Preliminary assessment on the bioaccessibility of contaminants of emerging concern in raw and cooked seafood
Alves, Ricardo N. ; Maulvault, Ana L. ; Barbosa, Vera L. ; Cunha, Sara ; Kwadijk, Christiaan J.A.F. ; Álvarez-Muñoz, Diana ; Rodríguez-Mozaz, Sara ; Aznar-Alemany, Òscar ; Eljarrat, Ethel ; Barceló, Damià ; Fernandez-Tejedor, Margarita ; Tediosi, Alice ; Marques, António - \ 2017
Food and Chemical Toxicology 104 (2017)June 2017. - ISSN 0278-6915 - p. 69 - 78.
Seafood - perfluorinated compounds - brominated flame retardants - Pharmaceuticals - personal care products - bioaccessibility - Steaming
A preliminary assessment of the bioaccessibility of contaminants of emerging concern (CeCs), including perfluorinated compounds (PFCs; i.e. PFOS and PFUnA), brominated flame retardants (BFRs; i.e. BDE47, BDE100, a-HBCD) and pharmaceuticals and personal care products (PPCPs; i.e. venlafaxine, methylparaben and UV-filter OC) was performed in seafood species available in the European markets. Additionally, the effect of steaming on CeCs bioaccessibility was also investigated for the first time. Overall, steaming affected differentially contaminants' concentrations, for instance, decreasing PFOS levels in flounder, but increasing both BDE47 and BDE100. CeCs bioaccessibility varied according to seafood species and contaminant group, i.e. in general, lower bioaccessibility values were obtained for PBDEs (<70%, except for mackerel), while PFCs and PPCPs revealed higher bioaccessibility percentages (between 71 and 95%). The lowest bioaccessibility value was obtained for a-HBCD (mussel; 14%), whereas the highest percentage was observed in venlafaxine (mullet; 95%). Our preliminary study reports also, for the first time, the effects of steaming on CeCs bioaccessibility. In most cases, bioaccessibility was not affected by cooking, however, a decrease was observed in PBDEs and and mullet, respectively, thus lowering the potential health risks associated with seafood consumption.
Successful validation of genomic biomarkers for human immunotoxicity in Jurkat T cells in vitro
Schmeits, P.C.J. ; Shao, J. ; Krieken, D.A. van der; Volger, O.L. ; Loveren, H. van; Peijnenburg, A.A.C.M. ; Hendriksen, P.J.M. - \ 2015
Journal of Applied Toxicology 35 (2015)7. - ISSN 0260-437X - p. 831 - 841.
polycyclic aromatic-hydrocarbons - brominated flame retardants - tetrabromobisphenol-a - balb/c mice - vitamin-c - chlorpyrifos - activation - exposure - rats - kinase
Previously, we identified 25 classifier genes that were able to assess immunotoxicity using human Jurkat T cells. The present study aimed to validate these classifiers. For that purpose, Jurkat cells were exposed for 6¿h to subcytotoxic doses of nine immunotoxicants, five non-immunotoxicants and four compounds for which human immunotoxicity has not yet been fully established. RNA was isolated and subjected to Fluidigm quantitative real time (qRT)–PCR analysis. The sensitivity, specificity and accuracy of the screening assay as based on the nine immunotoxicants and five non-immunotoxicants used in this study were 100%, 80% and 93%, respectively, which is better than the performance in our previous study. Only one compound was classified as false positive (benzo-e-pyrene). Of the four potential (non-)immunotoxicants, chlorantraniliprole and Hidrasec were classified immunotoxic and Sunset yellow and imidacloprid as non-immunotoxic. ToxPi analysis of the PCR data provided insight in the molecular pathways that were affected by the compounds. The immunotoxicants 2,3-dichloro-propanol and cypermethrin, although structurally different, affected protein metabolism and cholesterol biosynthesis and transport. In addition, four compounds, i.e.¿chlorpyrifos, aldicarb, benzo-e-pyrene and anti-CD3, affected genes in cholesterol metabolism and transport, protein metabolism and transcription regulation. qRT–PCR on eight additional genes coding for similar processes as defined in ToxPi analyzes, supported these results. In conclusion, the 25 immunotoxic classifiers performed very well in a screening with new non-immunotoxic and immunotoxic compounds. Therefore, the Jurkat screening assay has great promise to be applied within a tiered approach for animal free testing of human immunotoxicity.
Structural bisphenol analoques differentially target steroidogenesis in murine MA-10 Leydig cells as well as the glucocorticoid receptor
Roelofs, M.J.E. ; Berg, M. van den; Bovee, T.F.H. ; Piersma, A.H. ; Duursen, M.B.M. van - \ 2015
Toxicology 329 (2015). - ISSN 0300-483X - p. 10 - 20.
