[en] A series of thirteen regiospecifically chlorine-37 labeled polychlorodibenzo-p-dioxins were synthesized via the Sandmeyer reaction. Nitrochlorodibenzodioxins which were obtained by a base promoted condensation of catechols and dinitropolyhalobenzenes were reduced and converted to the diazonium salts. Chlorine-37 was introduced using cuprous chloride-37. The isotopic enrichment was in the range 75-96%. (Author)

[en] The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor and member of the basic helix-loop-helix-PAS family. AHR is activated by numerous dietary and endogenous compounds that contribute to its regulation of genes in diverse signaling pathways including xenobiotic metabolism, vascular development, immune responses and cell cycle control. However, it is most widely studied for its role in mediating 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity. The AHR target gene and mono-ADP-ribosyltransferase, TCDD-inducible poly-ADP-ribose polymerase (TIPARP), was recently shown to be part of a novel negative feedback loop regulating AHR activity through mono-ADP-ribosylation. However, the molecular characterization of how AHR regulates TIPARP remains elusive. Here we show that activated AHR is recruited to the TIPARP promoter, through its binding to two genomic regions that each contain multiple AHR response elements (AHREs), AHR regulates the expression of both TIPARP but also TIPARP-AS1, a long non-coding RNA (lncRNA) which lies upstream of TIPARP exon 1 and is expressed in the opposite orientation. Reporter gene and deletion studies showed that the distal AHRE cluster predominantly regulated TIPARP expression while the proximal cluster regulated TIPARP-AS1. Moreover, time course and promoter activity assays suggest that TIPARP and TIPARP-AS1 work in concert to regulate AHR signaling. Collectively, these data show an added level of complexity in the AHR signaling cascade which involves lncRNAs, whose functions remain poorly understood.

No abstract available

[en] Polyfunctional derivatives of xanthenes and benzoxanthenes in the form of organic perchlorates have been obtained by the interaction of 1,3-benzo(naphtho)dioxin-4(1)-ones with the Vilsmeier-Haack reagent at 110 °C for 5 h. The rearrangement has occurred as an electrophilic triggered recyclization due to the geminal arrangement of oxygen atoms in the six-membered ring as well as the presence of a lactone group in the structure of the starting 1,3-benzo(naphtho)dioxin-4(1)-ones. Graphic abstract:

[en] Quantifying polychlorinated biphenyl (PCB) residues in nestlings of avian species is a common method for assessing trophic transfer and risk at PCB-contaminated sites. The proportion of nestling PCB mass due to maternal transfer is often accounted for by subtracting total PCB mass in eggs from nestlings. However, variation in physicochemical properties and metabolism among congeners may lead to differences between egg contribution based on total PCBs and dioxin-like congeners. We examined congener-specific variation in contribution of PCBs from eggs to nestlings in tree swallows and European starlings. Egg contribution of total PCB mass was 14.3 and 16.2%, respectively, whereas contribution based on dioxin-like congeners was 14.8 and 13.6%, respectively. These data suggest that using total PCB mass in eggs to adjust estimates of PCB accumulation in nestlings may not reflect patterns for dioxin-like congeners, potentially over or under-estimating the risk of toxicity of PCBs. - Congener-specific contribution of PCBs from egg to nestlings was examined.

[en] Thermodynamic functions (ΔG_f and ΔH_f) of clorinated dibenzo-p-dioxins (Cl_nDD) with n = 0–8 were calculated at the DFT level of theory using the B3LYP functional and extended 6–31** basis sets and used to analyze possible relationship of the structures and energy characteristics of these compounds with their toxicity. A new sequence of successive isodesmic reactions, which makes it possible to calculate chemical potentials μ_G and μ_H from the ΔG_f and ΔH_f values, has been proposed. In the framework of this approach, satisfactory linear correlations between the chemical potentials μ and the logarithms of toxicity of the corresponding polychlorodioxins were obtained for the first time.

[en] Highlights: • Polyhalogenated carbazoles (PHCZs) are known as emergent dioxin-like contaminants. • Many studies concentrate on the environmental occurrences and behaviors of PHCZs. • Researches concerning the toxicological effects of PHCZs are relatively lagged. Polyhalogenated carbazoles (PHCZs) are well-known as emergent environmental contaminants. Given their wide distribution in the environment and structural similarity with dioxins and dioxin-like chemicals (DLCs), the environmental behavior and ecological risks of these chemicals have become the major issue concerned by the governments and scientists. Since the initial report of PHCZ residues in the environment in the 1980s, over 20 PHCZ congeners with different residual levels had been identified in various environmental media all over the world. Nevertheless, researches concerning the toxicological effects of PHCZs are of an urgent need for the relatively lagging study of their ecological risks. Currently, only limited evidence has indicated that PHCZs would pose dioxin-like toxicity, including developmental toxicity, cardiotoxicity, etc; and their toxicological effects were partially consistent with AhR activation. And yet, much remains to be done to fill in the knowledge gaps of their toxicological effects. In this review, the research progresses in environmental behavior and toxicology study of PHCZs were remarked; and the lack of current research, as well as future research prospects, were discussed.

