| 1. |
- Arnot, Jon A., et al.
(author)
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Prioritizing Chemicals and Data Requirements for Screening-Level Exposure and Risk Assessment
- 2012
-
In: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 120:11, s. 1565-1570
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Scientists and regulatory agencies strive to identify chemicals that may cause harmful effects to humans and the environment; however, prioritization is challenging because of the large number of chemicals requiring evaluation and limited data and resources. OBJECTIVES: We aimed to prioritize chemicals for exposure and exposure potential and obtain a quantitative perspective on research needs to better address uncertainty in screening assessments. METHODS: We used a multimedia mass balance model to prioritize > 12,000 organic chemicals using four far-field human exposure metrics. The propagation of variance (uncertainty) in key chemical information used as model input for calculating exposure metrics was quantified. RESULTS: Modeled human concentrations and intake rates span approximately 17 and 15 orders of magnitude, respectively. Estimates of exposure potential using human concentrations and a unit emission rate span approximately 13 orders of magnitude, and intake fractions span 7 orders of magnitude. The actual chemical emission rate contributes the greatest variance (uncertainty) in exposure estimates. The human biotransformation half-life is the second greatest source of uncertainty in estimated concentrations. In general, biotransformation and biodegradation half-lives are greater sources of uncertainty in modeled exposure and exposure potential than chemical partition coefficients. CONCLUSIONS: Mechanistic exposure modeling is suitable for screening and prioritizing large numbers of chemicals. By including uncertainty analysis and uncertainty in chemical information in the exposure estimates, these methods can help identify and address the important sources of uncertainty in human exposure and risk assessment in a systematic manner.
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| 2. |
- Arnot, Jon A., et al.
(author)
-
Toward a Consistent Evaluative Framework for POP Risk Characterization
- 2011
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:1, s. 97-103
-
Journal article (peer-reviewed)abstract
- The purpose of Annex E in the Stockholm Convention (SC) on Persistent Organic Pollutants (POPs) is to assess whether a chemical is likely, as a result of its long-range environmental transport, to lead to significant adverse human health or environmental effects, such that global action is warranted. To date, risk profiles for nominated POPs have not consistently selected assessment endpoints or completed mandated risk characterizations. An assessment endpoint hierarchy is proposed to facilitate risk characterization for the implementation of the SC. The framework is illustrated for a nominated POP, hexabromocyclododecane (HBCD), using three risk estimation methods. Based on current monitoring and toxicity data, the screening-level results indicate that humans and ecological receptors in remote regions such as the Arctic are unlikely to experience significant adverse effects (i.e., low risk) due to long-range environmental transport of HBCD. The results for birds are more uncertain than the results for fish and mammals due to the paucity of avian toxicity data. Risk characterization results for HBCD and for some listed POPs are compared to illustrate how the proposed methods can further assist decision-making and chemical management.
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| 3. |
- Arp, Hans Peter H., et al.
(author)
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The presence, emission and partitioning behavior of polychlorinated biphenyls in waste, leachate and aerosols from Norwegian waste-handling facilities
- 2020
-
In: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 715, s. 1-12
-
Journal article (peer-reviewed)abstract
- Even though production and open use of polychlorinated biphenyls (PCBs) have been phased out in Western industrialised countries since the 1980s, PCBs were still present in waste collected from different waste handling facilities in Norway in 2013. Sums of seven indicator-PCBs (I-PCB7:PCB-28, -52, -101, -118, -138, -153 and -180) were highest in plastic waste (3700 +/- 1800 mu g/kg, n=15), waste electrical and electronic equipment (WEEE) (1300 +/- 400 mu g/kg, n=12) and fine vehicle fluff (1800 = 1400 mu g/kg, n=4) and lowest in glass waste, combustibles, bottom ash and fly ash (0.3 to 65 mu g/kg). Concentrations in leachate water varied from 1.7 to 2900 ng/L, with higher concentrations found at vehicle and WEEE handling facilities. Particles in leachate water exhibited similar PCB sorption properties as solid waste collected on site, with waste-water partitioning coefficients ranging from 10(5)to 10(7) .I-PCB7 in air samples collected at the sites were mostly in the gas phase (100-24000 pg/m(3)), compared to those associated with particles (9-1900 pg/m(3)). In contrast, brominated flame retardants (BFRs) in the same samples were predominantly found associated with particles (e.g. sum of 10 brominated diethyl ethers, Sigma BDE10, associated with particles 77-194,000 pg/m(3)) compared to the gas phase (Sigma DE10 6-473 pg/m(3)). Measured gas-phase I-PCB7 concentrations are less than predicted, assuming waste-air partitioning in equilibrium with predominant waste on site. However, the gas-particle partitioning behavior of PCBs and BFRs could be predicted using an established partitioning model for ambient aerosols. PCB emissions from Norwegian waste handling facilities occurred primarily in the form of atmospheric vapor or leachate particles.