endocrine-disrupting chemicals - tetrabromobisphenol-a tbbpa - brominated flame retardants - one-generation reproduction - in-vitro - fetal testis - exogenous progesterone - gene-expression - risk-assessment - united-states
Although much information on the endocrine activity of bisphenol A (BPA) is available, a proper human hazard assessment of analogues that are believed to have a less harmful toxicity profile is lacking. Here the possible effects of BPA, bisphenol F (BPF), bisphenol S (BPS), as well as the brominated structural analogue and widely used flame retardant tetrabromobisphenol A (TBBPA) on human glucocorticoid and androgen receptor (GR and AR) activation were assessed. BPA, BPF, and TBBPA showed clear GR and AR antagonism with IC50 values of 67 µM, 60 µM, and 22 nM for GR, and 39 µM, 20 µM, and 982 nM for AR, respectively, whereas BPS did not affect receptor activity. In addition, murine MA-10 Leydig cells exposed to the bisphenol analogues were assessed for changes in secreted steroid hormone levels. Testicular steroidogenesis was altered by all bisphenol analogues tested. TBBPA effects were more directed towards the male end products and induced testosterone synthesis, while BPF and BPS predominantly increased the levels of progestagens that are formed in the beginning of the steroidogenic pathway. The MA-10 Leydig cell assay shows added value over the widely used H295R steroidogenesis assay because of its fetal-like characteristics and specificity for the physiologically more relevant testicular ¿4 steroidogenic pathway. Therefore, adding an in vitro assay covering fetal testicular steroidogenesis, such as the MA-10 cell line, to the panel of tests used to screen potential endocrine disruptors, is highly recommendable.
An overview of existing raptor contaminant monitoring activities in Europe
Gomez-Ramirez, P. ; Shore, R.F. ; Brink, N.W. van den; Hattum, B. van; Bustnes, J.O. ; Duke, G. ; Fritsch, C. ; Garcia-Fernandez, A.J. ; Helander, B.O. ; Jaspers, V. ; Krone, O. ; Martinez-Lopez, E. ; Mateo, R. ; Movalli, P. ; Sonne, C. - \ 2014
Environment International 67 (2014). - ISSN 0160-4120 - p. 12 - 21.
brominated flame retardants - eagles haliaeetus-albicilla - kestrel falco-tinnunculus - white-tailed eagles - long-term trends - environmental contaminants - organochlorine pesticides - southeastern spain - accipiter-gentilis - biomonitoring tool
Biomonitoring using raptors as sentinels can provide early warning of the potential impacts of contaminants on humans and the environment and also a means of tracking the success of associated mitigation measures. Examples include detection of heavy metal-induced immune system impairment, PCB-induced altered reproductive impacts, and toxicity associated with lead in shot game. Authorisation of such releases and implementation of mitigation is now increasingly delivered through EU-wide directives but there is little established pan-European monitoring to quantify outcomes. We investigated the potential for EU-wide coordinated contaminant monitoring using raptors as sentinels. We did this using a questionnaire to ascertain the current scale of national activity across 44 European countries. According to this survey, there have been 52 different contaminant monitoring schemes with raptors over the last 50 years. There were active schemes in 15 (predominantly western European) countries and 23 schemes have been running for > 20 years; most monitoring was conducted for > 5 years. Legacy persistent organic compounds (specifically organochlorine insecticides and PCBs), and metals/metalloids were monitored in most of the 15 countries. Fungicides, flame retardants and anticoagulant rodenticides were also relatively frequently monitored (each in at least 6 countries). Common buzzard (Buteo buteo), common kestrel (Falco tinnunculus), golden eagle (Aquila chrysaetos), white-tailed sea eagle (Haliaeetus albicilla), peregrine falcon (Falco peregrinus), tawny owl (Strix aluco) and barn owl (Tyto alba) were most commonly monitored (each in 6–10 countries). Feathers and eggs were most widely analysed although many schemes also analysed body tissues. Our study reveals an existing capability across multiple European countries for contaminant monitoring using raptors. However, coordination between existing schemes and expansion of monitoring into Eastern Europe is needed. This would enable assessment of the appropriateness of the EU-regulation of substances that are hazardous to humans and the environment, the effectiveness of EU level mitigation policies, and identify pan-European spatial and temporal trends in current and emerging contaminants of concern.
Metabolic Activation of Nonpolar Sediment Extracts Results in enhanced Thyroid Hormone Disrupting Potency
Montano, M. ; Weiss, J. ; Hoffmann, L. ; Gutleb, A.C. ; Murk, A.J. - \ 2013
Environmental Science and Technology 47 (2013)15. - ISSN 0013-936X - p. 8878 - 8886.
persistent organic pollutants - brominated flame retardants - effect-directed analysis - halogenated aromatic-hydrocarbons - polybrominated diphenyl ethers - in-vitro - polychlorinated-biphenyls - endocrine disruption - estrogenic activity - hepatic microsomes
Traditional sediment risk assessment predominantly considers the hazard derived from legacy contaminants that are present in nonpolar sediment extracts, such as polychlorinated biphenyls (PCBs), dioxins, furans (PCDD/Fs), and polyaromatic hydrocarbons (PAHs). Although in vivo experiments with these compounds have shown to be thyroid hormone disrupting (THD), in vitro their THD potency is not observed in nonpolar sediment extracts. This is hypothesized to be due to the absence of in vitro biotransformation which will result in bioactivation of the lipophilic compounds into THD hydroxyl metabolites. This study reveals that indeed metabolically activated nonpolar contaminants in sediments can competitively bind to thyroid hormone transport proteins. Sediment fractions were incubated with S9 rat microsomes, and the metabolites were extracted with a newly developed method that excludes most of the lipids to avoid interference in the applied nonradioactive 96-well plate TTR competitive binding assay. Metabolic activation increased the TTR binding potency of nonpolar fractions of POP-polluted sediments up to 100 times, resulting in potencies up to 240 nmol T4 equivalents/g sediment equivalent (nmol T4-Eq/g SEQ). This demonstrates that a more realistic in vitro sediment THD risk characterization should also include testing of both polar and medium polar sediment extracts for THD, as well as bioactivated nonpolar sediment fractions to prevent underestimation of its toxic potency.
