Persistent Problem: Global Challenges to Managing PCBs.

Polychlorinated biphenyls (PCBs), "famous" as persistent organic pollutants (POPs), have been managed nationally since the 1970s and globally under the Stockholm Convention on POPs since 2004, requiring environmentally sound management (ESM) of PCBs by 2028. At most, 30% of countries are on track to achieve ESM by 2028. Globally over 10 million tonnes of PCB-containing materials remain, mostly in countries lacking the ability to manage PCB waste. Canada (Ontario) and Czechia, both parties to the Stockholm Convention, are close to achieving the 2028 goal, having reduced their stocks of pure PCBs by 99% in the past 10 years. In contrast, the USA, not a party to the Stockholm Convention, continues to have a substantial but poorly inventoried stock of PCBs and only ∼3% decrease in mass of PCBs since 2006. PCB management, which depends on Stockholm Convention support and national compliance, portends major challenges for POP management. The failure to manage global PCB stocks >30 years after the end of production highlights the urgent need to prioritize reducing production and use of newer, more widely distributed POPs such as chlorinated paraffins and per- and polyfluorinated alkyl substances, as these management challenges are unlikely to be resolved in the coming decades.

Line ferries and cargo ships for the monitoring of marine contaminants of emerging concern: Application along a Europe-Arctic transect.

Contaminants of emerging concern (CEC) are a focus in marine protection. Several CECs are released with wastewater effluents to coastal environments and their offshore occurrence has been recently documented. Routine monitoring is key for implementing marine protection acts, however infrastructural, financial, and technical limitations hinder this task along broad spatial transects. Here we show the efficacy of a new infrastructure enabling unmanned sampling of surface water from ships of opportunity in providing reliable and cost-effective routine monitoring of CECs along a Europe-Arctic transect. The distribution and long-range transport of several pharmaceuticals and personal care products, artificial food additives, and stimulants were assessed. Validation of operations through strict procedural and analytical quality criteria is presented. A framework to estimate a compound-specific spatial range (SR) index of marine long-range transport based on monitoring results and information on source spatial distribution, is introduced. Estimated SR values ranged 50-350 km depending on compound, yielding a ranking of long-range transport potential which reflected expectations based on degradation half-lives. SR values were used to calculate prior maps of detection probability that can be used to plan future routine monitoring in the region.

User-Centred Design of a Final Results Report for Participants in Multi-Sensor Personal Air Pollution Exposure Monitoring Campaigns.

Using low-cost portable air quality (AQ) monitoring devices is a growing trend in personal exposure studies, enabling a higher spatio-temporal resolution and identifying acute exposure to high concentrations. Comprehension of the results by participants is not guaranteed in exposure studies. However, information on personal exposure is multiplex, which calls for participant involvement in information design to maximise communication output and comprehension. This study describes and proposes a model of a user-centred design (UCD) approach for preparing a final report for participants involved in a multi-sensor personal exposure monitoring study performed in seven cities within the EU Horizon 2020 ICARUS project. Using a combination of human-centred design (HCD), human-information interaction (HII) and design thinking approaches, we iteratively included participants in the framing and design of the final report. User needs were mapped using a survey (n = 82), and feedback on the draft report was obtained from a focus group (n = 5). User requirements were assessed and validated using a post-campaign survey (n = 31). The UCD research was conducted amongst participants in Ljubljana, Slovenia, and the results report was distributed among the participating cities across Europe. The feedback made it clear that the final report was well-received and helped participants better understand the influence of individual behaviours on personal exposure to air pollution.

Harmonization and Visualization of Data from a Transnational Multi-Sensor Personal Exposure Campaign.

