Dioxins and Human Toxicity

Comprehensive metabolic profiling of dioxin-like compounds exposure in laying hens: Implications for toxicity assessment

The evaluation of toxicity related to polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) is crucial for a comprehensive risk assessment in real-world exposure scenarios. This study employed a controlled feeding experiment to investigate the metabolic effects of dioxin-like compounds (DLCs) on laying hens via feed exposure. Diets enriched with two concentrations (1.17 and 5.13 pg toxic equivalents (TEQ)/g dry weight (dw)) were administered over 14 days, followed by 28 days of clean feed. Metabolomics analyses of blood samples revealed significant metabolic variations between PCDD/Fs and DL-PCBs exposed groups and controls, reflecting the induced metabolic disruption. Distinct changes were observed in sphingosine, palmitoleic acid, linoleate, linolenic acid, taurocholic acid, indole acrylic acid, and dibutyl phthalate levels, implying possible connections between PCDD/Fs and DL-PCBs toxic effects and energy-neuronal imbalances, along with lipid accumulation and anomalous amino acid metabolism, impacting taurine metabolism. Moreover, we identified three differential endogenous metabolites-L-tryptophan, indole-3-acetaldehyde, and indole acrylic acid-as potential ligands for the aryl hydrocarbon receptor (AhR), suggesting their role in mediating PCDD/Fs and DL-PCBs toxicity. This comprehensive investigation provides novel insights into the metabolic alterations induced by PCDD/Fs and DL-PCBs in laying hens, thereby enhancing our ability to assess risks associated with their exposure in human populations.

Global dioxin research trends and focal points: A century-long visual and bibliometric analysis (1923-2022)

Dioxin-like compounds, recognized by the World Health Organization (WHO) as among the most enduring toxic chemical substances in the environment, are linked to various occupational activities and industrial accidents worldwide. The aim of this study was to examine and present research publications on dioxins, pinpoint current research trends, identify research gaps, and highlight potential avenues for future exploration in the field. The study period for relevant research articles ranged from 1923 to December 31, 2022, and these articles were sourced from the Scopus database. The analysis involved the identification of key contributors to the field and the visualization of topics, themes, and international collaboration. VOSviewer software (version 1.6.20) was used for visualization analysis. A total of 11,620 publications on dioxins were documented in the Scopus database. The predominant category of these documents comprised 9780 original articles, which represents 84.17% of the total publications. The United States lead in the number of publications, with 3992 (34.35%), followed by Japan, with 1429 (12.3%), China, with 1005 (8.65%), and Germany, with 974 (8.38%). Before 2002, scholarly attention in this field focused primarily on the health effects, environmental fate, and mechanism of toxicity of tetrachlorodibenzo-p-dioxin (TCDD). However, a noticeable change in research focus has been observed since 2002, highlighting the emergence of a topic related to the health effects and environmental fate of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PFDFs). This study is the first to conduct a comprehensive quantitative bibliometric analysis of dioxins over time. These findings indicate a significant increase in the overall growth of the dioxin literature over the past 30 years. These findings may prove crucial in guiding and organizing subsequent investigations related to dioxins.

Toxicity evolution of triclosan during environmental transformation and human metabolism: Misgivings in the post-pandemic era

In the context of pandemic viruses and pathogenic bacteria, triclosan (TCS), as a typical antibacterial agent, is widely used around the world. However, the health risks from TCS increase with exposure, and it is widespread in environmental and human samples. Notably, environmental transformation and human metabolism could induce potentially undesirable risks to humans, rather than simple decontamination or detoxification. This review summarizes the environmental and human exposure to TCS covering from 2004 to 2023. Particularly, health impacts from the environmental and metabolic transformation of TCS are emphasized. Environmental transformations aimed at decontamination are recognized to form carcinogenic products such as dioxins, and ultraviolet light and excessive active chlorine can promote the formation of these dioxin congeners, potentially threatening environmental and human health. Although TCS can be rapidly metabolized for detoxification, these processes can induce the formation of lipophilic ether metabolic analogs via cytochrome P450 catalysis, causing possible adverse cross-talk reactions in human metabolic disorders. Accordingly, TCS may be more harmful in environmental transformation and human metabolism. In particular, TCS can stimulate the transmission of antibiotic resistance even at trace levels, threatening public health. Considering these accruing epidemiological and toxicological studies indicating the multiple adverse health outcomes of TCS, we call on environmental toxicologists to pay more attention to the toxicity evolution of TCS during environmental transformation and human metabolism.

Pollutants, microbiota and immune system: frenemies within the gut

Pollution is a critical concern of modern society for its heterogeneous effects on human health, despite a widespread lack of awareness. Environmental pollutants promote several pathologies through different molecular mechanisms. Pollutants can affect the immune system and related pathways, perturbing its regulation and triggering pro-inflammatory responses. The exposure to several pollutants also leads to alterations in gut microbiota with a decreasing abundance of beneficial microbes, such as short-chain fatty acid-producing bacteria, and an overgrowth of pro-inflammatory species. The subsequent intestinal barrier dysfunction, together with oxidative stress and increased inflammatory responses, plays a role in the pathogenesis of gastrointestinal inflammatory diseases. Moreover, pollutants encourage the inflammation-dysplasia-carcinoma sequence through various mechanisms, such as oxidative stress, dysregulation of cellular signalling pathways, cell cycle impairment and genomic instability. In this narrative review, we will describe the interplay between pollutants, gut microbiota, and the immune system, focusing on their relationship with inflammatory bowel diseases and colorectal cancer. Understanding the biological mechanisms underlying the health-to-disease transition may allow the design of public health policies aimed at reducing the burden of disease related to pollutants.

Endocrine disrupting chemicals: gestational diabetes and beyond

Gestational Diabetes Mellitus (GDM) has been on the rise for the last two decades along with the growing incidence of obesity. The ubiquitous use of Endocrine-Disrupting Chemicals (EDCs) worldwide has been associated with this increase in GDM incidence. Epigenetic modifications such as DNA methylation, histone acetylation, and methylation have been associated with prenatal exposure to EDCs. EDC exposure can also drive a sustained disruption of the hypothalamus-pituitary-thyroid axis and various other signaling pathways such as thyroid signaling, PPARγ signaling, PI3K-AKT signaling. This disruption leads to impaired glucose metabolism, insulin resistance as well as β-cell dysfunction, which culminate into GDM. Persistent EDC exposure in pregnant women also increases adipogenesis, which results in gestational weight gain. Importantly, pregnant mothers transfer these EDCs to the fetus via the placenta, thus leading to other pregnancy-associated complications such as intrauterine growth restriction (IUGR), and large for gestational age neonates. Furthermore, this early EDC exposure of the fetus increases the susceptibility of the infant to metabolic diseases in early life. The transgenerational impact of EDCs is also associated with higher vascular tone, cognitive aberrations, and enhanced susceptibility to lifestyle disorders including reproductive health anomalies. The review focuses on the impact of environmental toxins in inducing epigenetic alterations and increasing the susceptibility to metabolic diseases during pregnancy needs to be extensively studied such that interventions can be developed to break this vicious cycle. Furthermore, the use of EDC-associated ExomiRs from the serum of patients can help in the early diagnosis of GDM, thereby leading to triaging of patients based on increasing risk factor of the clinicopathological condition.

