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  • 101. van Gils, Jos
    et al.
    Posthuma, Leo
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lindim, Claudia
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    de Zwart, Dick
    Bunke, Dirk
    Kutsarova, Stela
    Mueller, Christin
    Munthe, John
    Slobodnik, Jaroslav
    Brack, Werner
    The European Collaborative Project SOLUTIONS developed models to provide diagnostic and prognostic capacity and fill data gaps for chemicals of emerging concern2019In: Environmental Sciences Europe, ISSN 2190-4707, E-ISSN 2190-4715, Vol. 31, no 1, article id 72Article in journal (Refereed)
    Abstract [en]

    The European Union Water Framework Directives aims at achieving good ecological status in member states' water bodies. Insufficient ecological status could be the result of different interacting stressors, among them the presence of many thousands of chemicals. The diagnosis of the likelihood that these chemicals negatively affect the ecological status of surface waters or human health, and the subsequent development of abatement measures usually relies on water quality monitoring. This gives an incomplete picture of chemicals' contamination, due to the limited number of monitoring stations, samples and substances. Information gaps thus limit the possibilities to protect against and effectively manage chemicals in aquatic ecosystems. The EU FP7 SOLUTIONS project has developed and validated a collection of integrated models (Model Train) to increase our understanding of issues related to emerging chemicals in Europe's river basins and to complement information and knowledge derived from field data. Unlike pre-existing models, the Model Train is suitable to model mixtures of thousands of chemicals, to better approach a real-life mixture exposure situation. It can also be used to model new chemicals at a stage where not much is known about them. The application of these models on a European scale provides temporally and spatially variable concentration data to fill gaps in the space, time and substance domains left open by water quality monitoring, and it provides homogeneous data across Europe where water quality data from monitoring are missing. Thus, it helps to avoid overlooking candidate chemicals and possible hot spots for management intervention. The application of the SOLUTIONS Model Train on a European scale presents a relevant line of evidence for water system level prognostic and diagnostic impact assessment related to chemical pollution. The application supports the design of cost-effective programmes of measures by helping to identify the most affected sites and the responsible substances, by evaluating alternative abatement options and by exploring the consequences of future trends.

  • 102.
    Vestergren, R
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, I
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Human Exposure to Perfluorinated Compounds2008In: Naturvårdsverket: 27 May, 2008Conference paper (Refereed)
  • 103.
    Vestergren, R
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, I
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trudel, D.
    Wormuth, M.
    Scheringer, M.
    Considering the role of precursor compounds in consumer exposure to PFOS and PFOA2008In: Fluorinated Surfactants New Developments: 1st International Workshop: 26-28 June, Idstein, Germany, 2008Conference paper (Refereed)
  • 104.
    Vestergren, R
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, I
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trudel, D.
    Wormuth, M.
    Scheringer, M.
    Considering the role of precursor compounds in consumer exposure to PFOS and PFOA2008In: Dioxin 2008: 17-22 August, Birmingham, UK, 2008Conference paper (Refereed)
  • 105.
    Vestergren, R
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, I
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trudel, D.
    Wormuth, M.
    Scheringer, M.
    Considering the role of precursor compounds in consumer exposure to PFOS and PFOA2008In: Organohalogen Compd., Vol. 70, p. 1442-1466Article in journal (Refereed)
  • 106.
    Vestergren, R
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, I
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trudel, D.
    Wormuth, M.
    Scheringer, M.
    Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA2008In: Chemosphere, Vol. 73, p. 1617-1624Article in journal (Refereed)
  • 107.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Glynn, Anders
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Dietary intake estimates of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids for the general Swedish population in 1999, 2005 and 2010Manuscript (preprint) (Other academic)
    Abstract [en]

    Dietary intake has been estimated to be the major ongoing pathway of human exposure to perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs). However, difficulties associated with the analysis of food samples have hampered the reliable quantification of dietary exposure. Here the dietary exposure of the average Swedish population to PFCAs and PFSAs is estimated through analysis of a range of homologues in representative food basket samples from 1999, 2005 and 2010. Exposure to perfluorooctane sulfonate (796−1424 pg kg

    -1day-1), perfluoroundecanoic acid (88−212 pg kg-1day-1), perfluorodecanoic acid (52−102 pg kg-1day-1) and perfluorononanoic acid (62−83 pg kg-1day-1) was dominated by the consumption of fish and meat. In contrast, exposure to perfluorooctanoic acid (322−513 pg kg-1day-1) originated from low levels (8−62 pg g-1) found in several ―high consumption‖ food categories including cereals, dairy products, vegetables and fruit. The average body weight normalized dietary intakes (pg kg-1day-1) were fairly constant between 1999 and 2010 for all PFCAs and PFSAs demonstrating that dietary intake has been a continuous exposure pathway for these compounds during this period when many manufacturing changes occurred. Although statistically significant temporal trends in the average dietary intake estimates could not be determined, there is preliminary evidence of a downward time trend in the concentrations of PFOS in eggs and meat products and an upward trend of PFDA, PFUnDA, perfluorododecanoic acid and perfluorotridecanoic acid in fish products, which both warrant further investigation. In line with recent studies, dietary intake was found to be the major ongoing human exposure pathway for both PFOA and PFOS (~70% of the total exposure) for the Swedish population compared to exposure via ingestion of household dust and drinking water. The calculated higher total dietary exposure to PFOA compared to PFNA is consistent with the pattern observed in human serum, although there are several other exposure pathways which could explain this homologue pattern in serum.