Use of a multi-sensor approach can provide citizens with holistic insights into the air quality of their immediate surroundings and their personal exposure to urban stressors. Our work, as part of the ICARUS H2020 project, which included over 600 participants from seven European cities, discusses the data fusion and harmonization of a diverse set of multi-sensor data streams to provide a comprehensive and understandable report for participants. Harmonizing the data streams identified issues with the sensor devices and protocols, such as non-uniform timestamps, data gaps, difficult data retrieval from commercial devices, and coarse activity data logging. Our process of data fusion and harmonization allowed us to automate visualizations and reports, and consequently provide each participant with a detailed individualized report. Results showed that a key solution was to streamline the code and speed up the process, which necessitated certain compromises in visualizing the data. A thought-out process of data fusion and harmonization of a diverse set of multi-sensor data streams considerably improved the quality and quantity of distilled data that a research participant received. Though automation considerably accelerated the production of the reports, manual and structured double checks are strongly recommended.

Application of land use regression modelling to describe atmospheric levels of semivolatile organic compounds on a national scale.

Despite the success of passive sampler-based monitoring networks in capturing global atmospheric distributions of semivolatile organic compounds (SVOCs), their limited spatial resolution remains a challenge. Adequate spatial coverage is necessary to better characterize concentration gradients, identify point sources, estimate human exposure, and evaluate the effectiveness of chemical regulations such as the Stockholm Convention on Persistent Organic Pollutants. Land use regression (LUR) modelling can be used to integrate land use characteristics and other predictor variables (industrial emissions, traffic intensity, demographics, etc.) to describe or predict the distribution of air concentrations at unmeasured locations across a region or country. While LUR models are frequently applied to data-rich conventional air pollutants such as particulate matter, ozone, and nitrogen oxides, they are rarely applied to SVOCs. The MONET passive air sampling network (RECETOX, Masaryk University) continuously measures atmospheric SVOC levels across Czechia in monthly intervals. Using monitoring data from 29 MONET sites over a two-year period (2015-2017) and a variety of predictor variables, we developed LUR models to describe atmospheric levels and identify sources of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and DDT across the country. Strong and statistically significant (R2 > 0.6; p < 0.05) models were derived for PAH and PCB levels on a national scale. The PAH model retained three predictor variables - heating emissions represented by domestic fuel consumption, industrial PAH point sources, and the hill:valley index, a measure of site topography. The PCB model retained two predictor variables - site elevation, and secondary sources of PCBs represented by soil concentrations. These models were then applied to Czechia as a whole, highlighting the spatial variability of atmospheric SVOC levels, and providing a tool that can be used for further optimization of sampling network design, as well as evaluating potential human and environmental chemical exposures.

NPAHs and OPAHs in the atmosphere of two central European cities: Seasonality, urban-to-background gradients, cancer risks and gas-to-particle partitioning.

Derivatives of polycyclic aromatic hydrocarbons (PAHs) such as nitrated- and oxygenated-PAHs (NPAHs and OPAHs) could be even more toxic and harmful for the environment and humans than PAHs. We assessed the spatial and seasonal variations of NPAHs and OPAHs atmospheric levels, their cancer risks and their gas-to-particle partitioning. To this end, about 250 samples of fine particulate matter (PM2.5) and 50 gaseous samples were collected in 2017 in central Europe in the cities of Brno and Ljubljana (two traffic and two urban background sites) as well as one rural site. The average particulate concentrations were ranging from below limit of quantification to 593 pg m-3 for Σ9NPAHs and from 1.64 to 4330 pg m-3 for Σ11OPAHs, with significantly higher concentrations in winter compared to summer. In winter, the particulate levels of NPAHs and OPAHs were higher at the traffic site compared to the urban background site in Brno while the opposite was found in Ljubljana. NPAHs and OPAHs particulate levels were influenced by the meteorological parameters and co-varied with several air pollutants. The significance of secondary formation on the occurrence of some NPAHs and OPAHs is indicated. In winter, 27-47% of samples collected at all sites were above the acceptable lifetime carcinogenic risk. The gas-particle partitioning of NPAHs and OPAHs was influenced by their physico-chemical properties, the season and the site-specific aerosol composition. Three NPAHs and five OPAHs had higher particulate mass fractions at the traffic site, suggesting they could be primarily emitted as particles from vehicle traffic and subsequently partitioning to the gas phase along air transport. This study underlines the importance of inclusion of the gas phase in addition to the particulate phase when assessing the atmospheric fate of polycyclic aromatic compounds and also when assessing the related health risk.