Fluoxetine removal by anodic oxidation using different anode materials and graphite cathode

Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRI) medication commonly used to treat mental health disorders, but it can be harmful to the environment if not properly disposed of due to incomplete metabolism. In this study, electrochemical anodic oxidation with mixed metal oxide anodes was studied as a method to remove FLX from water and wastewater. Iridium dioxide-coated titanium (Ti/IrO2) and ruthenium dioxide-coated Ti (Ti/RuO2) electrodes were found to be more effective than platinum-coated Ti (Ti/Pt) electrodes, with removal efficiencies of 91.5% and 93.9%, respectively. Optimal conditions for FLX removal were determined to be an applied current of 150 mA, initial pH of 5, and oxidation time of 120 min. The rate of FLX degradation (kFLX) for the Ti/Pt, Ti/IrO2, and Ti/RuO2 electrodes were determined to be 0.0081 min-1 (R2:0,8161), 0.0163 min-1 (R2:0,9823), and 0.0168 (R2:0,9901) min-1 for 25 mg/L initial FLX concentration, respectively. The kFLX values varied based on the initial FLX concentration and decreased as the initial FLX concentration increased. The specific energy consumption (SEC) after 120 min of operation was 51.0 kWh/m3 for the Ti/Pt electrode, 39.6 kWh/m3 for the Ti/IrO2 electrode, and 48.6 kWh/m3 for the Ti/RuO2 electrode under optimised conditions. Overall, electrochemical anodic oxidation is an effective method for removing FLX from water and wastewater, with Ti/IrO2 and Ti/RuO2 electrodes providing superior performance compared to Ti/Pt electrodes.

Association between combined exposure to dioxins and arthritis among US adults: a cross-sectional study

Dioxins and dioxin-like compounds (DLCs) are common pollutants hazardous to human health. We applied 12 dioxins and DLCs data of 1851 participants (including 484 arthritis patients) from National Health Examination Survey (NHANES) 2001-2004 and quadrupled them into rank variables. Multivariate logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to explore the relationship between individual or mixed exposure to the pollutants and arthritis after adjusting for multiple covariates. In multivariable logistic regression with an individual dioxin or DLC, almost every chemical was significantly positively associated with arthritis, except PCB66 (polychlorinated biphenyl 66) and 1,2,3,4,6,7,8-heptachlorodibenzofuran (hpcdf). The WQS model indicated that the combined exposure to the 12 dioxins and DLCs was positively linked to arthritis (OR: 1.884, 95% CI: 1.514-2.346), with PCB156 (weighted 0.281) making the greatest contribution. A positive trend between combined exposure and arthritis was observed in the BKMR model, with a posterior inclusion probability (PIP) of 0.987 for PCB156, which was also higher than the other contaminants.

Hepatic cholesterol biosynthesis and dioxin-induced dysregulation: A multiscale computational approach

Humans are constantly exposed to lipophilic persistent organic pollutants (POPs) that accumulate in fatty foods. Among the numerous POPs, dioxins, in particular 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), can impact several organ systems. While the hazard is clearly recognized, it is still difficult to develop a comprehensive understanding of the overall health impacts of dioxins. As chemical toxicity testing is steadily adopting new approach methodologies (NAMs), it becomes imperative to develop computational models that can bridge the data gaps between in vitro testing and in vivo outcomes. As an effort to address this challenge, we propose a multiscale computational approach using a "template-and-anchor" (T&A) structure. A template is a high-level umbrella model that permits the integration of information from various, detailed anchor models. In the present study, we use this T&A approach to describe the effect of TCDD on cholesterol dynamics. Specifically, we represent hepatic cholesterol biosynthesis as an anchor model that is perturbed by TCDD, leading to steatosis, along with alterations of plasma cholesterol. In the future, incorporating pertinent information from all anchor models into the template model will allow the characterization of the global effects of dioxin, which can subsequently be translated into overall - and ultimately personalized - human health risk assessment.

Aryl hydrocarbon receptor: A bridge linking immuno-inflammation and metabolism in atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, and atherosclerosis is a major contributor to this etiology. The ligand-activated transcription factor, known as the aryl hydrocarbon receptor (AhR), plays an essential role in the interactions between genes and the environment. In a number of human diseases, including atherosclerosis, the AhR signaling pathway has recently been shown to be aberrantly expressed and activated. It's reported that AhR can regulate the immuno-inflammatory response and metabolism pathways in atherosclerosis, potentially serving as a bridge that links these processes. In this review, we highlight the involvement of AhR in atherosclerosis. From the literature, we conclude that AhR is a potential target for controlling atherosclerosis through precise interventions.

Developing an Improved Strategy for the Analysis of Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-like Polychlorinated Biphenyls in Contaminated Soils Using a Combination of a One-Step Cleanup Method and Gas Chromatography with Triple Quadrupole Mass Spectrometry

Soils contaminated with polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), and dioxin-like (dl) polychlorinated biphenyls (PCBs), known as persistent organic pollutants (POPs), have garnered global attention because of their toxicity and persistence in the environment. The standard method for target analytes has been used; however, it is an obstacle in large-scale sample analysis due to the comprehensive sample preparation and high-cost instrumental analysis. Thus, analytical development of inexpensive methods with lower barriers to determine PCDDs/Fs and dl-PCBs in soil is needed. In this study, a one-step cleanup method was developed and validated by combining a multilayer silica gel column and Florisil micro-column followed by gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS). To optimize the separation and quantification of 17 PCDDs/Fs and 12 dl-PCBs in soils, the sample cleanup and instrumental conditions were investigated. For quantification method validation, spiking experiments were conducted to determine the linearity of the calibration, recovery, and method detection limit of PCDDs/Fs and dl-PCBs using isotopic dilution GC-QqQ-MS/MS. The applicability of the simultaneous determination of PCDDs/Fs and dl-PCBs was confirmed by the recovery of native target congeners and labeled surrogate congeners spiked into the quality-control and actual soil samples. The results were in good agreement with the requirements imposed by standard methods. The findings in this work demonstrated the high accessibility of the sample cleanup and analysis methods for the efficient determination of PCDDs/Fs and dl-PCBs in contaminated soils.

Deciphering the roles of aryl hydrocarbon receptor (AHR) in regulating carcinogenesis

Aryl hydrocarbon receptor (AHR) is a ligand-dependent receptor that belongs to the superfamily of basic helix-loop-helix (bHLH) transcription factors. The activation of the canonical AHR signaling pathway is known to induce the expression of cytochrome P450 enzymes, facilitating the detoxification metabolism in the human body. Additionally, AHR could interact with various signaling pathways such as epidermal growth factor receptor (EGFR), signal transducer and activator of transcription 3 (STAT3), hypoxia-inducible factor-1α (HIF-1α), nuclear factor ekappa B (NF-κβ), estrogen receptor (ER), and androgen receptor (AR) signaling pathways. Over the past 30 years, several studies have reported that various chemical, physical, or biological agents, such as tobacco, hydrocarbon compounds, industrial and agricultural chemical wastes, drugs, UV, viruses, and other toxins, could affect AHR expression or activity, promoting cancer development. Thus, it is valuable to overview how these factors regulate AHR-mediated carcinogenesis. Current findings have reported that many compounds could act as AHR ligands to drive the expressions of AHR-target genes, such as CYP1A1, CYP1B1, MMPs, and AXL, and other targets that exert a pro-proliferation or anti-apoptotic effect, like XIAP. Furthermore, some other physical and chemical agents, such as UV and 3-methylcholanthrene, could promote AHR signaling activities, increasing the signaling activities of a few oncogenic pathways, such as the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathways. Understanding how various factors regulate AHR-mediated carcinogenesis processes helps clinicians and scientists plan personalized therapeutic strategies to improve anti-cancer treatment efficacy. As many studies that have reported the roles of AHR in regulating carcinogenesis are preclinical or observational clinical studies that did not explore the detailed mechanisms of how different chemical, physical, or biological agents promote AHR-mediated carcinogenesis processes, future studies should focus on conducting large-scale and functional studies to unravel the underlying mechanism of how AHR interacts with different factors in regulating carcinogenesis processes.

Origin, dietary exposure, and toxicity of endocrine-disrupting food chemical contaminants: A comprehensive review

Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.

Endocrine-disrupting chemicals (EDCs) and cancer: new perspectives on an old relationship

PURPOSE

Environmental endocrine-disrupting chemicals (EDCs) are a mixture of chemical compounds capable to interfere with endocrine axis at different levels and to which population is daily exposed. This paper aims to review the relationship between EDCs and breast, prostate, testicle, ovary, and thyroid cancer, discussing carcinogenic activity of known EDCs, while evaluating the impact on public health.

