Spatial distributions, behaviors, and sources of PCDD/Fs in surface water and sediment from the Yangtze River Delta.

The Yangtze River Delta (YRD), one of the most economically developed and industrialized regions in China, is confronted with challenges arising from rapid urbanization, particularly environmental pollution. The collection of surface water and sediment samples from forty-nine sites in the YRD was conducted to analyze 2378-substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) congeners. The detected concentrations of PCDD/Fs were 0-5.3 pg TEQ/L in water and 0.12-1493 pg TEQ/g dw in sediment. The PCDD/Fs contamination in the sediment was widespread in the YRD. There were variations in the congener characteristics of PCDD/Fs in surface water and sediment. The proportion of OCDD was significantly lower in surface water samples compared to sediment, while the less chlorine-substituted homologs were found in larger proportions. To understand the partitioning and behavior of dioxins within the water-sediment system, we calculated the organic carbon normalized partition coefficients and fugacity fraction (ff) of PCDD/F congeners. The results revealed that the PCDD/Fs had not attained a state of distributional equilibrium, and the non-specific hydrophobic effect seemed minimally influential on their partitioning between sediment and water. The average ff values, which varied between 0.06 and 0.63, indicated differing migration directions for the PCDD/F congeners. Source identification analysis provided evidence that the dioxins in the river water were primarily attributed to industrial thermal processes. Iron and steel smelting, along with pesticide production and use, were likely responsible for the sediment contamination. This comprehensive analysis underscores the complex nature of PCDD/Fs pollution in the YRD and highlights the necessity for targeted environmental management strategies.

Occurrence, physicochemical properties and environmental behavior of polychlorinated dibenzothiophenes: A comprehensive review and future perspectives.

Polychlorinated dibenzothiophenes (PCDTs) are a form of emerging pollutant that has attracted great attention due to their structural resemblance to dioxins, which cast detrimental influence on the ecosystem and human health. This review shows the current status of research on PCDTs, focusing on their environmental occurrence, physicochemical properties, environmental behavior, and toxicity. Studies have suggested that the steps leading to the formation of PCDTs resemble those generating polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs), indicating their probable origin from the same sources. Furthermore, they may undergo a dechlorination process as a result of their photodegradation in the environment and metabolic reaction occurring within organisms, which could result in the conversion of these substances into additional pollutants like dibenzothiophene. PCDTs exist widely in the environmental media and have high logKOW values (>4.0), indicating their tendency to bioaccumulate. Moreover, the prediction results of EPI (Estimation Program Interface) Suite demonstrated a strong accumulation capacity for tetra-CDTs in fish compared to other chlorinated PCDTs. The biotransformation half-life of PCDTs would prolong with an increasing number of substituted Cl atoms in fish. A limited number of studies have also suggested that PCDTs can cause damage to the liver and immune system in living organisms, and the toxicity of PCDTs depends on the number and position of substituted Cl atoms. Future studies should be conducted on processes causing PCDT toxicity as well as their behavior and fate in actual environments.

Probabilistic human health risk assessment of PCDD/Fs near municipal solid-waste incinerator using Monte Carlo analysis coupled with triangular fuzzy numbers.

PCDD/Fs are dioxins produced by waste incineration and pose risks to human health. We aimed to detail the health risks of airborne and soil PCDD/Fs near a municipal solid-waste incinerator (MSWI) for the surrounding population and develop a new model that improves upon existing methods. Thus, we conducted field sampling and then investigated a MSWI in the Pearl River Delta (2016-2018). Our results showed that the carcinogenic and non-carcinogenic risk values of PCDD/Fs exposed to residents in nearby areas were acceptable, with hazard index (HI) values lower than 1.0 and a total carcinogenic risk lower than 1.0E-6. Notably, the results raised concerns regarding higher non-carcinogenic risks in children than in adults. Comparative analysis of the frequency accumulation diagram, accumulated probability risk, and the absolute value of error (δ) between the 95% confidence interval (CI) and the 90% CI of the Monte Carlo stochastic simulation-triangular fuzzy number (MCSS-TFN) and the MCSS model, respectively, demonstrated that the MCSS-TFN exhibited less uncertainty than the MCSS model, regardless of the health risk value of PCDD/Fs in ambient air or in soil. This observation underscores the superiority of the MCSS-TFN model over other models in assessing the health risks associated with PCDD/Fs in situations with limited data. Our new method overcomes the limited dataset size and high uncertainty in assessing the health risks of dioxin substances, providing a more comprehensive understanding of their associated health risks than MCSS models.

