Polychlorinated Dibenzofurans Research Articles

Đánh giá mức độ phát thải của các chất polyclodibenzo-p-dioxin và polyclodibenzofuran phát sinh không chủ định từ lò đốt rác chất thải sinh hoạt và rác thải công nghiệp ở Việt Nam

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are the most toxic substances among the group of unintentional persistent organic pollutants (U - POP) generated from many sources, in which domestic and industrial waste incinerators are the highest emission risk. Assessment of pollution potential and dioxin/furan emissions from incinerators in developing countries, including Vietnam, is still limited; especially in-depth studies on the content and characteristics of PCDD/PCDF emitted into the atmosphere. Therefore, the research team evaluated the emission potential and characteristics of 07 PCDD and 10 PCDF, those are considered to be the most toxic isomers and congeners, from stack gas samples collected from incinerators at 33 facilities in 11 provinces in Vietnam. The total concentration of PCDD/PCDF in the industrial incinerators’ emission ranged from 37.3 to 3348.6 pg TEQs/m3 and domestic waste incinerators had lower total concentrations and fluctuated within about 37.3-1323.8 pg TEQs/m3. The characteristic of incinerator emissions is that the proportion of 2,3,7,8- TCDD accounts for 2.9 to 9.04%. The highest contributing concentrations were congeners 1,2,3,7,8-PeCDD, with its contributing percentage from 22.95-32.42%. The second largest contributor is congeners 2,3,4,7,8- PeCDF, accounting for 20.94- 21.50% of the total toxic congeners of PCDD/PCDF in both types of incinerators. However, in terms of toxic equivalency (TEQ), the concentration of industrial waste incinerators is much higher than that of domestic waste incinerators. The results of stack gas samples showed that the PCDD/PCDF content for domestic waste incinerators has 5/17 establishments that exceeded the permissible standard threshold: 0.6 ng/Nm3, according to QCVN 61-MT:2016/BTNMT. Industrial waste incinerators have 5/16 establishments that exceeded the permissible standard threshold: 0.6ng/Nm3 for furnaces with a capacity of 300kg/hour according to QCVN 30:2012/BTNMT.

Environmental transformation and hazards of decachlorobiphenyl on suspended particles under sunlight irradiation.

Decachlorobiphenyl (PCB-209) can be widely detected in suspended particles and sediments due to its large hydrophobicity, and some of its transformation products may potentially threaten organisms through the food chain. Here we investigate the photochemical transformation of PCB-209 on suspended particles from the Yellow River. It was found that the suspended particles had an obvious shielding effect to largely inhibit the photodegradation of PCB-209. Meanwhile, the presence of inorganic ions (e.g. Mg2+ and NO3-) and organic matters (e.g. humic acid, HA) in the Yellow River water inhibited the reaction. The main transformation products of PCB-209 were lower-chlorinated and hydroxylated polychlorinated biphenyls (OH-PCBs), and small amounts of pentachlorophenol (PCP) and polychlorinated dibenzofurans (PCDFs) were also observed. The mechanisms of PCP formation by double •OH attacking carbon bridge and PCDFs formation by elimination reaction of ionic state OH-PCBs were proposed using theoretical calculations, which provided some new insights into the inter-transformations between persistent organic pollutants. In combination with VEGA and EPI Suite software, some intermediates such as PCDFs were more toxic to organisms than PCB-209. This study deepens the understanding of the transformation behavior of PCB-209 on suspended particles under sunlight.

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.

Micropollutants in biochar produced from sewage sludge: A systematic review on the impact of pyrolysis operating conditions