Nitrated monoaromatic hydrocarbons (nitrophenols, nitrocatechols, nitrosalicylic acids) in ambient air: levels, mass size distributions and inhalation bioaccessibility.

Nitrated monoaromatic hydrocarbons (NMAHs) are ubiquitous in the environment and an important part of atmospheric humic-like substances (HULIS) and brown carbon. They are ecotoxic and with underresearched toxic potential for humans. NMAHs were determined in size-segregated ambient particulate matter collected at two urban sites in central Europe, Ostrava and Kladno, Czech Republic. The average sums of 12 NMAHs (Σ12NMAH) measured in winter PM10 samples from Ostrava and Kladno were 102 and 93 ng m-3, respectively, and 8.8 ng m-3 in summer PM10 samples from Ostrava. The concentrations in winter corresponded to 6.3-7.3% and 2.6-3.1% of HULIS-C and water-soluble organic carbon (WSOC), respectively. Nitrocatechols represented 67-93%, 61-73% and 28-96% of NMAHs in PM10 samples collected in winter and summer at Ostrava and in winter at Kladno, respectively. The mass size distribution of the targeted substance classes peaked in the submicrometre size fractions (PM1), often in the PM0.5 size fraction especially in summer. The bioaccessible fraction of NMAHs was determined by leaching PM3 samples in two simulated lung fluids, Gamble's solution and artificial lysosomal fluid (ALF). More than half of NMAH mass is found bioaccessible, almost complete for nitrosalicylic acids. The bioaccessible fraction was generally higher when using ALF (mimics the chemical environment created by macrophage activity, pH 4.5) than Gamble's solution (pH 7.4). Bioaccessibility may be negligible for lipophilic substances (i.e. log KOW > 4.5).

Oxygenated and Nitrated Polycyclic Aromatic Hydrocarbons in Ambient Air-Levels, Phase Partitioning, Mass Size Distributions, and Inhalation Bioaccessibility.

Among the nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) are some of the most hazardous substances to public health, mainly because of their carcinogenicity and oxidative potential. Despite these concerns, the concentrations and fate of NPAHs and OPAHs in the atmospheric environment are largely unknown. Ambient air concentrations of 18 NPAHs, 5 quinones, and 5 other OPAHs were determined at two urban and one regional background sites in central Europe. At one of the urban sites, the total (gas and particulate) concentrations of Σ10OPAHs were 10.0 ± 9.2 ng/m3 in winter and 3.5 ± 1.6 ng/m3 in summer. The gradient to the regional background site exceeded 1 order of magnitude. Σ18NPAH concentrations were typically 1 order of magnitude lower than OPAHs. Among OPAHs, 9-fluorenone and (9,10)-anthraquinone were the most abundant species, accompanied by benzanthrone in winter. (9,10)-Anthraquinone represented two-thirds of quinones. We found that a large fraction of the target substance particulate mass was carried by submicrometer particles. The derived inhalation bioaccessibility in the PM10 size fraction is found to be ≈5% of the total ambient concentration of OPAHs and up to ≈2% for NPAHs. For 9-fluorenone and (9,10)-anthraquinone, up to 86 and 18%, respectively, were found at the rural site. Our results indicate that water solubility could function as a limiting factor for bioaccessibility of inhaled particulate NPAHs and OPAHs, without considerable effect of surfactant lipids and proteins in the lung lining fluid.

Linking past uses of legacy SVOCs with today's indoor levels and human exposure.

