Persistent organic pollutants in ambient air – sources, patterns, and environmental behaviour

Long-term air monitoring datasets are needed for persistent organic pollutants (POPs) to assess the effectiveness of source abatement measures and the factors controlling ambient levels, and to provide governments, regulators, and researchers with valuable information on emission/source controls and on the effectiveness of international chemicals regulation such as the Stockholm Convention and UN/ECE Protocol on POPs. These data can be provided by active or passive air sampling. The UK Toxic Organic Micro Pollutants (TOMPs) Network, using high-volume active air samplers, has demonstrated the constant decline in UK air concentrations for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polybrominated diphenyl ethers (PBDEs) since 1991, in accordance with emission estimates. For a latitudinal passive ambient air sampling transect from the south of England to the north of Norway established in 1994, which had reported several years of decreasing PCB air concentrations previously, increased levels were observed between 2008 and 2016. The reasons for this could include local sources, effects of climate change, and impact of polluted air masses from Eastern Europe. In contrast, PBDE concentrations have decreased since 2000 in line with expectations. Furthermore, seasonal patterns for PCB and PBDE concentrations in UK ambient air are discussed. PCBs generally showed a summer > winter pattern, while ƩPBDE concentrations were distributed over a range of congeners with more uniform concentrations but greater differences in seasonal patterns, thus their overall seasonality was characterized by these contrasting patterns. In addition to long-term trends and regular seasonal variations, short-term emission events like the UK ‘Bonfire Night’, where increased PBDE concentrations possibly stemming from ‘backyard burning’ were observed, were shown to impact POPs concentrations in ambient air. In order to overcome some limitations of current air sampling methods, two potential improvements were evaluated and recommended: the addition of XAD® pods in standard active air samplers, and the addition of monofluorinated PCBs to the range of performance reference compounds for passive air sampling

Mechanistic Insight into the Uptake and Fate of Persistent Organic Pollutants in Sea Ice

The fate of persistent organic pollutants in sea ice is a poorly researched area and yet ice serves as an important habitat for organisms at the base of the marine foodweb. This study presents laboratory-controlled experiments to investigate the mechanisms governing the fate of organic contaminants in sea ice grown from artificial seawater. Sea ice formation was shown to result in the entrainment of chemicals from seawater, and concentration profiles in bulk ice generally showed the highest levels in both the upper (ice–atmosphere interface) and lower (ice–ocean interface) ice layers, suggesting their incorporation and distribution is influenced by brine advection. Results from a 1-D sea ice brine dynamics model supported this, but also indicated that other processes may be needed to accurately model low-polarity compounds in sea ice. This was reinforced by results from a melt experiment, which not only showed chemicals were more enriched in saltier brine, but also revealed that chemicals are released from sea ice at variable rates. We use our results to demonstrate the importance of processes related to the occurrence and movement of brine for controlling chemical fate in sea ice which provides a pathway for exposure to ice-associated biota at the base of the pelagic food web

The TOMPs ambient air monitoring network:continuous data on UK air quality for over 20 years

Long-term air monitoring datasets are needed for persistent organic pollutants (POPs) to assess the effectiveness of source abatement measures and the factors controlling ambient levels. The Toxic Organic Micro Pollutants (TOMPs) Network, which has operated since 1991, collects ambient air samples at six sites across England and Scotland, using high-volume active air samplers. The network provides long-term ambient air trend data for a range of POPs at both urban and rural locations. Data from the network provides the UK Government, regulators and researchers with valuable information on emission/source controls and on the effectiveness of international chemicals regulation such as the Stockholm Convention and UN/ECE Protocol on POPs. The target chemicals of TOMPs have been polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and, since 2010, polybrominated diphenyl ethers (PBDEs). The continuous monitoring of these compounds demonstrates the constant decline in UK air concentrations over the last two decades, with average clearance rates for PCDD/Fs in urban locations of 5.1 years and for PCBs across all sites 6.6 years. No significant declines in rural locations for PCDD/Fs have been observed. There is a strong observable link between the declining ambient air concentrations and the emission reductions estimated in the annually produced National Atmospheric Emission Inventory (NAEI) dataset. These findings clearly demonstrate the unique strengths of long-term consistent datasets for the evaluation of the success of chemical regulation and control

The TOMPs network:continuous data on the UK air quality for 20 years

The Toxic Organic Micro Pollutants (TOMPs) Network, which has operated since 1991, currently collects ambient air samples at six sites across England and Scotland, using high-volume active air samplers. Lancaster University has been operating this UK Department of Environment, Food and Rural Affairs (Defra) funded network from its inception, delivering long-term ambient air trend data for a range of Persistent Organic Pollutants (POPs) at both urban and rural locations. Data from the network provides Defra with valuable information on emission/source controls and on the effectiveness of international chemicals regulation. It is also used to demonstrate UK compliance with its obligations under the 2001 Stockholm Convention on Persistent Organic Pollutants and the 1998 UN/ECE Long-Range Atmospheric Transport Protocol. Moreover, long-term analysis of air pollutants at trace levels allows detailed studies on atmospheric fate and behaviour processes of persistent chemicals and is the inevitable basis of their successful modelling. The target chemicals of TOMPs have been polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and, since 2010, polybrominated diphenyl ethers (PBDEs). PCBs, PCDDs, PCDFs, and selected PBDEs are all listed under the Stockholm Convention. The continuous monitoring of these compounds has demonstrated the constant decline in their UK air concentrations over the last decades. The concentrations of all compounds are generally significantly higher at urban compared to semi-rural and rural sites, with estimated clearance rates between 2 and 9 years for PCBs at all sites, 2 to 4 years for PBDEs at urban and semi-rural sites, and 4 to 5 years for PCDDs and PCDFs at urban sites. All these data are in good agreement with emission estimates. Additionally, an archive is maintained, which can be used for analysing emerging chemicals, such as alternative flame retardants, pesticides, and further substances of interest as soon as they have been identified