Persistent Toxic Burdens of Halogenated Phenolic Compounds in Humans and Wildlife
Montano Garces, M. ; Gutleb, A.C. ; Murk, A.J. - \ 2013
Environmental Science and Technology 47 (2013)12. - ISSN 0013-936X - p. 6071 - 6081.
polybrominated diphenyl ethers - hydroxylated polychlorinated-biphenyls - brominated flame retardants - thyroid-hormone homeostasis - dolphins tursiops-truncatus - japanese coastal waters - pregnant faroese women - bears ursus-maritimus - seals phoca-hispida - in-
Halogenated phenolic compounds (HPCs) including hydroxylated polychlorobiphenyls (OH-PCBs) and hydroxylated polybromodiphenyl-ethers (OH-PBDEs) can be persistent organic pollutant (POP) metabolites or natural marine compounds. Structurally similar to thyroid hormones (THs), they are retained in blood, transported through selective barriers, and the cause of endocrine and neuronal POP effects. This study presents a meta-analysis of HPC burdens in human and wildlife tissues, including OH-PCBs, OH-PBDEs, Pentachlorophenol, and polybromophenols. HPC blood plasma levels were also compared to known in vitro and in vivo toxicological effect concentrations. Blood, highly perfused, and fetal tissues contained the highest levels of HPCs. Plasma concentrations of analyzed OH-PCBs/PBDEs ranged from 0.1 to 100 nM in humans and up to 240, 454, 800, and 7650 nM for birds, fish, cetaceans, and other mammals, respectively. These concentrations fully fall within the in vitro effect concentrations reported in literature for HPCs of 0.05–10000 nM. We strongly advise further study of HPC blood levels in the general population, children, and fetal tissue to establish background levels and the risk at sensitive development stages. As not all HPCs are, or can be, chemically analyzed, the application of additional bioanalysis might reveal an even greater toxicological relevance of HPCs. In addition, metabolic activation should always be included within in vitro hazard assessment of POPs
POPs analysis reveals issues in bringing laboratories in developing countries to a higher quality level
Leeuwen, S.P.J. van; Bavel, B. van; Abad, E. ; Leslie, H.A. ; Fiedler, H. ; Boer, J. de - \ 2013
TrAC : Trends in Analytical Chemistry 46 (2013). - ISSN 0165-9936 - p. 198 - 206.
polybrominated diphenyl ethers - brominated flame retardants - mass-spectrometry - human samples - perfluoroalkyl - substances - pbdes - polyfluoroalkyl - environment - sulfonate
We assessed the performance of laboratories in 18 developing countries in analyzing persistent organic pollutants (POPs) in environmental and human samples, as part of a capacity-building program with the goal of helping laboratories increase proficiency in the types of analyses required for the POPs Global Monitoring Program (GMP) under the Stockholm Convention. We identified several issues that need improvement before the laboratories can contribute to the GMP, including technical aspects of POPs analysis, QA/QC issues and laboratory-management problems. (C) 2013 Elsevier Ltd. All rights reserved.
Mechanism-based testing strategy using in vitro approaches for identification of thyroid hormone disrupting chemicals
Murk, A.J. ; Rijntjes, E. ; Blaauboer, B.J. ; Clewell, R. ; Crofton, K.M. ; Dingemans, M.M.L. ; Furlow, J.D. ; Kavlock, R. ; Kohrle, J. ; Opitz, R. ; Traas, T. ; Visser, T.J. ; Xia, M. ; Gutleb, A.C. - \ 2013
Toxicology in Vitro 27 (2013)4. - ISSN 0887-2333 - p. 1320 - 1346.
sodium-iodide symporter - polybrominated diphenyl ethers - thyrotropin-releasing-hormone - microsomal-enzyme inducers - hydroxylated polychlorinated-biphenyls - constitutive androstane receptor - brominated flame retardants - thyroxine-binding globulin - bears ur
The thyroid hormone (TH) system is involved in several important physiological processes, including regulation of energy metabolism, growth and differentiation, development and maintenance of brain function, thermo-regulation, osmo-regulation, and axis of regulation of other endocrine systems, sexual behaviour and fertility and cardiovascular function. Therefore, concern about TH disruption (THD) has resulted in strategies being developed to identify THD chemicals (THDCs). Information on potential of chemicals causing THD is typically derived from animal studies. For the majority of chemicals, however, this information is either limited or unavailable. It is also unlikely that animal experiments will be performed for all THD relevant chemicals in the near future for ethical, financial and practical reasons. In addition, typical animal experiments often do not provide information on the mechanism of action of THDC, making it harder to extrapolate results across species. Relevant effects may not be identified in animal studies when the effects are delayed, life stage specific, not assessed by the experimental paradigm (e.g., behaviour) or only occur when an organism has to adapt to environmental factors by modulating TH levels. Therefore, in vitro and in silico alternatives to identify THDC and quantify their potency are needed. THDC have many potential mechanisms of action, including altered hormone production, transport, metabolism, receptor activation and disruption of several feed-back mechanisms. In vitro assays are available for many of these endpoints, and the application of modern ‘-omics’ technologies, applicable for in vivo studies can help to reveal relevant and possibly new endpoints for inclusion in a targeted THDC in vitro test battery. Within the framework of the ASAT initiative (Assuring Safety without Animal Testing), an international group consisting of experts in the areas of thyroid endocrinology, toxicology of endocrine disruption, neurotoxicology, high-throughput screening, computational biology, and regulatory affairs has reviewed the state of science for (1) known mechanisms for THD plus examples of THDC; (2) in vitro THD tests currently available or under development related to these mechanisms; and (3) in silico methods for estimating the blood levels of THDC. Based on this scientific review, the panel has recommended a battery of test methods to be able to classify chemicals as of less or high concern for further hazard and risk assessment for THD. In addition, research gaps and needs are identified to be able to optimize and validate the targeted THD in vitro test battery for a mechanism-based strategy for a decision to opt out or to proceed with further testing for THD
Simultaneous extraction and determination of HBCD isomers and TBBPA by ASE and LC-MSMS in fish
Dam, G. ten; Pardo, O. ; Traag, W.A. ; Lee, M.K. van der; Peters, R.J.B. - \ 2012
Journal of Chromatography. B, Analytical technologies in the biomedical and life sciences 898 (2012). - ISSN 1570-0232 - p. 101 - 110.
