Dioxin- and POP-contaminated sites--contemporary and future relevance and challenges: overview on background, aims and scope of the series

Unintentionally-produced persistent organic pollutants in the aquatic environment contaminated from historical chlor-alkali production

Historical chlor-alkali production has led to substantial concentrations of persistent organic pollutant residues in the environment. This study systematically investigated the distribution of polycyclic aromatic hydrocarbons (PAHs), chlorinated/brominated-PAHs (Cl/Br-PAHs), polychlorinated naphthalenes (PCNs), and hexachlorobutadiene (HCBD) in sediment, lotus (Nelumbo nucifera), and fish samples from Ya-Er Lake, which is a site in China with historical chlor-alkali contamination. The average concentrations [(4.97-1.47) × 103 ng/g dry weight (dw)] of these pollutants in backfill sediments, which were dredged from the lake after chlor-alkali production stopped, were 2.68-70.87 times those in fresh lake sediments (0.622-218 ng/g dw) and reported concentrations in other areas. Correlation analyses indicated that Cl-PAHs, Br-PAHs, and PCNs likely originated from halogenation of parent PAHs in the study area, and the chlorination ratios were larger than those of bromination. The Cl(1/2/3)-PAHs/PAHs and Br(1)-PAHs/PAHs ratios were higher than those for PAHs with more halogen atoms. This contamination extended into the biota, with notable pollutant burdens found in lotus (Nelumbo nucifera, 0.305-77.3 ng/g dw) and even higher concentrations in fish (2.20-345 ng/g lipid weight). Estimated biological soil accumulation factors revealed significant enrichment in lotus organs (mean: 7.19) and fish muscle (mean: 10.65), especially the latter, which highlighted bioaccumulation and potential food chain transfer risks. The estimated daily intakes of PAHs, Cl/Br-PAHs, and HCBD through fish consumption currently pose negligible risks, while dietary intake of PCNs may present health concerns. Continuous monitoring and impact assessments are crucial for developing appropriate risk management strategies to safeguard public health.

Effects of inorganic and organic pollution on development of Steindachneridion melanodermatum from the Iguaçu river, Brazil

The Iguaçu River basin, known for its rich endemic ichthyofauna, faces a significant threat from chemical pollution. The Jordão River, a major tributary, drains extensive agricultural and livestock areas and receives poorly treated domestic and industrial effluents before joining the Iguaçu River. This study investigated the pollution and toxic effects of water samples from the Iguaçu upstream (UI), Jordão (JR), and their confluence (DI) on Steindachneridion melanodermatum embryos and larvae. Chemical analyses of the water samples revealed that most contaminants were present at levels below detection limits or within the limits established by Brazilian legislation. However, cadmium in UI, aluminum in JR, and lead in DI exceeded the legal limits. Exposure up to 96 h post-fertilization revealed higher mortality and deformity rates in individuals exposed to water samples from UI and JR, despite JR having fewer detected pollutants. JR and DI samples induced increased superoxide dismutase activity, indicating activation of the antioxidant defense system due to xenobiotic exposure. Overall, the integrated biomarker response indexes showed that individuals exposed to JR water displayed the most significant variations in their responses compared to the control treatment, suggesting a higher level of contamination and toxicity. Although a direct link between water quality and toxicity in the Jordão and Iguaçu Rivers was inconclusive, the results confirmed pollution and risks to local wildlife. The study highlighted the harmful effects of pollutants, even at low concentrations. These findings underscore the need for conservation measures to safeguard endemic and endangered species in the Iguaçu River basin. Understanding pollutant effects on native species is crucial for effective mitigation strategies and ecological health preservation.

Preliminary Evaluation of Historical used Pesticides in Quercus robur Wood in Belgium: a Negative Finding

Historically used pesticides poses a threat to biodiversity while their release pathways remain unclear. Trees could be a potential release source due to their long lifespan. This study examined 38 samples to assess pesticide concentrations in pedunculate oak from Belgium. Low concentrations of procymidone were detected in two samples from one stump. Our findings suggest that accumulations of historically used pesticides in pedunculate oaks within forests are improbable. We conclude that leaving dead wood poses no risks for pesticide release to the environment. However, further research involving diverse tree species and regions is needed to refine and validate this conclusion.

Generic methodology to prevent food contamination by soil born legacy POPs in free range livestock

Government monitoring commonly includes regulating POPs in animal feed and products of animal origin, with many countries setting Maximum Residue Levels (MRLs) to ensure safe tolerable concentrations. However, these MRLs do not address the presence of most POP families in soil, where concentrations can be much higher due to the contaminants' strong affinity and persistence in comparison to other environmental matrices. Extensive damage to food and production systems during a pollution incident causing soil contamination by POPs lead to severe economic and social consequences for the affected area. To mitigate these effects, it is crucial to implement necessary measures for consumer protection while also focusing on rehabilitating conditions for food production, tailored to both commercial farms and private holders. In this context, the present work aims to develop and test a methodology for assessing the tolerable concentration of the most cancerogenic legacy POPs in soil for various livestock animals in diverse rearing systems ensuring the safety of food of animal origin. Therefore, we summarize existing knowledge about the risk of POP transfer in different livestock breeding systems via soil exposure, and modeling via a backward calculation from the MRLs the corresponding tolerable quantity of POPs that may be ingested by animals in the considered rearing system. Results of these simulations showed that soil ingestion is a predominant contamination pathway, which is a central factor in the risk assessment of POP exposure on livestock farms, especially in free-range systems. In field conditions of POP exposure, low productive animals may be more susceptible to uptake through soil than high-yielding animals, even if the feed respected MRLs. Results show that PCDD/Fs revealed the lowest security ratio for low productive dairy cows (1.5) compared to high productive ones (52). Laying hens with a productivity of 45% show also as a high sensitivity to POPs exposure via soil ingestion. Indeed, their security ratio for PCDD/Fs, lindane and DDT were 3, 2 and 1, respectively. In perspective, proposed methodology can be adapted for assessing the risk of industrial POPs newly listed in the Stockholm Convention. In practice, it could be useful for food producers to apprehend their own risk of chemical contamination.

Assessment of legacy and alternative halogenated organic pollutants in outdoor dust and soil from e-waste sites in Nigeria: Concentrations, patterns, and implications for human exposure

E-waste is often processed informally, particularly in developing countries, resulting in the release of harmful chemicals into the environment. This study investigated the co-occurrence of selected persistent organic pollutants (POPs), including legacy and alternative halogenated flame retardants (10 polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), syn and anti-dechlorane plus (DP)), 32 polychlorinated biphenyls (PCBs) and 12 organochlorine pesticides (OCPs), in 20 outdoor dust and 49 soil samples from 7 e-waste sites in Nigeria. This study provides the first report on alternative flame retardants (DBDPE and DP) in Nigeria. The total concentration range of the selected classes of compounds was in the order: ∑10PBDEs (44-12300 ng/g) > DBDPE (4.9-3032 ng/g) > ∑2DP (0.7-278 ng/g) > ∑32PCBs (4.9-148 ng/g) > ∑12OCPs (1.9-25 ng/g) for dust, and DBDPE (4.9-9647 ng/g) > ∑10PBDEs (90.3-7548 ng/g) > ∑32PCBs (6.1-5025 ng/g) > ∑12OCPs (1.9-250 ng/g) > ∑2DP (2.1-142 ng/g) for soil. PBDEs were the major contributors to POP pollution at e-waste dismantling sites, while PCBs were the most significant contributors at e-waste dumpsites. DBDPE was found to be significantly associated with pollution at both e-waste dismantling and dumpsites. Estimated daily intake (EDI) via dust and soil ingestion and dermal adsorption routes ranged from 1.3 to 2.8 ng/kg bw/day and 0.2-2.9 ng/kg bw/day, respectively. In the worst-case scenario, EDI ranged from 2.9 to 10 ng/kg bw/day and 0.8-5.8 ng/kg bw/day for dust and soil, respectively. The obtained intake levels posed no non-carcinogenic risk, but could increase the incidence of cancer at some of the studied e-waste sites, with values exceeding the USEPA cancer risk lower limit (1.0 × 10-6). Overall, our results suggest that e-waste sites act as emission point sources of POPs.