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition.

BACKGROUND: The reuse of dredged sediments in ports and lagoons is a big issue as it should not affect the quality and the equilibrium of ecosystems. In the lagoon of Venice, sediment management is of crucial importance as sediments are often utilized to built-up structures necessary to limit erosion. However, the impact of sediment reuse on organisms inhabiting this delicate area is poorly known. The Manila clam is a filter-feeding species of high economic and ecological value for the Venice lagoon experiencing a drastic decline in the last decades. In order to define the molecular mechanisms behind sediment toxicity, we exposed clams to sediments sampled from different sites within one of the Venice lagoon navigable canals close to the industrial area. Moreover, we investigated the impacts of dredged sediments on clam's microbial communities. RESULTS: Concentrations of the trace elements and organic chemicals showed increasing concentrations from the city of Venice to sites close to the industrial area of Porto Marghera, where PCDD/Fs and PCBs concentrations were up to 120 times higher than the southern lagoon. While bioaccumulation of organic contaminants of industrial origin reflected sediments' chemical concentrations, metal bioaccumulation was not consistent with metal concentrations measured in sediments probably due to the activation of ABC transporters. At the transcriptional level, we found a persistent activation of the mTORC1 signalling pathway, which is central in the coordination of cellular responses to chemical stress. Microbiota characterization showed the over-representation of potential opportunistic pathogens following exposure to the most contaminated sediments, leading to host immune response activation. Despite the limited acquisition of new microbial species from sediments, the latter play an important role in shaping Manila clam microbial communities. CONCLUSIONS: Sediment management in the Venice lagoon will increase in the next years to maintain and create new canals as well as to allow the operation of the new mobile gates at the three Venice lagoon inlets. Our data reveal important transcriptional and microbial changes of Manila clams after exposure to sediments, therefore reuse of dredged sediments represents a potential risk for the conservation of this species and possibly for other organisms inhabiting the Venice lagoon.

Investigating the presence of dioxins in drinking water: implications for public health.

The presence of highly toxic dioxins, specifically polychlorinated dibenzo-p-dioxins (PCDDs), in drinking water is a matter of great concern due to their long-lasting nature and harmful effects. In this study, we detected three out of the five dioxin congeners: 2, 3, 7, 8-tetrachlorodibenzodioxin (TCDD), 1, 2, 3, 7, 8-pentachlorodibenzo-p-dioxin (PeCDD), and octachlorodibenzo-p-dioxin (OCDD). The investigation revealed that three dioxins were present in water samples of winter season, while TCDD and OCDD were found in the summer season. The geometric mean concentrations of PCDDs were 229.9 ng/L (winter) and 108.4 ng/L (summer), exceeded the maximum contaminant level of 30 pg/L set by the USEPA in surface water. The estimated daily intake of PCDDs for residents through drinking water was 273.97 ng-WHO2005-TEQ/kg/days during winter and 78.875 ng-WHO2005-TEQ/kg/days during summer. Our study emphasizes the urgent need for further research on persistent organic pollutants in drinking water to safeguard public health and community well-being.

Regulatory compliance of PCDD/F emissions by a municipal solid waste incinerator. A case study in Sant Adrià de Besòs, Catalonia, Spain.

Despite incineration is an important emission source of toxic pollutants, such as heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), it is still one of the most widely used methods for the management of municipal solid waste. The current paper summarizes the results of a 20-year follow-up study of the emissions of PCDD/Fs by a municipal solid waste incinerator (MSWI) in Sant Adrià de Besòs (Catalonia, Spain). Samples of ambient air, soils and herbage were periodically collected near the facility and the content of PCDD/Fs was analyzed. In the last (2017) survey, mean levels in soil were 3.60 ng WHO-TEQ/kg (range: 0.40-10.6), being considerably higher than the mean concentrations of PCDD/Fs in soil samples collected near other MSWIs in Catalonia. Moreover, air PCDD/F concentrations were even higher than those found in a previous (2014) survey, as they increased from 0.026 to 0.044 pg WHO-TEQ/m3. Ultimately, the PCDD/F exposure would be associated to a cancer risk (2.5 × 10-6) for the population living in the surrounding area. Globally, this information indicates that the MSWI of Sant Adrià de Besòs could have had a negative impact on the environment and potentially on public health, being an example of a possible inappropriate management for years. The application of Best Available Techniques to minimize the emission of PCDD/Fs and other chemicals is critical.