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| 4. |
- Barthel, Paul, et al.
(author)
-
Application of XAD-resin based passive air samplers to assess local (roadside) and regional patterns of persistent organic pollutants
- 2012
-
In: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 166, s. 218-225
-
Journal article (peer-reviewed)abstract
- We used XAD-resin based passive air samplers (PAS) to measure atmospheric levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) at five ombrotrophic bogs in Eastern Canada. The aims of our study were to investigate the influence of local roads on contaminant levels in the bogs, to derive the regional pattern of atmospheric concentrations, and to assess the uncertainties of the method. Expanded uncertainties based on the duplicate PAS deployed at 24 sites were good for the PAHs, while the deployment period of approx. 100 days was too short to yield acceptable uncertainties for PCBs. The regional PAH distribution was in good agreement with the calculated source proximity of the sampled bogs. We conclude that XAD-resin based PAS deployed for comparatively short periods are well suited for measuring atmospheric concentrations of volatile PAHs, while in remote regions longer deployment is necessary for less volatile PAHs and for PCBs.
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| 5. |
- Binnington, Matthew J, et al.
(author)
-
Effects of preparation on nutrient and environmental contaminant levels in Arctic beluga whale (Delphinapterus leucas) traditional foods
- 2017
-
In: Environmental Science. - : Royal Society of Chemistry. - 2050-7887 .- 2050-7895. ; 19:8, s. 1000-1015
-
Journal article (peer-reviewed)abstract
- For Canadian Arctic indigenous populations, marine mammal (MM) traditional foods (TFs) represent sources of both important nutrients and hazardous environmental contaminants. Food preparation is known to impact the nutrient and environmental contaminant content of processed items, yet the impacts of preparation on indigenous Arctic MM TFs remain poorly characterized. In order to determine how the various processes involved in preparing beluga blubber TFs affect their levels of nutrients and environmental contaminants, we collected blubber samples from 2 male beluga whales, aged 24 and 37 years, captured during the 2014 summer hunting season in Tuktoyaktuk, Northwest Territories, and processed them according to local TF preparation methods. We measured the levels of select nutrients [selenium (Se), polyunsaturated fatty acids (PUFAs)] and contaminants [organochlorine pesticides, perfluoroalkyl and polyfluoroalkyl substances (PFASs), polybrominated diphenyl ethers, polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), mercury (Hg)] in raw and prepared (boiled, roasted, aged) beluga blubber TFs. The impacts of beluga blubber TF preparation methods on nutrient and environmental contaminant levels were inconsistent, as the majority of processes either did not appear to influence concentrations or affected the two belugas differently. However, roasting and ageing beluga blubber consistently impacted certain compounds: roasting blubber increased concentrations of hydrophilic substances (Se and certain PFASs) through solvent depletion and deposited PAHs from cookfire smoke. The solid-liquid phase separation involved in ageing blubber depleted hydrophilic elements (Se, Hg) and some ionogenic PFASs from the lipid-rich liquid oil phase, while PUFA levels appeared to increase, and hydrophobic persistent organic pollutants were retained. Ageing blubber adjacent to in-use smokehouses also resulted in considerable PAH deposition to processed samples. Our findings demonstrated that contaminant concentration differences were greater between the two sets of whale samples, based on age differences, than they were within each set of whale samples, due to variable preparation methods. When considering means to minimize human contaminant exposure while maximizing nutrient intake, consumption of aged liquid from younger male whales would be preferred, based on possible PUFA enhancement and selective depletion of hydrophilic environmental contaminants in this food item.
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| 6. |
- Binnington, Matthew J., et al.
