) and the sterol regulatory element-binding protein 2 (SREBP2) signaling pathways in regulating the lipid damage response to PFOA in the livers of amphibians. Male and female frogs (Rana nigromaculata) were exposed to 0, 0.01, 0.1, 0.5 and 1 mg/L PFOA. After treatment, we evaluated the pathological changes in the liver by Oil Red O, staining and examined the total cholesterol (T-CHO) and triglyceride (TG) contents. The mRNA expression levels of PPARγ, Fatty acid synthase (FAS), Acetyl-CoA carboxylase (ACC), Glycerol-3-phosphate acyltransferase (GPAT), SREBP2 and 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The administration of PFOA caused marked lipid accumulation damage in the amphibian livers. The T-CHO contents were elevated significantly after PFOA treatment; these results show a dose-dependent manner in both sexes. The TG content showed a significant increase in male livers, while it was elevated significantly in female livers. The RT-PCR results showed that the mRNA expression levels of PPARγ, ACC, FAS, GPAT, SREBP2 and HMG-CoA were significantly dose-dependently increased in the PFOA-treated groups compared with those of the control group. Our results demonstrated that PFOA-induced lipid accumulation also affected the expression levels of genes FAS, ACC, GPAT and HMG-CoA in the PPARγ and SREBP2 signaling pathways in the liver. These finding will provide a scientific theoretical basis for the protection of Rana nigromaculata against PFOA effects.