METHODS

A literature review regarding EDCs and cancer was carried out with particular interest on meta-analysis and human studies.

RESULTS

The definition of EDCs has been changed through years, and currently there are no common criteria to test new chemicals to clarify their possible carcinogenic activity. Moreover, it is difficult to assess the full impact of human exposure to EDCs because adverse effects develop latently and manifest at different ages, even if preclinical and clinical evidence suggest that developing fetus and neonates are most vulnerable to endocrine disruption.

CONCLUSION

EDCs represent a major environmental and health issue that has a role in cancer development. There are currently some EDCs that can be considered as carcinogenic, like dioxin and cadmium for breast and thyroid cancer; arsenic, asbestos, and dioxin for prostate cancer; and organochlorines/organohalogens for testicular cancer. New evidence supports the role of other EDCs as possible carcinogenic and pregnant women should avoid risk area and exposure. The relationship between EDCs and cancer supports the need for effective prevention policies increasing public awareness.

Review on distribution, fate, and management of potentially toxic elements in incinerated medical wastes

Medical wastes include all solid and liquid wastes that are produced during the treatment, diagnosis, and immunisation of animals and humans. A significant proportion of medical waste is infectious, hazardous, radioactive, and contains potentially toxic elements (PTEs) (i.e., heavy metal (loids)). PTEs, including arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg), are mostly present in plastic, syringes, rubber, adhesive plaster, battery wastes of medical facilities in elemental form, as well as oxides, chlorides, and sulfates. Incineration and sterilisation are the most common technologies adopted for the safe management and disposal of medical wastes, which are primarily aimed at eliminating deadly pathogens. The ash materials derived from the incineration of hazardous medical wastes are generally disposed of in landfills after the solidification/stabilisation (S/S) process. In contrast, the ash materials derived from nonhazardous wastes are applied to the soil as a source of nutrients and soil amendment. The release of PTEs from medical waste ash material from landfill sites and soil application can result in ecotoxicity. The present study is a review paper that aims to critically review the dynamisms of PTEs in various environmental media after medical waste disposal, the environmental and health implications of their poor management, and the common misconceptions regarding medical waste.

Current Evidence on Bisphenol A Exposure and the Molecular Mechanism Involved in Related Pathological Conditions

Bisphenol A (BPA) is one of the so-called endocrine disrupting chemicals (EDCs) and is thought to be involved in the pathogenesis of different morbid conditions: immune-mediated disorders, type-2 diabetes mellitus, cardiovascular diseases, and cancer. The purpose of this review is to analyze the mechanism of action of bisphenol A, with a special focus on mesenchymal stromal/stem cells (MSCs) and adipogenesis. Its uses will be assessed in various fields: dental, orthopedic, and industrial. The different pathological or physiological conditions altered by BPA and the related molecular pathways will be taken into consideration.

Combined exposure to multiple dioxins and dioxin-like polychlorinated biphenyls on hypertension among US adults in NHANES: a cross-sectional study under three statistical models

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are mainly released as by-products of human activities, often in the form of mixtures, and the potential harm on human health deserves attention. Therefore, our study aimed to analyze the combined effect of dioxins and DL-PCB exposures on hypertension (HTN) among US adults. Data of eligible participants were acquired from the National Health and Nutrition Examination Survey (NHANES). Multiple logistic regression models with adjustment for covariates were applied to explore the associations between 13 persistent organic pollutants (POPs) and HTN. Stratified analyses and interaction analyses were then conducted by age and gender. Finally, the combined effects of dioxins and DL-PCBs on HTN were assessed by the weighted quantile sum (WQS) model and the Bayesian kernel machine regression (BKMR) model. A total of 976 adults were included in our study, of whom 397 had HTN. Spearman correlations indicated positive correlations among 13 POPs. And most of them (except PCB28, PCB66, and 1,2,3,4,7,8,9-hpcdf) had significant effects on HTN. The result of WQS revealed that mixed exposure to dioxins and DL-PCBs was significantly associated with increased risk of HTN (OR: 2.205; 95% CIs: 1.555, 3.127). The BKMR model also presented a positive trend of HTN risk with exposure to multiple dioxins and DL-PCBs. And 1,2,3,4,6,7,8,9-ocdd may be the main factor for this positive association. Considering the limitations of our cross-sectional study with the small sample, further prospective studies are necessary to validate our findings.

Endocrine disruptors and endometriosis

Endometriosis is a hormone-dependent inflammatory gynecological disease of reproductive-age women. It is clinically and pathologically characterized by the presence of functional endometrium as heterogeneous lesions outside the uterine cavity. The two major symptoms are chronic pelvic pain and infertility, which profoundly affect women's reproductive health and quality of life. This significant individual and public health concerns underscore the importance of understanding the pathogenesis of endometriosis. The environmental endocrine-disrupting chemicals (EDCs) are exogenous agents that interfere with the synthesis, secretion, transport, signaling, or metabolism of hormones responsible for homeostasis, reproduction, and developmental processes. Endometriosis has been potentially linked to exposure to EDCs. In this review, based on the robust literature search, we have selected four endocrine disruptors (i) polychlorinated biphenyls (PCB)s (ii) dioxins (TCDD) (iii) bisphenol A (BPA) and its analogs and (iv) phthalates to elucidate their critical role in the etiopathogenesis of endometriosis. The epidemiological and experimental data discussed in this review indicate that these four EDCs activate multiple intracellular signaling pathways associated with proinflammation, estrogen, progesterone, prostaglandins, cell survival, apoptosis, migration, invasion, and growth of endometriosis. The available information strongly indicates that environmental exposure to EDCs such as PCBs, dioxins, BPA, and phthalates individually or collectively contribute to the pathophysiology of endometriosis. Further understanding of the molecular mechanisms of how these EDCs establish endometriosis and therapeutic strategies to mitigate the effects of these EDCs in the pathogenesis of endometriosis are timely needed. Moreover, understanding the interactive roles of these EDCs in the pathogenesis of endometriosis will help regulate the exposure to these EDCs in reproductive age women.

Endometriosis Stem Cells as a Possible Main Target for Carcinogenesis of Endometriosis-Associated Ovarian Cancer (EAOC)

Endometriosis is a serious recurrent disease impairing the quality of life and fertility, and being a risk for some histologic types of ovarian cancer defined as endometriosis-associated ovarian cancers (EAOC). The presence of stem cells in the endometriotic foci could account for the proliferative, migrative and angiogenic activity of the lesions. Their phenotype and sources have been described. The similarly disturbed expression of several genes, miRNAs, galectins and chaperones has been observed both in endometriotic lesions and in ovarian or endometrial cancer. The importance of stem cells for nascence and sustain of malignant tumors is commonly appreciated. Although the proposed mechanisms promoting carcinogenesis leading from endometriosis into the EAOC are not completely known, they have been discussed in several articles. However, the role of endometriosis stem cells (ESCs) has not been discussed in this context. Here, we postulate that ESCs may be a main target for the carcinogenesis of EAOC and present the possible sequence of events resulting finally in the development of EAOC.

Association between mixed dioxin exposure and hyperuricemia in U.S. adults: A comparison of three statistical models

BACKGROUND

Previous studies on the relationship between dioxin exposures and hyperuricemia have usually been based on multi-chemical linear models. However, the complex nonlinear relationship and interaction between mixed dioxin exposures and hyperuricemia have seldom been studied. In this study, we applied three different statistical models to assess the joint effect of 12 dioxins on hyperuricemia.

METHODS

A total of 7 dioxin-like polychlorinated biphenyls (DL-PCBs), 3 polychlorinated dibenzo-p-dioxins (PCDDs), and 2 polychlorinated dibenzofurans (PCDFs) were measured in the serum of adults by the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2004. 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 hyperuricemia.