brominated flame retardants - enantiomer-specific accumulation - tandem mass-spectrometry - hexabromocyclododecane diastereoisomers - tetrabromobisphenol - biota
Since the EFSA enquired a call for data for TBBPA and HBCD in 2009, the analytical determination of these compounds in food became of regulatory interest. Therefore, a method for the simultaneous determination of TBBPA and the three major HBCD stereoisomers was developed. Conventional techniques like soxhlet, ASE, GPC, sulphuric acid digestion, and acidified silica SPE are generally used in sample pre-treatment while detection is mostly performed by LC–MSMS. A combined analysis of HBCD and TBBPA is problematic due to the hydroxyl groups in the TBBPA molecule. However, using a specific mesh-size sodium sulphate in ASE extraction and an acid silica column combined with a Sep-pack Plus silica cartridge for purification resulted in recoveries between 80% and 110% for all compounds. The accuracy and reproducibility determined using proficiency test samples were 104% and 4% for the sum of the HBCD isomers. Typical limits of detection were 0.01 ng/g product or 0.004 ng on column, while the linear dynamic range is between 0.01 ng and 10 ng on column. Levels of TBBPA and HBCD isomers were determined in eel samples. TBBPA was occasionally detected and only marginally above the quantification limit of 0.05 ng/g, whereas total amounts of HBCD were between 0.2 and 150 ng/g with a-HBCD being the dominant HBCD isomer.
Triple Bioaffinity Mass Spectrometry Concept for Thyroid Transporter Ligands
Aqai, P. ; Fryganas, C. ; Mizuguchi, M. ; Haasnoot, W. ; Nielen, M.W.F. - \ 2012
Analytical Chemistry 84 (2012). - ISSN 0003-2700 - p. 6488 - 6493.
brominated flame retardants - ms-binding assays - human transthyretin - in-vitro - tetrabromobisphenol-a - disrupting chemicals - surface-water - pharmaceuticals - identification - metabolites
For the analysis of thyroid transporter ligands, a triple bioaffinity mass spectrometry (BioMS) concept was developed, with the aim at three different analytical objectives: rapid screening of any ligand, confirmation of known ligands in accordance with legislative requirements, and identification of emerging yet unknown ligands. These three purposes share the same biorecognition element, recombinant thyroid transport protein transthyretin (rTTR), and dedicated modes of liquid chromatography-mass spectrometry (LC-MS). For screening, a rapid and radiolabel-free competitive inhibition MS binding assay was developed with fast ultrahigh performance-liquid chromatography-electrospray ionization-triple-quadrupole-MS (UPLC-QqQ-MS) as the readout system. It uses the nonradioactive stable isotopic thyroid hormone 13C6-l-thyroxine as the label of which the binding to rTTR is inhibited by any ligand such as thyroid drugs and thyroid endocrine disrupting chemicals (EDCs). To this end, rTTR is either used in solution or immobilized on paramagnetic microbeads. The concentration-dependent inhibition of the label by the natural thyroid hormone l-thyroxine (T4), as a model analyte, is demonstrated in water at part-per-trillion and in urine at part-per-billion level. For confirmation of identity of known ligands, rTTR was used for bioaffinity purification for confirmation of naturally present free T4 in urine. As a demonstrator for identification of unknown ligands, the same rTTR was used again but in combination with nano-UPLC-quadrupole time-of-flight-MS (nLC-Q-TOF-MS) and urine samples spiked with the model “unknown” EDCs triclosan and tetrabromobisphenol-A. This study highlights the potential of BioMS using one affinity system, both for rapid screening and for confirmation and identification of known and unknown emerging thyroid EDCs.
