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

TDP-43 and Alzheimer's Disease Pathology in the Brain of a Harbor Porpoise Exposed to the Cyanobacterial Toxin BMAA

Cetaceans are well-regarded as sentinels for toxin exposure. Emerging studies suggest that cetaceans can also develop neuropathological changes associated with neurodegenerative disease. The occurrence of neuropathology makes cetaceans an ideal species for examining the impact of marine toxins on the brain across the lifespan. Here, we describe TAR DNA-binding protein 43 (TDP-43) proteinopathy and Alzheimer's disease (AD) neuropathological changes in a beached harbor porpoise (Phocoena phocoena) that was exposed to a toxin produced by cyanobacteria called β-N-methylamino-L-alanine (BMAA). We found pathogenic TDP-43 cytoplasmic inclusions in neurons throughout the cerebral cortex, midbrain and brainstem. P62/sequestosome-1, responsible for the autophagy of misfolded proteins, was observed in the amygdala, hippocampus and frontal cortex. Genes implicated in AD and TDP-43 neuropathology such as APP and TARDBP were expressed in the brain. AD neuropathological changes such as amyloid-β plaques, neurofibrillary tangles, granulovacuolar degeneration and Hirano bodies were present in the hippocampus. These findings further support the development of progressive neurodegenerative disease in cetaceans and a potential causative link to cyanobacterial toxins. Climate change, nutrient pollution and industrial waste are increasing the frequency of harmful cyanobacterial blooms. Cyanotoxins like BMAA that are associated with neurodegenerative disease pose an increasing public health risk.

Association between per- and polyfluoroalkyl substances (PFAS) and depression in U.S. adults: A cross-sectional study of NHANES from 2005 to 2018

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widespread persistent organic pollutants (POPs) associated with diseases including osteoporosis, altered immune function and cancer. However, few studies have investigated the association between PFAS mixture exposure and Depression in general populations.

METHODS

Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) (2005-2018) were used to analyze the association between PFAS and Depression in U.S. adults. Total 12,239 adults aged 20 years or older who had serum PFAS measured and answered Patient Health Questionnaire-9 (PHQ-9) were enrolled in this study. PFAS monomers detected in all 7 investigation cycles were included in the study. Generalized additive model (GAM) was used to fit smooth curves and threshold effect analysis was carried out to find the turning point of smooth curves. Generalized linear model (GLM) was used to describe the non-linear relationship between PFAS and depression and unconditioned logistic regression was used to risk analysis.

RESULTS

The median of total serum PFAS concentration was 14.54 ng/mL. The curve fitting results indicated a U-shaped relationship between total serum PFAS and depression: PFAS< 39.66 ng/mL, A negative correlation between PHQ-9 score and serum PFAS concentration was observed (β 0.047,95%CI -0.059, -0.036). The depression PHQ-9 score decreased with the increase of serum PFAS concentration. PFAS ≥ 39.66 ng/mL, A positive correlation was observed between PFAS and PHQ-9 score (β 0.010,95% CI 0.003, 0.017). The depression PHQ-9 score increased with the increase of serum PFAS concentration.

CONCLUSIONS

Our study provides new clues to the association of PFAS with depression, and large population-based cohort studies that can validate the causal association as well as toxicological mechanism studies are needed for validation.

Differences in the internal PFAS patterns of herbivores, omnivores and carnivores - lessons learned from target screening and the total oxidizable precursor assay

Per- and polyfluorinated alkyl substances (PFAS) are a group of anthropogenic chemicals, which are not (fully) biodegradable and accumulate in different environmental compartments worldwide. A comprehensive, quantitative analysis - consisting of target analysis (66 different analytes, including e. g. ultrashort-chain perfluorinated carboxylic acids (PFCAs), precursor compounds and novel substitutes) and the Total Oxidisable Precursor (TOP) assay (including trifluoroacetic acid (TFA)) - were conducted to analyse the PFAS concentrations and patterns in 12 mammalian and two bird species from different areas of Germany and Denmark. The PFAS contamination was investigated in dependance of the trophic class (herbivores, omnivores, carnivores), ecological habitat (terrestrial, (semi-) aquatic) and body tissue (liver, musculature). PFAS concentrations were highest in carnivores, followed by omnivores and herbivores, with ∑PFAS concentration ranging from 1274 μg/kg (Eurasian otter liver) to 22 μg/kg (roe deer liver). TFA dominated in the herbivorous species, whereas perfluorooctanesulfonic acid (PFOS) and the long-chain PFCAs covered the majority of the PFAS contamination in carnivorous species. Besides trophic class, ecological habitat also affected the PFAS levels in the different species, with terrestrial herbivores and omnivores showing higher PFAS concentration than their aquatic counterparts, whereas for carnivores this relationship was reversed. The TOP assay analysis indicated similar trends, with the PFCA formation pattern differing significantly between the trophic classes. TFA was formed predominantly in herbivorous and omnivorous species, whereas in carnivorous species a broad spectrum of PFCAs (chain-length C2-C14) was formed. Musculature tissue of six species exhibited significantly lower PFAS concentrations than the respective liver tissue, but with similar PFAS patterns. The comprehensive approach applied in the present study showed, that primarily the trophic class is decisive for the PFAS concentration, as herbivores, omnivores and carnivores clearly differed in their PFAS concentrations and patterns. Additionally, the TOP assay gave novel insights in the PFCA formation potential in biota samples.

Spatiotemporal and life history related trends of per- and polyfluoroalkyl substances in Indo-Pacific finless porpoises from south China sea (2007-2020)

Per- and polyfluoroalkyl substances (PFASs) levels in Indo-Pacific finless porpoises (Neophocaena phocaenoides) in the Pearl River Estuary (PRE), near the most economically developed region in China, have not been characterized. We measured the hepatic concentrations of twelve PFASs, including nine perfluoroalkyl carboxylic acids (PFCAs) and three perfluoroalkane sulfonic acids (PFSAs) in the finless porpoises (n = 21) collected from the PRE between 2007 and 2020. The average level of PFSAs was more than 2-times higher than that of PFCAs. The order of six dominant PFASs was perfluorooctane sulfonate (PFOS) > perfluoroundecanoic acid (PFUdA) > perfluorodecanoic acid (PFDA) > perfluorotridecanoic acid (PFTrDA) > perfluorononanoic acid (PFNA) > perfluorododecanoic acid (PFDoDA). The levels of Hepatic PFOS of 29% samples exceeded the no observable adverse effect level (NOAEL) values. The concentration of PFASs in males was significant higher than in females. PFASs levels were significantly negatively correlated with body length in males and positively correlated in females. PFASs levels in the PRE finless porpoises were lower than in humpback dolphins possibly due to different foraging habitat toward the coast and the consumption of less fish. PFCAs levels in finless porpoises from the western PRE were higher compared to Hong Kong, possibly due to the high-intensity sources of terrestrial anthropogenic pollutants. Significant increasing spatiotemporal trends of PFSAs, PFCAs and PFASs were found in finless porpoises from 2007 to 2020, suggesting a continuously increased risk of PFASs exposure for PRE cetaceans in the last decade.

The Relationship between Typical Environmental Endocrine Disruptors and Kidney Disease

Endocrine disrupting chemicals (EDCs) are exogenous substances that alter the endocrine function of an organism, to result in adverse effects on growth and development, metabolism, and reproductive function. The kidney is one of the most important organs in the urinary system and an accumulation point. Studies have shown that EDCs can cause proteinuria, affect glomeruli and renal tubules, and even lead to diabetes and renal fibrosis in animal and human studies. In this review, we discuss renal accumulation of select EDCs such as dioxins, per- and polyfluoroalkyl substances (PFAS), bisphenol A (BPA), and phthalates, and delineate how exposures to such EDCs cause renal lesions and diseases, including cancer. The regulation of typical EDCs with specific target genes and the activation of related pathways are summarized.