RESULTS

Among the 1008 individuals included in our analysis, 20.04% had hyperuricemia. In the multivariable logistic regression established for each single dioxin, PCB28, PCB74, PCB105, PCB118, and 1,2,3,4,6,7,8-HPCDD were positively associated with hyperuricemia. With including all dioxins in the multivariable logistic regression model simultaneously, only PCB28 and 1,2,3,4,6,7,8-HPCDD were positively associated with hyperuricemia. In the WQS regression model, the WQS index was significantly associated (OR (95% CI): 2.32 (1.26, 4.28)) with hyperuricemia, and 1,2,3,4,6,7,8-HPCDD (weighted 0.22) had the largest contribution. In BKMR analysis, a significant positive association was found between mixed dioxin exposure and hyperuricemia when all dioxins were at their 60th percentile or above, compared to their 50th percentile. The univariate exposure-response function showed that PCB105 and PCB118 were positively associated with hyperuricemia.

CONCLUSION

By comparing the three statistical models, we concluded that the whole-body burden of 12 dioxins was significantly positively associated with hyperuricemia. PCB105, PCB118, and 1,2,3,4,6,7,8-HPCDD played the most important roles in hyperuricemia.

Bisphenol A and 2,3,7,8-tetrachlorodibenzo-p-dioxin at non-cytotoxic doses alter the differentiation potential and cell function of rat adipose-stem cells

The possibility of chemical contamination is an important issue to consider when designing a cell therapy strategy. Both bisphenol A (BPA) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are among the most environmentally relevant endocrine disrupting chemicals (EDCs, compounds with a high affinity for adipose tissue) recently studied. Adipose-derived stem cells (ASCs) are mesenchymal stromal cells (MSCs) obtained from adipose tissue widely used in regenerative medicine to prevent and treat diseases in several tissues and organs. Although the experimental use of tissue-engineered constructs requires careful analysis for approval and implantation, there has been a recent increase in the number of approved clinical trials for this promising strategy. This study aimed to evaluate cell viability, apoptosis, DNA damage, and the adipogenic or osteogenic differentiation potential of rat adipose-derived stem cells (rASCs) exposed to previously established non-cytotoxic doses of BPA and TCDD in vitro. Results demonstrated that 10 μM of BPA and 10 nM of TCDD were able to significantly reduce cell viability, while all exposure levels resulted in DNA damage, although did not increase the apoptosis rate. According to the analysis of adipogenic differentiation, 1 μM of BPA induced the significant formation of oil droplets, suggesting an increased adipocyte differentiation, while both 10 μM of BPA and 10 nM of TCDD decreased adipocyte differentiation. Osteogenic differentiation did not differ among the treatments. As such, BPA and TCDD in the concentrations tested can modify important processes in rASCs such as cell viability, adipogenic differentiation, and DNA damage. Together, these findings prove that EDCs play an important role as contaminants, putatively interfering in cell differentiation and thus impairing the therapeutic use of ASCs.

Dehydrochlorination of PCDDs on SWCN-Supported Ni10 and Ni13 Clusters, a DFT Study

Polychlorinated dibenzo-p-dioxins (PCDDs) are known to be a group of compounds of high toxicity for animals and, particularly, for humans. Given that the most common method to destroy these compounds is by high-temperature combustion, finding other routes to render them less toxic is of paramount importance. Taking advantage of the physisorption properties of nanotubes, we studied the reactions of atomic hydrogen on physisorbed PCDDs using DFT; likewise, we investigated the reaction of molecular hydrogen on PCDDs aided by Ni10 and Ni13 clusters adsorbed on single-wall carbon nanotubes. Because dihydrogen is an easily accessible reactant, we found these reactions to be quite relevant as dehydrohalogenation methods to address PCDD toxicity.

Dioxin-like compounds formation mediated by Fe3+-montmorillonite: The substituent effects of halophenols

Toxic dioxin or/and dioxin-like compounds could be naturally formed from the reaction of halophenols on Fe³⁺-montmorillonite minerals under ambient conditions. Given that the toxicities and productions of dioxin or/and dioxin-like compounds are largely determined by the number, species, and position of the carried halogen atoms, it is necessary to explore the substituent effects on the reaction of halophenols with Fe³⁺-montmorillonite. Herein, Fe³⁺-montmorillonite catalyzed polymerizations of six halophenols were examined in a wide range of relative humidity (10%∼80%) using combinations of mass spectrometry identifications and density functional theory calculations. Results show that both the position and species of the substituents substantially impact the reaction rate, product species, and transformation pathways. In general, regardless of humidity ortho-substituted chlorophenols are more reactive than meta-substituted chlorophenols, which is also supported by the density functional theory calculations indicating that the ortho positions are more likely to be attacked. Regarding substituent species, bromophenols are slightly more reactive and also more easily affected by humidities than chlorophenols, which is due to the weaker electron absorbing ability of the bromine atom than the chlorine atom. Hydroxylated polyhalogenated diphenyl ethers are more frequently detected polymerization products, although hydroxylated polyhalogenated biphenyls are greater quantity of products. Overall, this study provides useful information for understanding the natural formation of dioxin or/and dioxin-like compounds mediated by clay minerals and underlying reaction mechanisms.

Aryl Hydrocarbon Receptor-Dependent and -Independent Pathways Mediate Curcumin Anti-Aging Effects

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor whose activity can be modulated by polyphenols, such as curcumin. AhR and curcumin have evolutionarily conserved effects on aging. Here, we investigated whether and how the AhR mediates the anti-aging effects of curcumin across species. Using a combination of in vivo, in vitro, and in silico analyses, we demonstrated that curcumin has AhR-dependent or -independent effects in a context-specific manner. We found that in Caenorhabditis elegans, AhR mediates curcumin-induced lifespan extension, most likely through a ligand-independent inhibitory mechanism related to its antioxidant activity. Curcumin also showed AhR-independent anti-aging activities, such as protection against aggregation-prone proteins and oxidative stress in C. elegans and promotion of the migratory capacity of human primary endothelial cells. These AhR-independent effects are largely mediated by the Nrf2/SKN-1 pathway.

Sex-specific Associations Between Type 2 Diabetes Incidence and Exposure to Dioxin and Dioxin-like Pollutants: A Meta-analysis

The potential for persistent organic pollutants (POPs), including dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs), to increase the risk of incident diabetes in adults has been extensively studied. However, there is substantial variability in the reported associations both between and within studies. Emerging data from rodent studies suggest that dioxin disrupts glucose homeostasis in a sex-specific manner. Thus, we performed a review and meta-analysis of relevant epidemiological studies to investigate sex differences in associations between dioxin or DL-PCB exposure and type 2 diabetes incidence. Articles that met our selection criteria (n = 81) were organized into the following subcategories: data stratified by sex (n = 13), unstratified data (n = 45), and data from only 1 sex (n = 13 male, n = 10 female). We also considered whether exposure occurred either abruptly at high concentrations through a contamination event (“disaster exposure”) or chronically at low concentrations (“non-disaster exposure”). There were 8 studies that compared associations between dioxin/DL-PCB exposure and diabetes risk in males versus females within the same population. When all sex-stratified or single-sex studies were considered in the meta-analysis (n = 18), the summary relative risk (RR) for incident diabetes among those exposed relative to reference populations was 1.78 (95% CI = 1.37–2.31) and 1.95 (95% CI = 1.56–2.43) for female and males, respectively. However, when we restricted the meta-analysis to disaster-exposed populations, the RR was higher in females than males (2.86 versus 1.59, respectively). In contrast, in non-disaster exposed populations the RR for females was lower than males (1.40 and 2.02, respectively). Our meta-analysis suggests that there are sex differences in the associations between dioxin/DL-PCBs exposure and incident diabetes, and that the mode of exposure modifies these differences.

