Covalent adduct formation of histone with organophosphorus pesticides in vitro.

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.

A targeted and non-targeted discovery screening approach for poly-and per-fluoroalkyl substances in model environmental biota samples.

A comprehensive analytical approach for targeted and non-targeted discovery screening of per- and polyfluoroalkyl substances (PFAS) was developed and applied to model complex environmental biotic samples. Samples were extracted by formic acid-acetonitrile solution and cleaned up and fractionated by SPE (WAX). Target PFAS quantification was performed by ultra-high performance liquid chromatography interfaced with a triple quadrupole mass spectrometer (UPLC-QqQ-MS/MS).

Bottom-up proteomics analysis for adduction of the broad-spectrum herbicide atrazine to histone.

Histones are the major proteinaceous components of chromatin in eukaryotic cells and an important part of the epigenome. The broad-spectrum herbicide atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino]-1, 3, 5-triazine) and its metabolites are known to form protein adducts, but the formation of atrazine-histone adducts has not been studied. In this study, a bottom-up proteomics analysis method was optimized and applied to identify histone adduction by atrazine in vitro.

Biotransformation of bisphenol-A bis(diphenyl phosphate): In vitro, in silico, and (non-) target analysis for metabolites in rat and bird liver microsomal models.

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.

Identification and characterization of serum albumin covalent adduct formed with atrazine by liquid chromatography mass spectrometry.

The present study developed an analytical technique to investigate the possible covalent adduct formation of albumin with the herbicide atrazine, and to characterize the protein modifications in vitro using liquid chromatography separation coupled with high resolution time-of-flight mass spectrometry (LC-TOF-MS). Tandem mass spectrum analysis (MS/MS) with collision induced dissociation (CID) revealed the specific sites of rat, human and bovine serum albumin adduct with atrazine. The formation of b-ion, y-ion series in MS/MS showed a covalent adduct with an addition mass of 179.

Side-chain fluorinated polymer surfactants in biosolids from wastewater treatment plants.

High concentrations of the main components in Scotchgard™ fabric protector products (pre-2002 and post-2002; side-chain fluorinated polymer surfactants, S1 and S2, respectively) were detected in biosolids samples from twenty pan-Canadian wastewater treatment plants (WWTPs). Based on mass spectrometric analysis, S1 and S2 can be named as side-chain perfluorooctane sulfonamide-urethane polymer and side-chain perfluorobutane sulfonamide-urethane polymer, respectively. S1 (with CF side-chain) concentrations ranged from 1.

Uptake, Deposition, and Metabolism of Triphenyl Phosphate in Embryonated Eggs and Chicks of Japanese Quail (Coturnix japonica).

The toxicokinetics of triphenyl phosphate (TPHP) in vivo including the uptake, deposition, and biotransformation into the metabolite diphenyl phosphate (DPHP) is presently reported in embryonated eggs and chicks of Japanese quail. Quail were dosed with TPHP at 3 concentrations by air cell egg injection on embryonic day 0, followed by daily oral dosing after chicks hatched (5 d). Vehicle-only exposed controls were also used.

In vitro metabolic activation of triphenyl phosphate leading to the formation of glutathione conjugates by rat liver microsomes.

The present study investigated the metabolism of the flame retardant and plasticizer chemical, triphenyl phosphate (TPHP), in a rat liver microsome-based in vitro assay with glutathione (GSH) in order to elucidate metabolic pathways leading to formation of conjugates. A highly sensitive and efficient method was developed for the detection and characterization of GSH reactive metabolites using LC-Q-TOF-MS/MS both in the negative and positive electrospray ionization modes. Seven GSH conjugates formed as a result of microsomal incubation, which were identified as S-conjugates based on MS/MS spectra, and confirmed by subsequent time-dependent incubation assays.

Covalent binding of the organophosphate insecticide profenofos to tyrosine on α- and β-tubulin proteins.

Organophosphorus (OP) compounds can bind covalently to many types of proteins and form protein adducts. These protein adducts can indicate the exposure to and neurotoxicity of OPs. In the present work, we studied adduction of tubulin with the OP insecticide profenofos in vitro and optimized the method for detection of adducted peptides.

A mixed-mode chromatographic separation method for the analysis of dialkyl phosphates.

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.

Side-chain fluorinated polymer surfactants in aquatic sediment and biosolid-augmented agricultural soil from the Great Lakes basin of North America.