Biochar obtained from sewage sludge serves as a valuable soil amendment in agriculture, enhancing soil properties by increasing the nutrient content, cation exchange capacity, water retention, and oxygen transmission. However, its utilisation is hampered by the presence of micropollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and volatile organic compounds (VOCs). Previous studies indicate that the type and amount of micropollutants can be significantly adjusted by selecting the right process parameters. This literature review provides an overview of how (1) pyrolysis temperature, (2) carrier gas flow and type, (3) heating rate, and (4) residence time affect the concentration of micropollutants in biochar produced from sewage sludge. The micropollutants targeted are those listed by the European Biochar Certificate (EBC) and by the International Biochar Institution (IBI), including PAHs, PCDD/Fs, PCBs and VOCs. In addition, per- and poly-fluoroalkyl substances (PFAS) are also considered due to their presence in sewage sludge.The findings suggest that higher pyrolysis temperatures reduce micropollutant levels. Moreover, the injection of a carrier gas (N2 or CO2) during the pyrolysis and cooling processes effectively lowers PAHs and PCDD/Fs, by reducing the contact of biochar with oxygen, which is crucial in mitigating micropollutants. Nevertheless, limited available data impedes an assessment of the impact of these parameters on PFAS in biochar. In addition, further research is essential to understand the effects of carrier gas type, heating rate, and residence time in order to determine the optimal pyrolysis process parameters for generating clean biochar.

A Study on the Influence and Mechanism of Temperature and Dosage on PCDD/Fs Adsorption via Coal-Based Activated Carbon

Using a trace polychlorinated-ρ-dibenzodioxins and dibenzofurans (PCDD/Fs) stabilizing generator, an experimental study related to the influence of temperature (150, 165, and 180 °C) and activated carbon (AC) dosage (0.10, 0.15, and 0.20 g) on the adsorption effect of gas-phase PCDD/Fs via coal-based AC was conducted. Increasing the AC dosage is the most efficient method to improve the PCDD/Fs adsorption efficiency from 65.8% (0.10 g) to 93.0% (0.20 g) at 150 °C in an exponential trend. Both the polychlorinated-ρ-dibenzodioxins (PCDD)/polychlorinated dibenzofurans (PCDF) ratio and the Cl-PCDD/Fs value showed positive correlations, with the AC dosage under the same temperature. Increasing adsorption temperature declined the adsorption capacity of AC, resulting in the exponentially decreased average I-TEQ value adsorbed per gram of AC, from 131.3 ng TEQ/Nm3 (150 °C) to 55.9 ng TEQ/Nm3 (180 °C). The coal-based AC used in this study preferred to adsorb lower chlorinated PCDD/Fs, tetrachlorianted dibenzo-p-dioxin and dibenzofurans (TCDD/Fs), and pentachlorianted dibenzo-p-dioxin and dibenzofurans (PeCDD/Fs) than highly chlorinated PCDD/Fs, heptachlorianted dibenzo-p-dioxin and dibenzofurans (HpCDD/Fs), hexachlorinated dibenzo-p-dioxin and dibenzofurans (HxCDD/Fs), and octachlorianted dibenzo-p-dioxin and dibenzofurans (OCDD/Fs), which was aggravated by the increasing temperature. The characterization of the surface properties of AC revealed that slight oxidation occurred on the AC surface during the adsorption process, introducing oxygen to the competitive adsorption. In addition, it was found in this study that an increased temperature led to a higher content of hydrophilic carboxyl and anhydride groups and weakened π-π interactions, which were also partly responsible for the negative impact of the increasing temperature on the AC adsorption capacity. The results of this study can contribute to the operation optimization for controlling PCDD/F emissions from municipal solid waste incineration (MSWI).

Low-temperature catalytic oxidation of PCDD/Fs over MnCeCoOx/PPS catalytic filter.

Catalytic destruction of nitrogen oxides (NOx) combined with dust removal technique has attracted much attention, yet the application in the solid waste incineration air pollution control process is still lacking due to the complex flue gas atmosphere. In this work, the Mn-Ce-Co-Ox catalyst-coated polyphenylene sulfide (PPS) filter fiber with efficient dust removal and low-temperature polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) destruction has been prepared with a redox-precipitation method. The catalyst was uniformly grown around the PPS fiber with appropriate catalyst loading. The effects of several key operating parameters (e.g., reaction temperature, catalyst loading amount, and filtration velocity) on the catalytic efficiency were comprehensively investigated. The results show that the Mn-Ce-Co-Ox/PPS has a decomposition yield of 78.0% in PCDD/Fs and 96% in nitric oxide (NO) conversion at 200 °C. The poisoned catalytic filter exhibits a removal efficiency of 88.6% for PCDD/Fs. In addition, the catalytic filter can completely reject particles smaller than 1.0 μm with a low filtration resistance. Therefore, this efficient and energy-conserving catalytic filter shows promising applications in flue gas pollution treatments.

