The Emissions Fractions Approach to Assessing the Long-Range Transport Potential of Organic Chemicals.

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.

Main sources controlling atmospheric burdens of persistent organic pollutants on a national scale.

National long-term monitoring programs on persistent organic pollutants (POPs) in background air have traditionally relied on active air sampling techniques. Due to limited spatial coverage of active air samplers, questions remain (i) whether active air sampler monitoring sites are representative for atmospheric burdens within the larger geographical area targeted by the monitoring programs, and thus (ii) if the main sources affecting POPs in background air across a nation are understood. The main objective of this study was to explore the utility of spatial and temporal trends in concert with multiple modelling approaches to understand the main sources affecting polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in background air across a nation. For this purpose, a comprehensive campaign was carried out in summer 2016, measuring POPs in background air across Norway using passive air sampling. Results were compared to a similar campaign in 2006 to assess possible changes over one decade. We furthermore used the Global EMEP Multi-media Modeling System (GLEMOS) and the Flexible Particle dispersion model (FLEXPART) to predict and evaluate the relative importance of primary emissions, secondary emissions, long-range atmospheric transport (LRAT) and national emissions in controlling atmospheric burdens of PCB-153 on a national scale. The concentrations in air of both PCBs and most of the targeted OCPs were generally low, with the exception of hexachlorobenzene (HCB). A limited spatial variability for all POPs in this study, together with predictions by both models, suggest that LRAT dominates atmospheric burdens across Norway. Model predictions by the GLEMOS model, as well as measured isomeric ratios, further suggest that LRAT of some POPs are dictated by secondary emissions. Our results illustrate the utility of combining observations and mechanistic modelling approaches to help identify the main factors affecting atmospheric burdens of POPs across a nation, which, in turn, may be used to inform both national monitoring and control strategies.

Global Historical Stocks and Emissions of PBDEs.

The first spatially and temporally resolved inventory of BDE28, 47, 99, 153, 183, and 209 in the anthroposphere and environment is presented here. The stock and emissions of PBDE congeners were estimated using a dynamic substance flow analysis model, CiP-CAFE. To evaluate our results, the emission estimates were used as input to the BETR-Global model. Estimated concentrations were compared with observed concentrations in air from background areas. The global (a) in-use and (b) waste stocks of ∑5BDE(28, 47, 99, 153, 183) and BDE209 are estimated to be (a) ∼25 and 400 kt and (b) 13 and 100 kt, respectively, in 2018. A total of 6 (0.3-13) and 10.5 (9-12) kt of ∑5BDE and BDE209, respectively, has been emitted to the atmosphere by 2018. More than 70% of PBDE emissions during production and use occurred in the industrialized regions, while more than 70% of the emissions during waste disposal occurred in the less industrialized regions. A total of 70 kt of ∑5BDE and BDE209 was recycled within products since 1970. As recycling rates are expected to increase under the circular economy, an additional 45 kt of PBDEs (mainly BDE209) may reappear in new products.

Time trends of persistent organic pollutants in 30 year olds sampled in 1986, 1994, 2001 and 2007 in Northern Norway: Measurements, mechanistic modeling and a comparison of study designs.