Semivolatile organic compounds (SVOCs) emitted from consumer products, building materials, and indoor and outdoor activities can be highly persistent in indoor environments. Human exposure to and environmental contamination with polychlorinated biphenyls (PCBs) was previously reported in a region near a former PCB production facility in Slovakia. However, we found that the indoor residential PCB levels did not correlate with the distance from the facility. Rather, indoor levels in this region and those reported in the literature were related to the historic PCB use on a national scale and the inferred presence of primary sources of PCBs in the homes. Other SVOCs had levels linked with either the activities in the home, e.g., polycyclic aromatic hydrocarbons (PAHs) with wood heating; or outdoor activities, e.g., organochlorine pesticides (OCPs) with agricultural land use and building age. We propose a classification framework to prioritize SVOCs for monitoring in indoor environments and to evaluate risks from indoor SVOC exposures. Application of this framework to 88 measured SVOCs identified several PCB congeners (CB-11, -28, -52), hexachlorobenzene (HCB), benzo(a)pyrene, and γ-HCH as priority compounds based on high exposure and toxicity assessed by means of toxicity reference values (TRVs). Application of the framework to many emerging compounds such as novel flame retardants was not possible because of either no or outdated TRVs. Concurrent identification of seven SVOC groups in indoor environments provided information on their comparative levels and distributions, their sources, and informed our assessment of associated risks.

An overview of worldwide and regional time trends in total mercury levels in human blood and breast milk from 1966 to 2015 and their associations with health effects.

BACKGROUND: Mercury is a pollutant of global concern. To protect human health and environment from mercury pollution, the Minamata Convention on mercury entered into force in 2017. OBJECTIVES: To support a future effectiveness evaluation of the convention, this study assesses worldwide and regional time trends of total mercury levels in human blood and breast milk across different population sub-groups in the last half-century prior to entry-into-force of the Minamata Convention. This study also provides an overview of the epidemiological literature showing evidence of associations between mercury exposure (in terms of total mercury levels in whole blood, cord blood, and breast milk) and human health. METHODS: We searched electronic databases to identify articles published prior to June 14, 2017 and reported total mercury levels in any of three biological matrices (whole blood, cord blood, or breast milk) and/or associations with human health. Temporal trends of total mercury levels in the selected biological matrices across different population sub-groups were estimated using a linear fit of the log-transformed data. In parallel, statistical methods were employed to assess any possible effect of sources of inhomogeneity (i.e. study and population characteristics such as age, sex, ethnicity, source of exposure, sampling period, and geographical region) in the collected studies. Furthermore, a summary of significant and relevant associations between mercury exposure and human health conditions in children and adults was prepared. FINDINGS: We found significant declines in total mercury levels in whole blood, cord blood, and breast milk between 1966 and 2015. A regional overview of total mercury levels in whole blood, cord blood, and breast milk suggests the highest levels in South America, followed by Africa or Asia whereas the population groups from Europe or North America displayed the lowest levels of total mercury in the selected biological matrices. We observed conclusive consistent associations of mercury exposure with selected health conditions, especially neurodevelopment and neurotoxicity in children and adults. For several other health conditions, reported findings in the collected studies do not support conclusive associations. We also found that several studies demonstrated significant associations between mercury exposure below the USEPA reference level and various health conditions. CONCLUSIONS: This study provides a worldwide and regional overview of trends in total mercury levels in human blood and breast milk and associated health risks prior to entry-into-force of the Minamata Convention and calls for further epidemiological investigations from across the globe to fully understand the health implications of mercury exposure.

Characterizing Spatial Diversity of Passive Sampling Sites for Measuring Levels and Trends of Semivolatile Organic Chemicals.