Microbial Communities Along 2,3,7,8-tetrachlorodibenzodioxin Concentration Gradient in Soils Polluted with Agent Orange Based on Metagenomic Analyses.

The 2,3,7,8-tetrachlorodibenzodioxin (TCDD), a contaminant in Agent Orange released during the US-Vietnam War, led to a severe environmental crisis. Approximately, 50 years have passed since the end of this war, and vegetation has gradually recovered from the pollution. Soil bacterial communities were investigated by 16S metagenomics in habitats with different vegetation physiognomies in Central Vietnam, namely, forests (S0), barren land (S1), grassland (S2), and developing woods (S3). Vegetation complexity was negatively associated with TCDD concentrations, revealing the reasoning behind the utilization of vegetation physiognomy as an indicator for ecological succession along the gradient of pollutants. Stark changes in bacterial composition were detected between S0 and S1, with an increase in Firmicutes and a decrease in Acidobacteria and Bacteroidetes. Notably, dioxin digesters Arthrobacter, Rhodococcus, Comamonadaceae, and Bacialles were detected in highly contaminated soil (S1). Along the TCDD gradients, following the dioxin decay from S1 to S2, the abundance of Firmicutes and Actinobacteria decreased, while that of Acidobacteria increased; slight changes occurred at the phylum level from S2 to S3. Although metagenomics analyses disclosed a trend toward bacterial communities before contamination with vegetation recovery, non-metric multidimensional scaling analysis unveiled a new trajectory deviating from the native state. Recovery of the bacterial community may have been hindered, as indicated by lower bacterial diversity in S3 compared to S0 due to a significant loss of bacterial taxa and recruitment of fewer colonizers. The results indicate that dioxins significantly altered the soil microbiomes into a state of disorder with a deviating trajectory in restoration.

Characterization of PCDD/F and dl-PCB levels in air in Gipuzkoa (Basque Country, Spain).

This research examines the levels and trends of pollutants, specifically 17 congeners of PCDD/Fs and 12 dl-PCBs, in the air measured in the province of Gipuzkoa (Basque Country, Spain). The study used PCDD/Fs, dl-PCB, and the sum of dioxin-like compounds as separate response variables. A total of 113 air samples were collected and analyzed using the method described in the European Standard (EN-1948:2006) from two industrial areas. The results were analyzed using non-parametric test to assess the variability of these pollutants based on different factors (year, season and day of the week) and General Linear Models to assess the weight of each factor. The study found that the toxic equivalents (TEQs) for PCDD/Fs were 12.29 fg TEQm-3 and for dl-PCBs were 1.63 fg TEQm-3, which were in a similar range or lower than those observed in other national and international studies in industrial areas. The results showed temporal variations, with higher levels of PCDD/Fs in autumn-winter than in spring-summer and higher levels of PCDD/Fs and dl-PCBs during weekdays than on weekends. The industrial area where the energy recovery plant (ERP) will be located had higher levels of air pollutants due to the presence of two PCDD/Fs emitting industries nearby, as indicated by the Spanish Registry of Polluting Emission Sources. Both industrial areas showed similar profiles of PCDD/Fs and dl-PCBs, with the PCDD/F profiles dominated by OCDD, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF in terms of concentrations and 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF, and 2,3,7,8-TCDD in terms of TEQs. The dl-PCB profiles were dominated by PCB 118, PCB 105, and PCB 77 in terms of concentrations and PCB 126 in terms of TEQs. The findings of this study can serve as an indicator of the potential impact of ERP on the health of the resident population and the environment.

Residential proximity to dioxin emissions and risk of breast cancer in the sister study cohort.