BACKGROUND: Human biomonitoring studies have demonstrated decreasing concentrations of many persistent organic pollutants (POPs) in years after emission peaks. OBJECTIVES: To describe time trends of POPs in blood using four cross-sectional samples of 30 year olds from Tromsø, Norway across 1986-2007, and to compare the measured concentrations of polychlorinated biphenyl 153 (PCB-153) to model-estimated values. A second objective was to compare the repeated cross-sectional time trends with those observed in our previous longitudinal study using repeated individual measurements in older men from the same surveys. METHODS: Serum from 45 persons aged 30 years in each of the following years: 1986, 1994, 2001, and 2007 was analyzed for 14 POPs. Further, predicted concentrations of PCB-153 in each sampling year were derived using the emission-based CoZMoMAN model. RESULTS: The median decreases in summed serum POP concentrations (lipid-adjusted) in 1994, 2001, and 2007 relative to 1986 were - 71%, - 81%, and - 86% for women and - 65%, - 77%, and - 87% for men, respectively. The overall time trend in predicted PCB-153 concentrations demonstrated agreement with the observed trend although model predictions were higher than the measured concentrations at all time points. Compared to our previous longitudinal study of repeated individual measurements in older men, similar although more prominent declines were observed in the younger cross-sectional samples. DISCUSSION: Observed declines in serum concentrations from 1986 to 2007 were substantial for legacy POPs in men and women at reproductive ages in Northern Norway and are generally consistent with previous longitudinal biomonitoring efforts in the study population. The measured concentrations and observed declines likely reflect a combination of recent and historic exposures. Small differences in time trends observed between the studies could be attributed to different study designs (i.e. the chosen age group or sex and cross-sectional versus repeated individual measurement sampling).

Modeling the Time-Variant Dietary Exposure of PCBs in China over the Period 1930 to 2100.

This study aimed for the first time to reconstruct historical exposure profiles for PCBs to the Chinese population, by examining the combined effect of changing temporal emissions and dietary transition. A long-term (1930-2100) dynamic simulation of human exposure using realistic emission scenarios, including primary emissions, unintentional emissions, and emissions from e-waste, combined with dietary transition trends was conducted by a multimedia fate model (BETR-Global) linked to a bioaccumulation model (ACC-HUMAN). The model predicted an approximate 30-year delay of peak body burden for PCB-153 in a 30-year-old Chinese female, compared to their European counterpart. This was mainly attributed to a combination of change in diet and divergent emission patterns in China. A fish-based diet was predicted to result in up to 8 times higher body burden than a vegetable-based diet (2010-2100). During the production period, a worst-case scenario assuming only consumption of imported food from a region with more extensive production and usage of PCBs would result in up to 4 times higher body burden compared to consumption of only locally produced food. However, such differences gradually diminished after cessation of production. Therefore, emission reductions in China alone may not be sufficient to protect human health from PCB-like chemicals, particularly during the period of mass production. The results from this study illustrate that human exposure is also likely to be dictated by inflows of PCBs via the environment, waste, and food.

Long-Term Temporal Trends of Polychlorinated Biphenyls and Their Controlling Sources in China.

Polychlorinated biphenyls (PCBs) are industrial organic contaminants identified as persistent, bioaccumulative, toxic (PBT), and subject to long-range transport (LRT) with global scale significance. This study focuses on a reconstruction and prediction for China of long-term emission trends of intentionally and unintentionally produced (UP) ∑7PCBs (UP-PCBs, from the manufacture of steel, cement and sinter iron) and their re-emissions from secondary sources (e.g., soils and vegetation) using a dynamic fate model (BETR-Global). Contemporary emission estimates combined with predictions from the multimedia fate model suggest that primary sources still dominate, although unintentional sources are predicted to become a main contributor from 2035 for PCB-28. Imported e-waste is predicted to play an increasing role until 2020-2030 on a national scale due to the decline of intentionally produced (IP) emissions. Hypothetical emission scenarios suggest that China could become a potential source to neighboring regions with a net output of ∼0.4 t year-1 by around 2050. However, future emission scenarios and hence model results will be dictated by the efficiency of control measures.

Elucidating the Behavior of Cyclic Volatile Methylsiloxanes in a Subarctic Freshwater Food Web: A Modeled and Measured Approach.