Bioaccumulation and trophic transfer of perfluorinated alkyl substances (PFAS) in marine biota from the Belgian North Sea: Distribution and human health risk implications

Per- and polyfluorinated alkyl substances (PFAS) are highly persistent chemicals, which pose a potential risk for aquatic wildlife due to their bioaccumulative behaviour and toxicological effects. Although the distribution of PFAS in marine environments has been studied worldwide, little is known on the contamination of PFAS in the southern North Sea. In the present study, the bioaccumulation and trophic transfer of Perfluoroalkyl acids (PFAAs) was studied in liver and muscle tissue of seven fish species and in whole-body tissue of two crustacean species, collected at 10 sites in the Belgian North Sea. Furthermore, the human and ecological health risks were examined. Overall, perfluorooctane sulfonate (PFOS) was predominant in all matrices and other long-chain PFAS were frequently detected. Mean PFOS concentrations ranged from <LOQ to 107 ng/g (ww) in fish liver, from <LOQ to 24 ng/g ww in fish muscle and from 0.29 to 5.6 ng/g ww in crustaceans. Elevated perfluorotridecanoic acid (PFTrDA) concentrations were detected in fish liver from the estuarine and coastal region (<LOQ-116 ng/g ww), indicating a specific point source of this compound. Based on stable isotope analysis, no distinctive trophic transfer patterns of PFAS could be identified which implies that the bioconcentration of PFAS from the surrounding abiotic environment is most likely dominating over the biomagnification in the studied biota. The consumption of commercially important species such as the brown shrimp (Crangon crangon), plaice (Pleuronecta platessa), sole (Solea solea) and whiting (Merlangus merlangus) might pose potential health risks if it exceeds 17 g/day, 18 g/day, 26 g/day and 43 g/day respectively. Most PFOS measurements did not exceed the QS_biota,hh of 9.1 ng/g ww, however, the benchmark of 33 ng/g ww targeting the protection of wildlife from secondary poisoning was exceeded for 43% and 28% of the samples in plaice and sole.

The BDNF-TrkB-CREB Signalling Pathway Is Involved in Bisphenol S-Induced Neurotoxicity in Male Mice by Regulating Methylation

Bisphenol S (BPS), the most common substitute for bisphenol A in manufacturing, is associated with neurotoxicity, but its molecular mechanisms are unclear. Here, we studied the role of the BDNF-TrkB-CREB (brain-derived neurotrophic factor-tropomyosin-related kinase B-CAMP response element-binding protein) signalling pathway in bisphenol S-induced neurotoxicity via methylation regulation in male C57BL/6 mice. The mice were treated with sesame oil or 2, 20 and 200 mg/kg body weight BPS for 28 consecutive days, and the hippocampus was extracted. We recorded the body weight, organ index, and hippocampal pathology and ultrastructure of the mice. The BDNF, TrkB, CREB, phosphorylated (p)-CREB, DNMTs (DNA methyltransferases) levels were determined by qRT-PCR and/or Western blotting. BDNF promoter IV methylation level was detected by bisulfite sequencing PCR. BPS damaged the mouse hippocampus ultrastructure and reduced the number of synapses. Further, it increased the methylation rate of BDNF promoter IV; downregulated BDNF, CREB, p-CREB/CREB and DNMT1 expression; and upregulated DNMT3a and DNMT3b expression. Therefore, we speculate that the BDNF-TrkB-CREB pathway may be involved in BPS-induced neurotoxicity in male mice by regulating methylation.

Absorption, distribution, and toxicity of per- and polyfluoroalkyl substances (PFAS) in the brain: a review

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals colloquially known as "forever chemicals" because of their high persistence. PFAS have been detected in the blood, liver, kidney, heart, muscle and brain of various species. Although brain is not a dominant tissue for PFAS accumulation compared to blood and liver, adverse effects of PFAS on brain functions have been identified. Here, we review studies related to the absorption, accumulation, distribution and toxicity of PFAS in the brain. We summarize evidence on two potential mechanisms of PFAS entering the brain: initiating blood-brain barrier (BBB) disassembly through disrupting tight junctions and relying on transporters located at the BBB. PFAS with diverse structures and properties enter and accumulate in the brain with varying efficiencies. Compared to long-chain PFAS, short-chain PFAS may not cross cerebral barriers effectively. According to biomonitoring studies and PFAS exposure experiments, PFAS can accumulate in the brain of humans and wildlife species. With respect to the distribution of PFAS in specific brain regions, the brain stem, hippocampus, hypothalamus, pons/medulla and thalamus are dominant for PFAS accumulation. The accumulation and distribution of PFAS in the brain may lead to toxic effects in the central nervous system (CNS), including PFAS-induced behavioral and cognitive disorders. The specific mechanisms underlying such PFAS-induced neurotoxicity remain to be explored, but two major potential mechanisms based on current understanding are PFAS effects on calcium homeostasis and neurotransmitter alterations in neurons. Based on the information available about PFAS uptake, accumulation, distribution and impacts on the brain, PFAS have the potential to enter and accumulate in the brain at varying levels. The balance of existing studies shows there is some indication of risk in animals, while the human evidence is mixed and warrants further scrutiny.

Role of the BDNF/TrkB/CREB signaling pathway in the cytotoxicity of bisphenol S in SK-N-SH cells

Bisphenol S (BPS) is associated with neurotoxicity, but its molecular mechanisms are unclear. Our aim was to investigate the role of the brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB)/cAMP-response element-binding protein (CREB) signaling pathway in BPS-induced cytotoxicity in SK-N-SH cells. The cells were treated with various concentrations of BPS, and cell viability, apoptosis rate, mitochondrial membrane potential (MMP), and the BDNF, cleaved-caspase-3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), TrkB, CREB, and phospho-CREB (p-CREB) levels were determined. The effects of pretreatment with the TrkB activator 7,8-dihydroxyflavone (7,8-DHF) were also explored. BPS decreased SK-N-SH cell viability and altered their morphology. Their apoptosis rate was increased, as were the levels of the proapoptotic proteins Bax and cleaved-caspase-3, but MMP was decreased. Thus, BPS may induce mitochondria-dependent apoptosis pathways. BPS also reduced the BDNF, TrkB, and p-CREB levels, and pretreatment with 7,8-DHF alleviated its cytotoxic effects. Thus, BPS-induced cytotoxicity might be mediated by the BDNF/TrkB/CREB signaling pathway.

Per- and polyfluoroalkyl substances (PFASs) in contaminated coastal marine waters of the Saudi Arabian Red Sea: a baseline study

Per- and polyfluoroalkyl substances (PFASs) are today considered important constituents of the continuously growing substance group of persistent contaminants of emerging environmental concern (PCEC). Here, we report for the first time the concentrations of 12 relevant PFASs in 28 marine water samples from the Saudi Arabian coastal waters of the Red Sea. The sum levels of 12 PFASs (Σ₁₂ PFAS) in surface seawater ranged from <LOQ to 956 ngL^-1. For the reference background site of this study, Σ₁₂ PFAS levels ranged from <LOQ to 10.9 ng/L. The highest PFAS levels have been found in Al-Arbaeen and Al-Shabab, two lagoons continuously receiving treated sewage effluents. PFHxA, PFHxS, and 6:2 FTS were the most prevalent PFASs with relatively high concentrations. Discharge of municipal and industrial wastewaters is considered an important source of PFASs. The pattern of PFASs observed here suggests that the usage of PFAS-containing aqueous film-forming foams (AFFFs) is a potential additional source for these compounds in Al-Arbaeen and Al-Shabab lagoons. However, a systematic elucidation of local PFASs sources is needed. Contamination of the Red Sea waters with PFASs poses a potential imminent risk to the marine environment of the Red Sea and ultimately may even affect the health of human consumers through the consumption of local seafood.