Policy relevant Results from an Expert Elicitation on the Human Health Risks of Decabromodiphenyl ether (decaBDE) and Hexabromocyclododecane (HBCD)
Ravnum, S. ; Zimmer, K.E. ; Keune, H. ; Gutleb, A.C. ; Murk, A.J. ; Koppe, J.G. ; Magnanti, B. ; Lyche, J.L. ; Eriksen, G.S. ; Ropstad, E. ; Skaare, J.U. ; Kobernus, M. ; Yang, A. ; Bartonova, A. ; Krayer von Krauss, M. - \ 2012
Environmental Health : a global access science source 11 (2012)Suppl 1. - ISSN 1476-069X
brominated flame retardants - polybrominated diphenyl ethers - spontaneous behavior - neonatal exposure - serum - toxicity - trends - pbde - rat - neurotoxicity
Aim: Apply a recently developed expert elicitation procedure to evaluate the state of the current knowledge of the two brominated flame retardants (BFRs) most commonly used today; decabromo-diphenyl ether (decaBDE) and hexabromocyclododecane (HBCD) and their potential impact on human health in order to support policy considerations. This expert elicitation was organized by the HENVINET (Health and Environment Network) Consortium. Method: The HENVINET expert elicitation procedure that was used in the evaluations of decaBDE and HBCD is a rapid assessment tool aimed at highlighting areas of agreement and areas of disagreement on knowledge-related key issues for environment and health policy decision making. Results: The outcome of the expert consultation on BFRs was concrete expert advice for policy makers with specific priorities for further action made clear for both stakeholders and policy makers. The experts were not in agreement whether or not the knowledge currently available on decaBDE or HBCD is sufficient to justify policy actions, but most experts considered that enough data already exists to support a ban or restriction on the use of these compounds. All experts agreed on the necessity of more research on the compounds. Priority issues for further research were, among others: more studies on the extent of human exposure to the compounds. more studies on the fate and concentration in the human body of the compounds.
Organohalogen exposure in a Eurasian owl (Bubo bubo) population from Southeastern Spain: Temporal-spatial trends and risk assessment
Gomez-Ramirez, P. ; Martinez-Lopez, E. ; Garcia-Fernandez, A. ; Zweers, A.J. ; Brink, N.W. van den - \ 2012
Chemosphere 88 (2012)8. - ISSN 0045-6535 - p. 903 - 911.
brominated flame retardants - polybrominated diphenyl ethers - polychlorinated-biphenyls - organochlorine contaminants - haliaeetus-albicilla - hieraaetus-pennatus - breeding success - residue levels - great-lakes - eggs
Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) were analysed in 58 Eurasian Eagle owl (Bubo bubo) unhatched eggs collected between 2004 and 2009 in Southeastern Spain. Levels of p,p'-DDE were found to be higher than in eggs laid by other European owls in the same decade, probably due to the greater agricultural activity in our study area. Compared to other European raptors, exposure to PCBs can be considered intermediate, but low to PBDEs. Land use differences and prey availability were the rationale to divide the study area in two subareas in further assessments. Temporal trends of HCB, p,p'-DDE, ß-HCH, PCBs and PBDEs were significantly different in each subarea, generally increasing over time in the Southern but decreasing or remaining stable in the Northern. On the contrary, levels of cyclodienes tended to decrease in both subareas. Dietary shifts with a greater amount of birds are suggested as a cause for increasing organochlorine loads in raptors. This may explain the increasing trend in the Southern territories. However, due to the proximity of most of these nests to Cartagena, an important industrial city, increasing environmental pollution cannot be ruled out. Although average levels of the compounds analysed are below threshold levels, 17% of the samples exceeded 400 pg g-1 ww (wet weight), the LOAEC for Total TEQs. Moreover, a negative correlation between TEQ concentrations and the metabolizable fraction of PCBs (Fprob = 0.0018) was found when TEQs values were above 10 pg g-1 ww. This could be indicative of hepatic enzymes induction in the birds exposed at higher concentrations, which are mainly breeding in the Southern subarea. These females could be suffering from Ah-receptor-related toxic effects, some of which have been related to altered bird reproduction. Finally, a significant negative correlation between p,p'-DDE levels and eggshell thickness (r = -0.469, p <0.001) was observed, with about 17% of eggshell thinning for eggs with p,p'-DDE levels above 100 µg g -1 lw. The persistence of this degree of thinning over a period of time has been related to population declines in other raptor species
New Approaches to Assess the Transthyretin Binding Capacity of Bioactivated Thyroid Hormone Disruptors
Montano, M. ; Cocco, E. ; Guignard, C. ; Marsh, G. ; Hoffmann, L. ; Bergman, A. ; Gutleb, A.C. ; Murk, A.J. - \ 2012
Toxicological sciences 130 (2012)1. - ISSN 1096-6080 - p. 94 - 105.