  • 108.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Human dietary exposure to per- and poly-fluoroalkyl substances (PFASs)2013In: Persistent organic pollutants and toxic metals in foods / [ed] Rose, M.; Fernandes, A., Cambridge: Woodhead Publishing Limited, 2013, no 247, p. 279-307Chapter in book (Refereed)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a class of emerging contaminants with numerous industrial and commercial applications. Within this class the best studied substances are the perfluoroalkane sulfonates (PFSAs) and perfluoroalkyl carboxylates (PFCAs). PFSAs and PFCAs have been detected in human serum samples from all around the world and are ubiquitous in the global environment and wildlife. As well as being completely resistant to environmental degradation, some PFSAs and PFCAs are bioaccumulative and potentially toxic, which raises a concern about population-wide exposure to this group of substances. Dietary intake has been suggested as a major pathway of human exposure to the two most widely studied substances among PFSAs and PFCAs, namely perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the difficulties associated with the analysis of PFSAs, PFCAs and related PFASs at ultra-trace levels in food samples have hampered the understanding of human exposure. Recent advances in analytical chemistry have dramatically improved the ability to measure these substances and other PFASs in food matrices, and method detection limits down to low picogram per gram food can now be reached. Worldwide interlaboratory studies also indicate that the accuracy and precision of analytical methods have significantly improved over the last decade. These modern methods have been applied to quantify human dietary exposure to PFCAs and PFSAs in several European countries. Overall, the exposure to PFOS and PFOA from diet is typically a factor of 6 to 10 higher than the exposure from other known exposure pathways for the general adult population of Western countries. Furthermore, application of toxicokinetic models indicates that present day serum concentrations of PFOS and PFOA can largely be explained by the estimated dietary exposures. Despite the recent advances in analytical techniques, the sources of food contamination are not very well characterized. It has been demonstrated that bioaccumulation and biomagnification in aquatic food webs is a primary transfer mechanism for PFOS and several long-chain perfluoroalkyl carboxylic acids to the human diet. However, more research is needed to understand the accumulation of PFASs in terrestrial food webs and the transfer of a range of PFASs from food-contact materials.

  • 109.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Tracking the pathways of human exposure to perfluorocarboxylates2009In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, no 15, p. 5565-75Article in journal (Refereed)
    Abstract [en]

    Recent analyses of perfluorooctanoate (PFOA) in human blood sera show that the background-exposed population in industrialized countries worldwide exhibits a narrow concentration range; arithmetic means of published studies range between 2 and 8 microg/L PFOA, with the exception of a few outlier studies. The globally comparable human serum concentrations of PFOA and characteristic dominance of PFOA with respect to other perfluorocarboxylate (PFCA) homologues indicate that exposure pathways of humans differ from those of wildlife, where perfluorononanoate (PFNA) is often the dominant homologue. The observed correlations between perfluorooctane sulfonate (PFOS) and PFOA in human serum together with a simultaneous downward time trend of these compounds in human blood sera and blood spots from the year 2000 onward indicate a connection between historical perfluorooctanesulfonyl (POSF) production (phased out by the major manufacturer in 2000-2002) and exposure to both PFOS and PFOA. A comparison of estimated daily intakes to humans based on samples from exposure media (collected post 2000) indicates that food intake is the major contemporary exposure pathway for the background population, whereas drinking water exposure is dominant for populations near sources of contaminated drinking water. A one-compartment pharmacokinetic model used to back-calculate daily intakes from serum levels is shown to provide agreement within a factor of 1.5-5.5 of the daily intakes derived from exposure media, which provides further supporting evidence that dietary exposure is a major ongoing exposure pathway of PFOA to the background population.

  • 110.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Trudel, David
    Wormuth, Mattias
    Scheringer, Martin
    Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 73, no 10, p. 1617-1624Article in journal (Refereed)
    Abstract [en]

    The exposure of humans to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was quantified with emphasis on assessing the relative importance of metabolic transformation of precursor compounds. A Scenario-Based Risk Assessment (SceBRA) approach was used to model the exposure to these compounds from a variety of different pathways, the uptake into the human body and resulting daily doses. To capture the physiological and behavioral differences of age and gender, the exposure and resulting doses for seven consumer groups were calculated. The estimated chronic doses of a general population of an industrialized country range from 3.9 to 520 ng/(kg day) and 0.3 to 140 ng/(kg day) for PFOS and PFOA, respectively. The relative importance of precursor-based doses of PFOS and PFOA was estimated to be 2–5% and 2–8% in an intermediate scenario and 60–80% and 28–55% in a high-exposure scenario. This indicates that sub groups of the population may receive a substantial part of the PFOS and PFOA doses from precursor compounds, even though they are of low importance for the general population. Similar to a preceding study, uptake of perfluorinated acids from contaminated food and drinking water was identified as the most important pathway of exposure for the general population. The biotransformation yields of telomer-based precursors and to a lesser extent perfluorooctanesulfonylfluoride-based precursors were identified as influential parameters in the uncertainty analysis. Fast food consumption and fraction of food packaging paper treated with PFCs were influential parameters for determining the doses of PFOA.

  • 111. Vestergren, Robin
    et al.
    Herzke, Dorte
    Wang, Thanh
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Are imported consumer products an important diffuse source of PFASs to the Norwegian environment?2015In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 198, p. 223-230Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to measure perfluoroalkyl substances in a selection of imported consumer products (n = 45) and estimate population normalized emission rates during the use phase. 6:2 and 8:2 fluorotelomer alcohol (FTOH) were found in the highest concentrations ranging from <MDL to 374 and 163 mu g m(-2) respectively. Concentrations of FTOHs were approximately 2-3 orders of magnitude higher than those of perfluoroalkyl carboxylic acids (PFCAs). Although perfluorooctane sulfonate (PFOS) was detected in one carpet sample at 1.7 mu g m(-2), the majority of samples complied with regulatory limits for PFOS in the EU. Population normalized emission rates of perfluorooctanoic acid, 6:2 FTOH and 8:2 FTOH from imported consumer products were estimated to be 6.6, 2130 and 197 mu g year(-1) capita(-1) respectively for the intermediate emistion scenario. The results from this study suggest that emissions from imported products would have a small impact on the environmental concentrations of perfluoroalkyl acids on a regional scale.