Cyclic volatile methylsiloxanes (cVMS) are used in personal care products and emitted to aquatic environments through wastewater effluents, and their bioaccumulation potential is debated. Here, a new bentho-pelagic version of the ACC-HUMAN model was evaluated for polychlorinated biphenyls (PCBs) and applied to cVMS in combination with measurements to explore their bioaccumulation behavior in a subarctic lake. Predictions agreed better with measured PCB concentrations in Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) when the benthic link was included than in the pelagic-only model. Measured concentrations of decamethylcyclopentasiloxane (D5) were 60 ± 1.2 (Chironomidae larvae), 107 ± 4.5 (pea clams Pisidium sp.), 131 ± 105 (three-spined sticklebacks: Gasterosteus aculeatus), 41 ± 38 (char), and 9.9 ± 5.9 (trout) ng g-1 wet weight. Concentrations were lower for octamethylcyclotetrasiloxane (D4) and dodecamethylcyclohexasiloxane (D6), and none of the cVMS displayed trophic magnification. Predicted cVMS concentrations were lower than measured in benthos, but agreed well with measurements in fish. cVMS removal through ventilation was an important predicted loss mechanism for the benthic-feeding fish. Predictions were highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence, as this controlled bioavailability for benthos (the main source of cVMS for fish).

E-Waste Driven Pollution in Pakistan: The First Evidence of Environmental and Human Exposure to Flame Retardants (FRs) in Karachi City.

Informal e-waste recycling activities have been shown to be a major emitter of organic flame retardants (FRs), contributing to both environmental and human exposure to laborers at e-waste recycling sites in some West African countries, as well as in China and India. The main objective of this study was to determine the levels of selected organic FRs in both air and soil samples collected from areas with intensive informal e-waste recycling activities in Karachi, Pakistan. Dechlorane Plus (DP) and "novel" brominated flame retardants (NBFRs) were often detected in high concentrations in soils, while phosphorus-based FRs (OPFRs) dominated atmospheric samples. Among individual substances and substance groups, decabromodiphenyl ether (BDE-209) (726 ng/g), decabromodiphenyl ethane (DBDPE) (551 ng/g), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) (362 ng/g), and triphenyl-phosphate (∑TPP) (296 ng/g) were found to be prevalent in soils, while OPFR congeners (5903-24986 ng/m3) were prevalent in air. The two major e-waste recycling areas (Shershah and Lyari) were highly contaminated with FRs, suggesting informal e-waste recycling activities as a major emission source of FRs in the environment in Karachi City. However, the hazards associated with exposure to PM2.5 appear to exceed those attributed to exposure to selected FRs via inhalation and soil ingestion.

Understanding of Cyclic Volatile Methyl Siloxane Fate in a High Latitude Lake Is Constrained by Uncertainty in Organic Carbon-Water Partitioning.

Cyclic volatile methyl siloxanes (cVMS) are emitted to aquatic environments with wastewater effluents. Here, we evaluate the environmental behavior of three cVMS compounds (octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6)) in a high latitude lake (Storvannet, 70°N 23°E), experiencing intermittent wastewater emissions and high latitude environmental conditions (low temperatures and seasonal ice cover). Measured cVMS concentrations in lake water were below detection limits in both March and June 2014. However, mean concentrations in sediments were 207 ± 30, 3775 ± 973 and 848 ± 211 ng g-1 organic carbon for D4, D5 and D6, respectively. To rationalize measurements, a fugacity-based model for lakes (QWASI) was parametrized for Storvannet. The key removal process for cVMS from the lake was predicted to be advection due to the low hydraulic retention time of the lake, followed by volatilization. Predicted cVMS behavior was highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence. Predictions indicated lower overall persistence with decreasing temperature due to enhanced partitioning from sediments to water. Inverse modeling to predict steady-state emissions from cVMS concentrations in sediment provided unrealistically high emissions, when evaluated against measured concentrations in sewage. However, high concentrations of cVMS in sediment and low concentrations in water could be explained via a hypothetical dynamic emission scenario consistent with combined sewer overflows. The study illustrates the importance of considering compound-specific behavior of emerging contaminants that may differ from legacy organic contaminants.

Tracking the Global Distribution of Persistent Organic Pollutants Accounting for E-Waste Exports to Developing Regions.