(author)
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Evaluating the Effectiveness of Fish Consumption Advisories : Modeling Prenatal, Postnatal, and Childhood Exposures to Persistent Organic Pollutants
- 2014
-
In: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 122:2, s. 178-186
-
Journal article (peer-reviewed)abstract
- Background: Because human exposure to persistent organic pollutants (POPs) occurs mainly through ingestion of contaminated food, regulatory bodies issue dietary consumption advisories to describe safe intake levels for food items of concern, particularly fish. Objectives: Our study goal was to estimate the effectiveness of fish consumption advisories in reducing exposure of infants and children to POPs. Methods: We used the time-variant mechanistic model CoZMoMAN to estimate and compare prenatal, postnatal, and childhood exposure to polychlorinated biphenyl congener PCB-153 under different scenarios of maternal guideline adherence for both hypothetical constant and realistic time-variant chemical emissions. The scenarios differed in terms of length of compliance (1 vs. 5 years), extent of fish substitution (all vs. half), and replacement diet (uncontaminated produce vs. beef). We also estimated potential exposure reductions for a range of theoretical chemicals to explore how guideline effectiveness varies with a chemical's partitioning and degradation properties. Results: When assuming realistic time periods of advisory compliance, our findings suggest that temporarily eliminating or reducing maternal fish consumption is largely ineffective in reducing pre-and postnatal exposure to substances with long elimination half-lives in humans, especially during periods of decreasing environmental emissions. Substituting fish with beef may actually result in higher exposure to certain groups of environmental contaminants. On the other hand, advisories may be highly effective in reducing exposure to substances with elimination half-lives in humans shorter than the length of compliance. Conclusions: Our model estimates suggest that fish consumption advisories are unlikely to be effective in reducing prenatal, postnatal, and childhood exposures to compounds with long elimination half-lives in humans.
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| 7. |
- Breivik, Knut, et al.
(author)
-
Added value of the emissions fractions approach when assessing a chemical's potential for adverse effects as a result of long-range transport
- 2023
-
In: Environmental Science Advances. - 2754-7000. ; 2:10, s. 1360-1371
-
Journal article (peer-reviewed)abstract
- It is of considerable interest to identify chemicals which may represent a hazard and risk to environmental and human health in remote areas. The OECD POV and LRTP Screening Tool (“The Tool”) for assessing chemicals for persistence (P) and long-range transport potential (LRTP) has been extensively used for combined P and LRTP assessments in various regulatory contexts, including the Stockholm Convention (SC) on Persistent Organic Pollutants (POPs). The approach in The Tool plots either the Characteristic Travel Distance (CTD, in km), a transport-oriented metric, or the Transfer Efficiency (TE, in %), which calculates the transfer from the atmosphere to surface compartments in a remote region, against overall persistence (POV). For a chemical to elicit adverse effects in remote areas, it not only needs to be transported and transferred to remote environmental surface media, it also needs to accumulate in these media. The current version of The Tool does not have a metric to quantify this process. We screened a list of >12 000 high production volume chemicals (HPVs) for the potential to be dispersed, transferred, and accumulate in surface media in remote regions using the three corresponding LRTP metrics of the emission fractions approach (EFA; ϕ1, ϕ2, ϕ3), as implemented in a modified version of The Tool. Comparing the outcome of an assessment based on CTD/TE and POV with the EFA, we find that the latter classifies a larger number of HPVs as having the potential for accumulation in remote regions than is classified as POP-like by the existing approach. In particular, the EFA identifies chemicals capable of accumulating in remote regions without fulfilling the criterion for POV. The remote accumulation fraction of the EFA is the LRTP assessment metric most suited for the risk assessment stage in Annex E of the SC. Using simpler metrics (such as half-life criteria, POV, and LRTP–POV combinations) in a hazard-based assessment according to Annex D is problematic as it may prematurely screen out many of the chemicals with potential for adverse effects as a result of long-range transport.
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| 8. |
- Breivik, Knut, et al.