Biotechnological recycling of hazardous waste PCBs using Sulfobacillus thermosulfidooxidans through pretreatment of toxicant metals: Process optimization and kinetic studies

The present study dealt with the restricted microbial tolerance for lead and tin during bioleaching of waste printed circuit boards (WPCBs) and lower extraction yields of valuable metals. Pretreatment of WPCBs in 4.0 mol/L HNO₃ at 90 °C for 180 min duration prominently dissolved the toxicant metals before the microbial mobilization of valuable metals. Acid pretreatment followed the first-order kinetics that exhibiting an intermediate-controlled mechanism with the apparent activation energy determined to be E_a(Pb), 25.1 kJ/mol and E_a(Sn), 21.9 kJ/mol. Thereafter, the parametric optimization of aeration rate, O₂-enrichment, external CO₂ supply, temperature, and time for bioleaching of ground WPCBs was examined using Sulfobacillus thermosulfidooxidans (strain RDB). A favourable condition for Cu-bioleaching under higher oxidative environment in comparison to Ni and Zn exhibited the auto-catalytic behaviour of Cu²⁺ in the biological system. More than 92% of valuable metals were extracted under the optimal condition of aeration rate, 0.5 L/min; O₂-enrichement dosage, 30%; external CO₂ supply, 0.1%; temperature, 55 °C; and time, 18 days. The bioleaching kinetics followed shrinking core model that exhibiting the shifting of mass transfer from chemically-controlled to the diffusion-controlled mechanism. This process offers two-fold advantages that restoring the valuable metals with low-emission biotechnological route for waste valorization.

The Improvement of the Adaptation Process of Tocopherol and Acetylsalicylic Acid in Offspring of Mothers Exposed to TCDD

Simple Summary

Dioxins are proinflammatory factors that may be transferred to offspring through the placenta during pregnancy. α-tocopherol and acetylsalicylic acid are popular agents that limit the spread of inflammation. A histopathological and biochemical analysis was performed to reveal possible changes in liver and blood plasma in response to dioxins, α-tocopherol, and acetylsalicylic acid. The conducted research demonstrated the presence of negative effects on the liver morphology and blood plasma proteins of offspring, due to dioxins that were derived from the mother. However, the use of both drugs can significantly reduce the negative effects on offspring whose mothers have been treated with dioxins.

Abstract

Dioxins are chemical compounds that may cause an inflammatory reaction. During dioxin-induced inflammation, generated reactive oxygen species lead to morphological changes in various tissues and in biochemical parameters. The aim of this study was to demonstrate the changes in the livers of rats whose mothers were exposed to dioxins and the protective role of α-tocopherol and acetylsalicylic acid in liver inflammation. The study material consisted of Buffalo rats who were the offspring of females treated with dioxin, dioxin + α-tocopherol, or dioxin + acetylsalicylic acid. Livers and blood samples were taken from the rats’ offspring, and then histopathological and biochemical analyses were performed. The histopathological analysis showed that the changes observed in the livers of neonates were the result of the dioxins derived from their mother. The biochemical analysis showed that the morphological changes in the liver affected its function, which manifested in a higher total protein concentration in the dioxin-treated group, and that the creatinine level in this group was significantly higher than that in the other groups. This effect was reduced by the protective role of α-tocopherol and acetylsalicylic acid. Based on these results, we came to the conclusion that dioxins significantly affect the structure of the liver, which negatively affects its function, mainly in the scope of the metabolism of plasma proteins and hepatic enzymes.

Urinary biohazard markers in firefighters

Firefighters are the professional force at high risk of suffering potential health consequences due to their chronic exposure to numerous hazardous pollutants during firefighting activities. Unfortunately, determination of fire emission exposure is very challenging. As such, the identification and development of appropriate biomarkers is critical in meeting this need. This chapter presents a critical review of current information related with the use of different urinary biomarkers of effect and exposure in occupationally exposed firefighters over the last 25 years. Evidence suggests that urinary isoprostanes and mutagenicity testing are promising biomarkers of early oxidative stress. Data indicate that firefighters participating in firefighting activities present with increased urinary biomarkers of exposure. These include polycyclic aromatic hydrocarbons, heavy metals and metalloids, organo-chlorine and -phosphorus compounds, environmental phenols, phthalates, benzene and toluene. More studies are urgently needed to better evaluate firefighter occupational safety and health and to support the implementation of preventive measures and mitigation strategies to promote the protection of this chronically exposed group of workers.

O2-enriched microbial activity with pH-sensitive solvo-chemical and electro-chlorination strategy to reclaim critical metals from the hazardous waste printed circuit boards

An innovative process integration for the sustainable recovery of critical metals from waste printed circuit boards (WPCBs) is demonstrated. In the acid pre-treatment of WPCBs, > 95% of highly toxic metals lead and tin could dissolve after 240 min of contact in 4.0 mol L^-1 HNO₃. Thereafter, the microbial activity of Sulfobacillus thermosulfidooxidans (strain RDB) under intense aeration is found favorable for base metals' liberation. ~92% copper, 89% nickel, and 93% zinc get extracted at the optimal condition of O₂-mixed-aeration, 30%; pulp density, 10 g L^-1; aeration rate, 0.5 L min^-1; sulfur dosage, 2%; temperature, 45 °C; and duration, 21 days. Quantitative separation of base metals is achieved using ketoxime as a function of equilibrium pH that yielding pH_0.5 order: Cu (1.45) < Ni (5.7) < Zn (8.1). The residual gold from WPCBs is uniquely leached (~99% efficiency) in brine solution (2.0 mol L^-1 NaCl) under the electro-chlorination rate, 0.62 mmol min^-1; dissolution pH, 1.0; pulp density, 20 g L^-1; temperature, 30 °C; and time, 60 min. Subsequently, gold from brine solution is solvated with tri-butyl-phosphate at pH_eq, ≤ 0.5, forming [2(RP=O)·HAuCl₄·H₂O]¯ complex in the organic phase. Finally, > 99% of high-purity gold is stripped from loaded organic while contacting ammoniacal thiosulfate solution in two-stages of counter-current flow.

The Association between Child and Parent Psychiatric Disorders in Families Exposed to Flood and/or Dioxin

Associations of disaster mental health sequelae between children and their parents have been demonstrated, but not using full diagnostic assessment. This study examined children and their parents after a series of disasters in 1982 to investigate associations of their psychiatric outcomes. Members of 169 families exposed to floods and/or dioxin or no disaster were assessed in 1986–1987 with structured diagnostic interviews. This vintage dataset collected several decades ago provides new information to this field because of the methodological rigor that is unparalleled in this literature. Disaster-related PTSD and incident postdisaster disorders in children were associated, respectively with disaster-related PTSD and incident postdisaster disorders in the chief caregiver and mother. More flood-only than dioxin-only exposed parents reported great harm by the disaster, but neither children nor parents in these two groups differed in incident psychiatric disorders. Although this study did not determine the direction of causal influences, its findings suggest that clinicians working with disaster-exposed families should work with children and adult members together, as their mental health outcomes may be intertwined.

Genetics-Based Approach to Identify Novel Genes Regulated by the Aryl Hydrocarbon Receptor in Mouse Liver

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor in the Per-Arnt-Sim superfamily of environmental sensors that is linked to several metabolic diseases, including nonalcoholic fatty liver disease. Much remains unknown regarding the impact of genetic variation in AHR-driven disease, as past studies have focused on a small number of inbred strains. Recently, the presence of a wide range of interindividual variability amongst humans was reported in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the prototypical ligand of the AHR. In this study, a panel of 14 diverse mouse strains was exposed to TCDD for 10 days to characterize the AHR-mediated response across genetic backgrounds. Responses to TCDD are heavily dependent on genetic background. Although mice carry 1 of 4 Ahr alleles known to impact the affinity to AHR-ligands, we observed significant intra-allelic variability suggesting the presence of novel genetic modifiers of AHR signaling. A regression-based approach was used to scan for genes regulated by the AHR and/or associated with TCDD-induced phenotypes. The approach identified 7 genes, 2 of which are novel, that are likely regulated by the AHR based on association with hepatic TCDD burden (p ≤ .05). Finally, we identified 1 gene, Dio1, which was associated with change in percent body fat across the diverse set of strains (p ≤ .05). Overall, the results in this study exemplify the power of genetics-based approaches in identifying novel genes that are putatively regulated by the AHR.