Elevated concentrations of various industrial-use Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls (PCBs), have been reported in some developing areas in subtropical and tropical regions known to be destinations of e-waste. We used a recent inventory of the global generation and exports of e-waste to develop various global scale emission scenarios for industrial-use organic contaminants (IUOCs). For representative IUOCs (RIUOCs), only hypothetical emissions via passive volatilization from e-waste were considered whereas for PCBs, historical emissions throughout the chemical life-cycle (i.e., manufacturing, use, disposal) were included. The environmental transport and fate of RIUOCs and PCBs were then simulated using the BETR Global 2.0 model. Export of e-waste is expected to increase and sustain global emissions beyond the baseline scenario, which assumes no export. A comparison between model predictions and observations for PCBs in selected recipient regions generally suggests a better agreement when exports are accounted for. This study may be the first to integrate the global transport of IUOCs in waste with their long-range transport in air and water. The results call for integrated chemical management strategies on a global scale.

High Concentrations of Organic Contaminants in Air from Ship Breaking Activities in Chittagong, Bangladesh.

The beaches on the coast of Chittagong in Bangladesh are one of the most intense ship breaking areas in the world. The aim of the study was to measure the concentrations of organic contaminants in the air in the city of Chittagong, including the surrounding ship breaking areas using passive air samplers (N = 25). The compounds detected in the highest amounts were the polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs), whereas dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs) were several orders of magnitude lower in comparison. PCBs, PAHs, and HCB were highest at sites near the ship breaking activities, whereas DDTs and SCCPs were higher in the urban areas. Ship breaking activities likely act as atmospheric emission sources of PCBs, PAHs, and HCB, thus adding to the international emphasis on responsible recycling of ships. Concentrations of PAHs, PCBs, DDTs, HCB, and SCCPs in ambient air in Chittagong are high in comparison to those found in similar studies performed in other parts of Asia. Estimated toxic equivalent quotients indicate elevated human health risks caused by inhalation of PAHs at most sites.

Combining plasma measurements and mechanistic modeling to explore the effect of POPs on type 2 diabetes mellitus in Norwegian women.

The number of studies on persistent organic pollutants (POPs) and type 2 diabetes mellitus (T2DM) is growing steadily. Although concentrations of many POPs in humans have decreased substantially, only some studies consider temporal and inter-individual changes in POP concentrations when assessing exposure. Here we combined plasma measurements with mechanistic modeling to generate complementary exposure measures to our single blood draw after disease diagnosis. Blood was collected between 2003-2006 from 106 subjects with T2DM and 106 age-matched controls, and POP concentrations were compared after adjustment for relevant risk factors and multiple testing. Area under the curve (AUC) of PCB-153 from birth until age 18, representing early-life exposure, and AUC from birth until time of diagnosis were generated as well as examples of life-time exposure trajectories using a mechanistic exposure model. The rank sum of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs, OR=16.9 (95% CI: 3.05-93.6)) as well as ß-hexachlorocyclohexane (ß-HCH, OR=203.8 (95% CI: 11.5-3620)) and 1, 1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE, OR=11.3 (95% CI: 2.55-49.9)) were associated with T2DM. Neither of the AUCs reflecting early life exposure and total life-time exposure at the time of diagnosis were associated with the disease. The predicted life course trajectories display clear differences within and between individuals in the past and suggest that a single blood draw provide limited information on POP exposure earlier in life. The predicted AUCs for PCB-153 did not support the positive association between T2DM and measured blood concentration of certain POPs. This may suggest that the model is either too simplistic and/or that strength of the association may vary through life and with time to/past diagnosis.

Tracking the global generation and exports of e-waste. Do existing estimates add up?