(author)
-
Introducing a nested multimedia fate and transport model for organic contaminants (NEM)
- 2021
-
In: Environmental Science. - : Royal Society of Chemistry (RSC). - 2050-7887 .- 2050-7895. ; :8
-
Journal article (peer-reviewed)abstract
- Some organic contaminants, including the persistent organic pollutants (POPs), have achieved global distribution through long range atmospheric transport (LRAT). Regulatory efforts, monitoring programs and modelling studies address the LRAT of POPs on national, continental (e.g. Europe) and/or global scales. Whereas national and continental-scale models require estimates of the input of globally dispersed chemicals from outside of the model domain, existing global-scale models either have relatively coarse spatial resolution or are so computationally demanding that it limits their usefulness. Here we introduce the Nested Exposure Model (NEM), which is a multimedia fate and transport model that is global in scale yet can achieve high spatial resolution of a user-defined target region without huge computational demands. Evaluating NEM by comparing model predictions for PCB-153 in air with measurements at nine long-term monitoring sites of the European Monitoring and Evaluation Programme (EMEP) reveals that nested simulations at a resolution of 1° × 1° yield results within a factor of 1.5 of observations at sites in northern Europe. At this resolution, the model attributes more than 90% of the atmospheric burden within any of the grid cells containing an EMEP site to advective atmospheric transport from elsewhere. Deteriorating model performance with decreasing resolution (15° × 15°, 5° × 5° and 1° × 1°), manifested by overestimation of concentrations across most of northern Europe by more than a factor of 3, illustrates the effect of numerical diffusion. Finally, we apply the model to demonstrate how the choice of spatial resolution affect predictions of atmospheric deposition to the Baltic Sea. While we envisage that NEM may be used for a wide range of applications in the future, further evaluation will be required to delineate the boundaries of applicability towards chemicals with divergent fate properties as well as in environmental media other than air.
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| 9. |
- Breivik, Knut, et al.
(author)
-
Screening organic chemicals in commerce for emissions in the context of environmental and human exposure
- 2012
-
In: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 14:8, s. 2028-2037
-
Journal article (peer-reviewed)abstract
- Quantitative knowledge of organic chemical release into the environment is essential to understand and predict human exposure as well as to develop rational control strategies for any substances of concern. While significant efforts have been invested to characterize and screen organic chemicals for hazardous properties, relatively less effort has been directed toward estimating emissions and hence also risks. Here, a rapid throughput method to estimate emissions of discrete organic chemicals in commerce has been developed, applied and evaluated to support screening studies aimed at ranking and identifying chemicals of potential concern. The method builds upon information in the European Union Technical Guidance Document and utilizes information on quantities in commerce (production and/or import rates), chemical function (use patterns) and physical-chemical properties to estimate emissions to air, soil and water within the OECD for five stages of the chemical life-cycle. The method is applied to 16 029 discrete substances (identified by CAS numbers) from five national and international high production volume lists. As access to consistent input data remains fragmented or even impossible, particular attention is given to estimating, evaluating and discussing uncertainties in the resulting emission scenarios. The uncertainty for individual substances typically spans 3 to 4 orders of magnitude for this initial tier screening method. Information on uncertainties in emissions is useful as any screening or categorization methods which solely rely on threshold values are at risk of leading to a significant number of either false positives or false negatives. A limited evaluation of the screening method's estimates for a sub-set of about 100 substances, compared against independent and more detailed emission scenarios presented in various European Risk Assessment Reports, highlights that up-to-date and accurate information on quantities in commerce as well as a detailed breakdown on chemical function are critically needed for developing more realistic emission scenarios.
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| 10. |
- Breivik, Knut, et al.
(author)
-
The Emissions Fractions Approach to Assessing the Long-Range Transport Potential of Organic Chemicals
- 2022
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 56:17, s. 11983-11990
-
Journal article (peer-reviewed)abstract
- The assessment of long-range transport potential (LRTP) is enshrined in several frameworks for chemical regulation such as the Stockholm Convention. Screening for LRTP is commonly done with the OECD Pov and LRTP Screening Tool employing two metrics, characteristic travel distance (CTD) and transfer efficiency (TE). Here we introduce a set of three alternative metrics and implement them in the Tool’s model. Each metric is expressed as a fraction of the emissions in a source region. The three metrics quantify the extent to which the chemical (i) reaches a remote region (dispersion, ϕ1), (ii) is transferred to surface media in the remote region (transfer, ϕ2), and (iii) accumulates in these surface media (accumulation, ϕ3). In contrast to CTD and TE, the emissions fractions metrics can integrate transport via water and air, enabling comprehensive LRTP assessment. Furthermore, since there is a coherent relationship between the three metrics, the new approach provides quantitative mechanistic insight into different phenomena determining LRTP. Finally, the accumulation metric, ϕ3, allows assessment of LRTP in the context of the Stockholm Convention, where the ability of a chemical to elicit adverse effects in surface media is decisive. We conclude that the emission fractions approach has the potential to reduce the risk of false positives/negatives in LRTP assessments.
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| 11. |
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| 12. |
- Harner, Tom, et al.