The urinary level of 2,4,5-trichlorophenol was positively associated with both all-cause and cause-specific mortalities in general adult residents of United States

Chlorophenols are widespread environmental organic pollutants with harmful effects on human beings. Although relationships between chlorophenols and various dysfunctions/diseases have been reported, the contribution of chlorophenols exposure to mortalities is underdetermined. In this cohort study, we included 4 types of urinary chlorophenols, aiming to estimate associations of chlorophenols exposure with all-cause and cause-specific mortalities. Urinary chlorophenols were examined at baseline of National Health and Nutrition Examination Survey (NHANES) 2003-2010, and adjusted for the urinary creatinine level. Associations between chlorophenols and mortalities were estimated using COX regression analyses, results were shown as hazard ratio (HR) and 95% confidence interval (95% CI). By dividing participants into four subgroups based on quartiles of urinary levels of chlorophenols, associations between mortalities and categorical variables of chlorophenols were estimated. Furthermore, the quantile g-computation analysis was used to estimate the joint effects of 4 chlorophenols on mortalities. Among 5817 adults (2863 men), 1034 were deceased during the follow-up. After adjusted for confounders, 2,4,5-trichlorophenol (2,4,5-TCP) was found to be positively associated with both all-cause (HR = 1.46; 95% CI: 1.16, 1.84) and cardiovascular disease (CVD) mortalities (HR = 1.60; 95% CI: 1.00, 2.55). Compared to the subgroup of the lowest level of chlorophenols, participants in subgroups of higher 2,4,5-TCP levels showed higher risk of all-cause mortality (P-value for trend = 0.003). For CVD mortality, HRs in subgroups of higher levels of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were statistically significant (P-values for trend were 0.017 for 2,4-DCP and 0.049 for 2,4,6-TCP). The HRs (95% CI) of joint effects of 4 chlorophenols were 1.11 (1.01, 1.21) and 1.32 (1.10, 1.57) for all-cause and CVD-specific mortalities, and 2,4,5-TCP showed the highest weight in joint effects. All of these findings implied that among 4 urinary chlorophenols we included, 2,4,5-TCP might be a sensitive one in associations with mortalities among general populations.

Synergistic potency of ultrasound and solar energy towards oxidation of 2,4-dichlorophenol: a chemometrics approach

Industrial units based on chemical processes-the textile and paper industries-are major sources of chlorophenols in the environment, and chlorophenolic compounds persist within the environment for a long time with high toxicity levels. The photo-assisted Fenton's and photocatalysis processes were investigated for the degradation of chlorophenols in the present study. Response surface methodology was employed to get optimised conditions for photocatalysis and photo-Fenton process-governing factors, thus, yielding a profound removal efficiency. Under optimised conditions, with a photocatalyst dose of 0.2 g/L, oxidant concentration of 10.0 mM and pH 5.0, complete removal of 2,4-dichlorophenol (2,4-DCP) was observed in 210 minutes in photocatalytic treatment. In the case of the photo-Fenton process, at an H2O2 dose of 5.0 mM and Fe2+ concentration of 0.5 mM, the organic pollutant was eliminated within 5 minutes of reaction time under acidic conditions (pH 3.0). The RSM model reported the perfect fit of experimental data with the predicted response. Among different isotherm models, the Langmuir isotherm was the best fit. The process followed pseudo-first order rate kinetics among various kinetics models. For the obtained optimised conditions, sonication and solar energy-driven processes were incorporated to study enhanced mineralisation. The solar-assisted Fenton process reported maximum mineralisation (90%) and cost-effective ($0.01/litre for 100 mg/L 2,4-DCP) treatment among different hybrid oxidation processes. The work provides insight into harnessing the naturally available solar energy, reducing the overall treatment cost and opting for a sustainable treatment method.

Unexpected Dioxin Formation During Digestion of Soil with Oxidizing Acids

Dioxins, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), are among the most toxic unintentionally produced persistent organic pollutants, and their emission is of great concern. Herein, we discovered abundant dioxin formation in soil and various organic carbon-containing matrices after digestion with aqua regia. Σ17PCDD/Fs concentrations were in the range of 66.6-142,834 pg/g dw (5.6-17,021 pg WHO2005-TEQ/g dw) in 19 soil samples after digestion with aqua regia for 6 h. Σ17PCDD/Fs concentration was significantly and positively correlated with soil organic carbon content (R2 = 0.89; p < 0.01). Compared with cellulose and lignin, humic acid served as an important organic matter component that was converted to PCDD/Fs during soil digestion. Strong oxidation and production of reactive chlorine by aqua regia may be the key factors in the formation of PCDD/Fs. The yearly emission of PCDD/Fs due to digestion with strong acids by the inspection and testing industry was estimated to be 83.8 g TEQ in China in 2021 based on the highest level, which was ∼0.9% of the total dioxin inventory in China. Great attention should be paid to unexpected dioxin formation during digestion processes considering the potential risk of release from laboratories and enterprises.

The effects of environmental aryl hydrocarbon receptor ligands on signaling and cell metabolism in cancer

Dioxin and dioxin-like compounds are chlorinated organic pollutants formed during the manufacturing of other chemicals. Dioxins are ligands of the aryl hydrocarbon receptor (AHR), that induce AHR-mediated biochemical and toxic responses and are persistent in the environment. 2,3,7,8- tetrachlorodibenzo para dioxin (TCDD) is the prototypical AHR ligand and its effects represent dioxins. TCDD induces toxicity, immunosuppression and is a suspected tumor promoter. The role of TCDD in cancer however is debated and context-dependent. Environmental particulate matter, polycyclic aromatic hydrocarbons, perfluorooctane sulfonamide, endogenous AHR ligands, and cAMP signaling activate AHR through TCDD-independent pathways. The effect of activated AHR in cancer is context-dependent. The ability of FDA-approved drugs to modulate AHR activity has sparked interest in their repurposing for cancer therapy. TCDD by interfering with endogenous pathways, and overstimulating other endogenous pathways influences all stages of cancer. Herein we review signaling mechanisms that activate AHR and mechanisms by which activated AHR modulates signaling in cancer including affected metabolic pathways.

Lingering Effects of Legacy Industrial Pollution on Yellow Perch of the Detroit River

We used yellow perch (Perca flavescens) captured at four sites differing in legacy industrial pollution in the Lake St. Clair-Detroit River system to evaluate the lingering sublethal effects of industrial pollution. We emphasized bioindicators of direct (toxicity) and indirect (chronic stress, impoverished food web) effects on somatic and organ-specific growth (brain, gut, liver, heart ventricle, gonad). Our results show that higher sediment levels of industrial contaminants at the most downstream Detroit River site (Trenton Channel) are associated with increased perch liver detoxification activity and liver size, reduced brain size, and reduced scale cortisol content. Trenton Channel also displayed food web disruption, where adult perch occupied lower trophic positions than forage fish. Somatic growth and relative gut size were lower in perch sampled at the reference site in Lake St. Clair (Mitchell's Bay), possibly because of increased competition for resources. Models used to determine the factors contributing to site differences in organ growth suggest that the lingering effects of industrial pollution are best explained by trophic disruption. Thus, bioindicators of fish trophic ecology may prove advantageous to assess the health of aquatic ecosystems. Environ Toxicol Chem 2023;42:2158-2170. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A data-driven analysis of global research trends on dirty-dozen persistent organic pollutants

The occurrence, distribution, and fate of persistent organic pollutants (POPs) have been extensively studied worldwide; however, the patterns and dynamics of scientific publications on POPs are still unclear. In this study, the research trends on dirty dozen POPs, which are identified under the Stockholm Convention (SC) for immediate action were investigated and evaluated in a broad context to obtain up-to-date information. For this purpose, bibliometric analysis was carried out between 1945 and 2021 using the Web of Science (WoS) database. A total of 197,029 publications were analyzed. "Environmental Sciences" was the most popular research category and the USA was the leading country in dirty dozen POPs studies. The research hotspots are related to the most used keywords such as "Polychlorinated Biphenyls", "Dioxin" and "Persistent Organic Pollutants". In the evaluation of keyword clusters with highlighted research points, 7 clusters were obtained from the publications, which are related to the chemical properties, synthesis, structures, health effects, and analysis methods of dirty dozen POPs. The number of publications and, accordingly, the scientific interest in dirty dozen POPs listed under the SC has not reached equilibrium and continues regardless of the level of development of countries in the world.

Polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs) contamination in sediments and fish from Msimbazi River in Dar es Salam, Tanzania: patterns, sources, and their exposure to humans

Results of a two-dimensional gas chromatograph time of flight mass spectroscopy (GCXGC-TOFMS) determination of polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDF) in sediments and catfish samples collected from the Msimbazi River are presented here. Samples were extracted using USEPA Method 1613. PCDD/Fs congeners in sediments ranged from 2.0 to 393.0 and 0.7 to 654.8 pg/g in the dry and wet seasons, respectively. 1,2,3,4,7,8,9-HepCDF was detected at the highest concentration, but all were lower than the USA action level of 1000 pg/g. Toxicity for each of the sampling points ranged from 19.7 to 36.5, with a mean concentration of 27.0 pg WHO 2005-TEQ g^-1 in the dry season and 2.0 to 38.7 with a mean concentration of 20.7 pg WHO 2005-TEQ g^-1 in the wet season. Analysis of variance (ANOVA) showed that there was no significant difference between PCDD/Fs TEQ during the dry and wet seasons (p = 0.08; α = 0.05). The highest TEQ value was estimated at Jangwani in the wet season. Toxicity of PCDD/Fs in catfish collected from the Msimbazi River ranged from 9.3 to 145.2, with a mean of 61.2 pg WHO2005-TEQg^-1. Tetrachlorodibenzo dioxin (2, 3, 7, and 8-TCDD) was detected in all fish samples and ranged from 3.5 to 12.7 with a mean of 8.1 pg/g. The concentration of TCDD in fish exceeded the Agency for Toxic Substance and Diseases Registry MRL, thus posing a probable high risk to people whose dietary requirements depend on fish from the Msimbazi River.

Framework of the Integrated Approach to Formation Mechanisms of Typical Combustion Byproducts─Polyhalogenated Dibenzo-p-dioxins/Dibenzofurans (PXDD/Fs)

Understanding the mechanisms through which persistent organic pollutants (POPs) form during combustion processes is critical for controlling emissions of POPs, but the mechanisms through which most POPs form are poorly understood. Polyhalogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs) are typical toxic POPs, and the formation mechanisms of PXDD/Fs are better understood than the mechanisms through which other POPs form. In this study, a framework for identifying detailed PXDD/Fs formation mechanisms was developed and reviewed. The latest laboratory studies in which organic free radical intermediates of PXDD/Fs have been detected in situ and isotope labeling methods have been used to trace transformation pathways were reviewed. These studies provided direct evidence for PXDD/Fs formation pathways. Quantum chemical calculations were performed to determine the rationality of proposed PXDD/Fs formation pathways involving different elementary reactions. Many field studies have been performed, and the PXDD/Fs congener patterns found were compared with PXDD/Fs congener patterns obtained in laboratory simulation studies and theoretical studies to mutually verify the dominant PXDD/Fs formation mechanisms. The integrated method involving laboratory simulation studies, theoretical calculations, and field studies described and reviewed here can be used to clarify the mechanisms involved in PXDD/Fs formation. This review brings together information about PXDD/Fs formation mechanisms and provides a methodological framework for investigating PXDD/Fs and other POPs formation mechanisms during combustion processes, which will help in the development of strategies for controlling POPs emissions.

Remediation of lindane contaminated soil by fluidization-like dielectric barrier discharge

This study proposed the fluidization-like dielectric barrier discharge (DBD) plasma for the remediation of lindane contaminated soil and integrated physical and chemical reaction pathway. Soil particle distribution within the reactor was simulated with Euler-Euler and Gidaspow drag models, and a bipolar pulsed power supply was applied to energize the DBD reactor after full fluidized. The effect of soil particles movement on electric features was discussed in terms of voltage waveforms and Lissajous figures. Lindane degradation was found to be related to electrics parameters and soil properties. Soil samples before and after treatment were analyzed by XRD and SEM methods. A 95.98% lindane decomposition and 0.66 mg_Lindane/h average reaction rate were obtained with 3 wt% CaO injection by pulse power drove fluidization-like DBD after 32 min treatment. Ozone was proved to play a major role during lindane degrading by plasma. The reaction potential pathway of lindane decomposition contains 4 steps, including dehydrogen, dehydrochlorination, and dechlorination, respectively.

Application of equilibrium passive sampling to assess the influence of anthropogenic activities and bioturbation on the distribution of hydrophobic organic chemicals in North Sea sediment cores

The pollution state in the German Bight was investigated by determination of pollutant concentrations of sediment samples using equilibrium passive sampling. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAH) were determined in the pore water of North Sea sediment. The freely dissolved pore water concentration (C_free) was measured applying Solid Phase Microextraction (SPME) by using PDMS-coated glass fibers. The obtained results show that the North Sea contamination level with the investigated pollutants is relatively low. However, the stations close to the sediment-dumping site were higher contaminated. A macrofauna analysis showed that bioturbation activities were mostly present in the upper sediment layers, but a direct bioturbation influence on the sediment concentration distribution could not be shown. Overall, the contamination load was below baseline toxicity, but considering that several other priority pollutants will also make a contribution to the baseline toxicity, it can be counted as relatively high.

Formation and Inventory of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Other Byproducts along Manufacturing Processes of Chlorobenzene and Chloroethylene

Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated byproducts [e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] formed during the commercial manufacturing processes and present in organochlorine products are rarely reported. The knowledge on the occurrences and fate of unintentional persistent organic chemicals in the manufacturing of organochlorine chemical is necessary for accurate assessment of the risks of commercial chemicals and their production. Here, PCDD/Fs were tracked throughout chlorobenzene and chloroethylene production processes (from raw materials to final products) by target analysis. Other byproducts that can further transform into PCDD/Fs were also identified by performing non-target screening. As a result, the PCDD/F concentrations were mostly the highest in bottom residues, and the octachlorinated congeners were dominant. Alkali/water washing stages may cause the formation of oxygen-containing byproducts including PCDD/Fs and acyl-containing compounds, so more attention should be paid to these stages. PCDD/Fs were of 0.17 and 0.21-1.2 ng/mL in monochlorobenzene and chloroethylene products, respectively. Annual PCDD/F emissions (17 g toxic equivalent in 2018) during chlorobenzene and chloroethylene production were estimated using PCDD/F emission factors. The results can contribute to the improvement of PCDD/F inventories for the analyzed commercial chemicals.

Serum levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in a sample of Lebanese pregnant women: The role of dietary, anthropometric, and environmental factors

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are unintentionally produced, toxic environmental chemicals that persist for long years and bioaccumulate along the food chain, contaminating humans through diet. A particularly critical population subgroup is pregnant women given the adverse health effects on fetuses and newborns. Several anthropogenic sources of exposure to PCDD/Fs exist in Lebanon. Therefore, the aim of the present cross-sectional study is to measure the levels of PCDD/Fs in a sample of pregnant women in Lebanon and to explore potential associated factors. In this study, we measured serum concentrations of seven dioxins and ten furans, among 423 pregnant women recruited at delivery, using gas chromatography MS/MS. Among 269 participants, maternal sociodemographic information was collected including vicinity to landfills, incineration, pesticide use, industrial activity, and smoking. Anthropometric data were registered regarding pre-pregnancy body mass index (BMI), pre-pregnancy weight loss from restrictive diet, and gestational weight gain. Intake of major food groups generally related to PCDD/Fs was reported (fish, red meat, poultry, and dairy). Bivariate and multivariate analyses were performed to identify associations. PCDD/Fs were detected in 0 to 56.1% of the sample. Geometric mean concentrations were 75.5 (2.35) pg/g lipid and 2.25 (1.39) TEQ₂₀₀₅ pg/g lipid for total dioxins, and 2.66 (1.76) pg/g lipid and 0.34 (1.78) TEQ₂₀₀₅ pg/g lipid for total furans. Levels were relatively lower than levels previously observed in France, Germany, Mexico, Ghana, and Japan. Red meat consumption was the most consistently associated factor with a 2.38-2.57 fold increase in PCDD/F levels. Pre-pregnancy weight loss showed inverse associations with PCDD/F congeners. Vicinity to illegal incineration was also associated with a 2.32-2.43 fold increase in PCDD/F levels. In conclusion, results showed the importance of dietary, anthropometric, and environmental factors in the present sample's exposure to PCDD/Fs, in a region that contains anthropogenic sources of contamination.