Applicability of Titanium-Based Catalysts in the Photocatalytic Degradation of 2,3,7,8-Tetrachlorodibenzofuran.

Polychlorinated dibenzofurans (PCDFs) are persistent toxic compounds that are ubiquitous in the environment. Nanocomposites of titanium(IV) oxide-vanadium(III) oxide (Ti3V2O7) and titanium(IV) oxide-silicon dioxide (Ti2Si7O30) were prepared and spectroscopically analyzed as potential decontaminants for dioxin-like materials. The analysis confirmed a homogeneous morphology with nanoscale particle size. The Ti-Si sample was found to have a high surface area compared to the Ti-V composite. Vanadium(III) oxide (V2O5) and silicon dioxide (SiO2) were chosen as materials for the formation of heterogeneous compounds with titanium(IV) oxide (TiO2) because they possess a suitable band alignment with TiO2, thus forming effective photocatalysts. This study evaluated the photodegradation of 2,3,7,8-tetrachlorodibenzo-furan (TCDF) in the presence of Ti-Si and Ti-V oxide composites, which was tested using high- (254 nm) and midenergy (302 nm) UV irradiation sources. While Ti-Si showed success in the photodegradation of 2,3,7,8-TCDF dissolved in a (1:1) methanol-tetrahydrofuran (MeOH-THF) solution, the Ti-V composite proved to be a powerful material in adsorbing TCDF with a high capacity immediately upon mixing. Ti-Si oxide was found to decompose TCDF under the two irradiation sources with 98-99% degradation occurring after 70 min. The use of 254 nm as an irradiation source in the presence of Ti-Si was 4.3 times faster than the analogue reaction irradiated without a catalyst. Byproducts of the degradation were evaluated using gas chromatography-mass spectrometry (GC-MS), resulting in a lower chlorinated congener and less toxicity, as the main degradation product.

Evaluation of Dioxin/Furan and Elements in Poultry from Zarqa Governorate, Jordan.

This study is the first to determine the concentration for 17 congeners of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and element contamination in poultry that is close to petroleum refinery at Al-Hashemiya Municipality, Zarqa Governorate, Jordan. Ten different samples (chicken) were collected to cover ten different locations of poultry farms in Al-Hashemiya Municipality. These locations are considered polluted areas as a result of exhaust gases produced from the refinery. The 17 PCDD/Fs congeners and elements of Pb, Cd, As, Zn, Cu, Se, Hg, Cr, and Ni were determined for three parts of each sample (liver, muscle, and gizzard). All samples were analyzed for PCDD/Fs after a Soxhlet extraction procedure and cleanup by column chromatography; then, all compounds were identified and determined using GC-MS techniques. The elements were analyzed after digestion and measured using an inductively coupled plasma optical emission spectrometer (ICP-OES) and validated with the Lab Mix24 RM NCS ZC73016 reference material. The highest total sum concentration of PCDD/Fs was found in liver samples to be 214.07 ng/kg (dry weight), while the highest sum of toxicity equivalent to PCDD/Fs of 22.54 ng TEQ/kg was found in gizzard samples. For element concentrations, the highest total sum of 16.89 mg/kg (dry weight) was found in liver samples. The concentration level of the elements of Se, Hg, Cr, and Ni for all parts of the chicken was within an acceptable range according to Jordanian standards and therefore the measured level of heavy and trace elements in the poultry samples (chicken) does not pose a danger to public health. The chickens found in poultry farms near the refinery are more likely to contain a higher concentration of PCDD/Fs congeners due to exhaust gas exposure.