Stranded cetaceans warn of high perfluoroalkyl substance pollution in the western Mediterranean Sea

Perfluoroalkyl substances (PFASs) are a class of organohalogenated compounds of environmental concern due to similar characteristics as the well-studied legacy persistent organic pollutants (POPs) that typically show environmental persistence, biomagnification and toxicity. Nevertheless, PFAS are still poorly regulated internationally and in many aspects poorly understood. Here, we studied liver and muscle concentrations in five cetacean species stranded at the southeastern coast of Spain during 2009-2018. Twelve of the fifteen targeted compounds were detected in >50% of the liver samples. Hepatic concentrations were significantly higher than those in muscle reflecting the particular toxicokinetics of these compounds. Bottlenose dolphins Tursiops truncatus showed the highest hepatic ΣPFAS (n = 5; 796.8 ± 709.0 ng g^-1 ww) concentrations, followed by striped dolphin Stenella coeruleoalba (n = 29; 259.5 ± 136.2 ng g^-1 ww), sperm whale Physeter macrocephalus (n = 1; 252.8 ng g^-1 ww), short-beaked common dolphin Delphinus delphis (n = 2; 240.3 ± 218.6 ng g^-1 ww) and Risso's dolphin Grampus griseus (n = 1; 78.7 ng g^-1 ww). These interspecies differences could be partially explained by habitat preferences, although they could generally not be related to trophic position or food chain proxied by stable N (δ¹⁵N) and C (δ¹³C) isotope values, respectively. PFAS profiles in all species showed a similar pattern of concentration prevalence in the order PFOS>PFOSA>PFNA≈PFFUnA>PFDA. The higher number of samples available for striped dolphin allowed for evaluating their PFAS burden and profile in relation to the stranding year, stable isotope values, and biological variables including sex and length. However, we could only find links between δ¹⁵N and PFAS burdens in muscle tissue, and between stranding year and PFAS profile composition. Despite reductions in the manufacturing industry, these compounds still appear in high concentrations compared to more than two decades ago in the Mediterranean Sea and PFOS remains the dominating compound.

Scientific Basis for Managing PFAS as a Chemical Class

This commentary presents a scientific basis for managing as one chemical class the thousands of chemicals known as PFAS (per- and polyfluoroalkyl substances). The class includes perfluoroalkyl acids, perfluoroalkylether acids, and their precursors; fluoropolymers and perfluoropolyethers; and other PFAS. The basis for the class approach is presented in relation to their physicochemical, environmental, and toxicological properties. Specifically, the high persistence, accumulation potential, and/or hazards (known and potential) of PFAS studied to date warrant treating all PFAS as a single class. Examples are provided of how some PFAS are being regulated and how some businesses are avoiding all PFAS in their products and purchasing decisions. We conclude with options for how governments and industry can apply the class-based approach, emphasizing the importance of eliminating non-essential uses of PFAS, and further developing safer alternatives and methods to remove existing PFAS from the environment.

Temporal Trends in Per- and Polyfluoroalkyl Substances in Bottlenose Dolphins (Tursiops truncatus) of Indian River Lagoon, Florida and Charleston, South Carolina

Temporal trends in plasma concentrations of per- and polyfluoroalkyl substances (PFAS) in free-ranging bottlenose dolphins (Tursiops truncatus) inhabiting two geographic areas: Indian River Lagoon, Florida over the years 2003-2015 and the waters surrounding Charleston, South Carolina over 2003-2013, were examined. Nine PFAS met the inclusion criteria for analysis based on percent of values below level of detection and sampling years. Proportionate percentiles parametric quantile regression assuming lognormal distributions was used to estimate the average ratio of PFAS concentrations per year for each chemical. Plasma concentrations decreased over time for perfluorodecanoate (PFDA), perfluorohexane sulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluoroundecanoate (PFUnDA) in both locations. Perfluorononanoate (PFNA) decreased with time in Indian River Lagoon dolphins. Perfluorododecanoate (PFDoDA) concentrations significantly increased over time among female Indian River Lagoon dolphins. Regulation and phaseout of specific PFAS groups may have led to the decreasing levels of those PFAS and increasing levels of other replacement PFAS.

Per- and polyfluoroalkyl substances (PFASs) in the blood of two colobine monkey species from China: Occurrence and exposure pathways

Per-/polyfluoroalkyl substances (PFASs), which are widely used in industrial and commercial products, have been identified as global and ubiquitous pollutants. Despite this, limited data are available regarding the impacts of PFAS exposure and intake in non-human primates. Here, we report for the first time on the occurrence of PFASs in the blood and dietary sources of two rare and endangered primate species, namely, the golden snub-nosed monkey (Rhinopithecus roxellana) and Francois' leaf monkey (Trachypithecus francoisi). Results showed that perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were dominant and found at the highest proportions in the blood of both species at the four study sites. The ∑PFAS levels in blood samples from captive golden snub-nosed monkeys in Tongling Zoo (mean: 2.51 ng/mL) and Shanghai Wild Zoo (3.52 ng/mL) near urbanized areas were one order of magnitude higher than the levels in wild monkeys from Shennongjia Nature Reserve (0.27 ng/mL). Furthermore, significant age positive relationships for perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonates (6:2 Cl-PFESA) were observed in both golden snub-nosed monkeys at Shanghai Wild Zoo and Francois' leaf monkeys at Wuzhou Breeding Center. In addition, PFAS levels in frequently consumed food and drinking water were analyzed for Francois' leaf monkeys. Results showed that tree leaves accounted for the highest percentage of total daily intake of PFASs, especially PFOA, thus highlighting tree leaf consumption as a primary PFAS exposure route for this species. Overall, however, dietary exposure to PFASs was of relatively low risk to Francois' leaf monkey health.

Levels and profiles of long-chain perfluoroalkyl carboxylic acids in Pacific cod from 14 sites in the North Pacific Ocean

We investigated the profiles and levels of perfluoroalkyl carboxylic acid (PFCA) contamination in Pacific cod (Gadus macrocephalus) from the North Pacific Ocean. The mean concentrations of PFCAs containing 8 to 14 carbon atoms (C8-C14) in edible Pacific cod muscle ranged from 216 to 670 pg g^-1 wet weight in the Northeast Pacific Ocean (Seattle, Vancouver, Alaska, and Russia), from 819 to 1710 pg g^-1 wet weight in Japanese coastal waters (Hokkaido, Aomori, Iwate, Miyagi, Tottori, and Shimane), and from 288 to 892 pg g^-1 wet weight in Korean waters (Sokcho, Busan, and Yeosu). These results indicate there are geographical differences in the distribution of PFCAs. The long-chain PFCAs (C9-C14) contributed 96% of the total PFCA concentration across Japan, whereas they contributed only 33% of the total PFCA concentration in the USA and Canada. Long-chain PFCA concentrations in cod samples collected in Japanese and Korean waters were about three to four times those in samples from the USA, Canada, and Russia. Because seafood is considered an important dietary source of PFCAs, high concentrations of long-chain PFCAs in Pacific cod from Japanese and Korean waters may affect human dietary exposure and blood concentrations of long-chain PFCAs.

Bioaccumulation behavior and spatiotemporal trends of per- and polyfluoroalkyl substances in Indo-Pacific humpback dolphins from the Pearl River Estuary, China

Sixteen per- and polyfluoroalkyl substances (PFASs) were measured in liver (n = 52) and kidney (n = 18) tissues of Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Estuary (PRE) of China between 2004 and 2016. The average concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and most of other PFASs in the liver samples were respectively greater than any records previously reported in cetaceans globally. PFOS levels in 46% of dolphin liver samples exceeded the hepatic toxicity threshold in cetaceans. For the first time, we found a U-shaped trend for the distribution pattern of perfluorinated carboxylic acids (PFCAs) between liver and kidney with increasing carbon chain lengths (C5-C16), whereas a descending trend (C4-C10) was found for perfluoroalkane sulfonic acids (PFASs), which may be explained by binding efficiencies of PFAS analogues to proteins. Dolphins with the highest levels of ∑PFASs (age-corrected) were clustered near the river outlets in Lingdingyang area, which agrees with the spatial distribution of PFASs in the environment. Significant temporal trends were observed for many PFASs. Concentrations of PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroheptanoic acid (PFHpA) all peaked in year 2011, followed by a decreasing trend, while a consistently descending trend was shown for perfluoroundecanoic acid (PFUdA) and perfluorodecane sulfonate (PFDS). Our findings contribute to the knowledge of tissue distribution and spatiotemporal trends of PFASs in the PRE dolphins, which are valuable for us to understand the PFASs exposure risk and their industrial emission in Southern China.

