Polychlorinated biphenyls (PCBs) as initiating agents in hepatocellular carcinoma

Multiple-component covalent organic frameworks for simultaneous extraction and determination of multitarget pollutants in sea foods

Persistent organic pollutants (POPs), such as perfluoroalkyl and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and bisphenols (BPs), have been raising global concerns due to their toxic effects on environment and human health. The monitoring of residues of POPs in seafood is crucial for assessing the accumulation of these contaminants in the study area and mitigating potential risks to human health. However, the diversity and complexity of POPs in seafood present significant challenges for their simultaneous detection. Here, a novel multi-component fluoro-functionalized covalent organic framework (OH-F-COF) was designed as SPE adsorbent for simultaneous extraction POPs. On this basis, the recognition and adsorption mechanisms were investigated by molecular simulation. Due to multiple interactions and large specific surface area, OH-F-COF displayed satisfactory coextraction performance for PFASs, PCBs, and BPs. Under optimized conditions, the OH-F-COF sorbent was employed in a strategy of simultaneous extraction and stepwise elution (SESE), in combination with HPLC-MS/MS and GC-MS method, to effectively determined POPs in seafood collected from coastal areas of China. The method obtained low detection limits for BPs (0.0037 -0.0089 ng/g), PFASs (0.0038 -0.0207 ng/g), and PCBs (0.2308 -0.2499 ng/g), respectively. This approach provided new research ideas for analyzing and controlling multitarget POPs in seafood. ENVIRONMENTAL IMPLICATIONS: Persistent organic pollutants (POPs), such as perfluoroalkyl and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and bisphenols (BPs), have caused serious hazards to human health and ecosystems. Hence, there is a need to develop a quantitative method that can rapidly detect POPs in environmental and food samples. Herein, a novel multi-component fluorine-functionalized covalent organic skeletons (OH-F-COF) were prepared at room temperature, and served as adsorbent for POPs. The SESE-SPE strategy combined with chromatographic techniques was used to achieve a rapid detection of POPs in sea foods from the coastal provinces of China. This method provides a valuable tool for analyzing POPs in environmental and food samples.

DNA modifications: Biomarkers for the exposome?

The concept of the exposome is the encompassing of all the environmental exposures, both exogenous and endogenous, across the life course. Many, if not all, of these exposures can result in the generation of reactive species, and/or the modulation of cellular processes, that can lead to a breadth of modifications of DNA, the nature of which may be used to infer their origin. Because of their role in cell function, such modifications have been associated with various major human diseases, including cancer, and so their assessment is crucial. Historically, most methods have been able to only measure one or a few DNA modifications at a time, limiting the information available. With the development of DNA adductomics, which aims to determine the totality of DNA modifications, a far more comprehensive picture of the DNA adduct burden can be gained. Importantly, DNA adductomics can facilitate a "top-down" investigative approach whereby patterns of adducts may be used to trace and identify the originating exposure source. This, together with other 'omic approaches, represents a major tool for unraveling the complexities of the exposome and hence allow a better a understanding of the environmental origins of disease.

Chronic Aroclor 1260 exposure alters the mouse liver proteome, selenoproteins, and metals in steatotic liver disease

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to increase due in part to the obesity epidemic and to environmental exposures to metabolism disrupting chemicals. A single gavage exposure of male mice to Aroclor 1260 (Ar1260), an environmentally relevant mixture of non-dioxin-like polychlorinated biphenyls (PCBs), resulted in steatohepatitis and altered RNA modifications in selenocysteine tRNA 34 weeks post-exposure. Unbiased approaches identified the liver proteome, selenoproteins, and levels of 25 metals. Ar1260 altered the abundance of 128 proteins. Enrichment analysis of the liver Ar1260 proteome included glutathione metabolism and translation of selenoproteins. Hepatic glutathione peroxidase 4 (GPX4) and Selenoprotein O (SELENOO) were increased and Selenoprotein F (SELENOF), Selenoprotein S (SELENOS), Selenium binding protein 2 (SELENBP2) were decreased with Ar1260 exposure. Increased copper, selenium (Se), and zinc and reduced iron levels were detected. These data demonstrate that Ar1260 exposure alters the (seleno)proteome, Se, and metals in MASLD-associated pathways.

Complex roles for sulfation in the toxicities of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are persistent organic toxicants derived from legacy pollution sources and their formation as inadvertent byproducts of some current manufacturing processes. Metabolism of PCBs is often a critical component in their toxicity, and relevant metabolic pathways usually include their initial oxidation to form hydroxylated polychlorinated biphenyls (OH-PCBs). Subsequent sulfation of OH-PCBs was originally thought to be primarily a means of detoxication; however, there is strong evidence that it may also contribute to toxicities associated with PCBs and OH-PCBs. These contributions include either the direct interaction of PCB sulfates with receptors or their serving as a localized precursor for OH-PCBs. The formation of PCB sulfates is catalyzed by cytosolic sulfotransferases, and, when transported into the serum, these metabolites may be retained, taken up by other tissues, and subjected to hydrolysis catalyzed by intracellular sulfatase(s) to regenerate OH-PCBs. Dynamic cycling between PCB sulfates and OH-PCBs may lead to further metabolic activation of the resulting OH-PCBs. Ultimate toxic endpoints of such processes may include endocrine disruption, neurotoxicities, and many others that are associated with exposures to PCBs and OH-PCBs. This review highlights the current understanding of the complex roles that PCB sulfates can have in the toxicities of PCBs and OH-PCBs and research on the varied mechanisms that control these roles.

Evaluating the trophic transfer of PCBs from fish to humans: Insights from a synergism of environmental monitoring and physiologically-based pharmacokinetic modeling

Accumulation of polychlorinated biphenyls (PCBs) within fish tissues has prompted many states to issue consumption advisories. In Pennsylvania such advisories suggest one meal per month for most game species harvested from Lake Erie; however, these advisories do not account for the emergent properties of regional PCB mixtures, and the downstream accumulation of PCB congeners into human tissues is poorly documented. This study aimed to demonstrate the utility of pairing environmental monitoring with pharmacokinetic modeling for the purpose of estimating dietary PCB exposure in humans. We qualified and quantified the PCB congeners present in the filets of five Lake Erie fish species and used these data to estimate exposure under consumption scenarios that matched or exceeded the advisories. Physiologically-based pharmacokinetic (PBPK) modeling was then employed to predict PCB accumulation within seven tissue compartments of a hypothetical man and woman over 10 years. Twenty-one congeners were detected between the five fish species at concentrations ranging from 56.0 to 411.7 ng/g. Predicted accumulation in human tissues varied based on tissue type, the species consumed, biological sex, and fish-consumption rate. Notably, steady-state concentrations were higher in fatty tissue compartments ("Fat" and "Liver") and across all tissues in women compared to men. This study serves as a preliminary blueprint for generating predictions of site-specific and tissue-specific exposure through the integration of environmental monitoring and pharmacokinetic modeling. Although the details may vary across applications, this simple approach could complement traditional exposure assessments for vulnerable communities in the Great Lakes region that continue to suffer from legacy contamination.

The exposome and liver disease - how environmental factors affect liver health

Since the initial development of the exposome concept, much effort has been devoted to the characterisation of the exposome through analytical, epidemiological, and toxicological/mechanistic studies. There is now an urgent need to link the exposome to human diseases and to include exposomics in the characterisation of environment-linked pathologies together with genomics and other omics. Liver diseases are particularly well suited for such studies since major functions of the liver include the detection, detoxification, and elimination of xenobiotics, as well as inflammatory responses. It is well known that several liver diseases are associated with i) addictive behaviours such as alcohol consumption, smoking, and to a certain extent dietary imbalance and obesity, ii) viral and parasitic infections, and iii) exposure to toxins and occupational chemicals. Recent studies indicate that environmental exposures are also significantly associated with liver diseases, and these include air pollution (particulate matter and volatile chemicals), contaminants such as polyaromatic hydrocarbons, bisphenol A and per-and poly-fluorinated substances, and physical stressors such as radiation. Furthermore, microbial metabolites and the "gut-liver" axis play a major role in liver diseases. Exposomics is poised to play a major role in the field of liver pathology. Methodological advances such as the exposomics-metabolomics framework, the determination of risk factors' genomic and epigenomic signatures, and cross-species biological pathway analysis should further delineate the impact of the exposome on the liver, opening the way for improved prevention, as well as the identification of new biomarkers of exposure and effects, and additional therapeutic targets.