OR06-06 Association Between Mixed Dioxin Exposure And Thyroid Functions In U.S. Adults: A Comparison Of Three Statistical Models

Abstract Disclosure: C. Han: None. S. Lee: None. E.N. Pearce: None. Background: Previous studies of the relationship between dioxin exposure and thyroid function have usually been based on multi-chemical linear models and results have been inconsistent. However, complex nonlinear relationships and interactions between mixed dioxin exposures and thyroid function have not been studied. We applied three different statistical models to assess the joint effect of 20 dioxins on thyroid function. Methods: A total of 6 polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), 4 dioxin-like polychlorinated biphenyls (DL-PCBs) and serum TSH were measured in the serum of U.S. adults by the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2010. We fitted multivariable logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models to estimate the association of individual and mixed dioxin exposures with high TSH. Results: Among the 2818 individuals included in our analysis, 1.99% had TSH >5.6 uIU/mL. In the multivariable logistic regression established for each single dioxin, 1,2,3,7,8-pncdd, 1,2,3,4,7,8-hxcdd, 1,2,3,6,7,8-hxcdd, 1,2,3,7,8,9-hxcdd, 1,2,3,4,7,8-Hexachlorofuran, 1,2,3,6,7,8-Hexachlorofuran, 3,3',4,4',5,5'-hexachlorobiphenyl, 3,3',4,4',5-Pentachlorobiphenyl, and 2,3,7,8-Tetrachloro-p-dioxin were positively associated with high TSH, and 3,4,4',5-Tetrachlorobiphenyl was negatively associated with high TSH. In the WQS regression model, the WQS index was significantly associated (OR (95% CI): 2.03 (1.06, 3.88)) with high TSH, and 1,2,3,7,8-pncdd (weighted at 0.24) made the largest contribution. In the BKMR analysis, a significant positive association was found between mixed dioxin exposure and high TSH when all dioxins were at their 55 to 70th percentile, compared to their 50th percentile. TSH was lower when all dioxins were at their 30th to 45th percentile, compared to their 50th percentile. Conclusion: By comparing the three statistical models, we concluded that the whole-body burden of 20 dioxins was significantly positively associated with high TSH. 1,2,3,7,8-pncdd played the most important roles in hypothyroidism. Presentation: Thursday, June 15, 2023

Screening of ionic liquids and deep eutectic solvents for the extraction of persistent organic pollutants from edible oils and fat

Presence of persistent organic pollutants (POPs) like polychlorinated-p-dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in edible oils poses risk to human health. Ionic liquids (ILs) and deep eutectic solvents (DESs) are novel combinatorial solvents with a proven record of extraction of such persistent organic pollutants (POPs). However, the large possibility of such combinatorial solvents necessitates an a-priori screening strategy to select the best possible ILs and DESs. Therefore, a Conductor like Screening Model Segment Activity Coefficient (COSMO-SAC) based framework has been employed to extract 27 POPs (6 PCDDs, 9 PCDFs, 12 PCBs) from five types of edible oil and animal fat by ILs and DESs. The screening will create such a list and based on that experimentation can be performed. There are five different types of oils and fats such as sunflower oil, soya lecithin, rapeseed oil, fish oil, and milk fat that are selected as potential sources of PCDD/Fs and PCBs. A combination of 58 cations and 39 anions which will yield 2262 types of IL and 217 types of DESs with the proportional combination of 24 HBAs and 62 HBDs are considered. Infinite dilution activity coefficient (IDAC) and solubility are calculated based on COSMO-SAC modelling and a set of ILs and DESs are screened as a potential extractant for POPs. The study aims to select the most suitable green solvents to extract these POPs from edible oils to render them safe for consumption.

Analysis of PCDD/Fs in environmental samples by using gas chromatography in combination with high resolution mass spectrometry: optimization of sample preparation