Some dioxins are carcinogenic, but few studies have investigated the relationship between ambient polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) and risk of breast cancer. We evaluated associations between proximity-based residential exposure to industrial emissions of PCDD/F and breast cancer risk in a large U.S. cohort. Sister Study participants at enrollment (2003-2009) were followed for incident breast cancer through September 2018. After restricting to participants with ≥10 years of residential history prior to enrollment (n = 35,908), we generated 10-year distance- and toxic equivalency quotient (TEQ)-weighted average emissions indices (AEI [g TEQ/km2]) within 3, 5, or 10 km of participants' residences, overall and by facility type. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AEI quartiles (vs. zero AEI) and risk of breast cancer [invasive or ductal carcinoma in situ]. There were 2670 incident breast cancer cases over 11 years (median) of follow-up. Breast cancer risk was increased for those in the highest quartile [Q] of AEI exposure within 3 km (HRQ4:1.18, 95% CI: 0.99,1.40, Ptrend = 0.03). The HR was higher for the 10-year AEI at 3 km from municipal solid waste facilities (HR ≥ median.vs.0:1.50, 95% CI: 0.98, 2.29; Ptrend = 0.07). Risk was higher among ever smokers (vs. never smokers) in the top quartile of the 3 km AEI (HRQ4:1.41, 95% CI:1.12,1.77, Ptrend = 0.003; Pinteraction = 0.03) and higher risk for ER negative tumors was suggested (HRQ4:1.47, 95% CI: 0.95, 2.28, Ptrend = 0.07, Pheterogeneity = 0.17). Our findings suggest that residential exposure to PCDD/F emissions may confer an increased risk of breast cancer.

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.

Trace elements, dioxins and PCBs in different fish species and marine regions: Importance of the taxon and regional features.

Chemical contaminant concentrations in wild organisms are used to assess environmental status under the European Marine Strategy Framework Directive. However, this approach is challenged by the complex intra- and inter-species variability, and the different regional features. In this study, concentrations in trace elements (As, Cd, Hg and Pb), polychlorinated biphenyls (PCBs), polychlorodibenzo-para-dioxines (PCDDs) and polychlorodibenzofuranes (PCDFs) were monitored in 8 fish species sampled on the continental shelf of three French regions: the Eastern English Channel (EEC) and Bay of Biscay (BoB) in the Northeast Atlantic Ocean, and the Gulf of Lions (GoL) in Western Mediterranean Sea. Our objectives were to identify species or regions more likely to be contaminated and to assess how to take this variability into account in environmental assessment. While concentrations were higher in benthic and demersal piscivores, PCB and PCDD/F concentrations (lipid-weight) were similar in most teleost species. For Cd, Hg and Pb, the trophic group accumulating the highest concentrations depended on the contaminant and region. Concentrations in Hg, PCBs and PCDD/Fs were higher in the EEC and/or GoL than in BoB. Cadmium and Pb concentrations were highest in the BoB. Lipid content accounted for 35%-84% of organic contaminant variability. Lipid normalisation was employed to enhance robustness in the identification of spatial patterns. Contaminant patterns in chondrichthyans clearly differed from that in teleosts. In addition, trophic levels accounted for ≤1% and ≤33% of the contaminant variability in teleost fishes in the EEC and BoB, respectively. Therefore, developing taxa-specific thresholds might be a more practical way forward for environmental assessment than normalisation to trophic levels.

Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - Part I: state of knowledge and uncertainties.

Polychlorinated dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) (collectively and colloquially referred to as 'dioxins') as well as polychlorinated biphenyls (PCBs) are persistent and ubiquitous environmental contaminants that may unintentionally enter and accumulate along the food chain. Owing to their chronic toxic effects in humans and bioaccumulative properties, their presence in feed and food requires particular attention. One important exposure pathway for consumers is consumption of milk and dairy products. Their transfer from feed to milk has been studied for the past 50 years to quantify the uptake and elimination kinetics. We extracted transfer parameters (transfer rate, transfer factor, biotransfer factor and elimination half-lives) in a machine-readable format from seventy-six primary and twenty-nine secondary literature items. Kinetic data for some toxicologically relevant dioxin congeners and the elimination half-lives of dioxin-like PCBs are still not available. A well-defined selection of transfer parameters from literature was statistically analysed and shown to display high variability. To understand this variability, we discuss the data with an emphasis on influencing factors, such as experimental conditions, cow performance parameters and metabolic state. While no universal interpretation could be derived, a tendency for increased transfer into milk is apparently connected to an increase in milk yield and milk fat yield as well as during times of body fat mobilisation, for example during the negative energy balance after calving. Over the past decades, milk yield has increased to over 40 kg/d during high lactation, so more research is needed on how this impacts feed to food transfer for PCDD/Fs and PCBs.

Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - part II: toxicokinetic predictive models for risk assessment.