Perfluorinated Alkyl Acids in Hawaiian Cetaceans and Potential Biomarkers of Effect: Peroxisome Proliferator-Activated Receptor Alpha and Cytochrome P450 4A

Perfluorinated alkyl acids (PFAAs) are persistent in marine biota and are toxic to many species, including marine mammals. We measured the concentrations of 15 PFAAs in liver and kidney samples of 16 species of stranded cetaceans from Hawai'i and other tropical North Pacific regions utilizing high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Eleven PFAAs in liver and nine PFAAs in kidney were detected, including substantial perfluorooctanesulfonate (PFOS) and perfluoroundecanoic acid (PFUnA). Regression models indicated that phylogenetic family and age class significantly influenced concentrations of certain PFAAs. PFAAs can activate transcription factor peroxisome proliferator-activated receptor alpha (PPARα), which induces transcription of cytochrome P450 4A (CYP4A). Relative expression of PPARα and CYP4A mRNA was quantified using real-time PCR (qPCR) and CYP4A protein expression, using Western blot and then compared to PFAA concentrations in liver and kidney. Concentrations of four PFAA congeners, summation of perfluoroalkyl carboxylic acids (ΣPFCAs), and ΣPFAAs correlated significantly with PPARα mRNA expression and CYP4A protein expression in kidney, suggesting either may be biomarkers of PFAA exposure in cetaceans. This is the first study to quantify PFAAs in marine mammals from this region and the first observation of a direct relationship between PFAA exposure and PPARα and CYP4A expression in cetaceans.

Tissue-specific bioaccumulation of long-chain perfluorinated carboxylic acids and halogenated methylbipyrroles in Dall's porpoises (Phocoenoides dalli) and harbor porpoises (Phocoena phocoena) stranded in northern Japan

This study investigated accumulation of perfluoroalkyl substances (PFASs), persistent organochlorines (OCs), and naturally produced halogenated compounds (NHCs), including brominated methylbipyrroles and methoxylated bromodiphenyl ethers, in liver, blood, and blubber from Dall's porpoises (Phocoenoides dalli) and harbor porpoises (Phocoena phocoena) stranded in Hokkaido, northern Japan. Profiles of the PFASs were dominated by perfluoroundecanoic acid and perfluorotridecanoic acid, both of which accounted for 70% of the total measured PFAS concentrations in both porpoise species. The mean concentrations of the ∑PFCA were 573ng/g wet weight (ng/g-wet) in liver, 62ng/g-wet in whole blood, and 28ng/g-wet in blubber from the Dall's porpoises, and were significantly higher (p<0.05) than those in the harbor porpoises. The hepatic concentrations of perfluorooctane sulfonate (PFOS) were <14ng/g-wet, and accounted for only 3% of the total measured PFASs. The profiles of PFASs in the porpoises resembled those in fish species in this area, implying a common source of exposure to PFASs in East Asia. On the other hand, in the blubber of Dall's porpoises, NHCs were dominated by 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (867ng/g-wet), 5,5'-dichloro-1,1'-dimethyl-3,3',4,4'-tetrabromo-2,2'-bipyrrole (481ng/g-wet), and 6-methoxy-2,2',4,4'-tetrabromodiphenyl ether (30ng/g-wet), which were present at higher concentrations than in harbor porpoises. Factor analysis with varimax rotation revealed that factor 1 had higher eigenvectors (element in eigenvalues) for long-chain PFCAs and PFOS, which was found in the highest concentrations in the liver, whereas factor 2 was mainly associated with lipid soluble NHCs and OCs in both species. No correlations were observed between long-chain PFCAs and NHCs in the porpoises, probably because of the different sources and accumulation kinetics. Future research should assess the temporal trends and long-term effects of PFASs and NHCs in the tissues of mammals from the Asia-Pacific region.

Occurrence and Tissue Distribution of Novel Perfluoroether Carboxylic and Sulfonic Acids and Legacy Per/Polyfluoroalkyl Substances in Black-Spotted Frog (Pelophylax nigromaculatus)

Research on perfluoroalkyl substances (PFASs) continues to grow. However, very little is known about these substances in amphibians. Here we report for the first time on the occurrence, tissue distribution, and bioaccumulation of two novel PFASs, chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) and hexafluoropropylene oxide trimer acid (HFPO-TA), in the black-spotted frog (Pelophylax nigromaculatus) from China. Frogs from cities with large-scale fluorochemical industries had significantly greater liver ∑PFAS levels (mean 54.28 ng/g in Changshu; 31.22 ng/g in Huantai) than those from cities without similar industry (9.91 ng/g in Zhoushan; 7.68 ng/g in Quzhou). Females had significantly lower liver PFAS levels than males, and older frogs tended to have lower PFAS levels than younger frogs. Skin, liver, and muscle contributed nearly 80% to the whole body burden of 6:2 Cl-PFESA in males, whereas the female ovary alone accounted for 58.4%. These results suggest substantial maternal transfer of 6:2 Cl-PFESA to eggs, raising concern regarding its developmental toxicity on frogs and other species. The bioaccumulation factor results (6:2 Cl-PFESA > PFOS; HFPO-TA > PFOA) suggest a stronger accumulative potential in the black-spotted frog for these alternative substances compared to their predecessors. Future studies on their toxicity and ecology risk are warranted.

Species-specific profiles and risk assessment of perfluoroalkyl substances in coral reef fishes from the South China Sea

The contamination profiles of sixteen perfluoroalkyl substances (PFAS) were examined in coral reef fish samples collected from the South China Sea (SCS) where no information about this topic was available in the literature. The results revealed that six PFAS were found in coral reef fish samples from the SCS. Perfluorooctane sulfonate (PFOS) was the most predominant PFAS contaminant detected in most of the samples, with the highest concentration value of 27.05 ng/g wet weight (ww) observed in Cephalopholis urodelus. Perfluoroundecanoic acid (PFUnDA) and Perfluorotridecanoic acid (PFTrDA) were the second and third dominant PFAS, respectively. Mean PFOS concentrations in muscle of seven coral reef fish varied from 0.29 ng/g ww in Lethrinus olivaceus to 10.78 ng/g ww in Cephalopholis urodelus. No significant linear relationship was observed between PFOS levels and coral reef fish traits (length, weight) collected in this region. Average daily intake of PFOS for the seven coral reef fishes ranged from 0.79 ng/kg/d for Lethrinus olivaceus to 29.53 ng/kg/d for Cephalopholis urodelus. The hazard ratio (HR) values for human consumption of PFOS-contaminated coral reef fishes ranged from 0.04 to 1.48, with Cephalopholis urodelus having the highest HR value of 1.18 (higher than 1) among the species, indicating frequent consumption of Cephalopholis urodelus might pose potential health risk to local population. The present work have provided the first hand data of PFAS in coral reef fishes in the SCS and indirectly demonstrated the existence of low level PFAS pollution in the SCS in China.

Perfluoroalkyl Substances (PFASs) in Marine Mammals from the South China Sea and Their Temporal Changes 2002-2014: Concern for Alternatives of PFOS?