(author)
-
Air synthesis review : polycyclic aromatic compounds in the oil sands region
- 2018
-
In: Environmental Reviews. - : Canadian Science Publishing. - 1181-8700 .- 1208-6053. ; 26:4, s. 430-468
-
Research review (peer-reviewed)abstract
- This air synthesis review presents the current state of knowledge on the sources, fates, and effects for polycyclic aromatic compounds (PACs) and related chemicals released to air in the oil sands region (OSR) in Alberta, Canada. Through the implementation of the Joint Canada-Alberta Oil Sands Monitoring Program in 2012 a vast amount of new information on PACs has been acquired through directed monitoring and research projects and reported to the scientific community and public. This new knowledge addresses questions related to cumulative effects and informs the sustainable management of the oil sands resource while helping to identify gaps in understanding and priorities for future work. As a result of this air synthesis review on PACs, the following topics have been identified as new science priorities: (i) improving emissions reporting to better account for fugitive mining emissions of PACs that includes a broader range of PACs beyond the conventional polycyclic aromatic hydrocarbons (PAHs) including, inter alia, alkylated-PAHs (alk-PAHs), dibenzothiophene (DBT), alk-DBTs, nitro-PAHs, oxy-PAHs including quinones and thia-and aza-arenes; (ii) improving information on the ambient concentrations, long-range transport, and atmospheric deposition of these broader classes of PACs and their release (with co-contaminants) from different types of mining activities; (iii) further optimizing electricity-free and cost-effective approaches for assessing PAC deposition (e.g., snow sampling, lichens, passive ambient sampling) spatially across the OSR and downwind regions; (iv) designing projects that integrate monitoring efforts with source attribution models and ecosystem health studies to improve understanding of sources, receptors, and effects; (v) further optimizing natural deposition archives (e.g., sediment, peat, tree rings) and advanced forensic techniques (e.g., isotope analysis, marker compounds) to provide better understanding of sources of PACs in the OSR over space and time; (vi) conducting process research to improve model capabilities for simulating atmospheric chemistry of PACs and assessing exposure to wildlife and humans; and (vii) developing tools and integrated strategies for assessing cumulative risk to wildlife and humans by accounting for the toxicity of the mixture of chemicals in air rather than on a single compound basis.
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| 13. |
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| 14. |
- McLachlan, Michael S., et al.
(author)
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Using Model-Based Screening to Help Discover Unknown Environmental Contaminants
- 2014
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:13, s. 7264-7271
-
Journal article (peer-reviewed)abstract
- Of the tens of thousands of chemicals in use, only a small fraction have been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high-throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals likely to have high concentrations in specific environmental media, and we prioritized these for target analysis. This model-based screening was applied to 215 organosilicon chemicals culled from industrial chemical production statistics. The model-based screening prioritized several recognized organosilicon contaminants and generated hypotheses leading to the selection of three chemicals that have not previously been identified as potential environmental contaminants for target analysis. Trace analytical methods were developed, and the chemicals were analyzed in air, sewage sludge, and sediment. All three substances were found to be environmental contaminants. Phenyl-tris(trimethylsiloxy)silane was present in all samples analyzed, with concentrations of similar to 50 pg m(-3) in Stockholm air and similar to 0.5 ng g(-1) dw in sediment from the Stockholm archipelago. Tris(trifluoropropyl)trimethyl-cyclotrisiloxane and tetrakis(trifluoropropyl)tetramethyl-cyclotetrasiloxane were found in sediments from Lake Mjosa at similar to 1 ng g(-1) dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment.
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| 15. |
- Parajulee, Abha, et al.