  • 112.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Orata, Francis
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bioaccumulation of perfluoroalkyl acids in dairy cows in a naturally contaminated environment2013In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 20, no 11, p. 7959-7969Article in journal (Refereed)
    Abstract [en]

    Beef and dairy products may be important vectors of human exposure to perfluoroalkyl acids (PFAAs), but the understanding of how PFAAs are accumulated and transferred through agricultural food chains is very limited. Here, the bioaccumulation of PFAAs in dairy cows receiving naturally contaminated feed and drinking water was investigated by conducting a mass balance of PFAAs for a herd of dairy cows in a barn on a typical Swedish dairy farm. It was assumed that the cows were able to reach steady state with their dietary intake of PFAAs. Perfluorooctane sulfonic acid (PFOS) and perfluoroalkyl carboxylic acids (PFCAs) with 8 to 12 carbons were detected in cow tissue samples (liver, muscle, and blood) at concentrations up to 130 ng kg(-1). Mass balance calculations demonstrated an agreement between total intake and excretion within a factor of 1.5 and consumption of silage was identified as the dominant intake pathway for all PFAAs. Biomagnification factors (BMFs) were highly tissue and homologue specific. While BMFs of PFOS and PFCAs with 9 and 10 fluorinated carbons in liver ranged from 10 to 20, perfluorooctanoic acid (PFOA) was not biomagnified (BMF < 1) in any of the investigated tissues. Biotransfer factors (BTFs; defined as the concentration in tissue divided by the total daily intake) were calculated for muscle and milk. Log BTFs ranged from -1.95 to -1.15 day kg(-1) with the highest BTF observed for PFOS in muscle. Overall, the results of this study suggest that long-chain PFAAs have a relatively high potential for transfer to milk and beef from the diet of dairy cows. However, a low input of PFAAs to terrestrial systems via atmospheric deposition and low bioavailability of PFAAs in soil limits the amount of PFAAs that enter terrestrial agricultural food chains in background contaminated environments and makes this pathway less important than aquatic exposure pathways. The BTFs estimated here provide a useful tool for predicting human exposure to PFAAs via milk and beef under different contamination scenarios.

  • 113.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ullah, Shahid
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids at low parts per trillion levels in dietary samples2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1237, p. 64-71Article in journal (Refereed)
    Abstract [en]

    In recent exposure modeling studies diet has been identified as the dominant pathway of human exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the paucity of highly sensitive and accurate analytical data to support these studies means that their conclusions are open to question. Here a novel matrix effect-free method is described for ultra-trace analysis of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids in dietary samples of varied composition. The method employs ion pair extraction of the analytes into methyl tert-butyl ether and subsequent solid phase extraction clean-up on Florisil and graphitized carbon. The target compounds are separated and detected using ultra performance liquid chromatography coupled to tandem mass spectrometry. Special care was taken to avoid procedural blank contamination and potential contamination sources were elucidated. The performance of the method was validated for five different food test matrices including a duplicate diet sample. Method detection limits in the low to sub pg g(-1) range were obtained for all target analytes, which is 5-100 times more sensitive than previously reported for duplicate diet samples. Total method recoveries were consistently between 50 and 80% for all analytes in all tested food matrices and effects of co-extracted matrix constituents on ionization of the target compounds were found to be negligible. The precision of the method (defined as percentage relative standard deviation) at concentrations close to the respective method limits of quantification was <15% for all analytes. Accurate quantification at ultra-trace levels was demonstrated by laboratory control spike experiments. For the first time the presence of long-chain PFCAs in duplicate diet samples is reported. The method presented here can thus support an improved assessment of human exposure from dietary intake for a range of PFCA and PFSA homologues. Re-analysis of duplicate diet samples, which had been analyzed earlier using another analytical methodology, indicated that dietary intake of PFOA and PFOS may previously have been overestimated.

  • 114.
    Vestergren, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ullah, Shahid
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids at low parts per trillion levels in dietary samplesManuscript (preprint) (Other academic)
    Abstract [en]

    In recent exposure modeling studies diet has been identified as the dominant pathway of human exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the paucity of highly sensitive and accurate analytical data to support these studies means that their conclusions are open to question. Here a novel matrix effect-free method is described for ultra-trace analysis of perfluoroalkyl carboxylic acids (PFCAs, all homologues from perfluorohexanoic acid to perfluorododecanoic acid) and perfluoroalkane sulfonic acids (PFSAs, perfluorohexane and perfluorooctane sulfonic acid) in dietary samples of varied composition. The method employs ion pair extraction of the analytes into methyl

    tert-butyl ether and subsequent solid phase extraction clean-up on Florisil and graphitized carbon. Instrumental analysis was undertaken using ultra performance liquid chromatography coupled to tandem mass spectrometry. Special care was taken to avoid procedural blank contamination and potential contamination sources were elucidated. The performance of the method was evaluated for five different food test matrices including a duplicate diet sample. Method detection limits in the low to sub pg g-1 range were obtained for all target analytes, which are 5-100 times more sensitive than previously reported for duplicate diet samples. The method provided recoveries consistently between 50 and 80% for all analytes in the food matrices tested and effects of co-extracted matrix constituents on ionization were found to be negligible. Acceptable precision, defined as percentage relative standard deviation <30%, was achieved for all analytes. Accurate quantification at ultra-trace levels was demonstrated by a method intercomparison study with an independent recently developed method. For the first time the presence of long-chain PFCAs in duplicate diet samples is reported. The method presented here can thus support an improved assessment of dietary exposure to PFCAs and PFSAs. Re-analysis of duplicate diet samples, which had been previously analyzed using another older analytical methodology, indicated that human exposure to PFOA and PFOS from dietary sources may previously have been overestimated