Perfluorinated sulfonic acids (PFSAs) and perfluorinated carboxylic acids (PFCAs), as well as the replacement for the phase-out C8 PFSAs were determined in the liver samples of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from the South China Sea between 2002 and 2014. Levels of total perfluoroalkyl substances (PFASs) in samples ranged from 136-15,300 and 30.5-2,720 ng/g dw for dolphin and porpoise, respectively. Significant increasing trends of several individual PFCAs and perfluorobutane sulfonate (PFBS) were found in cetacean samples from 2002 to 2014, whereas no significant temporal trends of ∑PFASs appeared over the sampling period. This pattern may be attributed to the increasing usage of PFCAs and C4-based PFSAs following the restriction/voluntary withdrawal of the production and use of perfluorooctane sulfonate (PFOS) related products. In addition, significantly increasing temporal shifting trends of PFOS to PFBS were observed in the dolphin liver samples. This pattern may be attributed to the substitution of PFOS by its alternative, PFBS. The highest levels of PFOS were observed in the liver samples of dolphin as compared with other marine mammal studies published since 2006, indicating high contamination of PFAS in the South China region. An assessment of relatively high concentrations of C8-based PFASs in the liver samples of cetaceans predicted that concentrations of PFOS would be expected to affect some proportion of the cetacean populations studied, based on the toxicity thresholds derived.

How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances

This review examines the usefulness of the metrics BMF (biomagnification factor) and TMF (trophic magnification factor), derived from field measurements of the levels of contaminants in naturally occurring biota, for characterizing the bioaccumulation potential ("B") of chemicals. Trophic magnification factor and BMF values greater than 1.0 are often considered to be the most conclusive indicators of B status, and the TMF criterion has been referred to as the "gold standard" for B categorization. Although not wishing to dispute the theoretical primacy of field-derived BMFs and TMFs as B metrics, we make the case that, in practice, the study-to-study (and even within-study) variability of the results is so great that they are of very restricted usefulness for assessing B status, at least in the case of the per- and polyfluoroalkyl substances (PFASs), on which we focus here. This conclusion is based on an analysis of the results of 24 peer-reviewed studies reporting field-derived BMFs or TMFs for 14 PFASs, for which BMF values often range over several orders of magnitude from <<1.0 to >>1.0, sometimes even in the same study. For TMFs, the range is a factor of approximately 20 for the most intensely studied PFASs (perfluorooctanoic acid [PFOA] and perfluorooctanesulfonic acid [PFOS]). We analyze the possible causes for such variability: To some extent it results from the differing ways in which the metrics are expressed, but most of the scatter is likely attributable to such factors as nonachievement of the tacitly assumed steady-state conditions, uncertainties in the feeding ecology, the impact of metabolism of precursor compounds, and so forth. As more trustworthy alternatives to field-derived BMFs and TMFs, we suggest the implementation of dietary BMF studies performed under strictly controlled conditions on aquatic, terrestrial, and avian species, as well as the consideration of measured elimination half-lives, which have been demonstrated to be directly related to BMF values.

Toxic heritage: Maternal transfer of pyrethroid insecticides and sunscreen agents in dolphins from Brazil

Pyrethroids (PYR) and UV filters (UVF) were investigated in tissues of paired mother-fetus dolphins from Brazilian coast in order to investigate the possibility of maternal transfer of these emerging contaminants. Comparison of PYR and UVF concentrations in maternal and fetal blubber revealed Franciscana transferred efficiently both contaminants to fetuses (F/M > 1) and Guiana dolphin transferred efficiently PYR to fetuses (F/M > 1) different than UVF (F/M < 1). PYR and UVF concentrations in fetuses were the highest-ever reported in biota (up to 6640 and 11,530 ng/g lw, respectively). Muscle was the organ with the highest PYR and UVF concentrations (p < 0.001), suggesting that these two classes of emerging contaminants may have more affinity for proteins than for lipids. The high PYR and UVF concentrations found in fetuses demonstrate these compounds are efficiently transferred through placenta. This study is the first to report maternal transfer of pyrethroids and UV filters in marine mammals.

Repeated dose and reproductive/developmental toxicity of perfluorododecanoic acid in rats

Perfluoroalkyl carboxylic acids (PFCAs) are a series of environmental contaminants that have received attention because of their possible adverse effects on wildlife and human health. Although many toxicological studies have been performed on perfluorooctanoic acid with carbon chain length C8, available toxicity data on PFCAs with longer chains are still insufficient to evaluate their hazard. A combined repeated dose and reproductive/developmental toxicity screening study for perfluorododecanoic acid (PFDoA; C12) was conducted in accordance with OECD guideline 422 to fill these toxicity data gaps. PFDoA was administered by gavage to male and female rats at 0.1, 0.5, or 2.5 mg/kg/day. The administration of PFDoA at 0.5 and 2.5 mg/kg/day for 42-47 days mainly affected the liver, in which hypertrophy, necrosis, and inflammatory cholestasis were noted. Body weight gain was markedly inhibited in the 2.5 mg/kg/day group, and a decrease in hematopoiesis in the bone marrow and atrophic changes in the spleen, thymus, and adrenal gland were also observed. Regarding reproductive/developmental toxicity, various histopathological changes, including decreased spermatid and spermatozoa counts, were observed in the male reproductive organs, while continuous diestrous was observed in the females of the 2.5 mg/kg/day group. Seven of twelve females receiving 2.5 mg/kg/day died during late pregnancy while four other females in this group did not deliver live pups. No reproductive or developmental parameters changed at 0.1 or 0.5 mg/kg/day. Based on these results, the NOAELs of PFDoA were concluded to be 0.1 mg/kg/day for repeated dose toxicity and 0.5 mg/kg/day for reproductive/developmental toxicity.

Perfluoroalkyl sulfonates and carboxylic acids in liver, muscle and adipose tissues of black-footed albatross (Phoebastria nigripes) from Midway Island, North Pacific Ocean

The Great Pacific Garbage Patch (GPGP) is a gyre of marine plastic debris in the North Pacific Ocean, and nearby is Midway Atoll which is a focal point for ecological damage. This study investigated 13 C4-C16 perfluorinated carboxylic acids (PFCAs), four (C4, C6, C8 and C10) perfluorinated sulfonates and perfluoro-4-ethylcyclohexane sulfonate [collectively perfluoroalkyl acids (PFAAs)] in black-footed albatross tissues (collected in 2011) from Midway Atoll. Of the 18 PFCAs and PFSAs monitored, most were detectable in the liver, muscle and adipose tissues. The concentrations of PFCAs and PFSAs were higher than those in most seabirds from the arctic environment, but lower than those in most of fish-eating water birds collected in the U.S. mainland. The concentrations of the PFAAs in the albatross livers were 7-fold higher than those in Laysan albatross liver samples from the same location reported in 1994. The concentration ranges of PFOS were 22.91-70.48, 3.01-6.59 and 0.53-8.35 ng g(-1) wet weight (ww), respectively, in the liver, muscle and adipose. In the liver samples PFOS was dominant, followed by longer chain PFUdA (8.04-18.70 ng g(-1) ww), PFTrDA, and then PFNA, PFDA and PFDoA. Short chain PFBA, PFPeA, PFBS and PFODA were below limit of quantification. C8-C13 PFCAs showed much higher composition compared to those found in other wildlife where PFOS typically predominated. The concentrations of PFUdA in all 8 individual albatross muscle samples were even higher than those of PFOS. This phenomenon may be attributable to GPGP as a pollution source as well as PFAA physicochemical properties.

Occurrence and assessment of perfluorinated compounds in fish from the Danjiangkou reservoir and Hanjiang river in China

Residues of eight perfluorinated compounds (PFCs) were investigated in 15 fish samples from the Danjiangkou reservoir and Hanjiang river (Xiangyang and Zhongxiang sections). The total concentrations of PFCs in fish muscles ranged from 2.01 to 43.8 ng g(-)(1) dry weight. The mean concentration of total PFCs from related muscles showed the following trend in various regions: Zhongxiang section < Xiangyang section < Danjiangkou reservoir. Perfluorooctane sulphonate (PFOS) was the dominant PFC in the fish liver samples from the Danjiangkou reservoir. The calculated hazard ratio (HR) of PFCs, for all fish muscle samples, was less than 1.0, and could be classified at safe levels for the general population. However, yellow croaker fish from the Danjiangkou reservoir and Hanjiang river-Xiangyang section had HRs of 0.2, indicating that frequent consumption of this contaminated fish may pose an unacceptable risk to human health.