Influence of e-waste exposure on DNA damage and DNA methylation in people living near recycling sites

The association between long-term exposure to e-waste and poor health is well established, but how e-waste exposure affects DNA methylation is understudied. In this study, we measured the DNA damage levels and the alternation of DNA methylation in peripheral blood mononuclear cells (PBMCs) collected from a population exposed to e-waste. The concentration of 28 PCB congeners in the blood samples of e-waste recycling workers was elevated than those of the reference group. DNA damage levels were significantly higher than that of samples from the reference group by detecting the SCGE, CA, and CBMN assays. Eventually, we found that the methylation level of 1233 gene loci was changed in the exposure group. Bioinformatic analysis of differential genes revealed that the hypermethylated genes were enriched in cell component movement and regulation of cell function, and hypomethylated genes were involved in the cellular metabolic process. Among the 30 genes we tested, 14 genes showed a negative correlation between methylation level and expression level. Therefore, e-waste exposure potentially increased the levels of DNA damage and alters DNA methylation, which would likely impact human health.

Exposure to environmental chemicals and cancer risk: epidemiological evidence from Japanese studies

Exposure to certain chemicals in the environment may contribute to the risk of developing cancer. Although cancer risk from environmental chemical exposure among general populations is considered low compared to that in occupational settings, many people may nevertheless be chronically exposed to relatively low levels of environmental chemicals which vary by such various factors as residential area, lifestyle, and dietary habits. It is therefore necessary to assess population-specific exposure levels and examine their association with cancer risk. Here, we reviewed epidemiological evidence on cancer risk and exposure to dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), cadmium, arsenic, and acrylamide. Japanese are widely exposed to these chemicals, mainly through the diet, and an association with increased cancer risk is suspected. Epidemiological evidence from Japanese studies to date does not support a positive association between blood concentrations of DDT, HCH, PCBs, and PFASs and risk of breast or prostate cancer. We established assessment methods for dietary intake of cadmium, arsenic, and acrylamide using a food frequency questionnaire. Overall, dietary intakes of cadmium, arsenic, and acrylamide were not significantly associated with increased risk of total cancer and major cancer sites in the Japan Public Health Center-based Prospective Study. However, statistically significant positive associations were observed between dietary cadmium intake and risk of estrogen receptor-positive breast cancer among postmenopausal women, and dietary arsenic intake and risk of lung cancer among male smokers. In addition, studies using biomarkers as exposure assessment revealed statistically significant positive associations between urinary cadmium concentration and risk of breast cancer, and between ratio of hemoglobin adducts of acrylamide and glycidamide and risk of breast cancer. Epidemiological studies of general populations in Japan are limited and further evidence is required. In particular, studies of the association of organochlorine and organofluorine compounds with risk of cancer sites other than breast and prostate cancer are warranted, as are large prospective studies of the association between biomarkers of exposure and risk of cancer.

Derivatives of Plastics as Potential Carcinogenic Factors: The Current State of Knowledge

Simple Summary

Nowadays, micro- and nanoplastic particles can be found almost everywhere, being especially harmful for humans. Their absorption, primarily via inhalation and digestive routes, might lead to a particularly dangerous accumulation of those substances within the human body. Due to the alarming increase in contamination worldwide and excessive production of plastics and synthetic materials, there is an urgent need to investigate the effects of those substances on human health. So far, it has been observed that nano- and microplastics might be extremely harmful, leading to serious health conditions, such as cancers of various human body systems.

Abstract

Micro- and nanoplatics have been already reported to be potential carcinogenic/mutagenic substances that might cause DNA damage, leading to carcinogenesis. Thus, the effects of micro- and nanoplastics exposure on human health are currently being investigated extensively to establish clear relationships between those substances and health consequences. So far, it has been observed that there exists a definite correlation between exposure to micro- and nanoplastic particles and the onset of several cancers. Therefore, we have conducted research using PubMed, Web of Science, and Scopus databases, searching for all the research papers devoted to cancers that could be potentially related to the subject of exposure to nano- and microplastics. Ultimately, in this paper, we have discussed several cancers, including hepatocellular carcinoma, pancreatic cancer, pancreatic ductal adenocarcinoma, biliary tract cancer, and some endocrine-related cancers.

Metabolism of 3-Chlorobiphenyl (PCB 2) in a Human-Relevant Cell Line: Evidence of Dechlorinated Metabolites

Lower chlorinated polychlorinated biphenyls (LC-PCBs) and their metabolites make up a class of environmental pollutants implicated in a range of adverse outcomes in humans; however, the metabolism of LC-PCBs in human models has received little attention. Here we characterize the metabolism of PCB 2 (3-chlorobiphenyl), an environmentally relevant LC-PCB congener, in HepG2 cells with in silico prediction and nontarget high-resolution mass spectrometry. Twenty PCB 2 metabolites belonging to 13 metabolite classes, including five dechlorinated metabolite classes, were identified in the cell culture media from HepG2 cells exposed for 24 h to 10 μM or 3.6 nM PCB 2. The PCB 2 metabolite profiles differed from the monochlorinated metabolite profiles identified in samples from an earlier study with PCB 11 (3,3'-dichlorobiphenyl) under identical experimental conditions. A dechlorinated dihydroxylated metabolite was also detected in human liver microsomal incubations with monohydroxylated PCB 2 metabolites but not PCB 2. These findings demonstrate that the metabolism of LC-PCBs in human-relevant models involves the formation of dechlorination products. In addition, untargeted metabolomic analyses revealed an altered bile acid biosynthesis in HepG2 cells. Our results indicate the need to study the disposition and toxicity of complex PCB 2 metabolites, including novel dechlorinated metabolites, in human-relevant models.

The Effects of Physical Activity on the Gut Microbiota and the Gut–Brain Axis in Preclinical and Human Models: A Narrative Review

Increasing evidence supports the importance of the gut microbiota (GM) in regulating multiple functions related to host physical health and, more recently, through the gut–brain axis (GBA), mental health. Similarly, the literature on the impact of physical activity (PA), including exercise, on GM and GBA is growing. Therefore, this narrative review summarizes and critically appraises the existing literature that delves into the benefits or adverse effects produced by PA on physical and mental health status through modifications of the GM, highlighting differences and similarities between preclinical and human studies. The same exercise in animal models, whether performed voluntarily or forced, has different effects on the GM, just as, in humans, intense endurance exercise can have a negative influence. In humans and animals, only aerobic PA seems able to modify the composition of the GM, whereas cardiovascular fitness appears related to specific microbial taxa or metabolites that promote a state of physical health. The PA favors bacterial strains that can promote physical performance and that can induce beneficial changes in the brain. Currently, it seems useful to prioritize aerobic activities at a moderate and not prolonged intensity. There may be greater benefits if PA is undertaken from a young age and the effects on the GM seem to gradually disappear when the activity is stopped. The PA produces modifications in the GM that can mediate and induce mental health benefits.