  • 115. Vierke, Lena
    et al.
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Estimation of the Acid Dissociation Constant of Perfluoroalkyl Carboxylic Acids through an Experimental Investigation of their Water-to-Air Transport2013In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, no 19, p. 11032-11039Article in journal (Refereed)
    Abstract [en]

    The acid dissociation constants (pK(a)s) of perfluoroalkyl carboxylic acids (PFCAs) have been the subject of discussion in the literature; for example, values from -0.2 to 3.8 have been suggested for perfluorooctanoic acid (PFOA). The dissociated anionic conjugate bases of PFCAs have negligible air-water partition coefficients (K(AW)s) and do not volatilize from water. The neutral acids, however, have relatively high K(AW)s and volatilization from water has been demonstrated. The extent of volatilization of PFCAs in the environment will depend on the water pH and their pK(a). Knowledge of the pK(a)s of PFCAs is therefore vital for,understanding their environmental transport and fate. We investigated the water-to-air transfer of PFCAs in a novel experimental setup. We used similar to 1 mu g L-1 of PFCAs in water (above environmental background concentrations but below the concentration at which self-association occurs) at different water pH (pH 0.3 to pH 6.9) and sampled the PFCAs volatilized from water during a 2-day experiment. Our results suggest that the pK(a)s of C4-11 PFCAs are <1.6. For PFOA, we derived a pK(a) of 0.5 from fitting the experimental measurements with a volatilization model. Perfluoroalkane sulfonic acids were not volatilized, suggesting that their pK(a)s are below the investigated pH range (pK(a) <0.3).

  • 116. Waaijers, Susanne L.
    et al.
    Kong, Deguo
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Hendriks, Hester S.
    de Wit, Cynthia A.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Westerink, Remco H. S.
    Leonards, Pim E. G.
    Kraak, Michiel H. S.
    Admiraal, Wim
    de Voogt, Pim
    Parsons, John R.
    Persistence, Bioaccumulation, and Toxicity of Halogen-Free Flame Retardants2013In: Reviews of Environmental Contamination and Toxicology / [ed] David M. Whitacre, Springer, 2013, p. 1-71Chapter in book (Refereed)
    Abstract [en]

    Polymers are synthetic organic materials having a high carbon and hydrogen content, which make them readily combustible. Polymers have many indoor uses and their flammability makes them a fire hazard. Therefore, flame retardants (FRs) are incorporated into these materials as a safety measure. Brominated flame retardants (BFRs), which accounted for about 21% of the total world market of FRs, have several unintended negative effects on the environment and human health. Hence, there is growing interest in finding appropriate alternative halogen-free flame retardants (HFFRs). Many of these HFFRs are marketed already, although their environ- mental behavior and toxicological properties are often only known to a limited extent, and their potential impact on the environment cannot yet be properly assessed. Therefore, we undertook this review to make an inventory of the available data that exists (up to September 2011) on the physical-chemical properties, pro- duction volumes, persistence, bioaccumulation, and toxicity (PBT) of a selection of HFFRs that are potential replacements for BFRs in polymers. Large data gaps were identified for the physical-chemical and the PBT properties of the reviewed HFFRs. Because these HFFRs are currently on the market, there is an urgent need to fill these data gaps. Enhanced transparency of methodology and data are needed to reevaluate certain test results that appear contradictory, and, if this does not provide new insights, further research should be performed. TPP has been studied quite extensively and it is clearly persistent, bioaccumulative, and toxic. So far, RDP and BDP have demonstrated low to high ecotoxicity and persistence. The compounds ATH and ZB exerted high toxicity to some species and ALPI appeared to be persistent and has low to moderate reported ecotoxicity. DOPO and MPP may be persistent, but this view is based merely on one or two studies, clearly indicating a lack of information. Many degradation studies have been performed on PER and show low persistence, with a few exceptions. Additionally, there is too l ittle information on the bioaccumulation potential of PER. APP mostly has low PBT properties; however, moderate ecotoxicity was reported in two studies. Mg(OH)₂, ZHS, and ZS do not show such remarkably high bioaccumulation or toxicity, but large data gaps exist for these compounds also. Nevertheless, we consider the latter compounds to be the most promising among alternative HFFRs. To assess whether the presently reviewed HFFRs are truly suitable alternatives, each compound should be examined individually by comparing its PBT values with those of the relevant halogenated flame retardant. Until more data are available, it remains impossible to accurately evaluate the risk of each of these compounds, including the ones that are already extensively marketed.

  • 117. Wang, Thanh
    et al.
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Norwegian Institute for Air Research (NILU), FRAM − High North Research Centre on Climate and the Environment, Norway.
    Herzke, Dorte
    Yu, Junchao
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Levels, Isomer Profiles, and Estimated Riverine Mass Discharges of Perfluoroalkyl Acids and Fluorinated Alternatives at the Mouths of Chinese Rivers2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 21, p. 11584-11592Article in journal (Refereed)
    Abstract [en]

    An extensive sampling campaign was undertaken to study the levels, isomer profiles and riverine mass discharges of perfluoroalkyl acids (PFAAs) and fluorinated alternatives in 19 Chinese rivers. The levels and homologue profiles of Sigma(10)PFAAs varied considerably among the 19 rivers (mean 106; median 16.3, range 8.91240 ng/L), indicating the influence of specific point sources. Highly branched isomer profiles of perfluorooctanoic acid (1825% br-PFOA) in rivers with elevated concentrations (96352 ng/L) indicate that releases during production of PFOA by electrochemical fluorination and/or its use in fluoropolymer manufacture were the dominant sources to these rivers. The fluorinated alternatives 6:2 fluorotelomer sulfonate (detection frequency 21%, < 0.13.1 ng/L) and chlorinated polyfluoroalkyl ether sulfonate F-53B (51%, < 0.5678.5 ng/L) were also found in some rivers. The total Chinese riverine mass discharges of PFOA (mean 80.9; range 16.8168 t/y) (including monitoring data from this and other studies) were in good agreement with theoretical PFOA emission estimates (17.3203 t/y) whereas riverine mass discharges of PFOS (mean 3.6; range 1.95.6 t/y) could only account for a minor fraction of theoretically estimated PFOS releases (70 t/y). This study provides empirical evidence that emissions from Chinese point sources likely dominate the global emissions of several legacy PFASs (notably PFOA) and fluorinated alternatives (e.g., F-53B).