The transport of discarded electronic and electrical appliances (e-waste) to developing regions has received considerable attention, but it is difficult to assess the significance of this issue without a quantitative understanding of the amounts involved. The main objective of this study is to track the global transport of e-wastes by compiling and constraining existing estimates of the amount of e-waste generated domestically in each country MGEN, exported from countries belonging to the Organization for Economic Cooperation and Development (OECD) MEXP, and imported in countries outside of the OECD MIMP. Reference year is 2005 and all estimates are given with an uncertainty range. Estimates of MGEN obtained by apportioning a global total of ∼ 35,000 kt (range 20,000-50,000 kt) based on a nation's gross domestic product agree well with independent estimates of MGEN for individual countries. Import estimates MIMP to the countries believed to be the major recipients of e-waste exports from the OECD globally (China, India, and five West African countries) suggests that ∼ 5,000 kt (3,600 kt-7,300 kt) may have been imported annually to these non-OECD countries alone, which represents ∼ 23% (17%-34%) of the amounts of e-waste generated domestically within the OECD. MEXP for each OECD country is then estimated by applying this fraction of 23% to its MGEN. By allocating each country's MGEN, MIMP, MEXP and MNET = MGEN + MIMP - MEXP, we can map the global generation and flows of e-waste from OECD to non-OECD countries. While significant uncertainties remain, we note that estimated import into seven non-OECD countries alone are often at the higher end of estimates of exports from OECD countries.

Using model-based screening to help discover unknown environmental contaminants.

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 ∼50 pg m(-3) in Stockholm air and ∼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 Mjøsa at ∼1 ng g(-1) dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment.

Calibration and application of a passive air sampler (XAD-PAS) for volatile methyl siloxanes.

Because the atmosphere is key to understanding the environmental behavior of volatile methyl siloxanes (VMS), a variety of reliable air sampling methods are needed. The purpose of this study was to calibrate and evaluate an existing, polystyrene-divinylbenzene copolymeric resin-based passive air sampler (XAD-PAS) for VMS. Sixteen XAD-PAS were deployed for 7-98 days at a suburban site in Toronto, Canada, while the VMS concentration in air was monitored by an active sampling method. This calibration and a subsequent field test further allowed for investigation of the temporal and spatial variability of VMS in the region. Uptake in the XAD-PAS of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and three linear VMS was linear throughout the whole deployment period. Sampling rates were between 0.4 and 0.5 m(3)/day. The XAD-PAS measured ∑VMS concentrations ranged from nondetects in rural areas (n = 3), to 169 ± 49 ng/m(3) in the urban region (n = 21), to levels above 600 ng/m(3) at sewage treatment plants (n = 2). Levels and composition of VMS within the urban area were remarkably uniform in space. Levels, but not composition, were highly variable in time and weakly correlated with temperature, wind speed, and wind direction.

Occurrence and seasonality of cyclic volatile methyl siloxanes in Arctic air.

Cyclic volatile methyl siloxanes (cVMS) are present in technical applications and personal care products. They are predicted to undergo long-range atmospheric transport, but measurements of cVMS in remote areas remain scarce. An active air sampling method for decamethylcyclopentasiloxane (D5) was further evaluated to include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and dodecamethylcyclohexasiloxane (D6). Air samples were collected at the Zeppelin observatory in the remote Arctic (79° N, 12° E) with an average sampling time of 81 ± 23 h in late summer (August-October) and 25 ± 10 h in early winter (November-December) 2011. The average concentrations of D5 and D6 in late summer were 0.73 ± 0.31 and 0.23 ± 0.17 ng/m(3), respectively, and 2.94 ± 0.46 and 0.45 ± 0.18 ng/m(3) in early winter, respectively. Detection of D5 and D6 in the Arctic atmosphere confirms their long-range atmospheric transport. The D5 measurements agreed well with predictions from a Eulerian atmospheric chemistry-transport model, and seasonal variability was explained by the seasonality in the OH radical concentrations. These results extend our understanding of the atmospheric fate of D5 to high latitudes, but question the levels of D3 and D4 that have previously been measured at Zeppelin with passive air samplers.

Modelling PCB-153 in northern ecosystems across time, space, and species using the nested exposure model.