Polychlorinated Biphenyls (PCBs) in the Environment: Occupational and Exposure Events, Effects on Human Health and Fertility

In the last decade or so, polychlorinated biphenyls (PCBs) garnered renewed attention in the scientific community due to new evidence pointing at their continued presence in the environment and workplaces and the potential human risks related to their presence. PCBs move from the environment to humans through different routes; the dominant pathway is the ingestion of contaminated foods (fish, seafood and dairy products), followed by inhalation (both indoor and outdoor air), and, to a lesser extent, dust ingestion and dermal contact. Numerous studies reported the environmental and occupational exposure to these pollutants, deriving from building materials (flame-retardants, plasticizers, paints, caulking compounds, sealants, fluorescent light ballasts, etc.) and electrical equipment. The highest PCBs contaminations were detected in e-waste recycling sites, suggesting the need for the implementation of remediation strategies of such polluted areas to safeguard the health of workers and local populations. Furthermore, a significant correlation between PCB exposure and increased blood PCB concentrations was observed in people working in PCB-contaminated workplaces. Several epidemiological studies suggest that environmental and occupational exposure to high concentrations of PCBs is associated with different health outcomes, such as neuropsychological and neurobehavioral deficits, dementia, immune system dysfunctions, cardiovascular diseases and cancer. In addition, recent studies indicate that PCBs bioaccumulation can reduce fertility, with harmful effects on the reproductive system that can be passed to offspring. In the near future, further studies are needed to assess the real effects of PCBs exposure at low concentrations for prolonged exposure in workplaces and specific indoor environments.

Polychlorinated biphenyl quinone exposure promotes breast cancer aerobic glycolysis: An in vitro and in vivo examination

Polychlorinated biphenyls (PCBs) were classified as group I carcinogenic to humans, as their toxicological mechanisms have been associated with cancer initiation and promotion. However, whether PCBs have effects on cancer progression are still largely veiled. Here, we for the first time discovered that a PCB quinone-type metabolite, namely PCB29-pQ, exposure significantly promoted aerobic glycolysis, a hallmark property of metabolic reprogramming in cancer progression. PCB29-pQ exposure activated corresponding glucose transporter type 1 (GLUT1)/integrin β1/Src/focal adhesion kinase (FAK) signaling pathway in breast cancer MDA-MB-231 cells. Conversely, the inhibition of GLUT1 reversed this effect, as well as the ability of migration and invasion of MDA-MB-231 cells. In addition, PCB29-pQ-induced breast cancer metastasis in 4T1-luc cell inoculated nude mice is repressed by GLUT1 inhibition. Overall, our results demonstrated a novel mechanism that PCB29-pQ exposure promotes aerobic glycolysis in both in vitro and in vivo breast cancer models in a GLUT1-dependent fashion, which may provide a strategy to prevent breast cancer cell spread.

Environmental exposure as a risk-modifying factor in liver diseases: Knowns and unknowns

Liver diseases are considered to predominantly possess an inherited or xenobiotic etiology. However, inheritance drives the ability to appropriately adapt to environmental stressors, and disease is the culmination of a maladaptive response. Thus “pure” genetic and “pure” xenobiotic liver diseases are modified by each other and other factors, identified or unknown. The purpose of this review is to highlight the knowledgebase of environmental exposure as a potential risk modifying agent for the development of liver disease by other causes. This exercise is not to argue that all liver diseases have an environmental component, but to challenge the assumption that the current state of our knowledge is sufficient in all cases to conclusively dismiss this as a possibility. This review also discusses key new tools and approaches that will likely be critical to address this question in the future. Taken together, identifying the key gaps in our understanding is critical for the field to move forward, or at the very least to “know what we don't know.”

Human hepatic microsomal sulfatase catalyzes the hydrolysis of polychlorinated biphenyl sulfates: A potential mechanism for retention of hydroxylated PCBs

Polychlorinated biphenyls (PCBs) are persistent environmental contaminants that continue to be of concern due to their varied toxicities. Upon human exposure, many PCBs with lower numbers of chlorine atoms are metabolized to hydroxylated derivatives (OH-PCBs), and cytosolic sulfotransferases can subsequently catalyze the formation of PCB sulfates. Recent studies have indicated that PCB sulfates bind reversibly with a high affinity to human serum proteins, and that they are also taken up by cells and tissues. Since PCB sulfates might be hydrolyzed to the more toxic OH-PCBs, we have investigated the ability of human hepatic microsomal sulfatase to catalyze this reaction. Twelve congeners of PCB sulfates were substrates for the microsomal sulfatase with catalytic rates exceeding that of dehydroepiandrosterone sulfate as a comparison substrate for steroid sulfatase (STS). These results are consistent with an intracellular mechanism for sulfation and de-sulfation that may contribute to retention and increased time of exposure to OH-PCBs.

Reactive oxygen species: Role in carcinogenesis, cancer cell signaling and tumor progression

Cancer is one of the major causes of death in the world and its global burden is expected to continue increasing. In several types of cancers, reactive oxygen species (ROS) have been extensively linked to carcinogenesis and cancer progression. However, studies have reported conflicting evidence regarding the role of ROS in cancer, mostly dependent on the cancer type or the step of the tumorigenic process. We review recent studies describing diverse aspects of the interplay of ROS with cancer in the different stages of cancer progression, with a special focus on their role in carcinogenesis, their importance for cancer cell signaling and their relationship to the most prevalent cancer risk factors.

Mutagenicity, health risk, and disease burden of exposure to organic micropollutants in water from a drinking water treatment plant in the Yangtze River Delta, China

A wide variety of organic micropollutants in drinking water pose a serious threat to human health. This study was aimed to reveal the characteristics of organic micropollution profiles in water from a drinking water treatment plant (DWTP) in the Yangtze River Delta, China and investigate the mutagenicity, health risk and disease burden through mixed exposure to micropollutants in water. The presence of organic micropollutants in seven categories in organic extracts (OEs) of water from the DWTP was determined, and Ames test was conducted to test the mutagenic effect of OEs. Meanwhile, health risk of exposure to organic micropollutants in finished water through three exposure routes (ingestion, dermal absorption and inhalation) was assessed with the method proposed by U.S. EPA, and disability-adjusted life years (DALYs) were combined to estimate the disease burden of cancer based on the carcinogenic risk (CR) assessment. The results showed that 28 organic micropollutants were detected in the raw and finished water at total concentrations of 967.28 ng/L and 1073.45 ng/L, respectively, of which phthalate esters (PAEs) were the dominant category (95.79% in the raw water and 96.61% in the finished water). Although the results of the Ames test for OEs were negative and the non-carcinogenic hazard index of the organic micropollutants in the finished water was less than 1 in all age groups, the total CR was 2.17 × 10^-5, higher than the negligible risk level (1.00 × 10^-6). The total DALYs caused by the organic micropollutants in the finished water was 2945.59 person-years, and the average individual DALYs was 2.21 × 10^-6 per person-year (ppy), which was 2.21 times the reference risk level (1.00 × 10^-6 ppy) defined by the WHO. Exposure to nitrosamines (NAms) was the major contributor to the total CR (92.06%) and average individual DALYs (94.58%). This study demonstrated that despite the negative result of the mutagenicity test with TA98 and TA100 strains, the health risk of exposure to organic micropollutants in drinking water should not be neglected.

Endocrine disrupting chemicals and breast cancer cells

Many hundreds of endocrine disrupting chemicals (EDCs) have been measured as entering human breast tissue from a range of environmental sources, and this review focuses on discussion of mechanisms by which such EDCs may be contributing to the globally rising incidence of breast cancer. Many of the distinguishing features of breast cancer may be accounted for by EDC exposure, including, but not limited to, the fact that many EDCs possess estrogenic activity and exposure to estrogen is a main risk factor for breast cancer. Studies of the actions of EDCs in human breast cancer cells are aided by use of the conceptual framework of the hallmarks of cancer, and, acting by a variety of genomic and nongenomic mechanisms, EDCs have now been shown to enable all the hallmarks of cancer to develop in human breast cancer cells. Many studies report that hallmarks can develop at concentrations which are within the range of those measured in human breast tissues, especially when added as mixtures. The varied levels of different EDCs measured in individual breast tissue samples together with the overlapping and complementary mechanisms of action of the EDCs imply that thematic mechanisms will be driven inevitably by different chemical mixtures. Despite the complexity, EDCs do need to now be acknowledged as a risk factor for breast cancer in order for preventative strategies to include reduction in EDC exposure.