  • 118. Wang, Zhanyun
    et al.
    Boucher, Justin M.
    Scheringer, Martin
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hungerbühler, Konrad
    Toward a Comprehensive Global Emission Inventory of C-4-C-10 Perfluoroalkanesulfonic Acids (PFSAs) and Related Precursors: Focus on the Life Cycle of C-8-Based Products and Ongoing Industrial Transition2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 8, p. 4482-4493Article in journal (Refereed)
    Abstract [en]

    Here a new global emission inventory of C-4-C-10 perfluoroalkanesulfonic acids (PFSAs) from the life cycle of perfluorooctanesulfonyl fluoride (POSF)-based products in 1958-2030 is presented. In particular, we substantially improve and expand the previous frameworks by incorporating missing pieces (e.g., emissions to soil through land treatment, overlooked precursors) and updating parameters (e.g., emission factors, degradation half-lives). In 1958-2015, total direct and indirect emissions of perfluorooctanesulfonic acid (PFOS) are estimated as 1228-4930 tonnes, and emissions of PFOS precursors are estimated as 1230-8738 tonnes and approximately 670 tonnes for x-perfluorooctanesulfonamides/sulfonamido ethanols (xFOSA/Es) and POSF, respectively. Most of these emissions occurred between 1958 and 2002, followed by a substantial decrease. This confirms the positive effect of the ongoing transition to phase out POSF-based products, although this transition may still require substantial time and cause substantial additional releases of PFOS (8-153 tonnes) and xFOSA/Es (4-698 tonnes) in 2016 to 2030. The modeled environmental concentrations obtained by coupling the emission inventory and a global multimedia mass-balance model generally agree well with reported field measurements, suggesting that the inventory captures the actual emissions of PFOS and xFOSA/Es for the time being despite remaining uncertainties. Our analysis of the key uncertainties and open questions of and beyond the inventory shows that, among others, degradation of side-chain fluorinated polymers in the environment and landfills can be a long-term, (potentially) substantial source of PFOS.

  • 119. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Berger, Urs
    Hungerbuhler, Konrad
    Scheringer, Martin
    Comparative assessment of the environmental hazards of and exposure to perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs): Current knowledge, gaps, challenges and research needs2016In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 89-90, p. 235-247Article, review/survey (Refereed)
    Abstract [en]

    Perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs) are sub-groups of per- and polyfluoroalkyl substances (PFASs) that have been commercialized since the 1970s, particularly as defoamers in pesticide formulations and wetting agents in consumer products. Recently, C-4/C-4 PFPiA and its derivatives have been presented as alternatives to long-chain PFASs in certain applications. In this study, we systematically assess the publicly available information on the hazardous properties, occurrence, and exposure routes of PFPAs and PFPiAs, and make comparisons to the corresponding properties of their better-known carboxylic and sulfonic acid analogs (i.e. PFCAs and PFPAs). This comparative assessment indicates that [i] PFPAs likely have high persistence and long-range transport potential; [ii] PFPiAs may transform to PFPAs (and possibly PFCAs) in the environment and biota; [iii] certain PFPAs and PFPiAs can only be slowly eliminated from rainbow trout and rats, similarly to long-chain PFCAs and PFPAs; [iv] PFPAs and PFPiAs have modes-of-action that are both similar to, and different from, those of PFCAs and PFSAs; and [v] the measured levels of PFPAs/PFPiAs in the global environment and biota appear to be low in comparison to PFCAs and PFPAs, suggesting, for the time being, low risks from PFPAs and PFPiAs alone. Although risks from individual PFPAs/PFPiAs are currently low, their ongoing production and use and high persistence will lead to increasing exposure and risks over time. Furthermore, simultaneous exposure to PFPAs, PFPiAs and other PFASs may result in additive effects necessitating cumulative risk assessments. To facilitate effective future research, we highlight possible strategies to overcome sampling and analytical challenges.

  • 120. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Scheringer, Martin
    Buck, Robert C.
    Hungerbuehler, Konrad
    Global emission inventories for C-4-C-14 perfluoroalkyl carboxylic acid (PFCA) homologues from 1951 to 2030, Part I: production and emissions from quantifiable sources2014In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 70, p. 62-75Article, review/survey (Refereed)
    Abstract [en]

    We quantify global emissions of C-4-C-14 perfluoroalkyl carboxylic acid (PFCA) homologues during the life-cycle of products based on perfluorooctanoic acid (PFOA), perfluorononanoic add (PFNA), perfluorooctane sulfonyl fluoride (POSF), and fluorotelomer compounds. We estimate emissions of 2610-21400 tonnes of C-4-C-14 PFCAs in the period from 1951 to 2015, and project 20-6420 tonnes to be emitted from 2016 to 2030. The global annual emissions steadily increased in the period 1951-2002, followed by a decrease and then another increase in the period 2002-2012. Releases from fluoropolymer production contributed most to historical PFCA emissions (e.g. 55-83% in 1951-2002). Since 2002, there has been a geographical shift of industrial sources (particularly fluoropolymer production sites) from North America, Europe and Japan to emerging Asian economies, especially China Sources differ between PFCA homologues, sometimes Considerably, and the relative contributions of each source change over time. For example, whereas 98-100% of historical (1951-2002) PFOA emissions are attributed to direct releases during the life-cycle of products containing PFOA as ingredients or impurities, a much higher historical contribution from PFCA precursor degradation is estimated for some other homologues (e.g. 9-78% for PFDA). We address the uncertainties of the PFCA emissions by defining a lower and a higher emission scenario, which differ by approximately a factor of eight.

