The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa ...hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean Σ4PFSA (perfluoroalkyl sulfonic acid) concentration (C4, C6, C8 and C10) was 2611 ± 202 ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20 ± 3 ng/g ww (89% PFOS) concentration in fat. The mean Σ4PFSAs in seal liver was 111 ± 5 ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05 ± 0.01 ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10 ± 1.4 ng/g ww) and seal (mean 0.6 ± 0.1 ng/g ww) liver but not in fat or blubber. The mean Σ13PFCAs (C4–C18; perfluoroalkyl carboxylic acids) in bear liver (924 ± 71 ng/g ww) was much greater than in seal liver (74 ± 6 ng/g ww). In bear fat and seal blubber, the mean Σ13PFCAs were 15 ± 1.9 and 0.9 ± 0.1 ng/g ww, respectively. Longer chain C11 to C14 PFCAs dominated in bear fat and seal blubber (60–80% of Σ13PFCA), whereas shorter-chain C9 to C11 PFCAs dominated in the liver (85–90% of Σ13PFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C9 to C13 PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C9 to C13) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals.
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•Major PFASs were compared in liver and fat tissues of polar bears and ringed seals.•Polar bears had greater PFAS contamination than ringed seals.•The PFOS to precursor FOSA ratio was significantly greater in bears than in seals.•PFCA tissue concentration increased whereas biomagnification factors (BMFs) decreased with increased with PFCA chain length.•Comparing PFAS BMFs based in bear liver to seal blubber better reflects the dietary relationship.
Ringed seal to polar bear bioaccumulation and biomagnification of PFCAs, PFSAs (PFOS) and precursors are much greater when based on dietary relationship of seal blubber to bear liver.
Tris(1-chloro-2-propyl) phosphate (TCPP) and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) are organic flame retardants detected in the environment and biota for which avian toxicological data are ...limited. In this study, domestic chicken eggs were injected with TCPP or TDCPP (maximum dose = 51,600 and 45,000ng/g egg, respectively) to determine dose-dependent effects on pipping success, development, hepatic messenger RNA (mRNA) expression levels of genes associated with xenobiotic metabolism and the thyroid hormone (TH) pathway, and TH levels following 20-22 days of incubation. Neither compound reduced pipping success; however, TCPP significantly delayed pipping at 9240 and 51,600ng/g and reduced tarsus length at 51,600ng/g. TDCPP exposure resulted in significant decreases in head plus bill length, embryo mass, and gallbladder size at 45,000ng/g and reduced plasma free T4 levels at 7640ng/g. Type I deiodinase, liver fatty acid-binding protein, and cytochrome P450 (CYP) 3A37 mRNA levels were significantly induced by TCPP, whereas TDCPP induced CYP3A37 and CYP2H1. Chemical analysis of egg contents at incubation days 0, 5, 11, 18, and 19 revealed that > 92% of the injected TCPP or TDCPP concentration was detectable up to day 5; however, < 1% was detected by day 19. The observed phenotypic responses to TCPP and TDCPP exposure may be associated with disruption of the TH axis, which is critical for normal growth and development in birds. The effects of TDCPP on the gallbladder indicate that the disturbance of lipid metabolism is a likely mechanism of toxicity.
Increased production and usage of organophosphate esters (OPEs) as flame retardants and plasticizers has trended towards larger and ‘novel’ (oligomeric) OPEs, although there is a dearth of ...understanding of the environmental fate, stability, toxicokinetics, biotransformation and bioaccumulation of novel OPEs in exposed biota. The present study characterized in vitro biotransformation of the novel OPE bisphenol-A bis(diphenyl phosphate) (BPADP) using Wistar-Han rat and herring gull liver based microsomal assays. Hypothesized target metabolites bisphenol-A (BPA) and diphenyl phosphate (DPHP) and other metabolites were investigated by applying a lines of evidence approach. In silico modelling predicted both BPA and DPHP as rat metabolites of BPADP, these metabolites were quantified via UHPLC-QQQ-MS/MS. Additional non-target metabolites were determined by UHPLC-Q-Exactive-Orbitrap-HRMS/MS and identified by Compound Discoverer software. Mean BPADP depletion of 44 ± 10% was quantified with 3.9% and 2.6% conversion to BPA and DPHP, respectively, in the rat assay. BPADP metabolism was much slower when compared to the well-studied OPE, triphenyl phosphate (TPHP). BPADP depletion in gull liver assays was far slower relative to the rat. Additional non-target metabolites identified included two Phase I, O-dealkylation products, five Phase I oxidation products and one Phase II glutathione adduct, demonstrating agreement between lines of in vitro and in silico evidence. Lines of evidence suggest that BPADP is biologically persistent in exposed mammals or birds. These findings add to the understanding of BPADP stability and biotransformation, and perhaps of other novel OPEs, which are factors highly applicable to hazard assessments of exposure, persistence and bioaccumulation in biota.