Biotechnology-based microbial degradation of plastic additives

Plastic additives are agents responsible to the flame resistance, durability, microbial resistance, and flexibility of plastic products. High demand for production and use of plastic additives is associated with environmental accumulation and various health hazards. One of the suitable methods of depleting plastic additive in the environment is bioremediation as it offers cost-efficiency, convenience, and sustainability. Microbial activity is one of the effective ways of detoxifying various compounds as microorganisms can adapt in an environment with high prevalence of pollutants. The present review discusses the use and abundance of these plastic additives, their health-related risks, the microorganisms capable of degrading them, the proposed mechanism of biodegradation, and current innovations capable of improving the efficiency of bioremediation.

In vivo experimental study to investigate cytogenotoxicity of a contaminated estuary from Southeastern Brazilian Coast

The aim of this study was to evaluate cytogenotoxicity in mammalian cells induced by ingestion of superficial water from SESS. For this purpose, surface water was collected from two points of SESS: São Vicente Channel (SVC) and Piaçaguera Channel (PIC). Four groups (n = 5) of adult male Wistar (8 weeks old) received for 5 days: (a) filtered tap water (water control), (b) tap water with 2.4% of NaCl (saline control), (c) estuarine water from PIC and (d) estuarine water from SVC. Results demonstrated that Ki67 immunoexpression was higher in hepatocytes exposed to both sampling site, while caspase-3 demonstrated downregulation in rat liver exposed to estuarine water. There was also significant increase in micronuclei frequency in bone marrow cells and hepatocytes, and DNA damage in blood and liver of rats exposed to estuarine water from SVC and PIC. In summary, studies with complex mixtures, such as contaminated estuarine water are important since this work confirmed by experiments using in vivo mammalian cells of rats that SESS water are genotoxic, mutagenic and cytotoxic, denoting concern for environmental health.

Ceramide/protein phosphatase 2A axis is engaged in gap junction impairment elicited by PCB153 in liver stem-like progenitor cells

The widespread environmental pollutant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) is a non-dioxin-like toxicant. It is a potential carcinogen compound able to induce gap junction (GJ) intercellular communication impairment, probably the first non-genomic event leading to tumor promotion. Although PCBs have been known for many years, the molecular mode of PCB153 action is still unclear. Recent studies from our research group have shown that the toxicant elicits a transient modulation of connexin (Cx) 43-formed GJs in hepatic stem-like WB-F344 cells involving sphingosine 1-phosphate (S1P) path. Taking into account that other strictly related bioactive sphingolipids, such as ceramide (Cer), may have different effects from S1P, here we aim to clarify the signaling paths engaged by PCB153 in the control of GJs, focusing primarily on the role of Cer. Accordingly, we have achieved a combined biomolecular and electrophysiological analysis of GJs in cultured WB-F344 cells treated with PCB153 at different time points. We have found that the toxicant elicited a time-dependent regulation of GJs formed by different Cx isoforms, through a transient modulation of Cer/Cer kinase (CerK) axis and, in turn, of protein phosphatase 2A (PP2A). Our new findings demonstrate the existence of a specific molecular mechanism downstream to Cer, which distinctly affects the voltage-dependent and -independent GJs in liver stem-like cells, and open new opportunities for the identification of additional potential targets of these environmental toxicants.

3,3'-Dichlorobiphenyl Is Metabolized to a Complex Mixture of Oxidative Metabolites, Including Novel Methoxylated Metabolites, by HepG2 Cells

3,3'-Dichlorobiphenyl (PCB 11) is a byproduct of industrial processes and detected in environmental samples. PCB 11 and its metabolites are present in human serum, and emerging evidence demonstrates that PCB 11 is a developmental neurotoxicant. However, little is known about the metabolism of PCB 11 in humans. Here, we investigated the metabolism of PCB 11 and the associated metabolomics changes in HepG2 cells using untargeted high-resolution mass spectrometry. HepG2 cells were exposed for 24 h to PCB 11 in DMSO or DMSO alone. Cell culture media were analyzed with ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. Thirty different metabolites were formed by HepG2 cells exposed to 10 μM PCB 11, including monohydroxylated, dihydroxylated, methoxylated-hydroxylated, and methoxylated-dihydroxylated metabolites and the corresponding sulfo and glucuronide conjugates. The methoxylated PCB metabolites were observed for the first time in a human-relevant model. 4-OH-PCB 11 (3,3'-dichlorobiphenyl-4-ol) and the corresponding catechol metabolite, 4,5-di-OH-PCB 11 (3',5-dichloro-3,4-dihydroxybiphenyl), were unambiguously identified based on liquid and gas chromatographic analyses. PCB 11 also altered several metabolic pathways, in particular vitamin B6 metabolism. These results demonstrate that complex PCB 11 metabolite profiles are formed in HepG2 cells that warrant further toxicological investigation, particularly since catechol metabolites are likely reactive and toxic.

Cardiovascular Effects of Polychlorinated Biphenyls and Their Major Metabolites

BACKGROUND

Xenobiotic metabolism is complex, and accounting for bioactivation and detoxification processes of chemicals remains among the most challenging aspects for decision making with in vitro new approach methods data.

OBJECTIVES

Considering the physiological relevance of human organotypic culture models and their utility for high-throughput screening, we hypothesized that multidimensional chemical-biological profiling of chemicals and their major metabolites is a sensible alternative for the toxicological characterization of parent molecules vs. metabolites in vitro.

METHODS

In this study, we tested 25 polychlorinated biphenyls (PCBs) [PCB 3, 11, 52, 126, 136, and 153 and their relevant metabolites (hydroxylated, methoxylated, sulfated, and quinone)] in concentration-response (10 nM-100μM) for effects in human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) and endothelial cells (ECs) (iPSC-derived and HUVECs). Functional phenotypic end points included effects on beating parameters and intracellular Ca2+ flux in CMs and inhibition of tubulogenesis in ECs. High-content imaging was used to evaluate cytotoxicity, mitochondrial integrity, and oxidative stress.

RESULTS

Data integration of a total of 19 physicochemical descriptors and 36 in vitro phenotypes revealed that chlorination status and metabolite class are strong predictors of the in vitro cardiovascular effects of PCBs. Oxidation of PCBs, especially to di-hydroxylated and quinone metabolites, was associated with the most pronounced effects, whereas sulfation and methoxylation of PCBs resulted in diminished bioactivity.

DISCUSSION

Risk characterization analysis showed that although in vitro derived effective concentrations exceeded the levels measured in the general population, risks cannot be ruled out due to the potential for population variability in susceptibility and the need to fill data gaps using read-across approaches. This study demonstrated a strategy for how in vitro data can be used to characterize human health risks from PCBs and their metabolites. https://doi.org/10.1289/EHP7030.

Endocrine disruptors from the environment affecting breast cancer

Evaluation of carcinogenic substances from the environment is a challenge for scientists. Recently, a novel approach based on 10 key characteristics of human carcinogens classified by the International Agency for Research on Cancer (IARC) has emerged. Carcinogenesis depends on different mechanisms and factors, including genetic, infectious (bacteria, viruses) and environmental (chemicals) factors. Endocrine disruptors are exogenous chemicals that can interfere and impair the function of the endocrine system due to their interaction with estrogen receptors or their estrogen signaling pathways inducing adverse effects in the normal mammary development, originating cancer. They are heterogeneous chemicals and include numerous synthetic substances used worldwide in agriculture, industry and consumer products. The most common are plasticizers, such as bisphenol A (BPA), pesticides, such as dichlorodiphenyltrichloroethane, and polychlorinated biphenyls (PCBs). Xenoestrogens appear to serve an important role in the increased incidence of breast cancer in the United States and numerous other countries. Several studies have demonstrated the role of organochlorine xenoestrogens in breast cancer. Therefore, the overall cumulative exposure of women to estrogens results in an increased risk for this type of cancer. Factors like lifestyle and diet also serve a role in the increased incidence of this disease. The aim of the present study was to analyze these chemical compounds based on the key characteristics given by the IARC, with a special focus on breast cancer, to establish whether these compounds are carcinogens, and to create a model for future analysis of other endocrine disruptors.