  • 121. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Scheringer, Martin
    Buck, Robert C.
    Hungerbuehler, Konrad
    Global emission inventories for C-4-C-14 perfluoroalkyl carboxylic acid (PFCA) homologues from 1951 to 2030, part II: The remaining pieces of the puzzle2014In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 69, p. 166-176Article in journal (Refereed)
    Abstract [en]

    We identify eleven emission sources of perfluoroalkyl carboxylic adds (PFCAs) that have not been discussed in the past. These sources can be divided into three groups: [i] PFCAs released as ingredients or impurities, e.g., historical and current use of perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA) and their derivatives; [ii] PFCAs formed as degradation products, e.g., atmospheric degradation of some hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs); and [iii] sources from which PFCAs are released as both impurities and degradation products, e.g., historical and current use of perfluorobutane sulfonyl fluoride (PBSF)- and perfluorohexane sulfonyl fluoride (PHxSF)-based products. Available information confirms that these sources were active in the past or are still active today, but due to a lack of information, it is not yet possible to quantify emissions from these sources. However, our review of the available information on these sources shows that some of the sources may have been significant in the past (e.g., the historical use of PFBA-, PFHxA-, PBSF- and PHxSF-based products), whereas others can be significant in the long-term (e.g., (bio)degradation of various side-chain fluorinated polymers where PFCA precursors are chemically bound to the backbone). In addition, we summarize critical knowledge and data gaps regarding these sources as a basis for future research.

  • 122. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Scheringer, Martin
    Hungerbuehler, Konrad
    Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors2013In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 60, p. 242-248Article in journal (Refereed)
    Abstract [en]

    Since 2000 there has been an on-going industrial transition to replace long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic adds (PFSAs) and their precursors. To date, information on these replacements including their chemical identities, however, has not been published or made easily accessible to the public, hampering risk assessment and management of these chemicals. Here we review information on fluorinated alternatives in the public domain. We identify over 20 fluorinated substances that are applied in [i] fluoropolymer manufacture, [ii] surface treatment of textile, leather and carpets, [iii] surface treatment of food contact materials, [iv] metal plating, [v] fire-fighting foams, and [vi] other commercial and consumer products. We summarize current knowledge on their environmental releases, persistence, and exposure of biota and humans. Based on the limited information available, it is unclear whether fluorinated alternatives are safe for humans and the environment. We identify three major data gaps that must be filled to perform meaningful risk assessments and recommend generation of the missing data through cooperation among all stakeholders (industry, regulators, academic scientists and the public).

  • 123. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Scheringer, Martin
    Hungerbuehler, Konrad
    Hazard assessment of fluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors: Status quo, ongoing challenges and possible solutions2015In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 75, p. 172-179Article in journal (Refereed)
    Abstract [en]

    Because of concerns over the impact of long-chain perfluoroalkyl acids (PFAAs) on humans and the environment, PFAAs and their precursors are being substituted by alternative substances including fluorinated alternatives that are structurally similar to the substances they replace. Using publicly accessible information, we aimed to identify the status quo of the hazard assessment of identified fluorinated alternatives, to analyze possible systemic shortcomings of the current industrial transition to alternative substances, and to outline possible solutions. Fluorinated alternatives, particularly short-chain PFAAs and perfluoroether carboxylic and sulfonic acids (PFECAs and PFESAs), possess high environmental stability and mobility implying that they have a high global contamination potential. In addition to their potential for causing global exposures, certain fluorinated alternatives have been identified as toxic and are thus likely to pose global risks to humans and the environment. Various factors, particularly the information asymmetry between industry and other stakeholders, have contributed to the current lack of knowledge about the risks posed by fluorinated alternatives. Available cases show that a non-fluorinated substitution strategy (employing either chemical or functionality substitutions) can be a possible long-term, sustainable solution and needs to be further developed and assessed.

  • 124. Wang, Zhanyun
    et al.
    DeWitt, Jamie C.
    Higgins, Christopher P.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 5, p. 2508-2518Article in journal (Refereed)
    Abstract [en]

    More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain FASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast number of PFASs on the market and in the environment.

  • 125. Wang, Zhanyun
    et al.
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Scheringer, Martin
    Hungerbuehler, Konrad
    Using COSMOtherm to predict physicochemical properties of poly- and perfluorinated alkyl substances (PFASs)2011In: Environmental Chemistry, ISSN 1448-2517, E-ISSN 1449-8979, Vol. 8, no 4, p. 389-398Article in journal (Refereed)
    Abstract [en]

    Recently, there has been concern about the presence of poly- and perfluorinated alkyl substances (PFASs) in the environment, biota and humans. However, lack of physicochemical data has limited the application of environmental fate models to understand the environmental distribution and ultimate fate of PFASs. We employ the COSMOtherm model to estimate physicochemical properties for 130 individual PFASs, namely perfluoroalkyl acids (including branched isomers for C(4)-C(8) perfluorocarboxylic acids), their precursors and some important intermediates. The estimated physicochemical properties are interpreted using structure-property relationships and rationalised with insight into molecular interactions. Within a homologous series of linear PFASs with the same functional group, both air-water and octanol-water partition coefficient increase with increasing perfluorinated chain length, likely due to increasing molecular volume. For PFASs with the same perfluorinated chain length but different functional groups, the ability of the functional group to form hydrogen bonds strongly influences the chemicals' partitioning behaviour. The partitioning behaviour of all theoretically possible branched isomers can vary considerably; however, the predominant isopropyl and monomethyl branched isomers in technical mixtures have similar properties as their linear counterparts (differences below 0.5 log units). Our property estimates provide a basis for further environmental modelling, but with some caveats and limitations.