Emodin Inhibits the Proliferation of MCF-7 Human Breast Cancer Cells Through Activation of Aryl Hydrocarbon Receptor (AhR)

Natural products have proved to be a promising source for the development of potential anticancer drugs. Emodin, a natural compound from Rheum palmatum, is used to treat several types of cancers, including lung, liver, and pancreatic. However, there are few reports regarding its use in the treatment of breast cancer. Thus, the therapeutic effect and mechanism of emodin on MCF-7 human breast cancer cells were investigated in this study. Morphological observations and cell viability were evaluated to determine the anti-proliferation activity of emodin. Network pharmacology and molecular docking were performed to screen the potential targets. Western blot analysis was used to explore a potential antitumor mechanism. The results showed that emodin (50–100 μmol/L) could significantly inhibit the proliferation of MCF-7 cells in a time and dose-dependent manner. Furthermore, virtual screening studies indicated that emodin was a potent aryl hydrocarbon receptor (AhR) agonist in chemotherapy for breast cancer. Finally, when MCF-7 cells were treated with emodin (100 μmol/L) for 24 h, the AhR and cytochrome P450 1A1 (CYP1A1) protein expression levels were significantly upregulated compared with the control group. Our study indicated that emodin exhibited promising antitumor activity in MCF-7 cells, likely through activation of the AhR-CYP1A1 signaling pathway. These findings lay a foundation for the application of emodin in breast cancer treatment.

Dietary and environmental factors have opposite AhR-dependent effects on C. elegans healthspan

Genetic, dietary, and environmental factors concurrently shape the aging process. The aryl hydrocarbon receptor (AhR) was discovered as a dioxin-binding transcription factor involved in the metabolism of different environmental toxicants in vertebrates. Since then, the variety of pathophysiological processes regulated by the AhR has grown, ranging from immune response, metabolic pathways, and aging. Many modulators of AhR activity may impact on aging and age-associated pathologies, but, whether their effects are AhR-dependent has never been explored. Here, using Caenorhabditis elegans, as an elective model organism for aging studies, we show for the first time that lack of CeAHR-1 can have opposite effects on health and lifespan in a context-dependent manner. Using known mammalian AhR modulators we found that, ahr-1 protects against environmental insults (benzo(a)pyrene and UVB light) and identified a new role for AhR-bacterial diet interaction in animal lifespan, stress resistance, and age-associated pathologies. We narrowed down the dietary factor to a bacterially extruded metabolite likely involved in tryptophan metabolism. This is the first study clearly establishing C. elegans as a good model organism to investigate evolutionarily conserved functions of AhR-modulators and -regulated processes, indicating it can be exploited to contribute to the discovery of novel information about AhR in mammals.

Exposure to Endocrine Disrupting Chemicals and Risk of Breast Cancer

Breast cancer (BC) is the second most common cancer and the fifth deadliest in the world. Exposure to endocrine disrupting pollutants has been suggested to contribute to the increase in disease incidence. Indeed, a growing number of researchershave investigated the effects of widely used environmental chemicals with endocrine disrupting properties on BC development in experimental (in vitro and animal models) and epidemiological studies. The complex effects of endocrine disrupting chemicals (EDCs) on hormonal pathways, involving carcinogenic effects and an increase in mammary gland susceptibility to carcinogenesis-together with the specific characteristics of the mammary gland evolving over the course of life and the multifactorial etiology of BC-make the evaluation of these compounds a complex issue. Among the many EDCs suspected of increasing the risk of BC, strong evidence has only been provided for few EDCs including diethylstilbestrol, dichlorodiphenyltrichloroethane, dioxins and bisphenol A. However, given the ubiquitous nature and massive use of EDCs, it is essential to continue to assess their long-term health effects, particularly on carcinogenesis, to eradicate the worst of them and to sensitize the population to minimize their use.

Effects of prolonged subchronic benzo(α)pyrene exposure on rat liver morphology and CYP1A expression during treatment with menadione, quercetin, or tocopherol

Arylamines and polycyclic aromatic hydrocarbons (PAHs) are hazardous anthropogenic pollutants in the environment. The toxicity of PAHs, which include benzo(α)pyrene (BP), is mediated by the activation of Р450 cytochromes of the 1А subfamily (CYP1A1 and CYP1A2). Previously, we have demonstrated that tocopherol, quercetin, and menadione inhibit the expression and activity of CYP1A in the liver of male Wistar rats after administration of a high BP dose to the rats for 3 days. Here, we confirmed the effects of tocopherol, quercetin, and menadione on the expression and activity of CYP1A and on rat liver morphology during prolonged administration (90 days) of a low BP dose. We revealed that subchronic oral administration of a low BP dose has no influence on CYP1A expression as compared to controls but can cause pathomorphological changes in rat liver tissue. These changes are abrogated by tocopherol, attenuated by quercetin, and enhanced by menadione.

TCDD-induced antagonism of MEHP-mediated migration and invasion partly involves aryl hydrocarbon receptor in MCF7 breast cancer cells

Evidence has shown that the activation of AhR (aryl hydrocarbon receptor) can promote cancer cell metastasis. However, limited studies have been carried out on mixed exposure to endocrine-disrupting chemicals (EDCs), especially in human breast cancer. Therefore, using MCF7 human breast cancer cells, we investigated the effects of coexposure to MEHP (mono 2-ethylhexyl phthalate) and TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) on cell migration and invasion, as well as the roles of AhR and the MMP/slug pathway. Our data suggest that MEHP or TCDD can induce migration and invasion in MCF7 cells, and the promotion is partly AhR dependent. We also observed that MEHP antagonized TCDD to reduce AhR-mediated CYP1A1 expression. Subsequently, we revealed that MEHP recruited AhR to dioxin response element (DRE) sequences and decreased TCDD-induced AhR-DRE binding in CYP1A1 genes. Overall, MEHP is a potential AHR agonist, capable of decreasing TCDD-induced AhR-DRE binding in CYP1A1 genes. The antagonizing effect of coexposure led to the inhibition of the epithelial-mesenchymal transition (EMT) in MCF7 cells. Our study provides new evidence for the potential mechanisms involved in EDCs exposure and their interactions in EMT.

PCDD/Fs in paired hair and serum of workers from a municipal solid waste incinerator plant in South China: Concentrations, correlations, and source identification

Human hair has been widely used to evaluate the exposure to drugs and organic pollutants. However, reports on the relationship between polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) in hair and the body burden of PCDD/Fs are limited. In this study, the association between PCDD/Fs in paired hair and serum samples from workers was examined in a municipal solid waste incinerator (MSWI) plant in South China. Fly ash and flue gas from the MSWI plant were also analyzed to determine the source apportionment of PCDD/Fs in the hair. The median international toxic equivalents (I-TEQs) of ΣPCDD/F in serum and hair were 28.0 pg TEQ/g (lipid weight) and 0.30 pg TEQ/g (dry weight), respectively. The indicator congener of PCDD/Fs for the TEQ levels was 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) in both hair and serum, the concentrations of which both exhibited significant and strong linear dependence on the total TEQ levels (p < 0.01, R² = 0.966 and R² = 0.670, respectively). Significant positive correlations were found in the 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin (HxCDD) and octachlorodibenzo-p-dioxin (OCDD) levels between the hair and serum samples (p < 0.05). Flue gas (which is an external source) was identified as the primary source of PCDD/Fs in human hair. Blood and flue gas were accountable for, on average, 37% and 61% of the PCDD/Fs in hair, respectively.