Legacy Chemical Pollutants in House Dust of Homes of Pregnant African Americans in Atlanta

We developed and applied a method for measuring selected persistent organic pollutants (POPs) (i.e., polybrominated diphenyl ethers (PBDEs), organochlorine pesticides, and polychlorinated biphenyls (PCBs)) in dust collected from pregnant African Americans (AAs) in Atlanta using isotope dilution gas chromatography-tandem mass spectrometry. Limits of quantification were ranged from 0.10 to 2.50 ng/g dust. NIST standard reference material measurements demonstrated the robustness of our method. Our accuracies ranged from 82 to 108%, relative standard deviations ranged from 2 to 16%, and extraction recoveries ranged from 76 to 102%. We measured POPs in dust collected from 34 homes of pregnant AAs participating in the Atlanta AA birth cohort study who were enrolled from 2016 to 2019. Concentrations of POPs were detected in all samples with the frequencies of detection ranging from 8 to 100%. Concentrations of PBDE congeners 99 and 47, p,p'-DDT, and PCB153 were detected at some of the highest concentrations with geometric means of 1270, 730, 63.4 and 240 ng/g, respectively. The ratio of DDT/DDE was quite large (~2.7) indicating that p,p'-DDT remains intact in homes for long periods of time. These data demonstrate that care should be taken to remediate POPs in indoor dust, especially in vulnerable, disparate segments of the population.

Gas chromatography-triple quadrupole mass spectrometry as a cost-effective method for the determination of polychlorinated dibenzo-p-dioxins and furans in contaminated soils

The aim of this study was to evaluate the performance of gas chromatography (GC)-triple quadrupole mass spectrometry (QqQ, MS/MS) as an alternative to the standard GC-high resolution mass spectrometry (GC-HR/MS) for soils contaminated with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). GC-QqQ (MS/MS) using a dynamic multiple reaction monitoring (dMRM) mode was optimized for the quantitative analysis of 17 PCDD/Fs. A comparative study between GC-QqQ (MS/MS) and GC-HR/MS was carried out to validate the results of actual field soil samples. Although GC-HR/MS has excellent sensitivity and selectivity, the validation parameters obtained by GC-QqQ (MS/MS) also met the recommended criteria of the standard method. The results for total and I-TEQ (international toxic equivalent) value of the PCDD/F concentrations of over 86.0 pg/g and 4.3 pg I-TEQ/g, respectively, in actual field soil samples showed good agreement between the two methods, falling within ±25% relative difference. In consideration of the remediation goal (100 pg I-TEQ/g), GC-QqQ (MS/MS) can be an alternative cost-effective method for use in soil remediation research.

Urbanity as a source of genotoxicity in the synanthropic Kelp Gull (Larus dominicanus)

Increases in human population lead to an increase in urban wastes, which could affect wildlife in several ways. Urban pollutants can affect erythrocytes of birds generating morphological membrane and nuclear anomalies. The Kelp Gull (Larus dominicanus) is an opportunistic species, which take advantage of urban environments, thus being highly exposed to environmental pollution. In northeastern Patagonia, the dynamic of the waste management was transformed in the last decade and consequently, gulls changed their movements in response to changes in waste management systems. The food available to the seagulls went from being a mixture of urban/fishing discards until 2015, when this landfill closures, to being domestic urban offerings. In order of evaluating genotoxicity and changes in pollutants exposition due to these changes, we analyzed the frequencies of erythrocytes nuclear abnormalities and micronuclei (ENAs and MN respectively) in 58 blood smears from adults extracted during the non-breeding season in two periods in landfills with different waste compositions: a mixed landfill (ML) in 2013 before closure (n = 24) versus an urban landfill (UL) (n = 34) in 2021. We found that the Kelp Gull showed high values of abnormalities with an average of 151.5 /10,000 RBC in comparison with other seabird species. The bud and notched types of ENAs were the most prevalent abnormalities in both sites. We did not find significate differences in the overall abnormality frequency between sites, however we found significant higher frequencies in displaced and tailed types of ENAs in ML. We also found poikilocytosis, as seen previously in other animals exposed experimentally to pollutants such as metals and crude oil. Cellular abnormalities found in the Kelp Gull suggest an exposition of individuals to pollutants in foraging areas. The hemispheric distribution and the synanthropic characteristics of the species denote its importance as a suitable global monitor of genotoxicity.

Vermiremediation applied to PCB and PCDD/F contaminated soils and its implications for percolating water

PCDD/Fs (polychlorinated dibenzo-p-dioxins/dibenzofurans) and PCBs (polychlorinated biphenyls) are ubiquitous persistent pollutants with reduced bioavailability, which bioremediation using soil fauna is still managed to treat. This research set out to: (i) study the suitability of earthworms (Eisenia fetida), alone and associated with plants (Lepidium sativum), for the decontamination of PCDD/F and PCB polluted soils in Brescia-Caffaro (Italy), at total and congener concentration levels; (ii) simulate the action of earthworms in groundwater contamination process and nutrient mobility. Five treatments were set up: (i) uncontaminated soil with E. fetida (NC); (ii) contaminated soil (C); (iii) contaminated soil with E. fetida (CEf); (iv) contaminated soil with L. sativum (CLs); (v) contaminated soil with E. fetida and L. sativum (CEfLs). PCBs and PCDD/Fs in the soil prior to testing were measured. Analysis was repeated in soil treatments and percolating water at the end of the test period (4 months). Dissolved nutrient concentrations were measured in percolated water. PCB and PCDD/F concentrations, initially 259333.33 ± 10867.89 ng/kg and 176 ± 10.69 ngTE/kg, were significantly reduced after 4 months in all treatments. Treatments did not differ in total PCBs concentration (from 160,000 ng/kg to 194,000 ng/kg), but CEfLs congeners concentrations were less environmentally threatening; CEf and CLs resulted in lower PCDD/Fs concentration (79.43 ± 3.34 ngTE/kg and 73.03 ± 4.09 ngTE/kg, respectively). The action of earthworms could enhance contaminants and soluble reactive phosphorous content in percolating water.

PAHs, PCBs, PBDEs, and OCPs trapped and remobilized in the Lake of Cavazzo (NE Italy) sediments: Temporal trends, quality, and sources in an area prone to anthropogenic and natural stressors

Under the present climatic emergency, the environmental quality of freshwater reservoirs is an increasingly urgent topic as its deterioration threatens humans and ecosystems. It is evident that pollution by natural and anthropogenic contaminants must be avoided or reduced. The Lake of Cavazzo (NE Italy) is a natural perialpine basin which, from the mid-20th century, has sustained several anthropogenic impacts that added to the effects of the intense regional seismicity. Starting from 2015, in response to concerns raised by local authorities, a multidisciplinary investigation of the lake floor and sub-floor was conducted, including a geophysical survey and the collection of sediment cores. Two of them were studied to detect contamination by Polycyclic Aromatic Hydrocarbons (PAHs) and specific Persistent Organic Pollutants (POPs; i.e. PolyChlorinated Biphenyls - PCBs, PolyBrominated Diphenyl Ethers - PBDEs, and OrganoChlorine Pesticides - OCPs), and to verify the link with known anthropogenic stressors. Results were interpreted in light of previous studies suggesting modified conditions after the '50s, and recognized the effects of the 1976-1977 M_W 6.5 seismic sequence in resuspending sediments within the basin. Analyzed pollutants defined a potential critical situation only for few OCPs, above all 2,4'- and 4,4'-DDT isomers. In addition, PBDEs were found at concentrations exceeding those of other heavily polluted alpine lakes. Mass movements (either seismic or human induced) have likely resuspended and transferred pollutants from shallower locations to the lake depocenter, showing the potential of re-exposing contaminated layers to biomagnification processes along the lacustrine food chain. Local inputs of pollutants prevail over distributed sources, suggesting a link with local agricultural or industrial activities. Indeed, works connected to the construction of the hydroelectric power plant in the '50s might have reworked local sediments perturbing their natural accretion. Results of this work might inspire similar studies in other problematic lacustrine areas that sustain both natural and anthropogenic stressors.

A Theoretical Study of the Interactions between Persistent Organic Pollutants and Graphene Oxide

Persistent organic pollutants (POPs) have adverse effects on the human health and ecosystem functioning. Graphene oxide (GO) has been developed to remove trace levels of POPs from wastewater samples. However, many questions involved in these processes are still unresolved (e.g., the role of π-π interaction, the effect of GO on the degradation of POPs, and so on). Revealing the microscopic interactions between GO and POPs is of benefit to resolve these questions. In the present study, a quantum chemical calculation was used to calculate the molecular doping and adsorption energy between eight representative POPs and GO. The influences of GO on the thermodynamic parameters, such as the Gibbs free energy and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, were also reported. We found the molecular doping is dependent on the species of POPs. The adsorption energy of the majority of POPs on GO is between 7 and 8 kJ/mol. Consequently, the GO may make degradation of POPs in wastewater more productive and lead to a change of kinetics of the degradation of POPs.