polybrominated diphenyl ethers - brominated flame retardants - bears ursus-maritimus - in-vitro - thyroxine-binding - liver-microsomes - polychlorinated-biphenyls - transport proteins - bisphenol-a - fatty-acids
Polychlorinated biphenyls (PCBs) and polybrominated diphenyl-ethers (PBDEs) are metabolized into hydroxylated metabolites (OH-PCBs/PBDEs), which can disrupt the thyroid hormone homeostasis. Binding of these metabolites to transport proteins such as transthyretin (TTR) is an important mechanism of their toxicity. Several methods to quantify the competitive thyroxine (T4) displacement potency of pure metabolites exist. However, quantification of the potency of in vitro metabolized PCBs and PBDEs has drawbacks related to the coextraction of compounds disturbing the T4-TTR competitive binding assay. This study identifies and quantifies the major coextractants namely cholesterol, saturated and nonsaturated fatty acids (SFA and NSFA) at levels above 20 nmol per mg equivalent protein following various extraction methods. Their TTR binding potency was analyzed in a downscaled, nonradioactive fluorescence displacement assay. At concentration factors needed for TTR competitive binding, at least 10µM of these coextracts is present, whereas individual SFA and NSFA disturb the assay from 0.3µM. The effectiveness of the in vitro metabolism and extraction of the model compounds CB 77 and BDE 47 was chemically quantified with a newly developed chromatographic method analyzing silylated derivatives of the OH-metabolites and coextractants. A new method to selectively extract metabolites and limit coextraction of disturbing compounds to less than 5 nmol per mg equivalent protein is presented. It is now possible to make a dose-response curve up to 50% inhibition with bioactivated CB 77 and BDE 47. The toxic potencies of bioactivated persistent organic pollutants (POPs) should be taken into account to prevent serious underestimation of their hazard and risk
Effects of mixtures of persistent organic pollutants (POPs) derived from cod liver oil on H295R steroidogenesis
Montano, M. ; Zimmer, K.E. ; Dahl, E. ; Berge, V. ; Olsaker, I. ; Skaare, J.U. ; Murk, A.J. ; Ropstad, E. ; Verhaegen, S. - \ 2011
Food and Chemical Toxicology 49 (2011)9. - ISSN 0278-6915 - p. 2328 - 2335.
brominated flame retardants - polybrominated diphenyl ethers - adrenocortical carcinoma-cells - in-vitro - hormone production - gene-expression - aromatic-hydrocarbons - metabolite p,p'-dde - steroid-secretion - pbde metabolites
Crude cod liver oil and liver oil supplements are consumed as a source of vitamin A, D and polyunsaturated fatty acids; during winter and early pregnancy. Crude cod liver oil however constitutes a considerable source of persistent organic pollutants (POPs). This paper aimed at characterizing and quantifying the influence of POP mixtures extracted from three different steps in the cod liver oil industrial process on hormone production and the expression of steroidogenesis-related genes in H295R cells. Exposure to extracts from crude cod liver oil and from its industrial waste increased progesterone (P4), cortisol (Con), testosterone (T) and estradiol (E2) production; and among others, the expression of MC2R, CYP11B1 and HSD3B2 genes. Observed effects after exposure to pharmaceutical cod liver oil extract were considerably lower. The type of effects on gene expression and hormone production were similar to those induced by forskolin and PCBs, the latter being the major contaminants within the extracts. Additional research is required to further unveil the mechanisms behind the observed steroidogenic effects and to assess whether the potential risk might outweigh the potential benefits of crude and processed cod liver oil consumption.
Some OH-PCBs are more potent inhibitors of aromataseactivity and (anti-) glucocorticoids than non-dioxin like (NDL)-PCBs and MeSO2-PCBs
Antunes Fernandes, E.C. ; Bovee, T.F.H. ; Daamen, F. ; Helsdingen, J.R. ; Berg, M. van den; Duursen, M. van - \ 2011
Toxicology Letters 206 (2011)2. - ISSN 0378-4274 - p. 158 - 165.
methyl sulfone metabolites - adrenocortical carcinoma-cells - brominated flame retardants - polychlorinated-biphenyls - hydroxylated metabolites - methylsulfonyl metabolites - placental-transfer - eastern slovakia - gene-expression - hormone levels
Traditional risk assessment of potential endocrine-disruptive pollutants, including PCBs, focus mainly on the effects of parent compounds. Still, biotransformation results in systemic exposure to PCBs and their bioactive metabolites. In the present paper, the effects of twenty ultra-pure non-dioxin-like (NDL) PCBs and their environmentally relevant hydroxy- (OH-) and methylsulfonyl- (MeSO2-) metabolites on aromataseactivity and their glucocorticoid properties were investigated. Although most NDL-PCBs were inactive, PCB28 inhibited aromataseactivity in human placenta microsomes with an IC50 of 2.2 µM. Most of these NDL-PCBs were weak (ant-)agonist of the glucocorticoid receptor (GR). Interestingly, four OH-metabolites of the commonly found NDL-PCB180 were able to inhibit aromataseactivity (LOECs in the low µM range) and showed anti-glucocorticoid properties (LOECs in the low nM range), in a concentration-dependent manner. Further, four MeSO2-PCBs slightly inhibited aromataseactivity and showed anti-glucocorticoid properties. Although, these effects were also associated with cytotoxicity, they were dependent on the position of the MeSO2-group on the biphenyl ring. Our results are the first to show that OH-PCBs are both anti-glucocorticoids and aromataseinhibitors. Taken together, these results for PCBs again support the common idea that risk assessment of the endocrine disruptive potential of PCBs should also include their metabolites. --------------------------------------------------------------------------------
In vitro steroidogenic effects of mixtures of persistent organic pollutants (POPs) extracted from burbot (Lota lota) caught in two Norwegian lakes
Zimmer, K. ; Montano, M. ; Olsaker, I. ; Dahl, E. ; Berg, V. ; Karlsson, C. ; Murk, A.J. ; Skaare, J.U. ; Ropstad, E. ; Verhaegen, S. - \ 2011
Science of the Total Environment 409 (2011)11. - ISSN 0048-9697 - p. 2040 - 2048.