  • 126.
    Winkens, Kerstin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Giovanoulis, Georgios
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. IVL Swedish Environmental Research Institute, Sweden.
    Koponen, Jani
    Vestergren, Robin
    Berger, Urs
    Karvonen, Anne M.
    Pekkanen, Juha
    Kiviranta, Hannu
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Perfluoroalkyl acids and their precursors in floor dust of children’s bedrooms – Implications for indoor exposureManuscript (preprint) (Other academic)
  • 127.
    Winkens, Kerstin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Giovanoulis, Georgios
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. IVL Swedish Environmental Research Institute, Sweden.
    Koponen, Jani
    Vestergren, Robin
    Berger, Urs
    Karvonen, Anne M.
    Pekkanen, Juha
    Kiviranta, Hannu
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Perfluoroalkyl acids and their precursors in floor dust of children's bedrooms - Implications for indoor exposure2018In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 119, p. 493-502Article in journal (Refereed)
    Abstract [en]

    We analysed floor dust samples from 65 children's bedrooms in Finland collected in 2014/2015 for 62 different per- and polyfluoroalkyl substances (PFASs) with a simple and highly efficient method. Validation results from the analysis of standard reference material (SRM) 2585 were in good agreement with literature data, while 24 PFASs were quantified for the first time. In the dust samples from children's bedrooms, five perfluoroalkyl carboxylic acids (PFCAs) and perfluorooctane sulfonic acid (PFOS) were detected in more than half of the samples with the highest median concentration of 5.26 ng/g for perfluorooctanoic acid (PFOA). However, the dust samples were dominated by polyfluoroalkyl phosphoric acid esters (PAPs) and fluorotelomer alcohols (FTOHs) (highest medians: 53.9 ng/g for 6:2 diPAP and 45.7 ng/g for 8:2 FTOH). Several significant and strong correlations (up to p = 0.95) were found among different PFASs in dust as well as between PFASs in dust and air samples (previously published) from the same rooms. The logarithm of dust to air concentrations (log K-dust/air) plotted against the logarithm of the octanol-air partition coefficient (log K-oa) resulted in a significant linear regression line with R-2 > 0.88. Higher dust levels of PFOS were detected in rooms with plastic flooring material in comparison to wood (p < 0.05). Total estimated daily intakes via dust (EDIdust) and air (EDIair) of perfluoroalkyl acids (PFAA), including biotransformation of precursors to PFAAs, were calculated for 10.5-year-old children. The total EDIdust, for PFOA and PFOS were estimated to be 0.007 ng/kg bw/day and 0.006 ng/kg bw/day, respectively, in an intermediate exposure scenario. The sum of the total EDIs for all PFAAs was slightly higher for dust than air (0.027 and 0.019 ng/kg bw/day). Precursor biotransformation was generally important for total PFOS intake, while for the PFCAs, FTOH biotransformation was estimated to be important for air, but not for dust exposure.

  • 128.
    Winkens, Kerstin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Koponen, Jani
    Schuster, Jasmin
    Shoeib, Mahiba
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Berger, Urs
    Karvonen, Anne M.
    Pekkanen, Juha
    Kiviranta, Hannu
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms2017In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 222, p. 423-432Article in journal (Refereed)
    Abstract [en]

    The contamination levels and patterns of perfluoroallcyl acids (PFAAs) and their precursors in indoor air of children's bedrooms in Finland, Northern Europe, were investigated. Our study is among the most comprehensive indoor air monitoring studies (n = 57) and to our knowledge the first one to analyse air in children's bedrooms for PFASs (17 PFAAs and 9 precursors, including two acrylates, 6:2 FTAC and 6:2 FTMAC). The most frequently detected compound was 8:2 fluorotelomer alcohol (8:2 FTOH) with the highest median concentration (3570 pg/m(3)). FTOH concentrations were generally similar to previous studies, indicating that in 2014/2015 the impact of the industrial transition had been minor on FTOH levels in indoor air. However, in contrast to earlier studies (with one exception), median concentrations of 6:2 FTOH were higher than 10:2 FTOH. The C8 PFAAs are still the most abundant acids, even though they have now been phased out by major manufacturers. The mean concentrations of FOSE/As, especially MeFOSE (89.9 pg/m(3)), were at least an order of magnitude lower compared to previous studies. Collectively the comparison of FTOHs, PFAAs and FOSE/FOSAs with previous studies indicates that indoor air levels of PFASs display a time lag to changes in production of several years. This is the first indoor air study investigating 6:2 FTMAC, which was frequently detected (58%) and displayed some of the highest maximum concentrations (13 000 pg/m(3)). There were several statistically significant correlations between particular house and room characteristics and PFAS concentrations, most interestingly higher EtFOSE air concentrations in rooms with plastic floors compared to wood or laminate.