Sustainable remediation of dibenzofuran-contaminated soil by low-temperature thermal desorption: Robust decontamination and carbon neutralization

Thermal desorption (TD) is generally considered to be an effective but unsustainable technology. Decontamination performance, charring behaviors and physicochemical properties during TD of dibenzofuran-contaminated soil (DCS) are explored. After treatment at 300 °C for 20 min, the dibenzofuran concentration decreases from 3969.37 mg/kg to 17.29 mg/kg, lower than Chinese risk screening value. More than 99% of dibenzofuran in soil are removed at low temperature of 300 °C, meanwhile the organic carbon is partially retained in soil. Removal mechanism of DCS at 300 °C is proposed, including desorption, cracking, and charring. Char material of low H:C ratio is produced by the generation, polymerization and dehydrogenation of aromatic intermediates, and then increases carbon stocks and reduces the carbon footprint of contaminated soil. Meanwhile, due to the char generated, pH, cation exchange capacity and specific surface area of DCS heated at 300 °C are higher than those of raw DCS, promoting ecological restoration and enhancing carbon sink in soil ecosystems. The aforesaid saving energy, reducing carbon footprint and enhancing carbon sink are exactly the main innovative technologies for achieving carbon neutrality. Hence, it may be a contribution to climate change mitigation, in addition to a robust and sustainable remediation of organic contaminated soil.

Seasonal peculiarities of PCDD/Fs levels in bank voles inhabiting sites in the vicinity of the landfill with municipal wastes (Moscow, Russia)

Differences in PCDD/Fs concentrations were registered among adult bank voles (Myodes glareolus) inhabiting forest in the vicinity of the Landfill Salariyevo (Moscow, Russia) and caught in early spring (over-winter survivors) and late summer. The levels of highly toxic congeners and WHO-TEQ₀₅ in samples of wintering voles were much lower than those in samples got in summer. This difference was investigated analyzing PCDD/Fs in sexually matured animals and offspring obtained in vivarium. Practically, no significant differences of PCDD/Fs concentrations and general toxicity were revealed among sexes. The main impact to these seasonal differences in PCDD/Fs accumulation was assigned to the types of functional development and activity, diet variation as natural growth of all voles occurs on the same territory but in seasonally diverse conditions. So, the species functional ecology (lifestyle and seasonal features) should be considered in practical application of animal models from natural populations for local monitoring of PCDD/Fs body burden, and individual functional type of ontogenesis among cyclomorphic mammalian species, especially. Thus, the results obtained during monitoring should be carefully interpreted for a proper environmental management.

Microbial reductive dechlorination of polychlorinated dibenzo-p-dioxins: Pathways and features unravelled via electron density

Microbial reductive dechlorination provides a promising approach for remediating sites contaminated with polychlorinated dibenzo-p-dioxins (PCDDs). Nonetheless, the overall dechlorination pathways and features remain elusive. Herein, we address these issues by quantum chemical calculations, considering the calibrations of reductive dechlorination of 15 PCDDs mediated by three Dehalococcoides strains. Chlorine substituents with lower electron density are prone to be microbially abstracted, which differentiates 72 microbe-active PCDDs from 3 nonactive analogues with a success rate of 100%. For all 256 transformation routes of 75 PCDDs, electron density differences of chlorines pinpoint 105 viable and 125 unviable pathways, corresponding a success rate of 90%. The feasibility of 26 reductive dechlorination pathways are uncertain because of the limited available experimental data. 98% (251/256) of microbial chlorine abstraction follows an order of Cl_O,Cl>Cl_Cl,Cl>Cl_H,O>Cl_H,Cl>Cl_H,H=0. PCDDs solely containing chlorines at C₁, C₄, C₆, and/or C₉ can be completely dechlorinated to non-chlorinated dioxin; while PCDDs housing chlorines at C₂, C₃, C₇, and/or C₈ can be dechlorinated to 2-MCDD or 2,7/8-DCDD as final products. These findings also support reductive dechlorination of PCDDs in mixed cultures and sediments (> 98% and 83%). These findings would promote the application of dechlorinating bacteria in targeted remediation and facilitate the respective studies on other POPs.

Profile occurrences and in vitro effects of toxic organic pollutants in metal shredding facilities in Wallonia (Belgium)

End-of-life vehicles and e-waste contain several hazardous substances that can contaminate the environment during treatment processes. Occurrences and adverse effects of toxic organic pollutants emitted from 3 shredder plants located in Wallonia, Belgium, were investigated by chemical and biological analyses of fluff, dust, and scrubbing sludge sampled in 2019. Site 1 showed the highest concentrations of chlorinated compounds in sludge with 7.5 ng/g polychlorinated dibenzo-dioxins/furans and 84.5 µg/g estimated total polychlorinated biphenyls, while site 3 led the brominated flame retardant levels in dust (53.4 µg/g). The level of polycyclic aromatic hydrocarbons was highest in the sludge samples, 78 and 71 µg/g for sites 2 and 3, respectively. The samples induced significant dioxin-like activities in murine and human cells at concentrations of around 0.01-0.1 and 0.5-1 ng (sample) per ml (medium), respectively, with the efficacy similar to 2,3,7,8-tetrachlorodibenzodioxin and EC₅₀ values of around 1 and 10 ng/ml. The samples also displayed high estrogenic activities, already at 1 ng/ml, and several induced a response as efficient as 17β-estradiol, albeit a low androgenic activity. Shredder workers were estimated to be highly exposed to dioxin-like compounds through dust ingestion and dermal absorption, which is of concern.

PCDD/Fs and Dioxin-like PCBs in Chicken Eggs and Soils in Dong Nai Province, Southern Vietnam: Impacts of Raising Methods and Nearby Pollution Sources

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like PCBs (DL-PCBs) were examined in chicken egg and soil samples collected from Dong Nai Province, southern Vietnam. PCDD/F and DL-PCB levels in egg samples ranged from 5.74 to 1320 (median 350) and from 120 to 51,200 (median 1470) pg/g lipid weight (lw), respectively. Toxic equivalents to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TEQ) in egg samples ranged from 0.817 to 245 (median 10.8) pg TEQ/g lw. Higher dioxin levels were found in free-range eggs than non-free-range ones. We found significant correlation between TEQ levels in paired egg and soil samples collected from the Bien Hoa Airbase and some communities adjacent to industrial areas (Spearman's ρ = 0.671; p < 0.05), suggesting the co-occurrence of legacy and current dioxin emission sources in these areas.

Thermal treatment of decabrominated diphenyl ether in its highly contaminated soil in Taiwan

Polybrominated diphenyl ethers (PBDEs) were commonly used flame retardants in the world, while some of PBDEs have been listed as persistent organic pollutants (POPs). Decabrominated diphenyl ether (BDE-209) was the most commercially used PBDEs. A farm near the factory located in Northern Taiwan was highly contaminated with BDE-209. Since PBDEs in the contaminated soils can be uptake by crops shown in our previous studies and could be potentially consumed by humans, it is very important to establish a feasible treatment method for PBDE remediation in this contaminated farm. Thermal treatment of PBDEs in soil was studied. The initial concentration of BDE-209 in contaminated soil was 1.472 mg/kg. A series of thermal experiments under different operating conditions including various temperature (105, 150, 200, 250, 300, 350, 400 and 450 °C), holding time (10, 20 and 30 min), heating rate (5, 10, 20 and 40 °C/min), and soil amount (10, 100, 1000 and 2000 g) were investigated. The optimal heating conditions for thermal treatment of contaminated soil were heating at 450 °C for 30 min with a heating rate of 10 °C/min. Under this condition, the removal of BDE-209 in the different weights of contaminated soil was tested. The soils in the contaminated farm were tested to further evaluate the feasibility of remediating the on-site PBDE contaminated soil through thermal treatment, suggesting that the holding time was extended to 2 h for the field-scale contaminated soil. The results showed that BDE-209 had been removed to below the detection limit in on-site soil. This investigation is the first study using thermal treatment to remediate soils really contaminated with PBDEs.