Human CYP2E1-activated mutagenicity of dioxin-like PCBs 105 and 118-Experimental data consistent with molecular docking results

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with human carcinogenicity. Many lower chlorinated and non-dioxin-like PCBs have been observed to be mutagenic following activation by human CYP2E1, while activation of dioxin-like (DL-) PCBs by this enzyme has never been evidenced. In this study, each DL-PCB was analyzed by molecular docking to human CYP2E1 protein for predicting a substrate interaction. All compounds demonstrated high affinities with the active site of human CYP2E1, binding energy being -8.7 ∼ -9.7 kcal/mol. However, most compounds demonstrated ligand-heme distances as ≥ 6.8 Å, while the values for 2,3,3',4,4'- (PCB 105) and 2,3',4,4',5-pentachlorobiphenyl (PCB 118) were 5.3 and 5.4 Å, respectively (valid for electron transfer). Experimentally, both PCB 105 and 118 induced micronuclei in a V79-derived cell line engineered for expression of human CYP2E1 at low micromolar concentrations, while inactive or weakly positive in V79-Mz control cells; these effects were blocked or reduced by 1-aminobenzotriazole, a suicide CYP inhibitor. However, DL-PCBs 77, 81 and 126 were all negative in both cell lines. In a human hepatoma (C3A) cell line, PCB 105 and 118 induced micronuclei marginally, while with ethanol pretreatment (to stabilize CYP2E1) both compounds induced micronuclei efficiently, and co-exposure to trans-1,2-dichloroethylene (a selective CYP2E1 inhibitor) led to clearly negative results with both compounds. Finally, both PCB 105 and 118 induced PIG-A gene mutations in C3A cells, which was blocked by trans-1,2-dichloroethylene. In summary, in silico and experimental results consistently suggest that DL- PCBs 105 and 118 may be activated by human CYP2E1 for mutagenic activities.

Assessment of a potential PCB exposure among (former) underground miners by hydraulic fluids

Polychlorinated biphenyls (PCBs) were used in technical mixtures of different PCB congeners as hydraulic fluids in underground mining in Germany in North Rhine-Westphalia, Ibbenbueren, and Saarland from the mid-1960s to 1986. Mine workers who were involved in maintenance and repair or operation of hydraulically driven machines in underground mines were potentially exposed to liquids containing PCBs. The aim of the present study was to investigate whether this potential exposure which occurred more than 30 years ago was still detectable. Biomonitoring and a structured work anamnesis were conducted on a representative sample of 210 miners. PCBs in plasma were measured by gas chromatography coupled to mass spectrometry with an LOQ of 0.01 µg/L plasma for all congeners. The primary aim was comparison of the number of exceedances of the underlying comparative values for PCB congeners with those of the general population. Secondary endpoint was the question whether there were regional differences in potential PCB exposure. The biomonitoring showed a significant difference for PCB 74 with N= 94 (45%); for PCB 114 with N = 64 (31%) and for PCB 99 and PCB 105 with N = 23 (11%) and N = 19 (9%) of 210 measurements above the reference value compared to the general population (5%). The all over detection frequencies (µg/L plasma median | SD | min |max) of these congeners were as follows:PCB 74: 0.128 | 0.481 | < LOD | 3.098; PCB 99:0.035 | 0.078 | < LOD | 0.582PCB 105: 0.005 | 0.031 | < LOD | 0.307; PCB 114:0.005 | 0.024 | < LOD | 0.140Regional differences were not detectable.

Gut Microbiota Modulates Interactions Between Polychlorinated Biphenyls and Bile Acid Homeostasis

The gut microbiome is increasingly recognized as a second genome that contributes to the health and diseases of the host. A major function of the gut microbiota is to convert primary bile acids (BAs) produced from cholesterol in the liver into secondary BAs that activate distinct host receptors to modulate xenobiotic metabolism and energy homeostasis. The goal of this study was to investigate to what extent oral exposure to an environmentally relevant polychlorinated biphenyl (PCBs mixture), namely the Fox River mixture, impacts gut microbiome and BA homeostasis. Ninety-day-old adult female conventional (CV) and germ-free (GF) C57BL/6 mice were orally exposed to corn oil (vehicle), or the Fox River mixture at 6 or 30 mg/kg once daily for 3 consecutive days. The PCB low dose profoundly increased BA metabolism related bacteria Akkermansia (A.) muciniphila, Clostridium (C.) scindens, and Enterococcus in the large intestinal pellet (LIP) of CV mice (16S rRNA sequencing/qPCR). This correlated with a PCB low dose-mediated increase in multiple BAs in serum and small intestinal content (SIP) in a gut microbiota-dependent manner (UPLC-MS/MS). Conversely, at PCB high dose, BA levels remained stable in CV mice correlated with an increase in hepatic efflux transporters and ileal Fgf15. Interestingly, lack of gut microbiota potentiated the PCB-mediated increase in taurine conjugated α and β muricholic acids in liver, SIP, and LIP. Pearson's correlation identified positive correlations between 5 taxa and most secondary BAs. In conclusion, PCBs dose-dependently altered BA homeostasis through a joint effort between host gut-liver axis and intestinal bacteria.

Concentrations and risks of polychlorinated biphenyls (PCBs) in transformer oils and the environment of a power plant in the Niger Delta, Nigeria

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Soils and water resources around the power plant are contaminated with PCBs.

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The hepta- and octa-PCB homologues were dominant in the samples.

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Exposure to PCBs in soils from the power plant could cause human health risk.

The concentrations of Ʃ14 PCBs were determined, with the aid of gas chromatography-mass spectrometry (GC–MS), in transformer/turbine oils, soils, groundwater, and drainage water collected within a power plant in the Niger Delta of Nigeria. The Ʃ14 PCB concentrations in the transformer oils, drainage water, groundwater and soils ranged from 484 to 48506 mg kg⁻¹, 0.99 to 2.95 mg L⁻¹, 0.16 to 0.56 mg L⁻¹ and from 8.4 to 510 mg kg⁻¹ respectively. The congener distribution patterns in these samples indicate the dominance of highly chlorinated homologues (hepta- and octa-PCBs). The Σ14 PCB concentrations in the transformer oils were above the provisional definition of low persistent organic pollutant (POP) content for PCBs of 50 mg kg⁻¹ as defined in the guidelines on the management of POP waste of the Basel Convention. The concentrations of Ʃ14 PCBs in the soils were above the Dutch guideline value of 1000 μg kg⁻¹ and the estimated incremental lifetime cancer risks relating to exposure of humans to PCBs in soils indicate serious health risks. There is therefore a need to implement a surveillance programme in the vicinity of power plants to determine the impacts on the adjacent ecosystem.