ABSTRACT This study developed a simple, economical and time-saving clean-up procedure based on an in-house packed column system for the determination of the most toxic-relevant 17 PCDD (polychlorinated dibenzo-p-dioxin) and PCDF (polychlorinated dibenzofuran) congeners in environmental samples following accelerated solvent extraction. The extract solution was cleaned up using a manually packed column system consisting of a multi-layer silica gel column and an activated carbon column. After clean-up, dioxins and furans were analysed by using gas chromatography in combination with high-resolution mass spectrometry. Isotopic labelled spiking experiments investigated the recovery of all dioxin and furan congeners. Then, the clean-up procedure for environmental samples was validated by applying the analysis of both clean soil reference material (CRM EDF-5183) and heavily contaminated sediment reference material (CRM EDF-5184) samples, as well as participating in the proficiency test (PT) for sediment samples. The recovery efficiency of isotope-labelled standard compounds in certified reference material (CRM) samples and PT samples ranged from 35% to 101% and between 46.1% and 105%, respectively. The mass concentrations of 17 PCDD/Fs in CRM samples were in the acceptable range. The absolute z-score value for each PCDD/F congener in the PT samples was below 1, confirming the analytical procedure’s high accuracy. The applied clean-up procedure in this study has demonstrated accuracy, repeatability and a significant increase in sample extraction/preparation productivity by reducing the time for sample preparation.

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.

Persistent organic pollutants in Croatian breast milk: An overview of pollutant levels and infant health risk assessment from 1976 to the present.

This review article summarizes our research of persistent organic pollutants (POPs) in human milk from Croatian mothers over the last few decades. Our studies make up the bulk of all POPs research in human milk in Croatia and show a state-of-the art in the research area. The first investigations were made in 1970`s. Aim of our review article is to document the comprehensive results over several decades as the best tool to: 1.) contribute to understanding of POPs and their potential health risks, 2.) evaluate effectiveness of legislative bans and restrictions on human exposure to POPs in Croatia, and 3.) to suggest further actions. In our review we discuss: 1.) Human milk between 2011 and 2014 - evaluation of interrelations of organochlorine pesticides (OCP) and polychlorinated biphenyls (PCB) in human milk and their association with the mother's age and parity using artificial intelligence methods; and our yet unpublished research data on health risks for infants assessed through daily PCB and OCP intake. 2.) Time trends of PCB and OCP in human milk between 1976 and 2014.3.) polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran (PCDD/F) in human milk in 2000., and yet unpublished data on PCDD/F and polybrominated diphenyl ethers (PBDE) in 2014.

Biodegradability analysis of Dioxins through in silico methods: Model construction and mechanism analysis

The biodegradation treatment of dioxins has long been of interest due to its good ecological and economic effects. In this study, the biodegradability of polychlorinated dibenzo-p-dioxins (PCDDs) were investigated by constructing machine learning and multiple linear regression models. The maximum chlorine atomic charge (qHirshfeldCl+), which characterizes the biodegradation ability of PCDDs, was used as the response value. The random forest model was used to rank the importance on the 1471 descriptors of PCDDs, and the BCUTp-1 h, QXZ, JGI4, ATSC8c, VE3_Dt, topoShape, and maxwHBa were screened as the important descriptors by Pearson's correlation coefficient method. A quantitative structure-activity relationship (QSAR) model was constructed to predict the biodegradability of PCDDs. In addition, the extreme gradient boosting (XGBoost) and random forest model were also constructed and proved the good predictability of QSAR model. The biodegradability of polychlorinated dibenzofurans (PCDFs) can also be predicted by the constructed three models from a certain level after adjusting some model parameters, which further proved the versatility of the models. Besides, the sensitivity analysis of the QSAR model and a 3D-QSAR model was developed to investigate the biodegradability mechanisms of PCDDs. Results showed that the descriptors BCUTp-1 h, JGI4, and maxwHBa were the key descriptors in the biodegradability effect by the sensitivity analysis of the QSAR model. Coupled with the results of PCDDs biodegradability 3D-QSAR model, BCUTp-1 h, JGI4, and maxwHBa were confirmed as the main descriptors that affect the biodegradability of dioxins. This study provides a novel theoretical perspective for the research of the biodegradation of both PCDDs and PCDFs dioxins.