Emerging technologies for the recovery of rare earth elements (REEs) from the end-of-life electronic wastes: a review on progress, challenges, and perspectives

The demand for rare earth elements (REEs) has significantly increased due to their indispensable uses in integrated circuits of modern technology. However, due to the extensive use of high-tech applications in our daily life and the depletion of their primary ores, REE's recovery from secondary sources is today needed. REEs have now attracted attention to policymakers and scientists to develop novel recovery technologies for materials' supply sustainability. This paper summarizes the recent progress for the recovery of REEs using various emerging technologies such as bioleaching, biosorption, cryo-milling, electrochemical processes and nanomaterials, siderophores, hydrometallurgy, pyrometallurgy, and supercritical CO₂. The challenges facing this recovery are discussed comprehensively and some possible improvements are presented. This work also highlights the economic and engineering aspects of the recovery of REE from waste electrical and electronic equipment (WEEE). Finally, this review suggests that greener and low chemical consuming technologies, such as siderophores and electrochemical processes, are promising for the recovery of REEs present in small quantities. These technologies present also a potential for large-scale application.

The Photocatalytic Degradation of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in the Presence of Silver–Titanium Based Catalysts

Polychlorinated dibenzo-p-dioxins (PCDD) are persistent toxic compounds that are ubiquitous in the environment. The photodegradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the presence of silver titanium oxide (AgTi) and silver titanium doped into the Y-zeolite (AgTiY) was tested using high (254 nm) and mid (302 nm) energy UV irradiation sources. AgTi and AgTiY, both showed success in the photodegradation of 2,3,7,8-TCDD dissolved in methanol/tetrahydrofuran solution. Both catalysts were found to effectively decompose TCDD at 302 nm (lower energy) reaching in between 98–99% degradation after five hours, but AgTiY showed better performance than AgTi at 60 min reaching 91% removal. Byproducts of degradation were evaluated using Gas chromatography/mass spectrometry (GC–MS), resulting in 2,3,7-trichlorodibenzo-p-dioxin, a lower chlorinated congener and less toxic, as the main degradation product. Enzyme Linked Immunosorbent Assay (ELISA) was used to evaluate the relative toxicity of the degradation byproducts were a decrease in optical density indicated that some products of degradation could be potentially more toxic than the parent TCDD. On the other hand, a decrease in toxicity was observed for the samples with the highest 2,3,7,8-TCDD degradation, confirming that AgTiY irradiated at 302 nm is an excellent choice for degrading TCDD. This is the first study to report on the efficiency of silver titanium doped zeolites for the removal of toxic organic contaminants such as dioxins and furans from aquatic ecosystems.

The Protective Effect of Xanthohumol on the Content of Selected Elements in the Bone Tissue for Exposed Japanese Quails to TCDD

Dioxins (including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are highly toxic and persistent chemicals widely distributed in the environment in trace amounts, and are side products of industrial and chemical processes. Exposure to dioxins leads to multiorgan morphological and functional abnormalities, including within the bone tissue, disrupting its microarchitecture and mechanical properties. Xanthohumol (XN) is a chemical compound classified as a prenylated flavonoid, distinguished by multidirectional biological action. The aim of the study is to assess whether xanthohumol, as a substance with strong antioxidant and anti-inflammatory properties, has the ability to eliminate the negative effects of TCDD on bone tissue. The experiment was conducted on adult Japanese quails. Two different doses of TCDD and xanthohumol were administered to birds. After euthanasia of animals, the research material in the form of cranial vault and hind limb bone was collected, and their mineral compositions of calcium, phosphorus, magnesium, zinc, and iron concentrations were determined using atomic emission spectrometry in an acetylene-air flame method. Our results indicate that the administration of TCDD at a low dose causes more dynamic changes in the concentration of elements in bone, in comparison to a higher dose of dioxin. Results show also that higher doses of the XN cause the linear increase in the concentration of phosphorus and iron in the bone of the hind limb, and calcium in the bones of the cranial vault. In conclusion, our experiment shows that the use of TCDD and XN in Japanese quails together in various doses influences the content of phosphorus, magnesium, zinc, and iron in the research material.

A comprehensive analysis of AHRR gene as a candidate for cleft lip with or without cleft palate

Cleft lip and palate (CL/P) is among the most common congenital malformations and affects 1 in 700 newborns. CL/P is caused by genetic and environmental factors (maternal smoking, alcohol or drug use and others). Many genes and loci were associated with cleft lip/palate but the amount of heterogeneity justifies identifying new causal genes and variants. AHRR (Aryl-Hydrocarbon Receptor Repressor) gene has recently been related to CL/P however, few functional studies analyze the genotypephenotype interaction of AHRR with CL/P. Several studies associate the molecular pathway of AHRR to CL/P which indicates this gene as a functional candidate in CL/P etiology.

METHODS

Systematic Literature Review was performed using PUBMED database with the keywords cleft lip, cleft palate, orofacial cleft, AHRR and synonyms. SLR resulted in 37 included articles.

RESULTS

AHRR is a positional and functional candidate gene for CL/P. In silico analysis detected interactions with other genes previously associated to CL/P like ARNT and CYP1A1. AHRR protein regulates cellular toxicity through TCDD mediated AHR pathway. Exposure to TCDD in animal embryos is AHR mediated and lead to cleft palate due to palate fusion failure and post fusion rupture. AHRR regulates cellular growth and differentiation, fundamental to lip and palatogenesis. AHRR decreases carcinogenesis and recently a higher tumor risk has been described in CL/P patients and families. AHRR is also a smoking biomarker due to changed methylation sites found in smokers DNA although folate intake may partially revert these methylation alterations. This corroborates the role of maternal smoking and lack of folate supplementation as risk factors for CL/P.

CONCLUSION

This research identified the importance of AHRR in dioxin response and demonstrated an example of genetic and environmental interaction, indispensable in the development of many complex diseases.

Severe dioxin-like compound (DLC) contamination in e-waste recycling areas: An under-recognized threat to local health

Electrical and electronic waste (e-waste) burning and recycling activities have become one of the main emission sources of dioxin-like compounds (DLCs). Workers involved in e-waste recycling operations and residents living near e-waste recycling sites (EWRS) are exposed to high levels of DLCs. Epidemiological and experimental in vivo studies have reported a range of interconnected responses in multiple systems with DLC exposure. However, due to the compositional complexity of DLCs and difficulties in assessing mixture effects of the complex mixture of e-waste-related contaminants, there are few studies concerning human health outcomes related to DLC exposure at informal EWRS. In this paper, we have reviewed the environmental levels and body burdens of DLCs at EWRS and compared them with the levels reported to be associated with observable adverse effects to assess the health risks of DLC exposure at EWRS. In general, DLC concentrations at EWRS of many countries have been decreasing in recent years due to stricter regulations on e-waste recycling activities, but the contamination status is still severe. Comparison with available data from industrial sites and well-known highly DLC contaminated areas shows that high levels of DLCs derived from crude e-waste recycling processes lead to elevated body burdens. The DLC levels in human blood and breast milk at EWRS are higher than those reported in some epidemiological studies that are related to various health impacts. The estimated total daily intakes of DLCs for people in EWRS far exceed the WHO recommended total daily intake limit. It can be inferred that people living in EWRS with high DLC contamination have higher health risks. Therefore, more well-designed epidemiological studies are urgently needed to focus on the health effects of DLC pollution in EWRS. Continuous monitoring of the temporal trends of DLC levels in EWRS after actions is of highest importance.