Bulk atmospheric deposition of persistent organic pollutants and polycyclic aromatic hydrocarbons in Central Europe

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are ubiquitous and toxic contaminants. Their atmospheric deposition fluxes on the regional scale were quantified based on simultaneous sampling during 1 to 5 years at 1 to 6 background/rural sites in the Czech Republic and Austria. The samples were extracted and analysed by means of gas chromatography coupled to mass spectrometry. For all seasons and sites, total deposition fluxes for Σ15PAHs ranged 23-1100 ng m-2 d-1, while those for Σ6PCBs and Σ12OCPs ranged 64-4400 and 410-7800 pg m-2 d-1, respectively. Fluoranthene and pyrene were the main contributors to the PAH deposition fluxes, accounting on average for 19% each, while deposition fluxes of PCBs and OCPs were dominated by PCB153 (26%) and γ-hexachlorobenzene (30%), respectively. The highest deposition flux of Σ15PAHs was generally found in spring, while no seasonality was found for PCB deposition. For deposition fluxes for Σ12OCPs, no clear spatial trend was found, confirming the perception of long-lived regional pollutants. Although most OCPs and PCBs hardly partition to the particulate phase in ambient air, on average, 42% of their deposition fluxes were found on filters, confirming the perception that particle deposition is more efficient than dry gaseous deposition. Due to methodological constraints, fluxes derived from bulk deposition samplers should be understood as lower estimates, in particular with regard to those substances which in ambient aerosols mostly partition to the particulate phase.

PCB52 induces hepatotoxicity in male offspring through aggravating loss of clearance capacity and activating the apoptosis: Sex-biased effects on rats

Polychlorinated biphenyls (PCBs), a kind of persistent organic pollutant, can induce hepatotoxicity in mammals. However, PCB-induced hepatotoxicity in offspring and the underlying mechanisms have been rarely studied. In the present study, Wistar rats were administered with corn oil or PCB52 (1 mg/kg body weight/day, by gavage) from gestational day 7 to postnatal day 21. In the PCB52-treated group, birth body lengths and weights were significantly decreased compared with the control group, suggesting developmental toxicity. Cytoplasmic injury in hepatocytes was observed in PCB52-treated male offspring, while no pathologic change was observed in female offspring, suggesting sex-biased hepatotoxicity. Furthermore, using an RNA-Seq method, coincided with the sexual bias, 454 differential expression genes (DEGs) were screened out in liver tissues of PCB52-treated male offspring, while 10 DEGs were screened out in female offspring. By KEGG annotation analysis, 4 in 12 significant pathways in male offspring were metabolism-related. In the present study, together with cytoplasmic injury of hepatocytes, decreased metabolic enzymes both at RNA and protein levels might aggravate loss of clearance capacity of hepatocytes and induce hepatotoxicity. Moreover, over-expressed peroxisome proliferator-activated receptor delta and mitogen-activated protein kinase 9 might activate apoptosis, which was verified by the augments of cleaved poly ADP-ribose polymerase 1 and caspase 3 in PCB52-treated male offspring. Taken together, PCB52 had developmental toxicity and induced sex-biased hepatotoxicity. The hepatotoxicity in male offspring might be attributed to the aggravated loss of clearance capacity and activation of apoptosis.

Low-dose PCB126 compromises circadian rhythms associated with disordered glucose and lipid metabolism in mice

It has been documented that 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) elicits diverse detrimental effects on human health including metabolic syndrome and non-alcoholic fatty-liver disease (NAFLD), through a wide array of non-carcinogenic mechanisms, which require further detailed investigations. The circadian clock system consists of central clock machinery (located in the suprachiasmatic nucleus in the hypothalamus) and the peripheral clocks (located in nearly all peripheral tissues). Peripheral clocks in the liver play fundamental roles in maintaining liver homeostasis, including the regulation of energy metabolism and the expression of enzymes that fine-tune the absorption and metabolism of xenobiotics. However, the molecular basis of whether PCB126 disrupts liver homeostasis (e.g., glucose and lipid metabolism) by dysregulating the circadian clock system is still unknown. Thus, we performed a set of comprehensive analyses of glucose and lipid metabolism in the liver tissues from low-dose PCB126-treated mice. Our results demonstrated that PCB126 diminished glucose and cholesterol levels in serum and elevated glucose and cholesterol levels in the liver. Moreover, PCB126 compromised PGC1α and PDHE1α, which are the driving force for mitochondrial biogenesis and entry of pyruvate into the tricarboxylic acid (TCA) cycle, respectively, and resulted in the accumulation of glucose, glycogen and pyruvate in the liver after PCB126 exposure. Additionally, PCB126 blocked hepatic cholesterol metabolism and export pathways, leading to an elevated localization of hepatic cholesterol. Mechanistic investigations illustrated that PCB126 greatly altered the expression profile of core clock genes and their target rhythm genes involved in orchestrating glucose and cholesterol metabolism. Together, our results demonstrated that a close correlation between PCB126-disturbed glucose and lipid metabolism and disordered physiological oscillation of circadian genes.

A mixture of Persistent Organic Pollutants (POPs) and Azoxymethane (AOM) show potential synergistic effects on intestinal tumorigenesis in the A/J Min/+ mouse model

A multitude of cancer types, including breast, testicular, liver and colorectal cancer, have associations with exposure to Persistent Organic Pollutants (POPs). The present study aimed to investigate whether a mixture of POPs could affect intestinal tumorigenesis in the A/J Min/+ mouse, a model for human colorectal cancer (CRC). Pollutants were selected for their presence in Scandinavian food products and the mixture was designed based on defined human estimated daily intake levels. Mice were exposed through the diet, at control, low and high mixture concentrations, for 10 weeks. In a separate experiment, mice also received one subcutaneous injection of Azoxymethane (AOM) to explore whether this carcinogenic compound influenced the effect of the POPs. Intestinal tumorigenesis was examined by surface microscopy and histopathology. Moderate and dose-dependent increases in tumorigenesis were observed after dietary POP exposure. The AOM treatment alone stimulated the growth of colonic lesions, but did not increase the formation of new lesions. Combined AOM treatment and POP exposure demonstrated a synergistic effect on lesion formation in the colon, and to a lesser extent in the small intestine. This synergy was also evident by an increased number of malignant colonic tumors (carcinomas). In conclusion, the study shows that a mixture of POPs interacted synergistically with a known carcinogen (AOM), causing increased intestinal tumorigenesis in the A/J Min/+ mouse model.

Genomic damage induced by the widely used fungicide chlorothalonil in peripheral human lymphocytes

Chlorothalonil is an important broad spectrum fungicide widely used in agriculture, silviculture, and urban settings. As a result of its massive use, chlorothalonil was found in all environmental matrices, with consequent risks to the health of terrestrial and aquatic organisms, as well as for humans. We analyzed the effects of chlorothalonil on human lymphocytes using in vitro chromosomal aberrations (CAs) and micronuclei (MNi) assays. Lymphocytes were exposed to five concentrations of chlorothalonil: 0.600 µg/mL, 0.060 µg/mL, 0.030 µg/mL, 0.020 µg/mL, and 0.015 µg/mL, where 0.020 and 0.600 µg/mL represent the ADI and the ARfD concentration values, respectively, established by FAO/WHO for this compound; 0.030 and 0.060 μg/mL represent intermediate values of these concentrations and 0.015 μg/mL represents the ADI value established by the Canadian health and welfare agency. We observed cytogenetic effects of chlorothalonil on cultured human lymphocytes in terms of increased CAs and MNi frequencies at all tested concentrations, including the FAO/WHO ADI and ARfD values of 0.020 and 0.600 μg/mL, respectively, but with exception of the Canadian ADI value of 0.015 μg/mL. Finally, no sexes differences were found in the levels of CAs and MNi induced by different chlorothalonil concentrations. Similarly, the mitotic index and the cytokinesis-block proliferation index did not show any significant effect on the proliferative capacity of the cells, although at the chlorothalonil concentration of 0.600 μg/mL the P-values of both indices were borderline.