Failure of Supervised Chloroquine and Primaquine Regimen for the Treatment of Plasmodium vivax in the Peruvian Amazon

The widespread use of primaquine (PQ) and chloroquine (CQ), together, may be responsible for the relatively few, isolated cases of chloroquine-resistant P. vivax (CQRPV) that have been reported from South America. We report here a case of P. vivax from the Amazon Basin of Peru that recurred against normally therapeutic blood levels of CQ. Four out of 540 patients treated with combination CQ and PQ had a symptomatic recurrence of P. vivax parasitemia within 35 days of treatment initiation, possibly indicating CQ failure. Whole blood total CQ level for one of these four subjects was 95 ng/ml on the day of recurrence. Based on published criteria that delineate CQRPV as a P. vivax parasitemia, either recrudescence or relapse, that appears against CQ blood levels >100 ng/mL, we document the occurrence of a P. vivax strain in Peru that had unusually high tolerance to the synergistic combination therapy of CQ + PQ that normally works quite well

Persistent Organic Pollutants in sediment and fish in the River Thames catchment (UK)

Some organic pollutants including polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and hexachlorobenzene (HCB) have been banned from production and use in the UK for > 30 years but due to their toxicity and persistence are still of concern. However, due to their hydrophobicity they are present at very low concentrations and are difficult to measure in water, and so other matrices need to be sampled in order to best assess contamination. This study measured concentrations of ΣICES 7 PCBs (PCB congeners 28, 52, 101, 118, 138, 153 and 180) and Σ6 PBDEs (PBDE congeners 28, 47, 99, 100, 153, 154) and HCB in both bed-sediments and wild roach (a common pelagic fish) in the Thames Basin. The highest sediment concentrations were detected in an urbanised tributary of the Thames, The Cut at Bracknell (HCB: 0.03–0.40 μg/kg dw; ICES 7 PCBs: 4.83–7.42 μg/kg dw; 6 BDEs: 5.82–23.10 μg/kg dw). When concentrations were expressed on a dry weight basis, the fish were much more contaminated than the sediments, but when sediment concentrations were normalised to organic carbon concentration they were comparable to the fish lipid normalised concentrations. Thus, despite the variability in the system, both sediments and wild fish can be considered suitable for representing the level of POPs contamination of the river system given sufficient sample numbers

Selective Induction of Cell Death in Melanoma Cell Lines through Targeting of Mcl-1 and A1

Melanoma is an often fatal form of skin cancer which is remarkably resistant against radio- and chemotherapy. Even new strategies that target RAS/RAF signaling and display unprecedented efficacy are characterized by resistance mechanisms. The targeting of survival pathways would be an attractive alternative strategy, if tumor-specific cell death can be achieved. Bcl-2 proteins play a central role in regulating survival of tumor cells. In this study, we systematically investigated the relevance of antiapoptotic Bcl-2 proteins, i.e., Bcl-2, Bcl-xL, Bcl-w, Mcl-1, and A1, in melanoma cell lines and non-malignant cells using RNAi. We found that melanoma cells required the presence of specific antiapoptotic Bcl-2 proteins: Inhibition of Mcl-1 and A1 strongly induced cell death in some melanoma cell lines, whereas non-malignant cells, i.e., primary human fibroblasts or keratinocytes were not affected. This specific sensitivity of melanoma cells was further enhanced by the combined inhibition of Mcl-1 and A1 and resulted in 60% to 80% cell death in all melanoma cell lines tested. This treatment was successfully combined with chemotherapy, which killed a substantial proportion of cells that survived Mcl-1 and A1 inhibition. Together, these results identify antiapoptotic proteins on which specifically melanoma cells rely on and, thus, provide a basis for the development of new Bcl-2 protein-targeting therapies

Linking biochemical perturbations in tissues of the African catfish to the presence of polycyclic aromatic hydrocarbons in Ovia River, Niger Delta region

Petroleum hydrocarbons including polycyclic aromatic hydrocarbons (PAHs) are a pollution issue in the Niger Delta region due to oil industry activities. PAHs were measured in the water column of the Ovia River with concentrations ranging from 0.1 to 1055.6 ng L-1. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy detected alterations in tissues of the African catfish (Heter-bronchus bidorsalis) from the region showed varying degrees of statistically significant (P <0.0001, P <0.001, P <0.05) changes to absorption band areas and shifts in centroid positions of peaks. Alteration patterns were similar to those induced by benzoapyrene in MCF-7 cells. These findings have potential health implications for resident local communities as H. bidorsalis constitutes a key nutritional source. The study provides supporting evidence for the sensitivity of infrared spectroscopy in environmental studies and supports their potential application in biomonitoring. (C) 2015 Elsevier Ltd. All rights reserved