Augmentation of an Engineered Bacterial Strain Potentially Improves the Cleanup of PCB Water Pollution

Polychlorinated biphenyls (PCBs) are recalcitrant organohalide pollutants, consisting of 209 congeners. PCB cleanup in natural landscapes is expected to be achieved by the metabolic activity of microorganisms, but aerobic PCB-degrading bacteria that inhabit sites polluted by PCBs cannot degrade all PCB congeners due to the specificity of their enzymes. In this study, we investigated the degradability of PCBs when a genetically modified PCB-degrading bacterium was compounded with wild-type PCB-degrading bacteria. We used two bacterial strains, Comamonas testosteroni YAZ2 isolated from a PCB-uncontaminated natural landscape and Escherichia coli BL21(DE3) transformed with a biphenyl dioxygenase (BphA) gene from a well-known PCB degrader, Burkholderia xenovorans LB400. The enzymatic specificities of BphA were 2,3-dioxygenation in the YAZ2 and 2,3- and 3,4-dioxygenations in the recombinant E. coli. For the PCB-degrading experiment, a dedicated bioreactor capable of generating oxygen microbubbles was prototyped and used. The combined cells of the recombinant and the wild-type strains with an appropriate composite ratio degraded 40 mg/L of Kaneclor KC-300 to 0.3 ± 0.1 mg/L within 24 h. All of the health-toxic coplanar PCB congeners in KC-300 were degraded. This study suggested that the augmentation of an engineered bacterial strain could improve the cleanup of PCB water pollution. It also revealed the importance of the ratio of the strains with different PCB-degrading profiles to efficient degradation and that the application of oxygen microbubbles could rapidly accelerate the cleanup. IMPORTANCE PCB cleanup technique in a natural environment relies on the use of enzymes from microorganisms, primarily biphenyl dioxygenase and dehalogenase. Herein, we focused on biphenyl dioxygenase and created a recombinant PCB-degrading E. coli strain. Despite the development of environments for the field use of transgenic microbial strains around the world, verification of the applicability of transgenic microbial strains for PCB cleanup in the field has not yet been reported. We tentatively verified the extent to which degradability could be obtained by an augmentation model of a transgenic strain, the enzyme expression of which is easily regulated in rivers and lakes with PCB pollution. Our experiments used a dedicated bioreactor to model the natural landscape and produced results superior to those of bioremediation or biostimulation methods. The application of micro-nano bubbles, which has recently been discussed, to the cleanup of environmental pollution was also found to be useful in this study.

The deleterious effects induced by an acute exposure of human skin to common air pollutants are prevented by extracts of Deschampsia antarctica

The homeostatic and regenerative potential of the skin is critically impaired by an increasing accumulation of air pollutants in human ecosystems. These toxic compounds are frequently implicated in pathological processes such as premature cutaneous ageing, altered pigmentation and cancer. In this scenario, innovative strategies are required to tackle the effects of severe air pollution on skin function. Here we have used a Human Skin Organotypic Culture (HSOC) model to characterize the deleterious effects of an acute topic exposure of human skin to moderately high concentrations of common ambient pollutants, including As, Cd, Cr, dioxins and tobacco smoke. All these toxic compunds inflict severe damage in the tissue, activating the AHR-mediated response to xenobiotics. We have further evaluated the potential of an aqueous leaf extract of the polyextremophile plant Deschampsia antarctica (Edafence) to protect human skin against the acute exposure to toxic pollutants. Our results indicate that pre-treatment of HSOC samples with this aqueous extract conuterbalances the deleterious effects of the exposure to toxic comunds and triggers the activation of key genes invoved in the redox system and in the pro-inflammatory/wound healing response in the skin, suggesting that this natural compound might be effectively used in vivo to protect human skin routinely in different daily conditions.

High-Density Polyethylene Waste (HDPE)-Waste-Modified Lube Oil Nanocomposites as Pour Point Depressants

Sustainability metrics have been established that cover the economic, social, and environmental aspects of human activities. Reduce, reuse, and recycle (3R) strategy targets solid waste management in the waste generation sectors. The purpose of this work is to study the possibility of using various plastic wastes containing high-density polyethylene (HDPE) and high-density polyethylene nanoclay (PMON) as polymer additives to modify lubricating oil. The structure of these additives was elucidated by Fourier transform infrared (FTIR) spectra, and the particle size of PMON was determined by dynamic light scattering (DLS). The thermal stability of HDPE and nanoclay HDPE (PMON) was studied, which showed higher thermal stability, and these additives completed degradation above 500 °C. The performance of HDPE and nanoclay HDPE (PMON) in lubricating oil was evaluated as pour point depressants by standard ASTM methods. The results showed that the efficiency of these additives increases with the decrease in the dose of these additives and lubricating oil treated with HDPE at 0.25% dosage lowers PPT to -30 °C, while lubricating oil treated with nanoclay HDPE (PMON7) at 0.25% dosage reduces PPT to -36 °C. Photomicrographic analysis was conducted to study accumulations and modifications in the wax crystal morphology in lube oil without and with HDPE and nanoclay HDPE (PMON7). Photomicrographs revealed that wax morphology changes due to effective pour point depressants on crystal growth.

The footprint of dioxins in globally traded pork meat

The bioaccumulation of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), known as dioxins, in fatty meat is one of primary pathways of entry into the human body, but levels of human exposure to dioxins in fatty meat subject to global trade are unknown. We show high dioxin estimated dietary intake (EDI) via pork consumption in Europe, the United States, and China, owing to stronger dioxin environmental contamination and high pork consumption in these countries. The dioxin risk transfer embodied in pork trade is mostly significant in high-latitude countries and regions of Canada, Russia, and Greenland because these regions with low dioxin environmental levels import large amounts of pork meat from more severely dioxin-contaminated Europe and the United States. We demonstrate that global pig feed trading decreases the exposure of pork consumers to dioxins via the import of feed from countries with low dioxin environmental contamination by pig breeding countries.

Atmospheric PCDDs/PCDFs levels and occurrences in Southeast Asia: A review

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are toxic compounds derived from anthropogenic sources that stay in the environment for long periods. Ambient air has become the most important pathway for the transfer of PCDDs/PCDFs from emission sources to the environment. This review intends to summarise the information available on atmospheric PCDDs/PCDFs in the countries of Southeast Asia to provide a detailed description of the trends in PCDDs/PCDFs emissions, key sources, and levels in urban, rural, and industrial air as reported in peer-reviewed literature since 2000 and by the United Nations Environment Programme. As the largest country in Southeast Asia, Indonesia is the major PCDDs/PCDFs emitter, accounting for 72.81% of the total release of PCDDs/PCDFs in the air from all available inventories in this region, while Brunei Darussalam is the lowest emitter, contributing to less than 0.02%. Open burning processes have become the largest source of ambient PCDDs/PCDFs in the region (69.62%), followed by waste incineration (10.69%), and ferrous and non-ferrous metal production (8.78%). PCDDs/PCDFs levels in rural areas ranged between 10 and 38 fg TEQ m^-3; however, where open burning waste has occurred, the levels rose to 12-29 times higher. In urban areas, ambient levels were 15 times greater than in rural areas, varying from 23 to 565 fg TEQ m^-3. Atmospheric concentrations near industrial palm oil and waste incinerator sites were between 64 and 1530 fg TEQ m^-3. The non-cancer risk of ambient exposure to PCDDs/PCDFs through inhalation is low among populations near facilities emitting PCDDs/PCDFs. The lack of local technical capacity, the high economic costs, and the lack of established human resource capacities have been the major challenges in conducting ambient PCDDs/PCDFs studies in most countries in the region.

Human Biomonitoring Data Enables Evidence-Informed Policy to Reduce Internal Exposure to Persistent Organic Compounds: A Case Study

Human biomonitoring (HBM) monitors levels of environmental pollutants in human samples, which often is a topic of concern for residents near industrially contaminated sites (ICSs). Around an ICS area in Menen (Belgium), including a (former) municipal waste incinerator and a metal recovery plant, increasing environmental concentrations of dioxins and polychlorinated biphenyls (PCBs) were observed, causing growing concern among residents and authorities. The local community succeeded in convincing the responsible authorities to investigate the problem and offer research funding. Persistent organic pollutants (POPs) were measured in two consecutive HBM studies (2002-2006 and 2010-2011), in the context of the Flemish Environment and Health Study (FLEHS), as well as in soil and locally produced food. Meanwhile, local authorities discouraged consumption of locally produced food in a delineated area of higher exposure risk. Ultimately, HBM and environmental data enabled tailored dietary recommendations. This article demonstrates the usefulness of HBM in documenting the body burdens of residents near the ICS, identifying exposure routes, evaluating remediating actions and providing information for tailored policy strategies aiding to further exposure reduction. It also highlights the role of the local stakeholders as an example of community-based participatory research and how such an approach can create societal support for research and policy.