Distribution of perfluoroalkyl substances (PFASs) with isomer analysis among the tissues of aquatic organisms in Taihu Lake, China

The distribution of perfluoroalkyl substances (PFASs) and the isomers of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) was investigated among various tissues (including muscle, gill, kidney, liver) and eggs, in aquatic organisms in Taihu Lake, China. Highest concentration of ΣPFASs was mostly found in liver (278-685 ng/g ww) and eggs (66.0-467 ng/g ww) while the lowest was in muscle (40.6-165 ng/g ww). n-PFOS was the predominant PFOS isomer in most of the tissues with a proportion of 46.3-96.5%. Ratios of PFAS concentrations in eggs to those in liver (E/L) increased positively with the protein-water partition coefficient. The E/L of PFOS isomers descended in the order: linear > monomethyl > diperfluoromethyl isomers. The liver/muscle and kidney/muscle ratios of n-PFOS were higher than branched isomers, suggesting that n-PFOS has higher binding affinity with hepatic proteins or branched isomers are preferentially excreted though liver and kidney.

Bioaccumulation and risk assessment of per- and polyfluoroalkyl substances in wild freshwater fish from rivers in the Pearl River Delta region, South China

Per- and polyfluoroalkyl substances (PFASs) are used in various industries, which results in their ubiquitous occurrence in the environment. This study determined the concentrations of eighteen PFASs in muscle and liver of nine wild freshwater fish species collected from rivers in the Pearl River Delta (PRD) region, South China, and assessed their bioaccumulation and potential health risks to local people. The results showed that eight and twelve PFASs were detected in the fish muscle and liver samples, respectively. Perfluorooctane sulfonate (PFOS) was found to be the predominant PFAS both in muscle and liver with its highest concentrations of 79ng/g wet weight (ww) in muscle and 1500ng/g ww in liver, followed by Perfluoroundecanoic acid (PFUnDA) and Perfluorotridecanoic acid (PFTrDA) with trace concentrations. The mean PFOS concentrations in fish muscle and liver tissues of the nine collected species ranged from 0.40ng/g in mud carp to 25ng/g in snakehead, and from 5.6ng/g in mud carp to 1100ng/g in snakehead, respectively. Significant positive correlations were found among PFASs both in water and fish, indicating a similar pollution source for these PFASs. In tilapia samples, PFOS concentrations showed an increasing trend with increasing length and weight, but no significant difference between genders. Bioaccumulation factors (logBAF) in fish for the PFASs were in the range from 2.1 to 5.0. The calculated hazard ratios (HR) of PFOS for all fishes were in the range of 0.05-2.8, with four out of nine species (tilapia, chub, leather catfish and snakehead) having their HR values more than 1.0. The results suggest that frequent consumption of these four fish species may pose health risks to local population.

PFAS profiles in three North Sea top predators: metabolic differences among species?

Profiles of seven compounds of perfluoro-alkyl substances (PFASs) were compared among three species of top predators from the Danish North Sea: the white-beaked dolphin (Lagenorhynchus albirostris), the harbor porpoise (Phocoena phocoena), and the harbor seal (Phoca vitulina). The seals had higher total burdens (757.8 ng g(-1) ww) than the dolphins (439.9 ng g(-1) ww) and the porpoises (355.8 ng g(-1) ww), probably a reflection of feeding closer to the shore and thus contamination sources. The most striking difference among the species was the relative contribution of perfluorooctanesulfonamide (PFOSA) to the profiles; the seals (0.1%) had much lower levels than porpoises (8.3%) and dolphins (26.0%). In combination with the values obtained from the literature, this result indicates that Carnivora species including Pinnipedia have a much higher capacity of transforming PFOSA to perfluorooctane sulfonic acid (PFOS) than cetacean species. Another notable difference among the species was that the two smaller species (seals and porpoises) with supposedly higher metabolic rates had lower concentrations of the perfluorinated carboxylic acids, which are generally more easily excreted than perfluorinated sulfonamides. Species-specific characteristics should be recognized when PFAS contamination in marine mammals is investigated, for example, several previous studies of PFASs in cetaceans have not quantified PFOSA.

Bioaccumulation of perfluoroalkyl carboxylates (PFCAs) and perfluoroalkane sulfonates (PFSAs) by earthworms (Eisenia fetida) in soil

Earthworms were exposed to artificially contaminated soils with ten perfluoroalkyl substances (PFASs). PFASs with longer perfluorinated carbon chain displayed higher uptake rate coefficients (k(u)), longer half-life (t(½)) and time to steady-state (t(ss)) but lower elimination rate coefficients (k(e)) than the shorter ones. Similarly, perfluorosulfonates acids (PFSAs) displayed higher ku, longer t(½) and tss but lower ke than perflurocarboxylic acids (PFCAs) with the same perfluorinated chain length. All the studied PFASs, including those with seven or less perfluorinated carbons, were bioaccumulated in the earthworms and the biota-to-soil accumulation factors (BSAFs) increased with perfluorinated carbon chain length and were greater for PFSAs than for PFCAs of equal perfluoroalkyl chain length. The BSAFs were found to be dependent on the concentrations of PFASs in soil and decreased as the level of PFASs in soil increased.

Age- and gender-related accumulation of perfluoroalkyl substances in captive Chinese alligators (Alligator sinensis)

Fourteen perfluoroalkyl substances (PFASs) were measured in serum of the highly endangered captive Chinese alligators, whole body homogenates of six kinds of fish (alligator prey species), and pond water (alligator habitat) in the Anhui Research Center for Chinese Alligator Reproduction. Six PFASs, including PFOS and five perfluorinated carboxylates, were detected in all alligator samples. The most dominant PFAS was PFUnDA, with a mean value of 31.4 ng/mL. Significant positive correlations were observed among the six PFASs, suggesting that they shared similar sources of contamination. Significantly higher PFOS and PFUnDA levels were observed in males, but the other four PFCAs did not differ between genders. An age related PFAS bioaccumulation analysis showed a significant negative correlation of the concentrations for five PFCAs to age, which means that higher concentrations were found in younger animals. Bioaccumulation factors (BAF) in fish for PFASs ranged from 21 to 28,000, with lower BAF for PFOA than that for longer carbon chain PFCAs, including PFUnDA, PFDA, and PFNA.

Brain region distribution and patterns of bioaccumulative perfluoroalkyl carboxylates and sulfonates in east greenland polar bears (Ursus maritimus)

The present study investigated the comparative accumulation of perfluoroalkyl acids (PFAAs) in eight brain regions of polar bears (Ursus maritimus, n = 19) collected in 2006 from Scoresby Sound, East Greenland. The PFAAs studied were perfluoroalkyl carboxylates (PFCAs, C(6) -C(15) chain lengths) and sulfonates (C(4) , C(6) , C(8) , and C(10) chain lengths) as well as selected precursors including perfluorooctane sulfonamide. On a wet-weight basis, blood-brain barrier transport of PFAAs occurred for all brain regions, although inner regions of the brain closer to incoming blood flow (pons/medulla, thalamus, and hypothalamus) contained consistently higher PFAA concentrations compared to outer brain regions (cerebellum, striatum, and frontal, occipital, and temporal cortices). For pons/medulla, thalamus, and hypothalamus, the most concentrated PFAAs were perfluorooctane sulfonate (PFOS), ranging from 47 to 58 ng/g wet weight, and perfluorotridecanoic acid, ranging from 43 to 49 ng/g wet weight. However, PFOS and the longer-chain PFCAs (C(10) -C(15) ) were significantly (p < 0.002) positively correlated with lipid content for all brain regions. Lipid-normalized PFOS and PFCA (C(10) -C(15) ) concentrations were not significantly (p > 0.05) different among brain regions. The burden of the sum of PFCAs, perfluoroalkyl sulfonates, and perfluorooctane sulfonamide in the brain (average mass, 392 g) was estimated to be 46 µg. The present study demonstrates that both PFCAs and perfluoroalkyl sulfonates cross the blood-brain barrier in polar bears and that wet-weight concentrations are brain region-specific.