Passive air sampling of semivolatile organic compounds (SVOCs) is a relatively inexpensive method that facilitates extensive campaigns with numerous sampling sites. An important question in the design of passive-sampling networks concerns the number and location of samplers. We investigate this question with the example of 17 SVOCs sampled at 14 background sites across the Czech Republic. More than 200 time series (length 5-11 years) were used to characterize SVOC levels and trends in air between 2003 and 2015. Six polychlorinated biphenyls (PCBs), 6 polyaromatic hydrocarbons (PAHs), and 5 organochlorine pesticides (OCPs) at 14 sites were assessed using data from the MONET passive sampling network. Significant decreases were found for most PCBs and OCPs whereas hexachlorobenzene (HCB) and most PAHs showed (mostly insignificant) increases. Spatial variability was rather low for PCBs and OCPs except for dichlorodiphenyltrichloroethane (DDT) and rather high for PAHs. The variability of the SVOC levels and trends depends on characteristics of the sites including their remoteness, landscape, population, and pollution sources. The sites can be grouped in distinct clusters, which helps to identify similar and, thereby, potentially redundant sites. This information is useful when monitoring networks need to be optimized regarding the location and number of sites.

Estimation of p,p'-DDT degradation in soil by modeling and constraining hydrological and biogeochemical controls.

Despite not being used for decades in most countries, DDT remains ubiquitous in soils due to its persistence and intense past usage. Because of this it is still a pollutant of high global concern. Assessing long term dissipation of DDT from this reservoir is fundamental to understand future environmental and human exposure. Despite a large research effort, key properties controlling fate in soil (in particular, the degradation half-life (τsoil)) are far from being fully quantified. This paper describes a case study in a large central European catchment where hundreds of measurements of p,p'-DDT concentrations in air, soil, river water and sediment are available for the last two decades. The goal was to deliver an integrated estimation of τsoil by constraining a state-of-the-art hydrobiogeochemical-multimedia fate model of the catchment against the full body of empirical data available for this area. The INCA-Contaminants model was used for this scope. Good predictive performance against an (external) dataset of water and sediment concentrations was achieved with partitioning properties taken from the literature and τsoil estimates obtained from forcing the model against empirical historical data of p,p'-DDT in the catchment multicompartments. This approach allowed estimation of p,p'-DDT degradation in soil after taking adequate consideration of losses due to runoff and volatilization. Estimated τsoil ranged over 3000-3800 days. Degradation was the most important loss process, accounting on a yearly basis for more than 90% of the total dissipation. The total dissipation flux from the catchment soils was one order of magnitude higher than the total current atmospheric input estimated from atmospheric concentrations, suggesting that the bulk of p,p'-DDT currently being remobilized or lost is essentially that accumulated over two decades ago.

Spatial gradients of polycyclic aromatic hydrocarbons (PAHs) in air, atmospheric deposition, and surface water of the Ganges River basin.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous semi-volatile organic pollutants. Their environmental occurrence is of global concern as some of them are carcinogens, mutagens, and teratogens. In this study, concentrations and distributions of 16 priority PAHs (∑PAHs) were measured in air, atmospheric deposition, and surface water at various locations in Himalayan, Middle, and Lower Reaches of the Ganges River, covering a spatial transect of 2500km, during two seasons (pre-monsoon and monsoon). The concentration of ∑PAHs ranged between 2.2 and 182.2ngm-3 in air, between 186 and 8810ngm-2day-1 in atmospheric deposition, and between 0.05 and 65.9ngL-1 in surface water. Air concentrations were strongly correlated with human population density. In the Middle and Lower Reaches of the Ganges River, atmospheric PAHs were mainly attributed to fossil fuel combustion sources. In the Himalayan Reach the influence of forest fire or biomass combustion was evident during the dry pre-monsoon season. Seasonality in concentrations of PAHs in river water was evident in the Himalayan Reach of the river, as a probable consequence of climate-modulated secondary source intensity (i.e. releases from glacier melting). Seasonality faded in the Middle and Lower Reaches of the Ganges where water contamination is expected to mainly reflect anthropogenic primary sources. Ambient air concentrations were used to calculate the probabilistic incremental lifetime cancer risk (ILCR). It was expectedly found to be higher in the Middle and Lower Reaches compared to the Himalayan Reach. The strong correlation between population density and air concentrations suggests population density may be used as a surrogate variable to assess human health risk in data-sparse regions such as the Ganges River basin.

Melting Himalayan glaciers contaminated by legacy atmospheric depositions are important sources of PCBs and high-molecular-weight PAHs for the Ganges floodplain during dry periods.