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•44% bisphenol-A bis(diphenyl phosphate) (BPADP) in vitro was depleted in rat assays.•In rat assays 2.6% and 3.9% of BPADP was converted to DPHP and BPA, respectively.•No significant BPADP depletion or BPA and DPHP formation in herring gull assays.•In silico estimation of metabolites BPA and DPHP confirmed by rat and gull assays.•Other BPADP oxidation metabolites and conjugate identified by non-target screening.
Recent advances in environmental analytical chemistry have identified the presence of a large number of chemicals of emerging Arctic concern (CEACs) being transported long range to the region. There ...has been very limited temporal monitoring of CEACs and it is therefore unknown whether they are of increasing or decreasing concern. Likewise, information on potential biological adverse effects from CEACs on Arctic wildlife is lacking compared with legacy persistent organic pollutants (POPs) found at levels associated with health effects in marine mammals. Hence, there is a need to monitor CEACs along with POPs to support risk and regulatory CEAC assessments. We suggest pan-Arctic temporal trend studies of CEACs in wildlife including the establishment of toxicity thresholds to evaluate their potential effects on populations, biodiversity, and ecosystem services.
Industrial chemicals have been present in the Arctic for decades and levels are still high in Arctic biota, particularly in top predators, despite national and international bans and regulations.New and replacement chemicals are being produced in high volumes. A growing number of these are being detected in Arctic media including wildlife and are chemicals of emerging Arctic concern (CEACs).Environmental information, toxicity, and biological effects are largely unknown for many of the CEACs.Although recently established CEACs are being phased out or internationally regulated, there is a need to prioritize research on the numerous other CEACs. We have little knowledge regarding their biomagnification and potential toxicity to Arctic wildlife and we need to better define and ultimately fully identify their contribution to the chemical mixture cocktail of Arctic pollution.Both persistent organic pollutants (POPs) and strategic consideration of CEACs need to be part of long-term monitoring programs focusing on mixture toxicity, threshold levels of toxicological concern, climate change, and infectious diseases.
It is established that organophosphorus pesticide (OPP) toxicity results from modification of amino acids in active sites of target proteins. OPPs can also modify unrelated target proteins such as ...histones and such covalent histone modifications can alter DNA-binding properties and lead to aberrant gene expression. In the present study, we report on non-enzymatic covalent modifications of calf thymus histones adducted to selected OPPs and organophosphate flame retardants (OPFRs) in vitro using a bottom-up proteomics method approach. Histones were not found to form detectable adducts with the two tested OPFRs but were avidly modified by a few of the seven OPPs that were tested in vitro. Dimethyl phosphate (or diethyl phosphate) adducts were identified on Tyr, Lys and Ser residues. Most of the dialkyl phosphate adducts were identified on Tyr residues. Methyl and ethyl modified histones were also detected. Eleven amino residues in histones showed non-enzymatic covalent methylation by exposure of dichlorvos and malathion. Our bottom-up proteomics approach showing histone-OPP adduct formation warrants future studies on the underlying mechanism of chronic illness from exposure to OPPs.
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•Non-enzymatic covalent modifications detected of calf histones to OPPs in vitro.•Thirteen peptides identified as dimethyl phosphate adducts on histone treated with DDVP.•Twenty peptides identified as diethyl phosphate adducts on histone treated with paraoxon.•Dialkyl phosphate adducts were identified on Y, K and S residues of histone.•Alkylation was detected on histone treated with OPPs.