Understanding the transfer of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as well as polychlorinated biphenyls (PCBs) from oral exposure into cow's milk is not purely an experimental endeavour, as it has produced a large corpus of theoretical work. This work consists of a variety of predictive toxicokinetic models in the realms of health and environmental risk assessment and risk management. Their purpose is to provide mathematical predictive tools to organise and integrate knowledge on the absorption, distribution, metabolism and excretion processes. Toxicokinetic models are based on more than 50 years of transfer studies summarised in part I of this review series. Here in part II, several of these models are described and systematically classified with a focus on their applicability to risk analysis as well as their limitations. This part of the review highlights the opportunities and challenges along the way towards accurate, congener-specific predictive models applicable to changing animal breeds and husbandry conditions.

Hospital waste incinerator ash: characteristics, treatment techniques, and applications (A review).

The amount of medical waste generated has increased enormously since the COVID-19 outbreak. An incineration process is the main method that is usually used to treat this waste, causing an increase in both medical waste bottom ash (MWBA) and medical waste fly ash (MWFA). In this work, the physical and chemical characteristics of MWFA and MWBA were reviewed. This ash contains high levels of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofurans (PCDFs), and heavy metals. Furthermore, medical waste ash appears to have high leachability in the toxicity characteristics leaching procedure (TCLP) test and the European standard test (EN 12457). Owing to its toxicity, medical ash can be treated using various methods prior to disposal based on the covered review. These techniques include chemical, supercritical fluid, cement-based, melting, microwave, and mechanochemical techniques. The shortcomings of some of these treatment methods have been identified, such as the emission of high levels of chlorine from the melting technique, limited applications of the flotation method on the industrial scale, long-term stability of leachate treated by cement-based methods that have not been confirmed yet, and high energy consumption in the supercritical technique. This review also covers possible applications of medical waste ash in cement production, agriculture, and road construction.

Polychlorinated dibenzo-p-dioxins/dibenzofurans and mercury in vegetable of the contaminated Ya-Er Lake area: Concentrations, sources, and health risk.

The Ya-Er Lake is a seriously polychlorinated dibenzo-p-dioxins/dibenzo-furans (PCDD/Fs) and mercury (Hg)-contaminated lake by pesticide and chlor-alkali plants in China. The oxidation pond method has been conducted to control pollution, moreover, the contaminated sediment was dredged and stacked, becoming a sediment stack yard for vegetable cultivation. To assess effects of oxidation pond method and dredging programme on pollution management and long-term risks of PCDD/Fs and Hg, the concentrations of PCDD/Fs, total Hg (THg), and methylmercury (MeHg) in soil and vegetable sampled from the sediment stack yard were measured and analyzed. Significantly positive relationships between concentrations of PCDD/Fs (p < 0.01), THg, and MeHg (p < 0.05) in edible parts of vegetable and soil were found, suggesting that bioaccumulation from contaminated soil derived from sediment dredging is important sources of PCDD/Fs and Hg in vegetable. Much higher PCDD/Fs (12 ± 9 pg/g dw) and Hg (THg, 0.14 ± 0.23 µg/g dw; MeHg,12.63 ± 13.31 ng/g dw) levels in vegetable were found compared with those from other contaminated regions, indicative of serious PCDD/Fs and Hg pollution in vegetable harvested from contaminated soil. Finally, the calculated provisional tolerable daily intake (PTDI) values showed higher health risk of PCDD/Fs and Hg exposure to local residents through consumption of purple and white flowering stalk, and oilseed rape. Our study established a good model to evaluate the long-term risks of PCDD/Fs and Hg. Moreover, the results indicate that the oxidation pond method and dredging programme were not effective to remove PCDD/Fs and Hg in sediment, which shed new light on management strategy of PCDD/Fs and Hg pollution in contaminated regions.

Dioxin-like POPs emission trends as a decision support tool for developing sustainable MSW management scheme -an exploratory study.

The paper reports on an innovative application of dioxin-like persistent organic pollutants (dl-POPs) emission trends as a measure of environmental performance for designing feasible municipal solid waste management (MSWM) schemes. MSWM systems are highly dependent on the income status and the population density and it is quintessential for developing countries to devise strategies suiting to its characteristics rather than simply adapting successful processes/technologies in developed nations. Hence a lower-middle-income, high-density populated state of India - Kerala, which represents the typical scenario of majority of towns in developing countries was selected as the verification study site. Annual inventorisation of dl-POPs for the current scenario of the state was developed as a spatial model at the lowest administrative block level using geographical information system for the easy and effective comparative assessment. Further, a dl-POPs emission based MSWM scheme which could reduce up to 65% of emissions from current scenario has been developed and compared it with contemporary life cycle assessment (LCA) and life cycle cost analysis (LCCA) schemes in terms of green-house gas emissions (GHG) and landfill area requirements as environmental performance validation. Daily exposure dose of dl-POPs were predicted from the per-capita annual emission associated with different MSWM schemes and hazard quotients were also calculated to provide an overview of the health risk posed by the emissions. The predicted health risk factors were observed to be 5 times higher than the threshold level in current scenario whereas 10 times reduction in dose levels could be achieved through the proposed scheme of MSWM.

