PCDD/PCDFs and PCBs in the irrigation water in Egypt: levels, patterns, and potential sources

Polychlorinated biphenyl congeners in water canals and their relationships with water quality parameters: Insights into their risk assessment

Water pollution with pesticides is one of the most important environmental problems. Polychlorinated biphenyls (PCBs) reach water bodies via agricultural discharge. The aim of this study was to determine the contamination of different water bodies with PCB congeners, and detect the correlation between water quality parameters and seasonal distribution of these PCBs. The results indicated that water canals of AlGharbiah showed the highest ranges of temperature, total dissolved solids (TDS) in spring, and dissolved oxygen (DO) in autumn, while AlQaliobiah water bodies witnessed the highest pH and electrical conductivity (EC) ranges in summer. The highest range of a PCB congener was that of PCB44 (7.96-118.29 µg/g) in sediment samples of Giza, followed by its range (18.01-85.44 µgL-1) in surface water of AlQaliobiah. We found a potential cancer risk from dermal contact with all the investigated PCBs. Principal component analysis (PCA) showed positive correlations between most PCBs and each of EC and TDS, and a negative correlation with DO. While the correlation between PCBs and each of temperature and pH varied according to the geographic location of the governorate. In conclusion, the investigated water canals were contaminated with PCBs, which posed a potential cancer risk and deteriorated water quality.

In vitro effects of polychlorinated biphenyls and their hydroxylated metabolites on the synthesis and metabolism of iodothyronines in the chicken (Gallus domesticus) thyroid gland

To assess the effect of polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) on thyroid hormone [TH: thyroxine (T₄) and triiodothyronine (T₃)] secretion, the concentrations of iodothyronine deiodinases (DIO1, DIO2, DIO3), and mRNA expression of genes involved in TH synthesis (TSHR, NIS, TPO, TG), metabolism (DIO1, DIO2, DIO3), and transport (OATP1C1, MCT8, MCT10, LAT1), chicken thyroid explants were incubated in medium supplemented with TSH (250 mU/ml), PCB118, PCB153, 4-OH-PCB107, and 3-OH-PCB153 (0.5 × 10^-8 M), and TSH together with each PCB and OH-PCB. The results of the in vitro experiment revealed that, except for 4-OH-PCB107, all applied PCBs and OH-PCBs inhibited basal and TSH-stimulated T₄ secretion. Moreover, they increased basal and reduced TSH-stimulated T₃ secretion. PCBs and OH-PCBs decreased the TSH-stimulated TSHR expression. Following PCB and OH-PCB exposure, significant changes in mRNA expression of NIS, TPO, and TG were observed. PCBs and OH-PCBs affected DIO1 and DIO3 transcript levels and protein abundances of each DIO. Furthermore, PCB-dependent effects on OATP1C1, MCT8, and MCT10 mRNA expression were found. In conclusion, both PCB118 and PCB153 and their OH-PCBs affect TH synthesis and deiodination processes in the chicken thyroid gland and influence TH transport across the thyrocyte membrane. In addition, the effects of PCBs and OH-PCBs depended mainly on the type of PCB congener and the exposure time. These results indicate that not only parental PCBs but also OH-PCBs are hazardous for the thyroid gland and may disrupt its endocrine function. Further studies are necessary to explain a mechanism of PCB and OH-PCB action in the avian thyroid gland.

Trends in concentrations of selected dioxins and furans across various stages of kidney function for US adults