endocrine-disrupting chemicals - polybrominated diphenyl ethers - brominated flame retardants - h295r cell-line - polyhalogenated aromatic-hydrocarbons - adrenocortical carcinoma-cells - gene-expression - natural mixtures - transcriptional regulation - aldosterone
This study investigated the effects of two mixtures of persistent organic pollutants (POPs) on steroidogenesis in the H295R cell line. The two mixtures were obtained from the livers of burbot (Lota lota) caught in two Norwegian lakes (Mjøsa and Losna) with different contaminant profiles. Steroid hormone levels in the cell culture medium and mRNA levels of 16 genes involved in steroidogenesis were investigated. The crude Lake Mjøsa extract had to be diluted ten times more than the Lake Losna extract in order to prevent cytotoxicity. The ten times diluted Lake Mjøsa mixture had higher levels of DDT and derivates (¿DDTs, 1.7 times) and brominated flame retardants (¿BDEs and HBCD, 15-25 times) than the Lake Losna mixture, which, on the other hand, had higher concentrations of ¿PCBs (1.5 times higher) and also of HCB, ¿HCH isomers and ¿chlordane isomers (5-20 times higher). In the cell culture media, only cortisol levels were increased at the highest exposure concentration to the Lake Mjøsa mixture, while both cortisol and estradiol levels were increased following exposure to the two highest Lake Losna mixture exposure concentrations. Testosterone levels decreased only at the highest exposure concentration of the Lake Losna mixture. Multivariate models suggested that ¿PCBs, and to a lesser extent ¿DDTs, were responsible for the cortisol responses, while estradiol and testosterone alterations were best explained by HCB and ¿PCBs, respectively. Exposure to the mixtures generally increased mRNA levels, with smaller effects exerted by the Lake Mjøsa mixture than the Lake Losna mixture. It was concluded that both mixtures affected steroidogenesis in the H295R cells. Small differences in mixture composition, rather than the high content of brominated flame retardants in the Lake Mjøsa mixture, were suggested to be the most probable reason for the apparent differences in potencies of the two mixtures
Detection of thyroid hormone receptor disruptors by a novel stable in vitro reporter gene assay
Freitas, J. de; Cano, P. ; Craig-Veit, C. ; Goodson, M.L. ; Furlow, J.D. ; Murk, A.J. - \ 2011
Toxicology in Vitro 25 (2011)1. - ISSN 0887-2333 - p. 257 - 266.
pituitary-tumor-cells - brominated flame retardants - halogenated aromatic-hydrocarbons - cultured gh1 cells - polychlorinated-biphenyls - growth-hormone - transcriptional activity - environmental chemicals - tetrabromobisphenol-a - endocrine disruptor
A stable luciferase reporter gene assay was developed based on the thyroid hormone responsive rat pituitary tumor GH3 cell line that constitutively expresses both thyroid hormone receptor isoforms. Stable transfection of the pGL4CP-SV40-2xtaDR4 construct into the GH3 cells resulted in a highly sensitive cell line (GH3.TRE-Luc), which was further optimized into an assay that allowed the detection of Triiodothyronine (T3) and Thyroxine (T4) concentrations in the picomolar range after only 24 h of exposure. The greater than 20-fold induction of T3 relative to the solvent control is illustrative of the high responsiveness of the system. The assay was validated by the quantification of the agonistic effect of the natural hormones (T3 and T4), the acetic acid derivatives of T3 (triiodothyroaceticacid, or Triac) and T4 (tetraiodothyroacetic acid, or Tetrac), hydroxy polybrominated diphenylethers (OH-PBDEs), hydroxy polychlorinated biphenyls (OH-PCBs) and the antagonistic action of sodium arsenite (NaAsO2). The putative antagonist Amiodarone, Bisphenol A (BPA) and its halogenated derivatives (TCBPA and TBBPA) for which effects reported in the literature are not consistent, showed comparable dose–response curves with a slight agonistic effect (5% of T3-max) followed by a slight antagonistic effect. The magnitude and reproducibility of the responses to various compounds confirms this assay as a promising tool for the identification and quantification of specific thyroid hormone receptor disrupting potency of compounds.
Activation and potentiation of human GABAA receptors by non-dioxin-like-PCBs depends on chlorination pattern
Antunes Fernandes, E.C. ; Hendriks, H.S. ; Kleef, R.G.D.M. van; Reniers, A. ; Andersson, P.L. ; Berg, M.C. van den; Westerink, R.H.S. - \ 2010
Toxicological sciences 118 (2010)1. - ISSN 1096-6080 - p. 183 - 190.