Side-chain fluorinated polymer surfactants are the main components of fabric protector sprays and used extensively on furniture and textiles. The composition of these commercial protector products has changed, but there is currently a total dearth of information on these novel fluorinated polymers in the environment. Using a developed analytical approach, two complementary studies examined the distribution of Scotchgard™ fabric protector components in aquatic sediment and in agricultural soils where wastewater treatment plant (WWTP) sourced biosolid application occurred, and in samples from sites in the Laurentian Great Lakes basin of North America.

Exploring adduct formation between human serum albumin and eleven organophosphate ester flame retardants and plasticizers using MALDI-TOF/TOF and LC-Q/TOF.

Organophosphate (OP) and organophosphate ester (OPE) adducts of albumin are valuable biomarkers for retrospective verification of exposure. In the present study, our goal was to determine whether OPE flame retardants (OPE FRs) and OPE plasticizers can covalently bind to human serum albumin (HSA), which would allow the resulting adducts to be used to evaluate exposure. Eleven OPE FRs and plasticizers were examined in a HSA-adduct in vitro assay.

A New Fluorinated Surfactant Contaminant in Biota: Perfluorobutane Sulfonamide in Several Fish Species.

Environmental contamination and regulation of longer-chain perfluoroalkyl substances (PFASs) such as perfluorooctanesulfonate (PFOS) has given rise to the increased use of shorter-chain PFASs as alternatives in new products, although confirmation of their presence in the environment remains limited. In this study, the PFAS alternative, perfluoro-1-butane-sulfonamide (FBSA), was identified for the first time in biota in homogenate samples of fish by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-ToF-MS) and quantified by ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS). In one flounder (Platichthys flesus) muscle sample from the Western Scheldt, The Netherlands, FBSA concentration was at 80.

Organophosphate pesticide method development and presence of chlorpyrifos in the feet of nearctic-neotropical migratory songbirds from Canada that over-winter in Central America agricultural areas.

Recent modeling analysis suggests that numerous birds may be at risk of acute poisoning in insecticide-treated fields. Although the majority of avian field studies on pesticides have focused on treated seed, granule, insect or vegetation (oral exposure) ingestion, dermal exposure is an important exposure route when birds come into contact with deposited pesticides on foliage and other surfaces. Some nearctic-neotropical migratory songbirds are likely exposed to pesticides on their non-breeding habitats and include treated crops, plantations or farmlands.

Determination of organophosphate flame retardants and plasticizers in lipid-rich matrices using dispersive solid-phase extraction as a sample cleanup step and ultra-high performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry.

A fast, robust and highly sensitive analysis method for determination of trace levels of organophosphate ester (OPE) flame retardants and plasticizers in lipid-rich samples was presently developed, and based on ultra-high performance liquid chromatography-tandem mass spectrometry coupled to a positive atmospheric pressure chemical ionization source (UHPLC-MS/MS-APCI(+)). The target OPEs in the sample were extracted from the biota samples, such as egg and liver, by ultrasonic extraction, and cleaned up further by dispersive solid phase extraction (d-ESP). As a result, background contamination was largely reduced.

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.

Hexabromocyclododecane Flame Retardant Isomers in Sediments from Detroit River and Lake Erie of the Laurentian Great Lakes of North America.

Sediments collected in 2004 from along the Detroit River (n = 19) and across all of Lake Erie (n = 18) were analyzed for isomers of the flame retardant chemical, hexabromocyclododecane (HBCD), using liquid chromatography-tandem mass spectrometry. Sediment samples had ΣHBCD concentrations ranging from not detected to 1.6 ng/g d.

Methodology and determination of tetradecabromo-1, 4-diphenoxybenzene flame retardant and breakdown by-products in sediments from the Laurentian Great Lakes.

Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) is a brominated polyphenyl ether flame retardant (FR) that is known to photolytically degrade to produce lower brominated polybrominated-diphenoxybenzenes (PB-DiPhOBzs), which may be precursors to MeO-PB-DiPhOBzs recently reported in the Great Lakes herring gulls eggs. To our knowledge, there are no reports on TeDB-DiPhOBz or other PB-DiPhOBz by-products in any environmental sample. The present study analyzed for the presence of PB-DiPhOBzs (including TeDB-DiPhOBz) and MeO-PB-DiPhOBzs in surficial sediment from sites in Saginaw Bay in western Lake Huron (n = 7), and in comparison to southern Lake Huron (open water) (n = 5) and Lake Erie (n = 3) sediment collected in the summers of 2012 or 2013.

