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Concept: Persistent organic pollutants


Temporal trends of Persistent Organic Pollutants (POPs) measured in Arctic air are essential in understanding long-range transport to remote regions and to evaluate the effectiveness of national and international chemical control initiatives, such as the Stockholm Convention (SC) on POPs. Long-term air monitoring of POPs is conducted under the Arctic Monitoring and Assessment Programme (AMAP) at four Arctic stations: Alert, Canada; Stórhöfði, Iceland; Zeppelin, Svalbard; and Pallas, Finland, since the 1990s using high volume air samplers. Temporal trends observed for POPs in Arctic air are summarized in this study. Most POPs listed for control under the SC, e.g. polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and chlordanes, are declining slowly in Arctic air, reflecting the reduction of primary emissions during the last two decades and increasing importance of secondary emissions. Slow declining trends also signifies their persistence and slow degradation under the Arctic environment, such that they are still detectable after being banned for decades in many countries. Some POPs, e.g. hexachlorobenzene (HCB) and lighter PCBs, showed increasing trends at specific locations, which may be attributable to warming in the region and continued primary emissions at source. Polybrominated diphenyl ethers (PBDEs) do not decline in air at Canada’s Alert station but are declining in European Arctic air, which may be due to influence of local sources at Alert and the much higher historical usage of PBDEs in North America. Arctic air samples are screened for chemicals of emerging concern to provide information regarding their environmental persistence (P) and long-range transport potential (LRTP), which are important criteria for classification as a POP under SC. The AMAP network provides consistent and comparable air monitoring data of POPs for trend development and acts as a bridge between national monitoring programs and SC’s Global Monitoring Plan (GMP).

Concepts: Canada, Norway, Persistent organic pollutant, Arctic Ocean, Polychlorinated biphenyl, Persistent organic pollutants, Biphenyl, Polychlorinated dibenzodioxins


It has been speculated that marine microplastics may cause negative effects on benthic marine organisms and increase bioaccumulation of persistent organic pollutants (POPs). Here, we provide the first controlled study of plastic effects on benthic organisms including transfer of POPs. The effects of polystyrene (PS) microplastic on survival, activity, and bodyweight as well as the transfer of 19 polychlorinated biphenyls (PCBs), were assessed in bioassays with Arenicola marina (L.). PS was pre-equilibrated in natively contaminated sediment. A positive relation was observed between microplastic concentration in the sediment and both uptake of plastic particles and weight loss by A. marina. Furthermore, a reduction in feeding activity was observed at a PS dose of 7.4% dry weight (DW). A low PS dose of 0.074% increased bioaccumulation of PCBs by a factor 1.1 - 3.6, an effect that was significant for ΣPCBs and several individual congeners. At higher doses, bioaccumulation decreased compared to the low dose, which however, was only significant for PCB105. PS has statistically significant effects on the organisms' fitness and bioaccumulation, but the magnitude of the effects was not high. This may be different for sites with different plastic concentrations, or plastics with a higher affinity for POPs.

Concepts: Plastic, Persistent organic pollutant, Polychlorinated biphenyl, Persistent organic pollutants, Biomagnification, PCB Congener List, Biphenyl, Polychlorinated dibenzodioxins


This paper focuses on the risks of environmental carcinogenic and/or genotoxic contaminants in food. It describes, for each contaminant studied, the carcinogenicity and genotoxicity, the toxicological reference values, the exposure and the risk characterization. The compounds studied were classified into 3 categories based on a risk assessment. Effects others than carcinogenicity and/or genotoxicity (e.g. endocrine disruption activity) were also taken into account for the classification. Given the low margin of exposure values for arsenic and lead, these two compounds are classified as priority 1 (high concern) for food safety and as a first priority to take actions to reduce exposure. Cadmium, methylmercury, dioxins & dioxin-like polychlorinated biphenyls (PCB), non-dioxin like PCB and toxaphene are classified as priority 2 (medium concern). Polybrominated biphenyls, chlordane, heptachlor, dichlorodiphenyltrichloroethane (DDT) and metabolites, hexachlorobenzene, hexachlorocyclohexane (lindane included), polychlorophenols and their salts are classified as priority 3 (low concern).