A critical review on the formation, fate and degradation of the persistent organic pollutant hexachlorocyclohexane in water systems and waste streams

The environmental impacts of persistent organic pollutants (POPs) is an increasingly prominent topic in the scientific community. POPs are stable chemicals that are accumulated in living beings and can act as endocrine disruptors or carcinogens on prolonged exposure. Although efforts have been taken to minimize or ban the use of certain POPs, their use is still widespread due to their importance in several industries. As a result, it is imperative that POPs in the ecosystem are degraded efficiently and safely in order to avoid long-lasting environmental damage. This review focuses on the degradation techniques of hexachlorocyclohexane (HCH), a pollutant that has strong adverse effects on a variety of organisms. Different technologies such as adsorption, bioremediation and advanced oxidation process have been critically analyzed in this study. All 3 techniques have exhibited near complete removal of HCH under ideal conditions, and the median removal efficiency values for adsorption, bioremediation and advanced oxidation process were found to be 80%, 93% and 82% respectively. However, it must be noted that there is no ideal HCH removal technique and the selection of removal method depends on several factors. Furthermore, the fates of HCH in the environment and challenges faced by HCH degradation have also been explained in this study. The future scope for research in this field has also received attention.

Analysis of Microbial Communities in Aged Refuse Based on 16S Sequencing

Aged refuse is widely considered to have certain soil fertility. 16S rRNA amplicon sequencing is used to investigate the microbial community of aged refuse. The aged refuse is found to contain higher soil fertility elements (total nitrogen, total phosphorus, total potassium, etc.) and higher concentrations of heavy metals (Pb, Cd, Zn, and Hg). Taxonomy based on operational taxonomic units (OTUs) shows that Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, and Gemmatimonadetes are the main bacterial phyla in the two soils and there is a palpable difference in the microbial community composition between the two groups of samples. The genera Paramaledivibacter, Limnochorda, Marinobacter, Pseudaminobacter, Kocuria, Bdellovibrio, Halomonas, Gillisia, and Membranicola are enriched in the aged refuse. Functional predictive analysis shows that both the control soil and aged refuse have a high abundance of “carbohydrate metabolism” and “amino acid metabolism”, and show differences in the abundance of several metabolism pathways, such as “xenobiotics biodegradation and metabolism” and “lipid metabolism”. Aged refuse and undisturbed soil show significant differences in alpha diversity and microbial community composition. Multiple environmental factors (Hg, TN, Cr, Cd, etc.) significantly impact microorganisms’ abundance (Marinobacter, Halomonas, Blastococcus, etc.). Our study provides valuable knowledge for the ecological restoration of closed landfills.

Phytoremediation potential of Miscanthus sinensis And. in organochlorine pesticides contaminated soil amended by Tween 20 and Activated carbon

The organochlorine pesticides (OCPs) have raised concerns about being persistent and toxic to the environment. Phytoremediation techniques show promise for the revitalization of polluted soils. The current study focused on optimizing the phytoremediation potential of Miscanthus sinensis And. (M. sinensis), second-generation energy crop, by exploring two soil amendments: Tween 20 and activated carbon (AC). The results showed that when M. sinensis grew in OCP-polluted soil without amendments to it, the wide range of compounds, i.e., α-HCH, β-HCH, γ-HCH, 2.4-DDD, 4.4-DDE, 4.4-DDD, 4.4-DDT, aldrin, dieldrin, and endrin, was accumulated by the plant. The introduction of soil amendments improved the growth parameters of M. sinensis. The adding of Tween 20 enhanced the absorption and transmigration to aboveground biomass for some OCPs; i.e., for γ-HCH, the increase was by 1.2, for 4.4-DDE by 8.7 times; this effect was due to the reduction of the hydrophobicity which made pesticides more bioavailable for the plant. The adding of AC reduced OCPs absorption by plants, consequently, for γ-HCH by 2.1 times, 4.4-DDD by 20.5 times, 4.4-DDE by 1.4 times, 4.4-DDT by 8 times, α-HCH was not adsorbed at all, and decreased the translocation to the aboveground biomass: for 4.4-DDD by 31 times, 4.4-DDE by 2.8 times, and γ-HCH by 2 times; this effect was due to the decrease in the bioavailability of pesticides. Overall, the amendment of OCP-polluted soil by Tween 20 speeds the remediation process, and incorporation of AC permitted to produce the relatively clean biomass for energy.

Combined sediment desorption and bioconcentration model to predict levels of dioxin-like chemicals in fish

Flooding and other sediment disturbances can lead to increases in sediment resuspension. In this context, it is of central importance to understand the kinetics of release from these sediments and the uptake of pollutants, such as polychlorinated biphenyls (PCBs) and polychlorinated dioxins and furans (PCDD/Fs), into aquatic organisms. In the present study, we parameterized a sediment desorption model based on experimentally determined rapidly-desorbing fractions of dioxin-like chemicals (DLCs). We coupled this desorption model with a physiologically-based toxicokinetic model for rainbow trout. This combined model was used to predict DLC concentrations in the muscle of exposed fish. The performance of this model was evaluated using a previously published dataset on DLC uptake from sediment suspensions during simulated re-suspension events. Predictions generally differed less than 10-fold from measured values, and the model showed a good global coefficient of determination (R²) of 0.95. The root mean squared error (RMSE) for PCBs was 0.31 log units and 0.53 log units for PCDD/Fs. The results of our study demonstrate that the prediction of bioconcentration and related risk to fish resulting from sediment resuspension can be accurately predicted using coupled desorption and toxicokinetic models.

Persistent pollutants exceed toxic thresholds in a freshwater top predator decades after legislative control

Declining emissions of persistent organic pollutants (POPs), subject to international control under the Stockholm convention, are not consistently reflected in biotic samples. To assess spatial and temporal variation in organochlorine pesticides and PCBs in UK freshwaters, we analysed tissues of a sentinel predator, the Eurasian otter, Lutra lutra between 1992 and 2009. Past declines in otter populations have been linked to POPs and it is unclear whether otter recovery is hampered in any areas by their persistence. PCBs, DDT (and derivatives), dieldrin and HCB were detected in over 80% of 755 otter livers sampled. Concentrations of ∑PCB, ∑DDT and dieldrin in otter livers declined across the UK, but there was no significant time trend for ∑PCB-TEQ (WHO toxic equivalency, Van den Berg et al., 2006) or HCB. In general, higher concentrations were found in the midlands and eastern regions, and lowest concentrations in western regions. Concentrations of PCBs and HCB in otters increased near the coast, potentially reflecting higher pollutant levels in estuarine systems. Decades after legislative controls, concentrations of these legacy pollutants still pose a risk to otters and other freshwater predators, with spatially widespread exceedance of thresholds above which reproduction or survival has been reduced in related species.

Atmospheric Occurrence of Organochlorine Pesticides and Inhalation Cancer Risk in Urban Areas at Southeast Brazil

Organochlorine pesticides (OCPs) have been produced for almost a century and some of them are still used, even after they have been proved to be toxic, persistent, bioaccumulative and prone to long-range transport. Brazil has used and produced pesticides in industrial scales for both agricultural and public health purposes. Urban and industrial regions are of special concern due to their high population density and their increased exposure to chemical pollution, many times enhanced by chemical production, application or irregular dumping. Therefore, we aimed to investigate the occurrence of OCPs in outdoor air of urban sites from two major regions of southeast Brazil. Some of these sites have been affected by OCP production and their irregular dumping. Deterministic and probabilistic inhalation cancer risk (CR) assessments were conducted for the human populations exposed to OCPs in ambient air. Ambient air was mainly affected by Ʃ-HCH (median = 340 pg m^-3) and Ʃ-DDT (median = 233 pg m^-3), the only two OCPs registered for domissanitary purposes in Brazil. OCP concentrations tended to be higher in summer than in winter. Dumping sites resulted in the highest OCP atmospheric concentrations and, thus, in the highest CR estimations. Despite of all limitations, probabilistic simulations suggested that people living in the studied regions are exposed to an increased risk of hepatic cancer. Infants and toddlers (0 < 2 y) were exposed to the highest inhalation CRs compared to other age groups. Other exposure pathways (such as ingestion and dermic uptake) are needed for a more comprehensive risk assessment. Moreover, this study also highlights the need to review the human exposure to OCPs through inhalation and their respective CR in other impacted areas worldwide, especially where high levels of OCPs are still being measured.