Hepatic DNA damage in harbour porpoises (Phocoena phocoena) stranded along the English and Welsh coastlines

One level at which persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons PAHs) can exert damage is by causing DNA strand-breaks or nucleotide base modifications, which, if unrepaired, can lead to embryonic mutations, abnormal development and cancer. In marine ecosystems, genotoxicity is expected to be particularly strong in long-lived apex predators due to pollutant bioaccumulation. We conducted 32 P-postlabeling analyses optimized for the detection and quantification of aromatic/hydrophobic DNA adducts in the livers of 40 sexually-mature North Atlantic harbour porpoises (Phocoena phocoena) stranded along the English and Welsh coastlines. We examined hepatic tissue to search for inflammatory and preneoplastic lesions and examine their association with adduct levels. Adducts were found in all porpoises (mean: 17.56 ± 11.95 per 108 nucleotides), and were higher than levels reported for marine vertebrates from polluted sites. The pollutants causing the induced DNA adducts could not be further characterized. Hepatic DNA damage did not correlate with levels of blubber POP concentrations (including total polychlorinated biphenyl [PCBs], dichlorodiphenyltrichloroethane [DDT] and dieldrin); PAH concentrations were not available for the present study. However, DNA damage predicted occurrence of inflammatory and preneoplastic lesions. Further, our data showed a reduction in hepatic DNA adduct levels with age in the 40 animals examined while POP concentrations, particularly PCBs, increased with age. Using a different dataset of 145 mature male harbour porpoises confirmed that higher contaminant levels (total PCBs, DDT and dieldrin) are found in older animals. The reduction in hepatic DNA adduct levels in older animals was in accordance with other studies which show that suppression of hepatic CYP1A enzyme activity at high PCB concentrations might impact on CYP1A-mediated DNA adduct formation of PAHs which are ubiquitous environmental pollutants and readily metabolized by CYP1A to species binding to DNA. In summary, our study shows that pollutant-induced DNA damage is prevalent in harbour porpoises from UK waters and may lead to detectable sub-lethal hepatic damage. Environ. Mol. Mutagen. 59:613-624, 2018. © 2018 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Pollution and respiratory disease: can diet or supplements help? A review

Pollution is known to cause and exacerbate a number of chronic respiratory diseases. The World Health Organisation has placed air pollution as the world's largest environmental health risk factor. There has been recent publicity about the role for diet and anti-oxidants in mitigating the effects of pollution, and this review assesses the evidence for alterations in diet, including vitamin supplementation in abrogating the effects of pollution on asthma and other chronic respiratory diseases. We found evidence to suggest that carotenoids, vitamin D and vitamin E help protect against pollution damage which can trigger asthma, COPD and lung cancer initiation. Vitamin C, curcumin, choline and omega-3 fatty acids may also play a role. The Mediterranean diet appears to be of benefit in patients with airways disease and there appears to be a beneficial effect in smokers however there is no direct evidence regarding protecting against air pollution. More studies investigating the effects of nutrition on rapidly rising air pollution are urgently required. However it is very difficult to design such studies due to the confounding factors of diet, obesity, co-morbid illness, medication and environmental exposure.

Usefulness of RTL-W1 and OLCAB-e3 fish cell lines and multiple endpoint measurements for toxicity evaluation of unknown or complex mixture of chemicals

Fish are currently used for the assessment of chemical toxicity. The REACh regulation and the European directive on the protection of animals used for scientific purposes both recommend the use of methods other than animal testing. In view of this, fish cell lines are increasingly used to provide fast and reliable toxic and ecotoxic data on new chemicals. The sensitivity of the Rainbow trout liver cell line RTL-W1 and Japanese medaka embryos cell line OLCAB-e3 were used with different toxicity endpoints, namely cytotoxicity, EROD activity, ROS production and DNA damage for various classes of pollutants displaying different modes of action but also with complex environmental mixtures. Toxicity tests were coupled with chemical analysis to quantify the chemical concentrations in cell cultures. Differences in sensitivity were found between fish cell lines. MTT reduction assay revealed that OLCAB-e3 cells were more sensitive than RTL-W1 cells. On the contrary, RTL-W1 gave higher response levels for the Fpg-modified comet assay and ROS assay. The OLCAB-e3 cell line did not express EROD activity unlike RTL-W1. This study highlights the capacity of the two different fish cell lines to measure the toxicity of individual toxicants but also environmental mixtures. Then, results obtained here illustrate the interest of using different cell lines and toxicity endpoints to assess the toxicity of complex or unknown mixture of chemicals.

PCB28 and PCB52 induce hepatotoxicity by impairing the autophagic flux and stimulating cell apoptosis in vitro

Hepatotoxicity is one of the adverse health effects induced by polychlorinated biphenyls (PCBs). Recently, autophagy was revealed to play an important role in PCBs-induced toxicology, however, its precise role in PCBs-induced hepatotoxicity is as yet unknown. In this study, treatment of PCB28/PCB52 for 48 h dose-dependently induced hepatotoxicity at doses of 10, 20, 40 and 80 μM in homo and rattus hepatocytes. Expressions of proteins of BECN1, LC3-II and ULK1 significantly increased in PCB28/PCB52-treated cells at a dose of 40 μM, implying initiation of autophagy. Over-expression of p62 suggested deficient clearance of autophagosome. Consistently, accumulation of autophagosome was observed by transmission-electron microscopy and confocal fluorescence microscopy using adenovirus expressing mRFP-GFP-LC3, which may initiate apoptosis. Furthermore, increased reactive oxygen species levels might also induce autophagy and apoptosis. Consistently, cell apoptosis was evoked by the treatment of PCB28/PCB52 compared to the respective controls, which coincided with obvious hepatotoxicity. Subsequently, an inhibitor (3-methlyadenine) and an initiator (rapamycin) of autophagy were used. Compared to PCB28/PCB52 alone-treated cells, initiation of autophagy, blocked autophagic flux, cell apoptosis and hepatotoxicity were alleviated by 3-methlyadenine and aggravated by rapamycin, respectively. Taken together, PCB28 and PCB52 induced hepatotoxicity by impairing autophagic flux and stimulating cell apoptosis in vitro.

Acromegaly, genetic variants of the aryl hydrocarbon receptor pathway and environmental burden

Increasing evidence suggests that environmental contaminants can exert endocrine disruptors activities and that pollution exposition can have a role in tumorigenic processes. Several environmental pollutants have been shown to affect pituitary cells biology and function. The aryl hydrocarbon receptor (AHR) pathway is involved in xenobiotics' metabolism and in tumorigenesis. A deregulation of the AHR pathway could have a role in pituitary tumours' pathophysiology, especially in the GH secreting ones. AHR-interacting protein (AIP) is one of the key partners of AHR and is implicated in pituitary tumours' pathogenesis. Moreover, an increased prevalence of acromegaly has been reported in a highly polluted area of the province of Messina (Sicily, Italy). Nevertheless, at present, few data are available about the potential role of environmental factors in the pathogenesis and clinical expression of GH secreting pituitary tumours. This review is aimed at discussing the evidences on the potential links among environmental pollutants, the AHR pathway and the pathophysiology of GH-secreting pituitary adenomas.