Melting glaciers are natural redistributors of legacy airborne pollutants, affecting exposure of pristine proglacial environments. Our data shows that melting Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic Plain during the dry season. Glacial emissions can exceed in some cases inputs from diffuse sources within the catchment. We analyzed air, deposition and river water in several sections along the Ganges River and its major headwaters. The predominant glacial origin of these contaminants in the Himalayan reach was demonstrated using air-water fugacity ratios and mass balance analysis. The proportion of meltwater emissions compared to pollutant discharge at downstream sections in the central part of the Gangetic Plain was between 2 and 200%. By remobilizing legacy pollutants from melting glaciers, climate change can enhance exposure levels over large and already heavily impacted regions of Northern India.

Spatial distribution of old and emerging flame retardants in Chinese forest soils: sources, trends and processes.

The levels and distribution of polybrominated diphenylethers (PBDEs), novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) in soils and their dependence on environmental and anthropological factors were investigated in 159 soil samples from 30 background forested mountain sites across China. Decabromodiphenylethane (DBDPE) was the most abundant flame retardant (25-18,000 pg g(-1) and 5-13,000 pg g(-1) in O-horizon and A-horizon, respectively), followed by BDE 209 (nd-5900 pg g(-1) and nd-2400 pg g(-1) in O-horizon and A-horizon, respectively). FRs distributions were primarily controlled by source distribution. The distributions of most phasing-out PBDEs, DP isomers and TBPH were in fact correlated to a population density-based index used as proxy of areas with elevated usage and waste of FR containing products. High concentrations of some NBFRs were however observed in industrialized regions and FR manufacturing plants. Strongly positive correlations were observed between PBDEs and their replacement products suggesting similar emission pattern and environmental behavior. Exposure of mineral subsoils depended on precipitations driving leaching of FRs into the soil core. This was especially evident for some emerging BFRs (TBE, TBPH, and TBB etc.) possibly indicating potential for diffuse groundwater contamination.

Current challenges in air sampling of semivolatile organic contaminants: sampling artifacts and their influence on data comparability.

With current science and policy needs, more attention is being given to expanding and improving air sampling of semivolatile organic contaminants (SVOCs). However, a wide range of techniques and configurations are currently used (active and passive samplers, different deployment times, different sorbents, etc.) and as the SVOC community looks to assess air measurements on a global scale, questions of comparability arise. We review current air sampling techniques, with a focus on sampling artifacts that can lead to uncertainties or biases in reported concentrations, in particular breakthrough, degradation, meteorological influences, and assumptions regarding passive sampling. From this assessment, we estimate the bias introduced for SVOC concentrations from all factors. Due to the effects of breakthrough, degradation, particle fractions and sampler uptake periods, some current passive and active sampler configurations may underestimate certain SVOCs by 30-95%. We then recommend future study design, appropriateness of sampler types for different study goals, and finally, how the SVOC community should move forward in both research and monitoring to best achieve comparability and consistency in air measurements.

Does an analysis of polychlorinated biphenyl (PCB) distribution in mountain soils across China reveal a latitudinal fractionation paradox?

Organic and mineral soil horizons from forests in 30 mountains across China were analysed for polychlorinated biphenyl (PCB). Soil total organic carbon (TOC) content was a key determinant of PCB distribution explaining over 90% of the differences between organic and mineral soils, and between 30% and 60% of the variance along altitudinal and regional transects. The residual variance (after normalization by TOC) was small. Tri- to tetra-CB levels were higher in the South in relation to high source density and precipitation. Heavier congeners were instead more abundant at mid/high-latitudes where the advection pattern was mainly from long range transport. This resulted in a latitudinal fractionation opposite to theoretical expectations. The study showed that exposure to sources with different characteristics, and possibly accumulation/degradation trends of different congeners in soils being out-of-phase at different latitudes, can lead to an unsteady large scale distribution scenario conflicting with the thermodynamic equilibrium perception.