(author)
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Comparing winter-time herbicide behavior and exports in urban, rural, and mixed-use watersheds
- 2018
-
In: Environmental Science. - : Royal Society of Chemistry. - 2050-7887 .- 2050-7895. ; 20:5, s. 767-779
-
Journal article (peer-reviewed)abstract
- The presence of pesticides in streams in winter, five to six years following bans on their municipal use suggests that complicated transport behaviour, such as subsurface retention and/or accumulation of pesticides and its release during storms, could be important for understanding recovery time frames following bans or legislation that aim to reduce chemical inputs. We investigated late fall and winter dynamics of four herbicides in paired urban and rural watersheds in Toronto, Canada during rainfall and snowmelt. The range of average concentrations and loads of the sum of atrazine, metolachlor, 2,4-D and mecoprop overlapped in the two types of watersheds, with slightly higher average concentrations in the rural watershed. Relatively consistent herbicide concentration-discharge patterns (i. e. dilution) were observed in the urban sub-watersheds during rainfall, while concentration-discharge patterns were much more variable in the rural watershed. This suggests relatively uniform transport pathways across the urban sub-watersheds, compared to the rural watershed. Concentration-discharge patterns of the neutral herbicides atrazine and metolachlor were similar in both watersheds during snowmelt, though varying discharge patterns resulted in divergent timings of peak concentrations. In contrast, the acidic pesticides 2,4-D and mecoprop, which are primarily associated with urban uses, showed much more variable behavior across both watersheds and merit further investigation. Overall, this work highlights the need to consider pesticide dynamics throughout the year in order to more thoroughly assess the longterm efficacy of legislation governing their use.
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| 16. |
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| 17. |
- Plassmann, Merle M., et al.
(author)
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Laboratory Studies on the Fate of Perfluoroalkyl Carboxylates and Sulfonates during Snowmelt
- 2011
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:16, s. 6872-6878
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Journal article (peer-reviewed)abstract
- Perfluoroalkyl acids (PFAAs) are anthropogenic chemicals that occur in snow from both remote and source regions. Experiments were conducted to determine how PFAAs are released from a melting snowpack. Different PFAAs eluted from the snowpack at different times, those with short chains eluting early, those with long chains eluting late. The concentrations in the meltwater of PFAAs with medium chain lengths of 6 to 9 perfluorinated carbon atoms first increased and then decreased during the melt period. Such a peak elution had not been previously observed for any other chemicals. The specific snow surface area (SSA) influenced this elution type, with peak concentrations occurring earlier in a snowpack with lower SSA. Model simulations suggested that the snow surface decrease during the melt alone was insufficient to explain the observations. It was ruled out that the calcium concentration affected PFAA sorption to the snow surface in a similar way as sorption to sediments. Adsorption coefficients of PFAAs to the snow surface were estimated by fitting the measured and modeled elution profiles.
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| 18. |
- Plassmann, Merle M., et al.
(author)
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Theoretical and Experimental Simulation of the Fate of Semifluorinated n-Alkanes during Snowmelt
- 2010
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:17, s. 6692-6697
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Journal article (peer-reviewed)abstract
- Semifluorinated n-alkanes (SFAs) are highly fluorinated anthropogenic chemicals that are released into the environment through their use in ski waxes. Nothing is known about their environmental partitioning in general and their fate during snowmelt in particular. Properties were estimated for a range of SFAs with different chain lengths and degrees of fluorination using the SPARC calculator and poly parameter linear free energy relationships (ppLFERs). The calculations resulted in very low water solubility and vapor pressures and, consequently, high log KOW and log KOA values. Artificially produced snow in a cold room was spiked with a range of SFAs and subsequently melted with infrared lamps. Melt water, particles, and air samples taken during melting were analyzed. Both calculations and experiments showed that SFAs used in ski waxes will bind to particles or snow grain surfaces during snowmelt and thus are predicted to end up on the soil surface in skiing areas.
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| 19. |
- Thuens, Sabine, et al.
(author)
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Comparison of Atmospheric Travel Distances of Several PAHs Calculated by Two Fate and Transport Models (The Tool and ELPOS) with Experimental Values Derived from a Peat Bog Transect
- 2014
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In: Atmosphere. - : MDPI AG. - 2073-4433. ; 5:2, s. 324-341
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Journal article (peer-reviewed)abstract
- Multimedia fate and transport models are used to evaluate the long range transport potential (LRTP) of organic pollutants, often by calculating their characteristic travel distance (CTD). We calculated the CTD of several polycyclic aromatic hydrocarbons (PAHs) and metals using two models: the OECD P-OV& LRTP Screening Tool (The Tool), and ELPOS. The absolute CTDs of PAHs estimated with the two models agree reasonably well for predominantly particle-bound congeners, while discrepancies are observed for more volatile congeners. We test the performance of the models by comparing the relative ranking of CTDs with the one of experimentally determined travel distances (ETDs). ETDs were estimated from historical deposition rates of pollutants to peat bogs in Eastern Canada. CTDs and ETDs of PAHs indicate a low LRTP. To eliminate the high influence on specific model assumptions and to emphasize the difference between the travel distances of single PAHs, ETDs and CTDs were analyzed relative to the travel distances of particle-bound compounds. The ETDs determined for PAHs, Cu, and Zn ranged from 173 to 321 km with relative uncertainties between 26% and 46%. The ETDs of two metals were shorter than those of the PAHs. For particle-bound PAHs the relative ETDs and CTDs were similar, while they differed for Chrysene.