Occurrence and dietary intake of dioxins, furans (PCDD/Fs), PCBs, and flame retardants (PBDEs and HBCDDs) in baby food and infant formula

This study determines the levels of 49 persistent organic pollutants which were grouped into polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecanes (HBCDDs), in infant formula and varieties of baby food. The analyzed samples (n = 80) came from stores all over Poland.The presence of PCDD/F, PCDD/F/PCB and non dioxin-like (ndl)-PCB congeners above the maximum levels stipulated in Commission Regulation (EU) No 1259/2011 was not detected in any sample. The determined average content of PCDD/Fs/dl-PCBs in the tested baby foods was in the range of 4–10 % of the maximum level, and content of ndl-PCBs was in the range of 2–6 % of the maximum level. Despite these low levels of dioxins, furans, and PCBs, a risk analysis assuming weekly consumption of the recommended food intake showed exceedances of the tolerable weekly intake (TWI).The content of flame retardants was low in all examined categories of food for children and infant formula. The lower-bound concentration of the sum of HBCDD isomers (LB ∑HBCDDs) ranged from below the limit of quantification (LOQ) to 0.0313 ng/g w.w. and the concentration of ∑PBDEs was in a 0.001–1.014 ng/g w.w. range. Neither infant formula nor baby food contributed considerably to infant exposure to HBCDDs or PBDEs.Our research indicates that the safe exposure thresholds for dioxins and PCBs in foods for infants and young children may be too high and perhaps it may be necessary to amend the legislation setting acceptable limits for baby food. It seems reasonable to introduce a recommendation on the frequency of food consumption for children and the control of raw materials for food production, in particular fish and cow milk, should be a permanent control point in the food safety assurance system.

Influence of different loads on PCDD/F removal by SCR during municipal solid waste incineration

This study was conducted on a full-scale (500 t/d) municipal solid waste incinerator (MSWI), investigating the influence of different loads on the emission of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/Fs) and their removal by selective catalytic reduction (SCR) system. The total concentration of PCDD/Fs at the SCR inlet under 100% load was higher than that under 80% load. The changing loads caused different distribution characteristics of PCDD/Fs at the SCR inlet, and the dominant congeners changed from high-chlorinated PCDDs (80% load) to low-chlorinated PCDFs (100% load). Moreover, the increased load enhanced the removal efficiency of PCDD/Fs by SCR from 17.3% to 64.2%, which was influenced by the inlet PCDD/F distribution and the moisture content. The high-chlorinated PCDD/Fs with the more stable structure were more difficult to be deteriorated and the high moisture content can weaken the catalytic activity of SCR catalysts. Correlation analysis was used to study the relationship between major air pollutants and PCDD/F emissions. The results showed that HCl positively correlated with PCDD/F emission concentrations, while NOx and SO2 negatively correlated. The results of this study can provide a reference for MSWI to operate properly under variable loads.

Development of a Methodology for Determination of Dioxins and Dioxin-like PCBs in Meconium by Gas Chromatography Coupled to High-Resolution Mass Spectrometry (GC-HRMS)

An analytical strategy was applied to investigate polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in newborn meconium samples. The methodology includes extraction by selective pressurized liquid extraction (SPLE), followed by a clean-up multicolumn step. The samples were injected by gas chromatography coupled to a high-resolution mass spectrometer (GC-HRMS). The surrogate recoveries ranged from 68% to 95%, and the average of the limit of quantification (LOQ) ranged from 0.03 to 0.08 pg g−1 wet weight (ww) for PCDD/Fs and 0.2 to 0.88 pg g−1 ww for dl-PCBs. The strategy was applied to 10 samples collected in Valencia (Spain) in 2022. In total, 18 out of 29 analysed congeners were detected in at least one sample, whereas 6 of them were detected in all the samples (OCDD, PCB-123, PCB-118, PCB-105, PCB-167, and PCB-156). The levels for the sum of the 17 congeners of PCDD/Fs and 12 congeners of dl-PCBs in the upper-bound (UB), expressed as picograms of toxic equivalency quantity (TEQ) per gram of ww, ranged from 0.19 to 0.31 pg TEQ g−1 ww.

Polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in bivalve molluscs. Risk to Polish consumers?

Concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in six species of bivalve mollusc purchased on the Polish retail market. The risk to consumers was calculated as a percentage of the tolerable weekly intake (TWI) (2 pg World Health Organization toxic equivalent (WHO-TEQ) kg-1 body weight (b.w.)). Altogether 32 samples were analysed using an isotope dilution technique with high resolution gas chromatography coupled with high resolution mass spectrometry. Low levels of all analysed compounds were found. The range of PCDD/Fs was 0.08-0.37 pg WHO-TEQ g-1 of wet weight (w.w.) and 0.04-0.41 pg WHO-TEQ g-1 w.w. for DL-PCBs. The highest concentrations of all analysed compounds were found in Pacific oysters, at 0.30 pg WHO-TEQ g-1 w.w. for the sum of PCDD/Fs and 0.19 pg WHO-TEQ g-1 for the sum of DL-PCBs. These concentrations were 2-4 times higher than those detected in the other analysed mollusc species. Different species-dependent congener profiles were observed for PCDD/F concentrations, while PCB congener concentration profiles were species independent. The risk to consumers was assessed relating theoretical intakes of PCDD/Fs and DL-PCBs per 25, 50 and 100 g of consumption of molluscs per week to the TWI. Taking into account the low consumption of molluscs in Poland and low concentrations of analysed compounds, neither adults nor children are likely to exceed the TWI by ingestion of food in this category.

Biological wastewater treatment plants as sources of environmental pollution by persistent organic pollutants (on the example of Odesa industrial-and-urban agglomeration)

Formulation of the problem. Effective mechanism of wastewater treatment (WT) are important components of reducing anthropogenic load on the environment. One of the most widespread mechanisms of urban wastewater treatment is the biological treatment on a Biological Wastewater Treatment Plant (BWTP). However, increasing the nomenclature of pollutants concentrated in urban wastewater seriously affects the effectiveness of WT on BWTPs, which are not intended for such a wide spectrum of specific pollutants such as, in particular, Persistent Organic Pollutants (POPs). The control of their intake into the environment must be regulated according to the Stockholm convention. The goal of the research is the evaluation of the intake of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) into the environment from the wastewater of Odesa Industrial-and-Urban Agglomeration (IUA) and determining the volumes of their accumulation in the sea environment. Purpose. The assessment of the amount of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) entering the environment with the wastewater from Odesa IUA and determining the amount of their accumulation in the sea environment. Methods. In our research, all available official methods of calculation of the unintentional formation of POPs were reviewed, as a result – the main and most complete methods were selected: «UNEP (2013). Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional POPs» and «EMEP/EEA air pollutant emission inventory guidebook. Technical guidance to prepare national emission inventories, 2019». For evaluation of PCDD/F accumulation in the sea environment an improved by authors methodology for calculation of PCDD/F accumulation with their cumulative effect and half life taken into account was used. Results. The work provides justification for the necessity of use of calculation methodologies for determing the intake of PCDD/F to the sea environment adjacent to Odesa IUA; annual massed of PCDD/F entering the sea environment as part of treated, insufficiently treated and untreated wastewater are calculated; massed of PCDD/F that accumulate in waste activated sludge (WAS) on BWTP are calculated; volumes and specifics of PCDD/F accumulation in the sea basin, where the wastewater of Odesa IUA is being discharged to are determined using the improved methodology that enables taking into account the cumulative effect and half life period of these substances; mass and concentration of PCDD/F, immobilized in WAS, are determined, the excess level of concentration of PCDD/F in WAS compared to the maximum permissible concentration is determined. The total accumulation of PCDD/F in the sea environment over 2007-2017 period is determined. Conclusions. It was established that the use of calculation methodologies for evaluating PCDD/F volumes in the water environment is the only and necessary condition for satisfying the requirements of the Stockholm convention due to the impossibility of performing a regular instrumental monitoring of PCDD/F intake into the water environment. The use of suggested by us improved methodology for calculation of PCDD/F accumulation with their cumulative effect and half-life period taken into account allows for calculation of PCDD/F masses that were formed throughout the year under consideration, taking into account the PCDD/F masses that were formed during previous years as well.

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 654.8pg/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 1000pg/g. Toxicity for each of the sampling points ranged from 19.7 to 36.5, with a mean concentration of 27.0pg WHO 2005-TEQ g-1 in the dry season and 2.0 to 38.7 with a mean concentration of 20.7pg 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 61.2pg 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 8.1pg/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.