  • 129.
    Winkens, Kerstin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish Environmental Research Institute IVL, Sweden.
    Berger, Urs
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Early life exposure to per- and polyfluoroalkyl substances (PFASs): A critical review2017In: Emerging Contaminants, ISSN 2405-6650, E-ISSN 2405-6642, Vol. 3, no 2, p. 55-68Article in journal (Refereed)
    Abstract [en]

    Due to the dynamic developmental processes during pregnancy, infancy, childhood and adolescence, exposure to PFASs is hypothesized to have the most pronounced negative effects during this period. In this review we critically evaluate the current state of the science regarding human early life exposure processes (until 18 years of age) to per- and polyfluoroalkyl substances (PFASs). Efficient placental transfer of perfluoroalkyl acids (PFAAs) results in relatively high prenatal exposure compared with many neutral organic contaminants. The few biomonitoring studies that specifically target infants, toddlers and other children suggest relatively high serum concentrations of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in early life with peak concentrations occurring sometime before the child reaches 20 months. This peak in serum concentrations is most likely explained by exposure via breastfeeding, ingestion of house dust and/or specific contact events with consumer products leading to high body weight normalized estimated daily intakes (EDIs). Although children have higher EDIs of PFASs than adults, these are not always reflected by higher serum levels of PFASs in children in cross-sectional biomonitoring studies due to the confounding effect of age and birth cohort, and different exposure histories due to production changes. Longitudinal exposure studies measuring internal and external exposure (for multiple pathways and PFASs) at several time points during early life are strongly encouraged to understand temporal changes in exposure of individual children. A better quantitative understanding of early life exposure processes would help to improve the validity of epidemiological studies and allow informed decisions regarding setting of regulatory thresholds and appropriate mitigation actions.

  • 130.
    Wong, Fiona
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bounding uncertainties in intrinsic human elimination half-lives and intake of polybrominated diphenyl ethers in the North American population2013In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 59, p. 168-174Article in journal (Refereed)
    Abstract [en]

    We examine the balance between intake, intrinsic elimination half-lives and human body burdens measured in biomonitoring for polybrominated diphenyl ethers (PBDEs) in the North American population using the population-level pharmacokinetic model developed by Ritter et al. (2011). Empirical data are collected from two studies that made total intake estimates for the North American population for the years 2004 and 2005, and eight biomonitoring studies for the years 1992 to 2009. We assume intake of PBDEs increased exponentially to a peak in 2004, and has since exponentially declined. The model is fitted to the empirical PBDE intake and biomonitoring data on PBDE body burden using a least-square optimization method by adjusting the intake in 2004 and 2038, and the intrinsic elimination rate constants, which can be expressed as equivalent half-lives. We. fit the model in two types of scenarios using different combinations of PBDE intake estimates and biomonitoring data. Our modeling results indicate that there is an inconsistency between the PBDE intake estimates and the biomonitoring data, and that the inconsistency is likely due to underestimation of population-level intake. More efforts are needed to better characterize intake rates and identify potentially-unrecognized exposure pathways. Additional age-stratified biomonitoring data, and time trends of PBDE intakes would better constrain the model and provide an improved estimation of the intrinsic elimination half-lives.

  • 131.
    Wong, Fiona
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Mueller, Jochen F.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Enhanced Elimination of Perfluorooctane Sulfonic Acid by Menstruating Women: Evidence from Population-Based Pharmacokinetic Modeling2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 15, p. 8807-8814Article in journal (Refereed)
    Abstract [en]

    Human biomonitoring studies have shown that concentrations of perfluorooctane sulfonic acid (PFOS) in men are higher than in women. We investigate sex differences in elimination of PFOS by fitting a population-based pharmacokinetic model to six cross-sectional data sets from 1999 to 2012 from the US National Health and Nutrition Examination Survey (NHANES) and derive human first-order elimination rate constants (k(E)) and corresponding elimination half-lives (t(1/2)) for PFOS, where t(1/2) = In 2/k(E). We use a modified version of the Ritter population-based pharmacokinetic model and derive elimination rate constants separately for men and women. The model accounts for population-average lifetime changes in PFOS intake, body weight, and menstruation rate. We compare the model-derived elimination rate constant for hypothetical nonmenstruating women to the elimination rate constant for men and women when menstruation is included as a loss process to evaluate the hypothesis that loss of PFOS by menstruation is an important process for women. The modeled elimination half-life for men is 4.7 years, and the modeled elimination half-life for women when excluding losses from menstruation is 3.7 years. The elimination half-life for women when menstruation is included in the model is 4.0 years. Thus, menstruation accounts for 3096 of the discrepancy in elimination of PFOS between men and women. The remaining discrepancy is likely due to other sex-specific elimination routes that are not considered in our modeling.

  • 132.
    Wong, Fiona
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mueller, Jochen F.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Response to Comment on Enhanced Elimination of Perfluorooctane Sulfonic Acid by Menstruating Women: Evidence from Population-based Pharmacokinetic Modeling2015In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, no 9, p. 5838-5839Article in journal (Other academic)
  • 133. Yan, Hong
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Zhang, Chaojie
    Zhou, Qi
    Perfluoroalkyl acids in municipal landfill leachates from China: Occurrence, fate during leachate treatment and potential impact on groundwater2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 524, p. 23-31Article in journal (Refereed)
    Abstract [en]

    Raw and treated landfill leachate samples were collected from 5 municipal landfill sites in China to measure the concentrations and contamination profile of perfluoroalkyl acids (PFAAs) in leachate during different steps of treatment. The total concentration of PFAAs (Sigma PFAAs) ranged from 7280 to 292,000 ng L-1 in raw leachate and from 98.4 to 282,000 ng L-1 in treated leachate. The dominant compounds measured were PFOA (mean contribution 28.8% and 36.8% in raw and treated leachate, respectively) and PFBS (26.1% and 40.8% in raw and treated leachate, respectively). A calculation of mass flows during the leachate treatment processes showed that the fate of individual PFAAs was substance and treatment-specific. The Chinese national leakage of Sigma PFAAs to groundwater from landfill leachate was estimated to be 3110 kg year(-1), which is a significant environmental release that is potentially threatening the sustainable use of groundwater as a drinking water source.

123 101 - 133 of 133
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