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| 20. |
- Undeman, Emma, et al.
(author)
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The susceptibility of human populations to environmental exposure to organic contaminants
- 2010
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In: Environmental Science and Technology. - Washington, D.C. : American Chemical Society. - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:16, s. 6249-6255
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Journal article (peer-reviewed)abstract
- Environmental exposure to organic contaminants is a complex function of environmental conditions, food chain characteristics, and chemical properties. In this study the susceptibility of various human populations to environmental exposure to neutral organic contaminants was compared. An environmental fate model and a linked bioaccumulation model were parameterized to describe ecosystems in different climatic regions (temperate, arctic, tropical and steppe). The human body burden resulting from constant emissions of hypothetical chemicals was estimated for each region. An exposure susceptibility index was defined as the body burden in the region of interest normalized to the burden of the same chemical in a reference human from the temperate region eating an average diet. For most persistent chemicals emitted to air, the Arctic had the highest susceptibility index (max 520). Susceptibility to exposure was largely determined by the food web properties. The properties of the physical environment only had a marked effect when air or water, not food, was the dominant source of human exposure. Shifting the mode of emission markedly changed the relative susceptibility of the ecosystems in some cases. The exposure arising from chemical use clearly varies between ecosystems, which makes an understanding of ecosystem susceptibility to exposure important for chemicals management.
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| 21. |
- Undeman, Emma, et al.
(author)
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Who in the world is most exposed to polychlorinated biphenyls? Using models to identify highly exposed populations
- 2018
-
In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 13:6
-
Journal article (peer-reviewed)abstract
- Human subpopulations experience different exposure to persistent organic pollutants (POPs) because of differences in the structure of their food webs and the extent of environmental contamination. Here we quantify the time-variant exposure of different human populations around the world to one representative POP, namely the polychlorinated biphenyl (PCB) congener 153, based on a dynamic simulation of both global environmental fate (using the model BETR-Global) and human food chain bioaccumulation (using the model ACC-HUMAN). The approach identifies subpopulations whose diets include a carnivorous mammal as experiencing the world's highest PCB-153 exposure, i.e. the very large biomagnification potential of their food web more than makes up for the remoteness of their living environment. However, for subpopulations that do not eat warm-blooded carnivores, the proximity to sources of PCBs is more important than food web structure and environmental conditions for differentiating their exposure to PCBs.
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| 22. |
- Wania, Frank, et al.
(author)
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Seasonal and latitudinal variability in the atmospheric concentrations of cyclic volatile methyl siloxanes in the Northern Hemisphere
- 2023
-
In: Environmental Science. - : Royal Society of Chemistry (RSC). - 2050-7887 .- 2050-7895. ; 25:3, s. 496-506
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Journal article (peer-reviewed)abstract
- Field data from two latitudinal transects in Europe and Canada were gathered to better characterize the atmospheric fate of three cyclic methylsiloxanes (cVMSs), i.e., octamethyl-cyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). During a year-long, seasonally resolved outdoor air sampling campaign, passive samplers with an ultra-clean sorbent were deployed at 15 sampling sites covering latitudes ranging from the source regions (43.7–50.7 °N) to the Arctic (79–82.5 °N). For each site, one of two passive samplers and one of two field blanks were separately extracted and analyzed for the cVMSs at two different laboratories using gas-chromatography-mass spectrometry. Whereas the use of a particular batch of sorbent and the applied cleaning procedure to a large extent controlled the levels of cVMS in field blanks, and therefore also the method detection and quantification limits, minor site-specific differences in field blank contamination were apparent. Excellent agreement between duplicates was obtained, with 95% of the concentrations reported by the two laboratories falling within a factor of 1.6 of each other. Nearly all data show a monotonic relationship between the concentration and distance from the major source regions. Concentrations in source regions were comparatively constant throughout the year, while the concentration gradient towards remote regions became steeper during summer when removal via OH radicals is at its maximum. Concentrations of the different cVMS oligomers were highly correlated within a given transect. Changes in relative abundance of cVMS oligomers along the transect were in agreement with relative atmospheric degradation rates via OH radicals.
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