[en] Carbon nanotubes are thought to be a promising candidate for nano-scale sensing materials. They show good potential for detecting diverse air pollutants, including volatile organic compounds like benzene and toluene. In the present work, four different types of single walled nanotubes are considered for sensing dioxins and related compounds. These nanotubes include: (i) pristine carbon nanotube (CNT), (ii) silicon carbide nanotube (SiCNT), (iii) silicon nitride nanotube (SiNNT) and (iv) boron nitride nanotube (BNNT). These carbon nanotubes can be categorized into hydrophilic nanotubes (SiCNT and SiNNT) and hydrophobic nanotubes (Pristine CNT and BNNT), a crucial aspect in determining their suitability for sensor applications. Dioxins and furans are highly toxic and stable pollutants commonly known for human carcinogen. They are a tri-cyclic ring compound consisting of two benzene chloride rings bridged by oxygen atom(s). Here three highly toxic dioxins recognized by WHO viz., 2,3,7,8-tetrachloro dibenzo-p-dioxin, 1,2,3,7,8-pentachloro dibenzo-p-dioxin and 2,3,4,7,8-pentachloro dibenzofuran are considered for the study. The different position of dioxin congeners with respect to CNTs are investigated and their interactions are compared to find out the sensing capabilities of CNTs using density functional theory (DFT) based calculations. From the computed results, it was observed that the hexagonal arrays of carbon atoms present in carbon nanotubes attributed to re-electron cloud which shows a significant interaction with the hexagonal benzene ring present in dioxins structure and can be extended for the other benzene halides for sensor applications. (author)

[en] Organohalogen pollutants are of concern in many river and estuarine environments, such as the New York-New Jersey Harbor estuary and its tributaries. The Hackensack River is contaminated with various metals, hydrocarbons and halogenated organics, including polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins. In order to examine the potential for microbial reductive dechlorination by indigenous microorganisms, sediment samples were collected from five different estuarine locations along the Hackensack River. Hexachlorobenzene (HCB), hexabromobenzene (HBB), and pentachloroaniline (PCA) were selected as model organohalogen pollutants to assess anaerobic dehalogenating potential. Dechlorinating activity of HCB and PCA was observed in sediment microcosms for all sampling sites. HCB was dechlorinated via pentachlorobenzene (PeCB) and trichlorobenzene (TriCB) to dichlorobenzene (DCB). PCA was dechlorinated via tetrachloroaniline (TeCA), trichloroanilines (TriCA), and dichloroanilines (DCA) to monochloroaniline (MCA). No HBB debromination was observed over 12 months of incubation. However, with HCB as a co-substrate slow HBB debromination was observed with production of tetrabromobenzene (TeBB) and tribromobenzene (TriBB). Chloroflexi specific 16S rRNA gene PCR-DGGE followed by sequence analysis detected Dehalococcoides species in sediments of the freshwater location, but not in the estuarine site. Analysis targeting 12 putative reductive dehalogenase (rdh) genes showed that these were enriched concomitant with HCB or PCA dechlorination in freshwater sediment microcosms. - Highlights: • Indigenous bacteria from Hackensack River sediments were capable of dehalogenating hexachlorobenzene and pentachloroaniline. • Dehalococcoides species were enriched in freshwater sediment spiked with hexachlorobenzene and pentachloroaniline. • Putative reductive dehalogenase genes were enriched in hexachlorobenzene and pentachloroaniline dechlorinating microcosms. - Halogenated aromatic pollutants are reductively dehalogenated by indigenous microorganisms in an estuarine river system.

[en] The treatment of electron beam was tested for gaseous pollutants of volatile organic compounds (VOCs), dioxin, and inorganic oxides (NOX and SOX). The representative VOCs of xylene and toluene were oxidized completely with electron beams using prototype hybrid system equipped with electron accelerator and MnO₂ catalysts. More than 90% of dioxin in municipal solid waste incinerator gases was decomposed at a dose of 14 kGy. Nitrogen oxides and sulfur oxides in coal-fired flue gases were recovered as a fertilizer by the addition of NH₃ under electron-beam irradiation. Electron beam is expected to be a promising method for treating gaseous pollutants. (author)