First study on PCBs, organochlorine pesticides, and trace elements in the Eurasian otter (Lutra lutra) from southern Italy

Persistent organic pollutants (POPs), such as organochlorine pesticides (OCPs) and non dioxin-like polychlorinated biphenyls (ndl-PCBs), or also other toxic and potentially toxic elements tend to accumulate in the trophic web, and are associated with a wide range of deleterious effects in animals and humans. Although these contaminants have been banned since more than 30 years, their occurrence remains widespread in most of natural ecosystems. The Eurasian otter (Lutra lutra), being a top predator may cumulate large amounts of these contaminants, and could represent a keystone species serving as sentinel of ecosystem health in freshwater environments. The aim of this paper was to investigate the concentration of OCPs, ndl-PCBs, and essential and not essential elements in tissue samples of Eurasian otter in southern Italy. Six PCBs, seven OCPs, and thirteen trace elements were detected with high concentrations in few cases, however in general, the amounts of toxic compounds seem unlikely to hazard short-term conservation of this endangered mammal. The present paper is the first to provide baseline information concerning the presence of these substances in the Eurasian otter samples and from its fragile ecosystem in Italy.

Precursors of polychlorinated dibenzo-p-dioxins and dibenzofurans in Arctic and Antarctic marine sediments: Environmental concern in the face of climate change

Polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F) and their precursors - pentachlorophenol (PCP) and triclosan (TCS), constitute a group of persistent, highly toxic multimedia pollutants, being easily transported via atmosphere over long distances, thus particularly threatening to the polar areas. The global fate of PCDD/Fs is temperature-dependent, and their transfer and immobilization at the Poles are described by the grasshopper effect and the cold trap phenomenon. The aim of this interdisciplinary study was to perform a preliminary assessment of the present state of pollution of Arctic and Antarctic marine sediments by PCP and TCS along with determination of PCDD/Fs contamination by immunoassay. Sediments from 20 stations were collected during two polar expeditions (2013-2016). The study area covered Hornsund Fjord and the southwest coast of Wedel-Jarlsberg Land (Arctic) - Skodde Bay, Nottingham Bay, Isbjørnhamna Bay and Admiralty Bay (Antarctica) - Suszczewski Cove, Halfmoon Cove and Herve Cove. The studied contaminants were quantified in 60% of the collected sediments, with almost half exceeding the environmentally safe levels according European regulations and worldwide literature. The determined levels of PCP, TCS and PCDD/F in Arctic and Antarctic sediments were to be comparable to those reported in the southern Baltic Sea located in the intense industrialized mid-latitudes. Maximum concentrations were observed in the vicinity of retreating, marine terminating glaciers. This observation confirms reemission of POPs into the global cycle with respect to the worldwide ocean warming. The results of this study should gain attention of the international and regional environmental agencies as well as the main chlorine production decision makers.

Insights into the mechanisms underlying the remediation potential of earthworms in contaminated soil: A critical review of research progress and prospects

In recent years, soil pollution is a major global concern drawing worldwide attention. Earthworms can resist high concentrations of soil pollutants and play a vital role in removing them effectively. Vermiremediation, using earthworms to remove contaminants from soil or help to degrade non-recyclable chemicals, is proved to be an alternative, low-cost technology for treating contaminated soil. However, knowledge about the mechanisms and framework of the vermiremediation various organic and inorganic contaminants is still limited. Therefore, we reviewed the research progress of effects of soil contaminants on earthworms and potential of earthworm used for remediation soil contaminated with heavy metals, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides, as well as crude oil. Especially, the possible processes, mechanisms, advantages and limitations, and how to boost the efficiency of vermiremediation are well addressed in this review. Finally, future prospects of vermiremediation soil contamination are listed to promote further studies and application of vermiremediation in contaminated soils.

New Data Set of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Half-Lives: Natural Attenuation and Rhizoremediation Using Several Common Plant Species in a Weathered Contaminated Soil

In this paper, a new data set of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) half-lives (HLs) in soil is presented. Data are derived from a greenhouse experiment performed with an aged contaminated soil under semi-field conditions, obtained from a National Relevance Site (SIN) located in Northern Italy (SIN Brescia-Caffaro). Ten different treatments (combination of seven plant species with different soil conditions) were considered together with the respective controls (soil without plants). The ability of the plants to stimulate the biodegradation of these compounds was evaluated by measuring the PCDD/F concentration reduction in soil over a period of 18 months. The formation of new bound residues was excluded by using roots as a passive sampler of bioaccessible concentrations. The best treatment which significantly reduced PCDD/F concentrations in soil was the one with Festuca arundinacea (about 11-24% reduction, depending on the congener). These decreases reflected in HLs ranging from 2.5 to 5.8 years. Simulations performed with a dynamic air-vegetation-soil model (SoilPlusVeg) confirmed that these HLs were substantially due to biodegradation rather than other loss processes. Because no coherent PCDD/F degradation HL data sets are currently available for soil, they could substantially improve the predictions of soil remediation time, long-range transport, and food chain transfer of these chemicals using multimedia fate models.

Direct sample introduction GC-MS/MS for quantification of organic chemicals in mammalian tissues and blood extracted with polymers without clean-up

Solvent extracts of mammalian tissues and blood contain a large amount of co-extracted matrix components, in particular lipids, which can adversely affect instrumental analysis. Clean-up typically degrades non-persistent chemicals. Alternatively, passive sampling with the polymer polydimethylsiloxane (PDMS) has been used for a comprehensive extraction from tissue without altering the mixture composition. Despite a smaller fraction of matrix being co-extracted by PDMS than by solvent extraction, direct analysis of PDMS extracts was only possible with direct sample introduction (DSI) GC-MS/MS, which prevented co-extracted matrix components entering the system. Limits of quantitation (LOQ) ranged from 4 to 20 pg μL⁻¹ ethyl acetate (PDMS extract) for pesticides and persistent organic pollutants (POPs). The group of organophosphorus flame retardants showed higher LOQs up to 107 pg μL⁻¹ due to sorption to active sites at the injection system. Intraday precision ranged between 1 and 10%, while the range of interday precision was between 1 and 18% depending on the analyte. The method was developed using pork liver, brain, and fat as well as blood and was then applied to analyze human post-mortem tissues where polychlorinated biphenyls (PCBs) as well as dichlorodiphenyltrichloroethane (DDT) and DDT metabolites were detected.

Insights into PCDD/Fs and PAHs in Biomass Boilers Envisaging Risks of Ash Use as Fertilizers

Since ashes are a possible source of Persistent Organic Pollutants (POPs) contamination, their application in soils must be subject to more study and control. In this scope, feed residual forest biomasses and biomass ashes, collected along one year in four biomass power stations, were characterized mainly for their polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and Polycyclic Aromatic Hydrocarbons (PAHs) contents. The biomasses present concerning levels of Cl (0.04–0.28%) that may lead to PCDD/Fs formation. The biomasses also contain OCDD (29–260 ng/kg) and 1,2,3,4,6,7,8-HpCDD (35 ng/kg) that may contribute to increased Toxic Equivalents (TEQs) of ashes, possibly involving dechlorination and ash enrichment mechanisms. While the WHO2005-TEQs in bottom ashes (14–20 ng TEQ/kg) reaches the proposed limit (20 ng TEQ/kg) for ash use as fertilizers, in fly ashes (35–1139 ng TEQ/kg) the limit is exceeded. PAHs are below 0.02 mg/kg in bottom ashes and 1.5–2.5 mg/kg in fly ashes, complying with the proposed limit of 6 mg/kg. As bottom and fly ash streams may contain different ash flows, a clear definition of ash mixes is required. Correlations between unburned carbon (C), PAHs and PCDD/Fs were not found, which highlights the need for compulsory PCDD/Fs analysis in ashes, independently of their origin, burnout degree or levels of other contaminants. A sensitivity analysis was performed to evaluate the impact of handling non-detected values, which showed more impact for TEQs values close to the proposed regulatory limit of PCDD/Fs. These findings highlight the need to define reporting protocols of analytical results for risk assessments and conformity evaluation.