•A mixed mode chromatography (MMC)-based UHPLC/ESI-MS method was developed for DAP analysis.•Nine DAPs could be baseline resolved and including three shorter alkyl chain DAPs.•This novel DAP method ...allowed for instrumental detection limits as low as 0.01 ng/mL.
While reversed-phase (RP) liquid chromatography can separate a wide range of analytes, for strongly acidic compounds such as environmentally relevant dialkyl phosphates (DAPs), this remains a challenge because they have low affinity for standard RP columns or they exhibit inferior peak shapes. Mixed-mode chromatographic (MMC) columns, which contain both RP and ion-exchange functionalities, can address these resolution problems. However, using current MMC separation approaches, analyte peaks are relatively broad as compared to conventional RP chromatography. Herein we present an enhanced MMC-based UHPLC/ESI-MS method for the analysis of DAPs. In contrast to commonly available MMC-based methods, we applied the MMC Luna® Omega PS C18 column that was conditioned by 0.1% formic acid and equilibrated with the initial mobile phase before sample injection. This conditioning step tremendously improved the retention and separation of the DAPs, especially for those with high water solubility and shorter carbon chain lengths. Using water/methanol (95 v/5 v) and ammonium acetate in methanol as the mobile phases, nine DAPs could be baseline resolved with very sharp peaks, including the shorter-chain dimethyl phosphate, diethyl phosphate and bis(2-chloroethyl) phosphate. Other columns were examined to facilitate method optimization, and to identify stationary phases with the ability to separate DAPs as well as to elucidate the retention and separation mechanisms. With this novel UHPLC and post-column dication ion-pairing ESI-MS/MS method, instrumental detection limits as low as 0.01 ng/mL level were achieved. Representing other strongly acidic analytes, the short-chain perfluoroalkyl acid, perfluorobutyl sulfonic acid could also be analyzed with this method.
Whole body homogenates of Lake Trout (Salvelinus namaycush) or Walleye (Sander vitreus) collected from Canadian lakes were screened for organophosphate flame retardant (OPFR) and organosiloxane ...compounds. Six OPFR and five siloxane compounds were detected above quantitation limits in at least one individual fish from sampled lakes. The OPFRs, tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP), were most frequently quantified with concentrations ranging from <0.07 to 9.8 ng/g (ww). Levels of TBOEP were highest in fish from the Great Lakes region while TCEP was detected only in fish from the northernmost lakes in our network. Concentrations of the cyclic siloxanes, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), were above quantitation limits in all fish. D5 was the most abundant siloxane across all sampling locations with the highest concentrations (45–719 ng/g ww) observed in Lake Trout from the western end of Lake Ontario near the mouth of the Niagara River.
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•Canadian fish were screened for organophosphate flame retardants and siloxanes.•6 organophosphate flame retardants and 5 siloxanes were detected above MLOQs.•The organophosphate flame retardants TCEP and TBOEP were most frequently quantified.•The cyclic siloxanes D4, D5, and D6 were above quantitation limits in all fish.•This study provides a baseline for these compounds in Canadian freshwater fish.
Of the compounds screened, 6 organophosphate flame retardants and 5 siloxanes were detected in whole body homogenate of Lake Trout or Walleye collected from Canadian water bodies.
Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a re-emerging environmental contaminant that has been frequently detected at sub-ppb (<μg/L) concentrations in natural waters. The objective of this ...study was to evaluate effects of TDCIPP on growth in initial generation (F0) zebrafish after chronic exposure to environmentally relevant concentrations, and to examine possible parental transfer of TDCIPP and transgenerational effects on growth of first generation (F1) larvae. When zebrafish (1-month old) were exposed to 580 or 7500 ng TDCIPP/L for 240 days, bioconcentration resulted in significantly less growth as measured by body length, body mass, brain-somatic index (BSI) and hepatic-somatic index (HSI) in F0 females but not F0 males. These effects were possibly due to down-regulation of expression of genes along the growth hormone/insulin-like growth factor (GH/IGF) axis. Furthermore, residues of TDCIPP were detected in F1 eggs after exposure of parents, which resulted in less survival, body length and heart rate in F1 individuals. Down-regulation of genes in the GH/IGF axis (e.g., gh, igf1) might be responsible for transgenerational toxicity. This study provides the first known evidence that exposure of zebrafish to environmentally relevant concentrations of TDCIPP during development can inhibit growth of offspring, which were not exposed directly to TDCIPP.