Exposure to dioxins and furans has the potential to affect kidney function and could be associated with chronic kidney disease. Data for US adults aged ≥ 20 years from the National Health and Nutrition Examination Survey for 1999-2004 (N = 4433) were analyzed to study trends in adjusted concentrations (AGM) of 1,2,3,7,8-pentachlorodibenzo-p-dioxin, 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8-heptachlororodibenzo-p-dioxin, 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,6,7,8-hexachlorodibenzofuran, and 1,2,3,4,6,7,8-heptachlorodibenzofuran across the stages of kidney function (KF). Stages of KF were defined based on estimated glomerular filtration rate or eGFR expressed in mL/min/1.73 m2. For KF-1, eGFR was > 90, between 60 and 90 for KF-2, between 45 and 60 for KF-3A, and between 15 and 45 for KF-3B/4. AGMs for 1,2,3,7,8-pentachlorodibenzo-p-dioxin and 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin increased consistently across the full spectrum of kidney function. For example, AGMs for the total population for 1,2,3,7,8-pentachlorodibenzo-p-dioxin were 2.5, 4.5, 9.3, and 14.9 fg/g lipid for KF-1, KF-2, KF-3A, and KF-3B/4, respectively. For other six dioxins/furans, AGMs increased over KF-1 through KF-3A but then decreased for KF-3B/4, for example, 1,2,3,4,6,7,8-heptachlorodibenzofuran for males, and AGMs for KF-1, KF-2, KF-3A, and KF-3B/4 were 7.9, 8.4, 10.7, and 7.5 fg/g lipid, respectively. For 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin and 1,2,3,6,7,8-hexachlorodibenzofuran, smokers were found to have lower AGMs than nonsmokers. For example, for 1,2,3,4,6,7,8-heptaachlorodibenzo-p-dioxin, smoker-nonsmoker AGMs were 22.2 vs. 39.4 fg/g lipid at KF-1, 29.5 vs. 51.4 fg/g lipid at KF-2, 61.6 vs. 72.8 fg/g lipid at KF-3A, and 34.9 vs. 66.4 fg/g lipid at KF-3B/4. The reverse more often than not, was, however, observed for other six dioxins/furans. Smoker-nonsmoker AGMs for 1,2,3,7,8-pentachlorodibenzo-p-dioxin were 2.4 vs. 2.6 fg/g lipid at KF-1, 5.1 vs. 4.0 fg/g lipid at KF-2, 12.7 vs. 6.7 fg/g lipid at KF-3A, and 18.6 vs. 11.9 fg/g lipid at KF-3B/4. In conclusion, lipid-adjusted serum concentrations of dioxins and furans continue increasing as kidney function keeps deteriorating until KF-3A. However, these increases in serum concentrations until KF-3A may be followed by substantial decreases for selected dioxins/furans during KF-3B/4.

Dioxins and furans toxicity during the photocatalytic remediation of emerging pollutants. Triclosan as case study

The benefits of wastewater remediation technologies are offset in those cases where, as a result of operating conditions, harmful compounds are formed in the degradation routes of the original organic pollutants. This may be the case for the application of some advanced oxidation processes to wastewater containing precursors of dioxins and furans, as previously reported in the application of electrochemical and Fenton oxidation to degrade Triclosan and 2-chlorophenol. This work reports for the first time a detailed kinetic analysis of the formation of dioxins and furans during the photocatalytic treatment of aqueous samples containing 5-Chloro-2-[2,4-dichlorophenoxy] phenol, commercially known as Triclosan. After analysis of the PCDD/Fs concentration, the toxicity of the samples has been determined in terms of toxic equivalents (TEQ). TEQ values have been calculated, first with the group of 17 congeners with higher toxicity. Finally, a multivariable analysis and linear regression have been applied to reduce the significant number of congeners and optimize the analytical effort.

Assessment of Air Pollution with Polychlorinated Dibenzodioxins (PCDDs) and Polychlorinated Dibenzofuranes (PCDFs) in Lithuania

Polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/F) are highly bioavailable in humans, either through direct inhalation or indirectly by trophic transfer from contaminated food or water. The main sources of pollution with PCDD/F include industrial and non-industrial combustion sources, like domestic contaminated wood burning, house fires, burning of leaves from trees, etc. When looking for alternative energy sources and reduced energy costs, solid waste incineration plants are intended to be built in the vicinity of urbanized areas, and thus, the need emerges for examination and prediction of to what extent the solid waste incineration plants might affect the surrounding ecosystem, air pollution, and human health. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (or simply PCDD/F congeners) belong to the group of semi-volatile organic compounds with environmental stability and long-range transfer in the ambient air. Dioxin isomers are highly toxic and may have carcinogenic and mutagenic effects in humans. PCDD/F is detected in air, water, sediment, plants and animals. PCDD/F is generally distributed in the particulate phase in ambient air. For solid waste incineration plant emissions, the distribution of PCDD/F particles into particles with a diameter of <10 μm is more than 81% of the total particulate matter, and more than 54% of the PCDD/F is distributed into particles with a diameter of <2.5 μm. The aim of this study is to investigate the sources of PCDD/F, emissions and potential hazards, i.e., a toxic equivalent in Lithuania. The measurements were performed in two largest cities of Lithuania Vilnius and Kaunas, where the level of PCDD/F discovered was from 0.015 to 0.52 pg/m3 and from 0.02 to 0.05 pg/m3, respectively. The sites for the monitoring were selected based on their proximity to the locations of the planned cogeneration power plants in these cities.