There is concern over possible effects on ecosystems and humans from exposure to persistent organic pollutants (POPs) and chemicals with similar properties. The main objective of this study was to develop, evaluate, and apply the Nested Exposure Model (NEM) designed to simulate the link between global emissions and resulting ecosystem exposure while accounting for variation in time and space. NEM, using environmental and biological data, global emissions, and physicochemical properties as input, was used to estimate PCB-153 concentrations in seawater and biota of the Norwegian marine environment from 1930 to 2020. These concentrations were compared to measured concentrations in (i) seawater, (ii) an Arctic marine food web comprising zooplankton, fish and marine mammals, and (iii) Atlantic herring (Clupea harengus) and Atlantic cod (Gadus morhua) from large baseline studies and monitoring programs. NEM reproduced PCB-153 concentrations in seawater, the Arctic food web, and Norwegian fish within a factor of 0.1-31, 0.14-3.1, and 0.09-21, respectively. The model also successfully reproduced measured trophic magnification factors for PCB-153 at Svalbard as well as geographical variations in PCB-153 burden in Atlantic cod between the Skagerrak, North Sea, Norwegian Sea, and Barents Sea, but estimated a steeper decline in PCB-153 concentration in herring and cod during the last decades than observed. Using the evaluated model with various emission scenarios showed the important contribution of European and global primary emissions for the PCB-153 load in fish from Norwegian marine offshore areas.

Assessment of sorbent impregnated PUF disks (SIPs) for long-term sampling of legacy POPs.

Two field studies were conducted for one year using sorbent-impregnated polyurethane foam (SIP) disks for PCB and PBDE air sampling. SIP disks were introduced by Shoeib et al. (2008) as an alternative passive air sampling medium to the polyurethane foam (PUF) disk and have the advantage of a higher holding capacity for organic chemicals. The first study on SIP disks confirmed their application for measuring volatile perfluorinated compounds (PFCs) and their ability to maintain time-integrated (linear) air sampling. In this study, the suitability of the SIP disks for long-term sampling of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and hexachlorobenzene (HCB) was assessed. SIP disks were deployed at a rural site in the UK and harvested after periods ranging from 35-350 days. Atmospheric POP concentrations were monitored with a high-volume air sampler during the deployment period. Linear uptake was observed for all monitored PCBs and PBDEs over the full exposure time. Air-sampler equilibrium was observed for HCB after 6 months. In a second field study, SIP disks were deployed for one year at 10 sites on a latitudinal transect in the UK and Norway, at which air sampling has been undertaken previously with different passive air sampling media since 1994. The estimated concentrations and spatial distributions derived from the SIP disks were largely in agreement with previously reported data.

Using passive air samplers to assess local sources versus long range atmospheric transport of POPs.

Passive air samplers (PAS) are cost-efficient tools suitable for spatial mapping of atmospheric concentrations of persistent organic pollutants (POPs). The objective of this study was to use PAS to (i) determine atmospheric concentrations of selected POPs in Norwegian coastal zones with consumption advisories on seafood (N = 22), and (ii) evaluate a simple nested monitoring approach to assess the relative influence of local vs. long-range atmospheric transport (LRAT) at coastal sites. The latter was facilitated by comparison with data from a coordinated European-wide campaign in which an identical sampling and analytical approach was followed. Air concentrations were calculated based on the loss of performance reference compounds (PRCs), and results are presented for selected polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethanes (DDTs) and chlordanes. Air concentrations of PCBs were generally highest at sites within larger cities and up to about an order of magnitude higher than anticipated on the basis of LRAT alone. The distribution of PAHs and HCB occasionally showed elevated concentrations at coastal sites with ongoing or former industrial activity, while an urban site was significantly influenced by banned insecticides (technical DDT and lindane). Coastal sites were also elevated in α-HCH beyond the anticipated LRAT contribution, which we attribute to volatilization from the sea. We conclude that a simple nested PAS monitoring approach provides useful information for screening efforts aiming to assess both atmospheric burdens as well as the relative significance of local sources in controlling these burdens at sites in contaminated areas.

Screening organic chemicals in commerce for emissions in the context of environmental and human exposure.

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.