Concepts: Toxicology, Endocrine disruptor, Carcinogen, Insecticide, Polychlorinated biphenyl, Persistent organic pollutants, Mutagen, IARC Group 2B carcinogens


Perfluorooctane sulfonate (PFOS) found extensive use for over 60years up until its restriction in the early 2000s, culminating in its listing under the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2009. Efforts to minimise human body burdens are hindered by uncertainty over their precise origins. While diet appears the principal source for the majority of western populations (with other pathways like dust ingestion, drinking water and inhalation also important contributors); the role played by exposure to PFOS-precursor compounds followed by in vivo metabolism to PFOS as the ultimate highly stable end-product is unclear. Such PFOS-precursor compounds include perfluorooctane sulfonamide derivates, e.g., perfluorooctane sulfonamides (FOSAs) and sulfonamidoethanols (FOSEs). Understanding the indirect contribution of such precursors to human body burdens of PFOS is important as a significant contribution from this pathway would render the margin of safety between the current exposure limits and estimates of external exposure to PFOS alone, narrower than hitherto appreciated. Estimates derived from mathematical modelling studies, put the contribution of so-called “precursor exposure” at between 10% and 40% of total PFOS body burdens. However, there are substantial uncertainties associated with such approaches. This paper reviews current understanding of human exposure to PFOS, with particular reference to recent research highlighting the potential of environmental forensics approaches based on the relative abundance and chiral signatures of branched chain PFOS isomers to provide definitive insights into the role played by “precursor exposure”.

Concepts: Chirality, Persistent organic pollutant, Persistent organic pollutants, Conformational isomerism, Isomer, Perfluorooctanesulfonic acid, Stockholm Convention on Persistent Organic Pollutants, Perfluorooctanesulfonyl fluoride


Persistent organic pollutants (POPs) are present in almost all environments due to their high bioaccumulation potential. Especially species that adapted to human activities, like gulls, might be exposed to harmful concentrations of these chemicals. The nature and degree of the exposure to POPs greatly vary between individual gulls, due to their diverse foraging behavior and specialization in certain foraging tactics. Therefore, in order clarify the effect of POP-contaminated areas on gull populations, it is important to identify the sources of POP contamination in individual gulls. Conventional sampling methods applied when studying POP contamination are destructive and ethically undesired. The aim of this literature review was to evaluate the potential of using feathers as a nondestructive method to determine sources of POP contamination in individual gulls. The reviewed data showed that high concentrations of PCBs and PBDEs in feathers together with a large proportion of less bioaccumulative congeners may indicate that the contamination originates from landfills. Low PCB and PBDE concentrations in feathers and a large proportion of more bioaccumulative congeners could indicate that the contamination originates from marine prey. We propose a nondestructive approach to identify the source of contamination in individual gulls based on individual contamination levels and PCB and PBDE congener profiles in feathers. Despite some uncertainties that might be reduced by future research, we conclude that especially when integrated with other methods like GPS tracking and the analysis of stable isotopic signatures, identifying the source of POP contamination based on congener profiles in feathers could become a powerful nondestructive method.

Concepts: Sample size, Source code, Persistent organic pollutant, Polychlorinated biphenyl, Source, Persistent organic pollutants, Biomagnification, Polychlorinated dibenzodioxins


Human exposure to environmental chemicals as persistent organic pollutants (POPs) is usually assessed considering each pollutant individually, with little attention to concentrations of mixtures in individuals or social groups. Yet, it may be relatively common for humans to have low and high concentrations of numerous POPs. The study objectives were to analyze the number of POPs detected per person at high concentrations in the U.S. population, and the associations between such type of indicators and socioeconomic factors as gender, race / ethnicity, education, and poverty level. From 91 POPs analyzed in serum samples of 4,739 individuals in three subsamples of the National Health and Nutrition Examination Survey (NHANES) 2003-2004 (the last period with valid updated individual data for the compounds considered in the present study), we computed the number of POPs whose serum concentrations were above selected cutoff points. POPs included were 13 organochlorine compounds (OCs), 10 polybrominated diphenyl ethers (PBDEs), the polybrominated biphenyl (PBB) 153, 38 polychlorinated biphenyls (PCBs), 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs), and 12 perfluorinated compounds (PFCs). Over 13% of participants had ≥10 of the 37 most detected POPs each at a concentration in the top decile (P90). Over 30% of subjects with total toxic equivalency (TEQ) ≥P75, had ≥10 of 24 POPs not included in TEQ calculations at concentrations ≥P90. Compared to non-Hispanic whites, the adjusted odds ratio of having ≥10 of the 37 POPs at P90 was 9.2 for non-Hispanic blacks and 0.18 for Mexican Americans. Poverty, body mass index, age, and gender were also independently associated with having ≥10 POPs in the top decile. More than one tenth of the US population may have ≥10 POPs each at concentrations in the top decile. Such pattern is nine times more frequent in Non-Hispanic blacks and four times less frequent in Mexican Americans than in non-Hispanic whites.