The Aryl Hydrocarbon Receptor (AhR) in the Aging Process: Another Puzzling Role for This Highly Conserved Transcription Factor

Aging is the most important risk factor for the development of major life-threatening diseases such as cardiovascular disorders, cancer, and neurodegenerative disorders. The aging process is characterized by the accumulation of damage to intracellular macromolecules and it is concurrently shaped by genetic, environmental and nutritional factors. These factors influence the functionality of mitochondria, which play a central role in the aging process. Mitochondrial dysfunction is one of the hallmarks of aging and is associated with increased fluxes of ROS leading to damage of mitochondrial components, impaired metabolism of fatty acids, dysregulated glucose metabolism, and damage of adjacent organelles. Interestingly, many of the environmental (e.g., pollutants and other toxicants) and nutritional (e.g., flavonoids, carotenoids) factors influencing aging and mitochondrial function also directly or indirectly affect the activity of a highly conserved transcription factor, the Aryl hydrocarbon Receptor (AhR). Therefore, it is not surprising that many studies have already indicated a role of this versatile transcription factor in the aging process. We also recently found that the AhR promotes aging phenotypes across species. In this manuscript, we systematically review the existing literature on the contradictory studies indicating either pro- or anti-aging effects of the AhR and try to reconcile the seemingly conflicting data considering a possible dependency on the animal model, tissue, as well as level of AhR expression and activation. Moreover, given the crucial role of mitochondria in the aging process, we summarize the growing body of evidence pointing toward the influence of AhR on mitochondria, which can be of potential relevance for aging.

Characteristics, sources and health risks of toxic species (PCDD/Fs, PAHs and heavy metals) in PM2.5 during fall and winter in an industrial area

Particulate toxic species, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals may have significant health risks. This study investigated characteristics, sources and health risks of all three classes of toxic species in PM_2.5 (particles with aerodynamic diameter ≤2.5 μm) samples collected at an industrial area in Changzhou, a big city in the Yangtze Delta region of China. Fourteen heavy metals altogether constituted 2.87% of PM_2.5 mass, with Fe, Al and Zn as the major elements. Principal component analysis (PCA) suggested that heavy metals came from four sources: vehicles, industry, crustal dust, mixed coal combustion and industrial process. The daily average concentration of 18 PAHs was 235.29 ng/m³, accounting for 0.21% of PM_2.5 mass. The dominant PAHs were high molecular weight ones, contributing 73.5% to the total PAHs. Diagnostic analyses indicated that sources of PAHs included vehicle/coal combustion and petroleum emissions, wherein diesel emission played a more important role than gasoline emission. PCA showed that the largest contributor of PAHs was vehicle exhaust mixed with coal combustion, followed by three industry-related sources. Total concentration of 17 PCDD/Fs varied between 3.14 and 37.07 pg/m³, with an average of 14.58 pg/m³. The 10 PCDFs accounted for 70.5% of total concentration of 17 PCDD/Fs. Health risk assessments showed that the carcinogenic risk of heavy metals was acceptable, while risks from PAHs and PCDD/Fs cannot be ignored. Back trajectory analysis indicated that local/regional transported air masses from northern China was the major source areas of the toxic species.

Common differentially expressed proteins were found in mouse cleft palate models induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and retinoic acid

Cleft palate(CP) is a widely studied congenital malformation. However, its etiology and pathogenesis still remain unclear. Proteins are fundamental molecules that participate in every biological process within cells. In this study, we established CP mouse models induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and retinoic acid (RA), using proteomics technology isobaric tags for relative and absolute quantitation (iTRAQ) to investigate the key proteins in the formation of CP. Pregnant mice were given a gavage of TCDD 28μg/kg or retinoic acid 80mg/kg of body weight or equivalent corn oil at gestational day 10.5(GD10.5) and sacrificed at GD 17.5. Foetal mice were recorded and collected for further detection. Western blot was performed to verify the iTRAQ results. Eventually, we obtained 18 common differentially expressed proteins in TCDD group and RA group compared with normal control, 17 up-regulated and 1 down-regulated. 14-3-3sigma and Annexin A1 were up-regulated in experimental groups at GD17.5, which was consistent with Western blot. We speculated that the common differentially expressed proteins might be one of the molecular mechanisms in the formation of cleft palate.

Effect of Dioxins in Milk on the 3D Cultured Primary Buffalo Hepatocyte Model System

Cow and human milk have been reported to contain dioxins ranging from 0.023 to 26.46 and 0.88 to 19 pg/g of fat, respectively. However, the toxic effects of the dioxins in the milk in this range of concentrations were not explored. Therefore, considering the outbred livestock tissues as better models than inbred laboratory animals, the present study targeted to study the effect of dioxins present in the milk on three-dimensionally (3D) cultured buffalo primary hepatocyte spheroids. The spheroids were treated with a model dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), directly and also through milk fat at different concentrations (i.e, 0.02-20 pg/mL) for 24 h. Among the liver-cell-specific (ALB, HNF4α, and AFP) genes, a similar ALB and upregulated HNF4α expression at all treatments indicated the functional and transcriptionally active hepatocyte spheroids. Supportingly, no significant difference in the antiapoptotic gene expression between the treatments of milk fat and milk fat containing dioxins indicated the survivability of the spheroids during dioxin treatments. Among the selected TCDD responsive (CYP1A1, CYP1A2, AHR, CYP1B1, and TIPARP) genes, a nonsignificant increasing trend of the CYP1A1 expression was observed from 0.2 to 10 pg/mL of TCDD concentration through milk fat. This pattern was similar to the reported insensitive response of human primary hepatocytes toward dioxins than that of rat primary hepatocytes. This may indicate that the buffalo hepatocyte spheroids could be better models than rats for TCDD hepatotoxic studies. Further, TCDD in the milk in the range of 0.02-20 pg/mL concentration may not be very hepatotoxic.

Associations between polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans exposure and oxidatively generated damage to DNA and lipid

Polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans (PCDD/Fs) have been reported to induce reactive oxygen species and oxidative stress, but the dose-response relationships have not been explored in molecular epidemiological studies. In this study, a total of 602 participants were recruited, comprising of 215 foundry workers, 171 incineration workers and 216 residents living more than 5 km away from the plants as the reference group. Individual PCDD/Fs exposures were estimated according to PCDD/Fs levels of working and living ambient air and daily foods. Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-iso-prostaglandin-F2α (8-isoPGF2α) were determined to reflect oxidatively generated damage to DNA and lipid. Generalized linear models were used to access the associations between PCDD/Fs exposure and oxidative stress biomarkers. We found that PCDD/Fs exposure and urinary oxidative stress biomarkers of workers were all higher than those of the reference group. Significantly positive exposure-response relationships between individual PCDD/Fs exposures and urinary 8-oxodG and 8-iso-PGF2α were found. Each 1-unit increase in ln-transformed levels of PCDD/Fs exposure generated a 0.78 nmol/mmol creatinine increase in ln-transformed 8-oxodG and a 0.50 ng/mmol creatinine increase in ln-transformed 8-isoPGF2α in foundry workers, a 0.49 nmol/mmol creatinine increase in ln-transformed 8-oxodG and a 0.26 ng/mmol creatinine increase in ln-transformed 8-isoPGF2α in incineration workers, compared with the reference group. And such associations were not modified by tobacco use. Our findings could help to understand the dose-response relationships between PCDD/Fs and oxidatively generated damage to DNA and lipid, and provide an epidemiologic basis for conducting research on the carcinogenesis and other toxicity mechanisms of PCDD/Fs.

Can contamination of the environment by dioxins cause craniofacial defects?

Cleft lip and cleft palate also known as orofacial cleft is a congenital malformation involving the partial or total lack of anatomical continuity of craniofacial tissue. The most common environmental factors that may cause orofacial clefts include pharmaceuticals, alcohol, addictive drugs, and tobacco smoke. Living in the area of industrial factories, garbage, ironworks, crematoria, wastewater treatment plants, and plastic waste landfills also has a significant impact on the development of the craniofacial defects. Some of the main factors causing the formation of congenital craniofacial defects are dioxins, of which emission to the environment is an important environmental and health problem. Dioxins are a diverse group of organic chemical compounds, derivatives of oxanthrene and fumarates, which are organoleptically imperceptible. Acting mainly through induction of inflammation, they influence a number of metabolic processes, including the process of bone mineralization and embryonic development. In this work, we highlight the problem of orofacial cleft including the impact of dioxin on development of this defect and the recommended prevention.