Tissue-specific concentrations and patterns of perfluoroalkyl carboxylates and sulfonates in East Greenland polar bears

Several perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) of varying chain length are bioaccumulative in biota. However, wildlife reports have focused on liver and with very little examination of other tissues, and thus there is a limited understanding of their distribution and potential effects in the mammalian body. In the present study, the comparative accumulation of C(6) to C(15) PFCAs, C(4), C(6), C(8) and C(10) PFSAs, and select precursors were examined in the liver, blood, muscle, adipose, and brain of 20 polar bears (Ursus maritimus) from Scoresby Sound, Central East Greenland. Overall, PFSA and PFCA concentrations were highest in liver followed by blood > brain > muscle ≈ adipose. Liver and blood samples contained proportionally more of the shorter/medium chain length (C(6) to C(11)) PFCAs, whereas adipose and brain samples were dominated by longer chain (C(13) to C(15)) PFCAs. PFCAs with lower lipophilicities accumulated more in the liver, whereas the brain accumulated PFCAs with higher lipophilicities. The concentration ratios (±SE) between perfluorooctane sulfonate and its precursor perfluorooctane sulfonamide varied among tissues from 9 (±1):1 (muscle) to 36 (±7):1 (liver). PFCA and PFSA patterns in polar bears indicate that the pharmacokinetics of these compounds are to some extent tissue-specific, and are the result of several factors that may include differing protein interactions throughout the body.

Temporal trends and spatial differences of perfluoroalkylated substances in livers of harbor porpoise (Phocoena phocoena) populations from Northern Europe, 1991-2008

Long-term temporal trends (1991-2008) and spatial differences of perfluoroalkylated substances (PFASs) were investigated in harbor porpoise (Phocoena phocoena) liver samples of juvenile females from the Baltic and North Sea. Additionally, spatial differences between the populations in the Baltic Sea and Atlantic Ocean (i.e. Iceland and Norway) and the influence of the body mass, age and sex on the PFAS concentrations were examined. Perfluorooctane sulfonate (PFOS) was the predominant compound with a concentration range of 160-2425 ng/g wet weight (ww), followed by perfluorooctane sulfonamide (PFOSA, 1-237 ng/g ww) and perfluoroundecanoate (PFUnA, 3-124 ng/g ww). In terms of temporal trends, perfluoroalkyl sulfonates (PFSAs) and PFOSA concentrations decreased over time, while, conversely, the C(9)-C(13) perfluoroalkyl carboxylate (PFCA) concentrations increased. Spatial distribution of the contaminant concentrations showed consistently higher concentrations in the Baltic Sea and lowest concentrations in the Icelandic population of the Atlantic Ocean.

Comparative tissue and body compartment accumulation and maternal transfer to eggs of perfluoroalkyl sulfonates and carboxylates in Great Lakes herring gulls

The comparative accumulation of C(4)-C(15) perfluorinated sulfonates (PFSAs) and carboxylates (PFCAs), and several precursors (e.g., perfluorooctane sulfonamide, N-methyl-FOSA, and fluorotelomer unsaturated acids and alcohols) was examined in tissues (liver, brain, muscle, and adipose), plasma/red blood cells (RBCs) and whole egg clutches (yolk and albumen) of female herring gulls collected in 2010 from Chantry Island, Lake Huron of the Laurentian Great Lakes. Highest mean ∑PFSA concentrations were in yolk, followed by adipose, liver, plasma, muscle, RBCs, and brain. Highest mean ∑PFCA concentrations were in yolk, followed by brain, plasma, liver, RBC, adipose and muscle. PFOS accounted for >88% of ∑PFSA in all samples; the liver, plasma/RBCs, muscle and adipose PFCA patterns were dominated by C(8)-C(11) PFCAs, whereas C(10)-C(15) PFCAs in brain and yolk. Among PFSAs and PFCAs there is tissue-specific accumulation, which could be due to a number of pharmacokinetic processes.

Assessment of perfluorinated compounds (PFCs) in plasma of bottlenose dolphins from two southeast US estuarine areas: relationship with age, sex and geographic locations

Plasma PFCs were measured in 157 bottlenose dolphins (Tursiops truncatus) sampled from two US southeast Atlantic sites (Charleston (CHS), SC and Indian River Lagoon (IRL), FL) during 2003-2005. ∑PFCs, perfluoroalkyl carboxylates (∑PFCAs), perfluoroalkyl sulfonates (∑PFSAs) and individual compounds were significantly higher in CHS dolphins for all age/sex categories compared to IRL dolphins. Highest ∑PFCs concentrations occurred in CHS juvenile dolphins (2340 ng/g w.w.); significantly higher than found in adults (1570 ng/g w.w. males; 1330 ng/g w.w. females). ∑PFCAs were much greater in CHS dolphins (≈ 21%) compared to IRL dolphins (≈ 7%); ∑PFSAs were 79% in CHS dolphins versus 93% in IRL dolphins. PFOS, the dominant compound, averaged 72% and 84%, respectively, in CHS and IRL dolphins. Decreasing PFC levels occurred with age on the bioaccumulation of PFCs in both sites. These observations suggest PFC accumulation in these two dolphin populations are influenced by site-specific exposures with significantly higher levels in CHS dolphins.

Monitoring of perfluorinated compounds in aquatic biota: an updated review

The goal of this article is to summarize new biological monitoring information on perfluorinated compounds (PFCs) in aquatic ecosystems (post-2005) as a followup to our critical review published in 2006. A wider range of geographical locations (e.g., South America, Russia, Antarctica) and habitats (e.g., high-mountain lakes, deep-ocean, and offshore waters) have been investigated in recent years enabling a better understanding of the global distribution of PFCs in aquatic organisms. High concentrations of PFCs continue to be detected in invertebrates, fish, reptiles, and marine mammals worldwide. Perfluorooctane sulfonate (PFOS) is still the predominant PFC detected (mean concentrations up to 1900 ng/g ww) in addition to important concentrations of long-chain perfluoroalkyl carboxylates (PFCAs; sum PFCAs up to 400 ng/g ww). More studies have evaluated the bioaccumulation and biomagnification of these compounds in both freshwater and marine food webs. Several reports have indicated a decrease in PFOS levels over time in contrast to PFCA concentrations that have tended to increase in tissues of aquatic organisms at many locations. The detection of precursor metabolites and isomers has become more frequently reported in environmental assessments yielding important information on the sources and distribution of these contaminants. The integration of environmental/ecological characteristics (e.g., latitude/longitude, salinity, and/or trophic status at sampling locations) and biological variables (e.g., age, gender, life cycle, migration, diet composition, growth rate, food chain length, metabolism, and elimination) are essential elements in order to adequately study the environmental fate and distribution of PFCs and should be more frequently considered in study design.

Temporal and life history related trends of perfluorochemicals in harbor porpoises from the Danish North Sea

Eighty-five stranded or bycaught harbor porpoises collected from the Danish North Sea between 1980 and 2005 were analyzed for perfluorochemicals in the liver. PFOS was the predominant compound, making up on average 88.9% of the ∑PFC, followed by PFOSA (7.8%). PFUnA (1.9%) and PFDA (1.2%) were detected in most samples. PFHxS, PFNA and PFOA were only found in a minority of the samples. We found substantial differences in PFC concentrations among life history stages, the highest concentrations were found in neonates, suckling juveniles and lactating females. Such differences should be considered when PFC levels in wildlife are evaluated. The high concentrations found in young porpoises are of concern as PFCs have known toxic effects on the development of the central nervous system and reproductive organs. Despite efforts to reduce PFC emissions, a decreasing temporal trend of concentrations was not detected for any compound. PFCA concentrations were found to be increasing.