Concepts: United States, Race and ethnicity in the United States Census, Persistent organic pollutant, Hispanic and Latino Americans, Polychlorinated biphenyl, Persistent organic pollutants, Biphenyl, Polychlorinated dibenzodioxins


The environmental and human health concerns for organohalogen contaminants (OHCs) extend beyond the 23 persistent organic pollutants (POPs) regulated by the Stockholm Convention. The current, intense industrial production and use of chemicals in China and their bioaccumulation makes Chinese wildlife highly suitable for the assessment of legacy, novel and emerging environmental pollutants. In the present study, six species of amphibians, fish and birds were sampled from paddy fields in the Yangtze River Delta (YRD) were screened for OHCs. Some extensive contamination was found, both regarding number and concentrations of the analytes, among the species assessed. High concentrations of chlorinated paraffins were found in the snake, Short-tailed mamushi (range of 200-340μgg(-)(1)lw), Peregrine falcon (8-59μgg(-1)lw) and Asiatic toad (97μgg(-)(1)lw). Novel contaminants and patterns were observed; octaCBs to decaCB made up 20% of the total polychlorinated biphenyls (PCBs) content in the samples and new OHCs, substituted with 5-8 chlorines, were found but are not yet structurally confirmed. In addition, Dechlorane 602 (DDC-DBF) and numerous other OHCs (DDTs, hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), hexbromocyclododecane (HBCDD), chlordane, heptachlor, endosulfan and Mirex) were found in all species analyzed. These data show extensive chemical contamination of wildlife in the YRD with a suite of OHCs with both known and unknown toxicities, calling for further in-depth studies.

Concepts: Persistent organic pollutant, Polychlorinated biphenyl, Persistent organic pollutants, Soil contamination, Biomagnification, Polychlorinated dibenzodioxins, Nanjing, Shanghai


A total of 23 PBDE congeners were measured in soil samples collected in areas with no known point source (urban/rural/background sites, U/R/B sites) and in contaminated areas (brominated flame retardants (BFRs) related industrial and e-waste recycling sites) across five Asian countries. The highest PBDE concentrations were found in BFRs related industrial and e-waste recycling sites. The concentrations of PBDEs in U/R/B sites followed the order of: urban > rural > background sites. Total PBDE concentrations were dominated by BDE-209, while BDE-17, -85, -138, -191, -204 and -205 were the least abundant compounds. In both urban sites and rural sites, the mean concentrations of total PBDEs (∑23BDEs) in soils followed the order of: Japan > China > South Korea > India > Vietnam. The concentrations of PBDEs in soils were comparable with those reported in other studies. Among the three commercial PBDE mixtures, relatively high contribution of commercial penta-BDE were observed in Vietnam, whereas deca-BDE was the dominant mixtures contributing from 55.8 ± 2.5% to 100.0 ± 1.2% of the total PBDEs in soils collected from other four countries. Regression analysis suggested that local population density (PD) is a good indicator of PBDEs in soils of each country. Significant and positive correlation between soil organic content and PBDE level was observed in Chinese soil for most non-deca-BDE homologues with their usage stopped 10 years ago, indicating its important role in controlling the re-volatilization of PBDEs from soil and changing the spatial trend of PBDE in soil from the primary distribution pattern to the secondary distribution pattern, especially when primary emission is ceased.

Concepts: Population, Flame retardant, Decabromodiphenyl ether, Polybrominated diphenyl ethers, Persistent organic pollutants, Brominated flame retardant, Flame retardants, Organobromides


DDT was among the initial persistent organic pollutants listed under the Stockholm Convention and continues to be used for control of malaria and other vector-borne diseases in accordance with its provisions on acceptable purposes. Trends in the production and use of DDT were evaluated over the period 2001-2014.

Concepts: Malaria, Pesticide, Persistent organic pollutant, Persistent organic pollutants, Biomagnification, DDT


BACKGROUND. Adipose tissue (AT) is involved in several physiological functions, including metabolic regulations, energy storage, and endocrine functions. ONJECTIVES. The aim of this review is to analyze the evidence that an additional function of the AT is to modulate persistent organic pollutant (POP) toxicity through several mechanisms. METHODS. We have reviewed the literature on the interaction of AT with POPs in order to provide a comprehensive model for this additional function of the AT. DISCUSSION. As a storage compartment for lipophilic POPs, AT plays a critical role in the toxicokinetics of a variety of drugs and pollutants, in particular POPs. By sequestering the POPs, AT can protect other organs and tissues from POP overload. However, this protective function could prove to be a threat in the long run. The accumulation of lipophilic POPs will increase total body burden. These accumulated POPs are slowly released into the bloodstream, and more so during weight loss. Thus, AT constitutes a continual source of internal exposure to POPs. In addition to its buffering function, AT is also a target of POPs and may mediate part of their metabolic effects. This is particularly relevant as many POPs have been shown to display obesogenic effects leading to quantitative and qualitative alterations of AT. Some POPs also induce a proinflammatory state in the adipose tissue, which may lead to detrimental metabolic effects. CONCLUSION. The AT appears to play diverse functions both as a modulator and as a target of POP toxicity.

Concepts: Obesity, Tissues, Toxicology, IMAGE, Persistent organic pollutant, Persistent organic pollutants, Biomagnification, Ibn al-Nafis