Comparative hepatic in vitro depletion and metabolite formation of major perfluorooctane sulfonate precursors in Arctic polar bear, beluga whale, and ringed seal.

Perfluorooctane sulfonate (PFOS) has been reported to be among the most concentrated persistent organic pollutants in Arctic marine wildlife. The present study examined the in vitro depletion of major PFOS precursors, N-ethyl-perfluorooctane sulfonamide (N-EtFOSA) and perfluorooctane sulfonamide (FOSA), as well as metabolite formation using an assay based on enzymatically viable liver microsomes for three top Arctic marine mammalian predators, polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas), and ringed seal (Pusa hispida), and in laboratory rat (Rattus rattus) serving as a general mammalian model and positive control. Rat assays showed that N-EtFOSA (38 nM or 150 ng mL(-1)) to FOSA metabolism was >90% complete after 10 min, and at a rate of 23 pmol min(-1) mg(-1) protein.

In vitro metabolic formation of perfluoroalkyl sulfonamides from copolymer surfactants of pre- and post-2002 scotchgard fabric protector products.

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)-).

Halogenated phenolic compound determination in plasma and serum by solid phase extraction, dansylation derivatization and liquid chromatography-positive electrospray ionization-tandem quadrupole mass spectrometry.

A robust, sensitive and accurate method was developed for the simultaneous determination in plasma and serum of suite a halogenated phenolic compounds (HPCs) for which several are known to persist in the environment and analytically pure standards are available. Namely, 14 congeners of hydroxylated polybrominated diphenyl ethers (OH-PBDEs), six congeners of hydroxylated polychlorinated biphenyls (OH-PCBs), pentachlorophenol, pentabromophenol and the flame retardant tetrabromobisphenol A (TBBPA). Solid phase extraction (SPE) enriched the target compounds and cleaned up the samples as a result of efficient adsorption on a strong anion-exchange solid phase SPE cartridge (Oasis MAX).

Tetradecabromodiphenoxybenzene flame retardant undergoes photolytic debromination.

Highly brominated flame retardant compounds have relatively low bioavailability, but some of these compounds have been shown to be of environmental concern. Tetradecabromodiphenoxybenzene (TDBDPB) contains 14 bromine atoms and is the major component of commercial flame retardant mixtures such as the recently phased out SAYTEX 120. The chemical stability of TDBDPB has not been reported.

Alpha and beta isomers of tetrabromoethylcyclohexane (TBECH) flame retardant: depletion and metabolite formation in vitro using a model rat microsomal assay.

The metabolism of α- and β-isomers of the flame retardant chemical tetrabromoethylcyclohexane (TBECH) was investigated using a model in vitro enzyme-mediated biotransformation assay based on rat liver microsomes. In enzymatically active assays, concentrations of both α- and β-TBECH isomers were equally depleted by about 40% and in a time-dependent fashion over a 60-min assay incubation period, and determined by GC-MS(ECNI) analysis. No such depletion was observed in nonenzymatically active control assays.

Newly discovered methoxylated polybrominated diphenoxybenzenes have been contaminants in the Great Lakes herring gull eggs for thirty years.

We recently reported the discovery and identification of novel methoxylated polybrominated diphenoxybenzenes (MeO-PBDPBs) in herring gulls eggs from the Laurentian Great Lakes of North America. We presently investigated the temporal changes (1982-2010) in MeO-PBDPB concentrations and congener patterns, as well as chemical tracers of diet (ratios of carbon and nitrogen stable isotopes), in egg pool homogenates from five selected colony sites across the Great Lakes. Egg pool homogenates from the Channel-Shelter (C-S) Island (Lake Huron) contained ∑MeO-PBDPB concentrations orders of magnitude greater than those from other colonies, suggesting potential point contamination sources nearby.

Determination of non-halogenated, chlorinated and brominated organophosphate flame retardants in herring gull eggs based on liquid chromatography-tandem quadrupole mass spectrometry.

Numerous triester organophosphate flame retardants (OPFRs) have been used for several decades and continue to be used in a variety of commercial products. We developed a sensitive quantitative method for the analysis of, seven non-halogenated, three chlorinated and two brominated OPFRs of known or possible environmental relevance in herring gull eggs. This method is based on a simple two-step sample extraction followed by liquid chromatography-electrospray ionization(+)-tandem mass spectrometry.