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•TDCIPP could selectively inhibit the growth of female zebrafish.•Residues of TDCIPP were detected in F1 eggs after exposure of parents.•Parental exposure had effect on survival and growth of F1 individuals.•Expression of GH/IGF genes was associated with growth in both F0 and F1 zebrafish.
This study provides the first evidence that exposure of zebrafish to environmentally relevant concentrations of TDCIPP can inhibit growth of offspring.
There has been an increasing incidence rate of rice false smut in global rice cultivation areas. However, there is a dearth of studies on the environmental concentrations and hazards of ustiloxin A ...(UA), which is the major mycotoxin produced by a pathogenic fungus of the rice false smut. Here, the concentrations of UA in the surface waters of two paddy fields located in Enshi city, Hubei province, China, were measured, and its toxicity in T. Thermophila was evaluated. This is the first study to detect UA in the surface waters of the two paddy fields, and the measured mean concentrations were 2.82 and 0.26 μg/L, respectively. Exposure to 2.19, 19.01 or 187.13 μg/L UA for 5 days significantly reduced the theoretical population and cell size of T. thermophila. Furthermore, treatment with 187.13 μg/L UA changed the percentages of T. thermophila cells in different cell-cycle stages, and with an increased malformation rate compared with the control, suggesting the disruption of the cell cycle. The expressions of 30 genes involved in the enriched proteasome pathway, 7 cyclin genes (cyc9, cyc10, cyc16, cyc22, cyc23, cyc26, cyc33) and 2 histone genes (mlh1 and hho1) were significantly down-regulated, which might be the modes of action responsible for the disruption of cell cycling due to UA exposure.
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•For the first time, ustiloxin A was detected in the surface water of paddy fields.•Exposure to ustiloxin A reduced the theoretical population of T. Thermophila and caused cell malformation.•Cell cycle was disrupted by ustiloxin A.•Expressions of genes related to cell cycling were changed due to ustiloxin A exposure.
For the first time, it was founded that ustiloxin A (UA) was detected in surface waters of paddy fields, and exposure to UA in T. Thermophila caused toxicity by disrupting cell cycle.
Currently there is a scientific debate on whether fluorinated polymers (or copolymers) are a source, as a result of their degradation and subsequent formation, of perfluorinated carboxylic acids ...(PFCAs) and perfluorinated alkanesulfonates (PFSAs). The present study investigated whether commercially available fluorinated surfactants, such as Scotchgard fabric protector (3M Company), can be metabolically degraded, using a model microsomal in vitro assay (Wistar-Han rats liver microsomes), and with concomitant formation of PFCAs, PFASs, and/or their precursors. The results showed that the main in vitro metabolite from the pre-2002 product was perfluorooctane sulfonamide (FOSA), and coincident with the detection of the major fabric protector components, which contains the N-ethyl-perfluorooctanesulfonyl chemical moiety (C8F17SO2N(C2H5)−); the main in vitro metabolite of the post-2002 product was perfluorobutane sulfonamide (FBSA), which was coincident with the detection of the major fabric protector components, and contains the N-methyl-perfluorobutanesulfonyl chemical moiety (C4F9SO2N(CH3)−). FOSA or FBSA metabolite concentrations increased over the 0–60 min microsomal incubation period. However, concentrations of their small molecule precursors such as alkylated FOSAs or FBSAs were not detectable (<LODs) in these fabric protector original standard solutions. Thus, the FOSA or FBSA metabolites were derived from the copolymer product itself rather than nonreacted reagents in the Scotchgard products. This result is consistent with reports of high concentrations of PFASs detected in the plasma of persons in households where Scotchgard products are heavily used.
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