Perfluorinated compounds in minke whales (Balaenoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) from Korean coastal waters

This is the first study to report the concentrations and accumulation profiles of PFCs in marine mammals from Korea. The concentrations and profiles of 10 PFCs in the liver of minke whales and common dolphins from Korean coastal waters were recorded in this study. The mean concentrations of PFOS and PFUnDA were 3-20 times higher than that found for other PFCs analyzed. The concentrations of PFOS in cetaceans from Korea were relatively lower than those reported in other countries. Inter-species differences in the concentrations of PFOS, PFOSA and PFNA were found between two cetacean species, while no difference was observed in the concentrations of PFDA, PFUnDA and PFDoDA between the species. The dominant PFC compounds found in cetaceans were PFUnDA and PFOS, accounting for 70-80% of the PFCs. The accumulation profiles and correlation analysis indicated that two cetacean species have different exposure routes and metabolic capacity for PFCs.

Tissue distribution and maternal transfer of poly- and perfluorinated compounds in Chinese sturgeon (Acipenser sinensis): implications for reproductive risk

It is critical to investigate the tissue distribution and maternal transfer of poly- and perfluorinated compounds (PFCs) in wild fish for assessing potential effects on ecosystems. Concentrations of 23 PFCs in nine organs and egg were measured in 16 17- to 25-year-old female Chinese sturgeon (Acipenser sinensis, an anadromous fish), that died during propagation. Three polyfluorinated amides were detected in stomach, intestine, and gills and 7:3 FTCA was specifically accumulated in liver. The greatest total concentration of PFCs in egg was 35.1 +/- 10.4 ng/g ww and was predominated by perfluorooctane sulfonate (PFOS) and perfluorotridecanoate acid (PFTriDA). The longer-chain C(11)-C(14) and C(16) perfluorinated carboxylates were more accumulated in Chinese sturgeon than PFOS, partly due to the increasing trends of PFCAs with fish age. Maternal transfer ratios of PFCs expressed as ratios of concentrations in the egg to those in the liver ranged from 0.79 (perfluorooctanoate) to 5.5 (PFTriDA), depending on their carbon chain lengths or protein-water coefficients. The PFOS equivalent of PFC mixtures, calculated by multiplying the relative potency factor of each PFC to PFOS by the corresponding concentration, ranged from 90.6 to 262 ng/g. The hazard quotient was 0.20, implying potential reproductive effects of PFCs on Chinese sturgeon.

Perfluorododecanoic acid-induced steroidogenic inhibition is associated with steroidogenic acute regulatory protein and reactive oxygen species in cAMP-stimulated Leydig cells

Perfluorododecanoic acid (PFDoA) can be detected in environmental matrices and human serum and has been shown to inhibit testicular steroidogenesis in rats. However, the mechanisms that are responsible for the toxic effects of PFDoA remain unknown. The aims of this study were to investigate the mechanism of steroidogenesis inhibition by PFDoA and to identify the molecular target of PFDoA in Leydig cells. The effects of PFDoA on steroid synthesis in Leydig cells were assessed by radioimmunoassay. The expression of key genes and proteins in steroid biosynthesis was determined by real-time PCR and Western blot analysis. Reactive oxygen species (ROS) and hydrogen peroxide (H(2)O(2)) levels were determined using bioluminescence assays. PFDoA inhibited adenosine 3',5'-cyclophosphate (cAMP)-stimulated steroidogenesis in mouse Leydig tumor cells (mLTC-1) and primary rat Leydig cells in a dose-dependent manner. However, PFDoA (1-100 microM) did not exhibit effects on cell viability and cellular ATP levels in mLTC-1 cells. PFDoA inhibited steroidogenic acute regulatory protein (StAR) promoter activity and StAR expression at the messenger RNA (mRNA) and protein levels but did not affect mRNA levels of peripheral-type benzodiazepine receptor, cholesterol side-chain cleavage enzyme, or 3beta-hydroxysteroid dehydrogenase in cAMP-stimulated mLTC-1 cells. PFDoA treatment also resulted in increased levels of mitochondrial ROS and H(2)O(2). After excessive ROS and H(2)O(2) were eliminated in PFDoA-treated mLTC-1 cells by MnTMPyP (a superoxide dismutase analog), progesterone production was partially restored and StAR mRNA and protein levels were partially recovered. These data show that PFDoA inhibits steroidogenesis in cAMP-stimulated Leydig cells by reducing the expression of StAR through a model of action involving oxidative stress.

Branched perfluorooctane sulfonate isomer quantification and characterization in blood serum samples by HPLC/ESI-MS(/MS)

Perfluorooctane sulfonate (PFOS) is a global contaminant and is currently among the most prominent contaminants in human blood and wildlife samples. Although "total PFOS" (SigmaPFOS) analytical methods continue to be the most commonly used for quantification, recent analytical method developments have made it possible to resolve the various isomers of PFOS by HPLC-MS/MS. Characterized technical PFOS standards (i.e., containing a mixture of PFOS isomers) are now available that enable isomer specific quantification of PFOS, however the advantages of such an analysis have notyet been examined systematically. Herein, PFOS isomers have been individually quantified for the first time in real samples and the results are compared to a traditional SigmaPFOS method; the influence of analytical standards and isomer specific electrospray and MS/ MS behavior were also investigated. The two human serum standard reference materials chosen for analysis contained dramaticallydifferent PFOS isomer profiles (approximately 30-50% total branched isomers) emphasizing that isomer patterns should not be ignored and may provide useful information on exposure sources (i.e., direct exposure to PFOS vs indirect exposure from PFOS-precursors). Depending on the sample and the particular MS/MS transition chosen for SigmaPFOS analysis (i.e., 499-->80 or 499-->99), SigmaPFOS concentrations may be over- or underestimated compared to the isomer specific analysis. Differences in the extent of in-source fragmentation and MS/MS dissociation contributed to the systematic analytical bias. It was also shown that SigmaPFOS data are prone to interlaboratory variation due to various choices of PFOS standards and instrumental conditions used. In the future, for either SigmaPFOS or isomer specific PFOS analyses, we suggest that accuracy can be maximized and interlaboratory discrepancies minimized by using a common chemically pure technical PFOS standard characterized by 19F NMR.

Specific profiles of perfluorinated compounds in surface and drinking waters and accumulation in mussels, fish, and dolphins from southeastern Brazil

Despite the concern over widespread distribution of perfluorinated compounds (PFCs) even in sparsely populated regions of the world, few studies have reported their occurrence in South America. In this study, PFCs were measured in Rio de Janeiro State in southeast Brazil: in drinking water from various districts in the State, in river water and tucuxi dolphins from the Paraiba do Sul River, several species of fish from the State, and mussels from Guanabara Bay. Liver, kidney, and muscle from fishes were analyzed to enable an understanding of the tissue distribution of PFCs. PFOS, PFOA, and PFHxS were detected in all drinking water samples in concentration ranges of 0.58-6.70, 0.35-2.82, and 0.15-1.00 ng L(-1), respectively. The profiles of PFCs in drinking water from Brazil (with PFOS concentrations comparable to or higher than those of PFOA) were different from the profiles that have been reported for other countries. In fish, concentrations of PFOS were, in general, higher in liver than in muscle. Concentrations of PFOA in livers of fish were similar to or lower than fish muscle tissue concentrations. PFOS and PFOA were found in brown mussels from Guanabara Bay. Bioconcentration factors (BCFs) of PFOA calculated for mussels were higher than the BCFs calculated for fishes. Elevated concentrations of PFUnDA (mean: 109+/-17.4 ng g(-1) wet weight) were found in mussels from certain locations within Guanabara Bay. Although PFCs were detected in all types of samples analyzed, the concentrations were generally lower than the concentrations reported for Japan and the USA.