Insight into the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans in hazardous waste incineration and incinerators: Formation process and reduction strategy.

Incineration technology has been widely adopted to safely dispose of hazardous waste (HW). While the incineration process causes the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Due to its extreme toxicity, many scholars have been committed to determining the PCDD/F formation process and reducing emissions in incinerators. Previous studies ignored the impact of incineration and fluctuation of feeding materials on PCDD/F formation in hazardous waste incinerators (HWIs). In this study, differences in PCDD/F formation between HWIs and municipal solid waste incinerators (MSWIs) were pointed out. The incineration section in HWIs should be carefully considered. Laboratory experiments, conventional analysis and thermogravimetry experiments were conducted. An obvious disparity of PCDD/F formation between 12 kinds of HWs was found. Distillation residue was found with remarkably higher PCDD/F concentrations (11.57 ng/g). Except for the Cl content, aromatic rings and C-O bond organics were also found with high correlation coefficients with PCDD/F concentrations (>0.92). And PCDD/Fs were formed through a chlorination process and structure formation process. All of these are helpful to further understand the PCDD/F formation process during HW incineration, optimize the operation conditions in HWIs and reduce the emission pressure of PCDD/Fs in the future.

Spatial and temporal trends in polychlorinated naphthalenes in sediment from Ulsan and Onsan Bays of Korea: Potential sources and ecotoxicological concerns.

Few studies have been conducted on spatial and temporal trends in polychlorinated naphthalenes (PCNs) in coastal environments. Here, we describe 18 PCN congeners found in surface and dated sediment samples collected from highly industrialized bays of Korea. Measurable levels of PCN congeners were detected in all sediment samples, suggesting concurrent and historical contamination. The highest PCN concentrations were observed in sediment from rivers, streams, and the inner portions of the bays, which are surrounded by industrial complexes and commercial harbors. CNs 73, 66/67, and 52 were dominant in surface and dated sediment samples. Congener patterns and diagnostic ratios revealed that PCN contamination is originated from combustion processes and the use of polychlorinated biphenyl (PCB) technical mixtures. PCN concentrations in dated sediment increased from the 1980s to the mid-2000s and then decreased to 2015. Although the toxic equivalent (TEQ) levels of PCNs in our study did not exceed sediment quality guidelines proposed by international authorities, the cumulative risks from the TEQ concentrations of polychlorinated dibenzo-p-dioxins, furans, PCBs, and PCNs can be expected for benthic organisms.

Source apportionment of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sediments of an urban estuary.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in the sediments of aquatic systems are a persistent global problem that poses serious health risks. Identifying the sources of dioxins in natural water systems and the extent of their contributions to observed sediment concentrations is important from a health advisory and mitigation perspective. This paper proposes novel distribution-based qualitative and quantitative methods as source apportionment techniques and alternatives to conventional source attribution methods. Using sampled data, air, runoff, industrial effluent, and industrial paper and pulp wastes were identified as four distinct dioxin contributors to concentrations found in the sediments of the test bed region: the Houston Ship Channel-San Jacinto River-Galveston Bay (HSC-SJR-GB) estuarine system that also includes 2 Superfund sites with dioxin contamination. Two qualitative methods, the Kullback-Leibler divergence (K-L divergence) and the Bhattacharya measure (BM), and a quantitative method, the L2 norm, were used to investigate the spatial and temporal sourcing patterns of dioxins in the system sediments. The results indicated a global contribution from air and runoff sources across the estuarine system and over time with more localized impacts of the Superfund sites and the industrial sources. The results using the developed methodologies were compared with the output from the more conventional positive matrix factorization (PMF) method. Statistically significant correlations were observed among source contributions from the proposed methods and the PMF method, with Spearman's ρ ranging between - 0.596 to - 0.963 and 0.652 to 0.719, demonstrating the utility of the sourcing approaches used in the study. Additionally, the proposed methods were found to be rigorous in terms of elucidating spatial and temporal changes in the sourcing of dioxin to the estuary, indicating their suitability for use for other contaminants and other estuarine systems.

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.