brominated flame retardants - polychlorinated-biphenyls pcbs - recombinant gaba(a) - inhibition - congeners - exposure - neurotoxicity - dopamine - children - working
The neurotoxic potential of non-dioxin-like polychlorinated biphenyls (NDL-PCBs) is characterized by disruption of presynaptic processes, including calcium homeostasis and neurotransmitter transport. Recently, using a limited set of congeners, we demonstrated that PCB28 and PCB52 can potentiate postsynaptic GABAA receptors. In the present study, effects of 20 NDL-PCBs and 2 dioxin-like PCBs, selected based on their chemical variation and abundance in the environment, on human GABAA receptors were investigated. GABAA receptors were expressed in Xenopus oocytes, and NDL-PCB effects were determined using the two-electrode voltage-clamp technique. Results demonstrate that lower chlorinated PCB19, PCB28, PCB47, PCB51, PCB52, PCB95, and PCB100 act as a partial agonists (at low receptor occupancy), i.e., potentiating the receptor response during coapplication with GABA (at EC20). Importantly, PCB19, PCB47, PCB51, and PCB100 can also act as full agonist, i.e., activate the GABAA receptor in the absence of GABA. Potentiation and activation of the GABAA receptor is concentration dependent and limited to NDL-PCBs that have 3–5 chlorine atoms, 1–3 ortho-substitutions, an equal number (0–1) of meta-substitutions on both phenyl rings, and do not have an adjacent para- and meta-substitution on the same phenyl ring. Activation and potentiation of the GABAA receptor by PCB47, the most potent congener (lowest observed effect concentration of 10nM), is attenuated when coapplied with PCB19, PCB28, PCB153, or PCB180, indicative for competitive binding. Considering the importance of GABA-ergic signaling for brain development, motor coordination, learning, and memory, this mode of action can contribute to the previously observed NDL-PCB–induced neurobehavioral and neurodevelopmental effects and should be included in human risk assessment
Application of a congener-specific debromination model to study photodebromination, anaerobic microbial debromination, and FE0 reduction of polybrominated diphenyl ethers
Zeng, X. ; Simonich, S.L.M. ; Robrock, K.R. ; Korytar, P. ; Alvarez-Cohen, L. ; Barofsky, D.F. - \ 2010
Environmental Toxicology and Chemistry 29 (2010)4. - ISSN 0730-7268 - p. 770 - 778.
brominated flame retardants - decabromodiphenyl ether - degradation - environment - iron
A model was used to predict the photodebromination of the BDE-203, 197, 196, and 153, the major components of the octa-polybrominated diphenyl ether (PBDE) technical mixture, as well as BDE-47, and the predicted results were compared to the experimental results. The predicted reaction time profiles of the photodebromination products correlate well with the experimental results. In addition, the slope of the linear regression between the measured product concentrations of the first step of the photodebromination products and their enthalpies of formation was found to be close to their theoretical value. The photodebromination results of the octa-BDE technical mixture were compared with anaerobic microbial debromination results and were found to be the same in both experiments. The debromination pathways of technical octa-BDE mixture were identified and BDE-154, 99, 47, and 31 were found to be the most abundant hexa-, penta-, tetra-, and tri-BDE debromination products, respectively. In addition to photodebromination and anaerobic biodebromination, the model prediction was also compared to the zero-valent iron reduction of BDE-209, 100, and 47 and the same debromination products were observed. Good correlation was observed between the photodebromination rate constants of fifteen PBDE congeners and their calculated lowest unoccupied molecular orbital (LUMO) energies, indicating that PBDE photodebromination is caused by electron transfer. Furthermore, the rate constants for the three different PBDE debromination processes are controlled by C-Br bond dissociation energy. With the model from the present study, the major debromination products for any PBDE congener released into the environment can be predicted
Accumulation of background levels of persistent organochlorine and organobromine pollutants through the soil-earthworm-hedgehog food chain
Vermeulen, F. ; Covaci, A. ; Havé, H. D'; Brink, N.W. van den; Blust, R. ; Coen, W. De; Bervoets, L. - \ 2010
Environment International 36 (2010)7. - ISSN 0160-4120 - p. 721 - 727.
brominated flame retardants - polybrominated diphenyl ethers - pollution exposure assessment - polychlorinated-biphenyls - erinaceus-europaeus - risk-assessment - aromatic-hydrocarbons - organic pollutants - sewage-sludge - hair
The bioaccumulation of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and DDT and metabolites, was investigated in the soil–earthworm–hedgehog food chain. Concentrations of selected POPs were measured in soil and earthworms collected in grassland and open woodland and in hair and blood of hedgehogs foraging in two parks containing these habitats. Despite background concentrations in soil (ranging from 1.3 to 9.3 ng/g for DDTs, 2.3 to 6.5 ng/g for PCBs and 0.08 to 0.20 ng/g for PBDEs), biota-soil accumulation factors (BSAFs) indicated that earthworms accumulated POPs (0.48–1.70 for DDTs, 1.09–2.76 for PCBs and 1.99–5.67 for PBDEs) and that animals feeding on earthworms are potentially exposed to higher concentrations of pollutants. BSAFs decreased with increasing soil concentrations for the three groups of compounds, suggesting that steady-state equilibrium was not reached in soil or earthworms. Positive, but low, log-linear relationships were found for DDT (r2 = 0.23, p <0.05 for Brasschaat and r2 = 0.63, p <0.01 for Hoboken) and PCB (r2 = 0.13, p <0.05 for both parks) concentrations between soil and earthworms. In order to relate earthworm to hedgehog POP concentrations, the foraging behavior of each individual was taken into account. The use of hair as a potential biomonitoring tissue in exposure and risk assessment of POPs was evaluated by examining the relationship between PCB and p,p'-DDE levels in hedgehogs' hair and blood. Contaminant profiles were used to gain insight into biotransformation of the studied compounds in each step of the investigated food chain and in the blood of hedgehogs, as well as the consequences thereof for their incorporation in hair. The absence of a discernable relationship between POP concentrations in earthworms and hair is possible due to variation in individual foraging behavior and POP uptake. Our results suggest that POPs in tissues should be measured from an adequate number of individuals per population instead of relying on indirect estimates from levels in soil or prey items.