Fish Oil Contaminated with Persistent Organic Pollutants Induces Colonic Aberrant Crypt Foci Formation and Reduces Antioxidant Enzyme Gene Expression in Rats

Background: Epidemiologic, clinical, and experimental studies have suggested that fish oil (FO), a rich source of n-3 (ω-3) polyunsaturated fatty acids, protects against colon cancer. However, this message is confounded by the FDA's warning that the consumption of certain types of fish should be restricted because of contamination with persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and organochlorine pesticides.Objective: We examined FO contaminated with POPs (PCBs, dichlorodiphenyltrichloroethane, and chlordane) compared with unmodified FO on the risk factors of colon cancer development.Methods: Male Sprague-Dawley rats aged 28 d (n = 30) were allocated into 3 groups and fed 15% corn oil (CO), FO, or POP-contaminated FO for 9 wk with a subcutaneous injection of colon carcinogen azoxymethane at weeks 3 and 4. Colonic aberrant crypt foci (ACF) and cell proliferation were enumerated, and the gene expression of inflammation, antioxidant enzymes, and repair enzymes were determined with the use of real-time quantitative polymerase chain reaction analysis.Results: FO-fed rats had a lower number of ACF (mean ± SE: 29 ± 4.0 for FO compared with 53 ± 8.4 for CO and 44 ± 4.6 for POP FO) and higher-multiplicity ACF than the CO and POP FO groups (4.7 ± 0.9 for FO compared with 11 ± 1.5 for CO and 9.6 ± 1.8 for POP FO) (P < 0.05). FO feeding lowered the proliferation index compared with the CO and POP FO feeding groups (18% ± 1.1% for FO compared with 25% ± 1.6% for CO and 23% ± 0.7% for POP FO) (P = 0.009). Superoxide dismutase [2.4 ± 0.6 relative quantification (RQ) for FO compared with 1.2 ± 0.2 RQ for CO and 1.3 ± 0.3 RQ for POP FO] and catalase gene expression (10 ± 2.0 RQ for FO compared with 5.4 ± 1.1 RQ for CO and 6.6 ± 1.5 RQ for POP FO) were higher in the FO group than in the CO and POP FO groups (P < 0.05). There were no differences between CO and POP FO on the variables.Conclusion: These results indicate that POPs in FO reduce the preventive effects of FO on colon carcinogenesis by increasing preneoplastic lesion formation through the downregulation of antioxidant enzyme expression and increasing cell proliferation in rats.

Induction of micronuclei and cell cycle arrest by some tri- and tetrachlorobiphenyls in mammalian cells deficient in xenobiotic-metabolizing enzymes

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with continued public health concerns. The lower chlorinated biphenyls are supposed to be mutagenic following metabolic activation. However, in a preliminary study, we recently observed induction of micronuclei by several PCBs in a subclone of Chinese hamster V79 cell line, V79-Mz, which is deficient in xenobiotic-metabolizing enzyme activities. In this study, metabolism-free genotoxicity of PCBs was investigated, using 10 tri- and tetrachlorobiphenyls, in V79, V79-Mz, and human hepatoma (HepG2) cell lines. Among the four tetrachlorobiphenyls, 2,4,4',5- and 2,3'4,4'-tetrachlorobiphenyl-both having a noncoplanar configuration-induced micronuclei in V79-Mz cells, while their coplanar analogs 3,4,4',5- and 3,3',4,4'-tetrachlorobiphenyl were inactive. Furthermore, 2,3,3'- (PCB 20) and 2,3,4'-trichlorobiphenyl (PCB 22) started to induce micronuclei in V79-Mz cells at 10 μM and higher concentrations, demonstrating more potent effects than observed with 2,2',3-, 2,2',4-, 2,2',5, and 2,4,4'-trichlorobiphenyl. As representative compounds, PCB 20 and 22 induced micronuclei in relatively high concentrations in HepG2 cells (p53-proficient), though they did not induce Hprt gene mutations in V79-Mz cells. PCB 20 and 22 increased mitotic index and induced cell cycle arrest at the G2/M phase, with effects more potent in V79-Mz than in V79 cells. This study suggests that 2,3,4'- and 2,3,3'-substituted PCBs are micronuclei inducers and G2/M arresters among a number of trichlorobiphenyls in mammalian cell lines, though with potency lower than that observed recently in V79-derived cells expressing human CYP2E1. Similarly, some noncoplanar tetrachlorobiphenyls possess metabolism-independent chromosome-damaging potentials. Environ. Mol. Mutagen. 58:199-208, 2017. © 2017 Wiley Periodicals, Inc.

Engineering Rugged Field Assays to Detect Hazardous Chemicals Using Spore-Based Bacterial Biosensors

Bacterial whole cell-based biosensors have been genetically engineered to achieve selective and reliable detection of a wide range of hazardous chemicals. Although whole-cell biosensors demonstrate many advantages for field-based detection of target analytes, there are still some challenges that need to be addressed. Most notably, their often modest shelf life and need for special handling and storage make them challenging to use in situations where access to reagents, instrumentation, and expertise are limited. These problems can be circumvented by developing biosensors in Bacillus spores, which can be engineered to address all of these concerns. In its sporulated state, a whole cell-based biosensor has a remarkably long life span and is exceptionally resistant to environmental insult. When these spores are germinated for use in analytical techniques, they show no loss in performance, even after long periods of storage under harsh conditions. In this chapter, we will discuss the development and use of whole cell-based sensors, their adaptation to spore-based biosensors, their current applications, and future directions in the field.

Nutrition and Other Protective Behaviors Motivated by Environmental Health Risk Awareness

Background

Research findings have suggested that exposure to environmental pollutants contributes to increased health risks, which may be modulated by certain nutrition and other protective health behaviors. Nutrition professionals play an important role in effectively disseminating this information and in devising specific community-based nutrition education programs for audiences located in areas with environmental health issues.

Objective

To assess awareness of environmental health problems and motivation to adopt protective health behaviors for use in planning nutrition education programs for communities exposed to environmental pollutants.

Method

Data were collected from a modified, validated Environmental Health Engagement Profile (EHEP) survey instrument administered to adults (n=774) participating in community events in Kentucky based on location relative to hazardous waste sites.

Results

The modified EHEP survey instrument showed good internal consistency reliability, and demographic characteristics were evaluated. Correlation analyses revealed significant positive correlations in all groups, separately and combined, between awareness of environmental pollution in an individual’s surroundings and the extent of concern that pollutants cause adverse health effects (P < 0.01) and between concern that pollutants cause adverse health effects and taking personal actions to protect against such environmental insults (P < 0.01). The groups having the highest level of awareness posed by pollution are those residing near federally designated hazardous waste sites.

Conclusion

These results suggest that determining and expanding an audience’s knowledge and perceptions of environmental health risks will enhance effective nutrition education program planning.

Environmental exposure to human carcinogens in teenagers and the association with DNA damage

BACKGROUND

We investigated whether human environmental exposure to chemicals that are labeled as (potential) carcinogens leads to increased (oxidative) damage to DNA in adolescents.

MATERIAL AND METHODS

Six hundred 14-15-year-old youngsters were recruited all over Flanders (Belgium) and in two areas with important industrial activities. DNA damage was assessed by alkaline and formamidopyrimidine DNA glycosylase (Fpg) modified comet assays in peripheral blood cells and analysis of urinary 8-hydroxydeoxyguanosine (8-OHdG) levels. Personal exposure to potentially carcinogenic compounds was measured in urine, namely: chromium, cadmium, nickel, 1-hydroxypyrene as a proxy for exposure to other carcinogenic polycyclic aromatic hydrocarbons (PAHs), t,t-muconic acid as a metabolite of benzene, 2,5-dichlorophenol (2,5-DCP), organophosphate pesticide metabolites, and di(2-ethylhexyl) phthalate (DEHP) metabolites. In blood, arsenic, polychlorinated biphenyl (PCB) congeners 118 and 156, hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and perfluorooctanoic acid (PFOA) were analyzed. Levels of methylmercury (MeHg) were measured in hair. Multiple linear regression models were used to establish exposure-response relationships.

RESULTS

Biomarkers of exposure to PAHs and urinary chromium were associated with higher levels of both 8-OHdG in urine and DNA damage detected by the alkaline comet assay. Concentrations of 8-OHdG in urine increased in relation with increasing concentrations of urinary t,t-muconic acid, cadmium, nickel, 2,5-DCP, and DEHP metabolites. Increased concentrations of PFOA in blood were associated with higher levels of DNA damage measured by the alkaline comet assay, whereas DDT was associated in the same direction with the Fpg-modified comet assay. Inverse associations were observed between blood arsenic, hair MeHg, PCB 156 and HCB, and urinary 8-OHdG. The latter exposure biomarkers were also associated with higher fish intake. Urinary nickel and t,t-muconic acid were inversely associated with the alkaline comet assay.

CONCLUSION

This cross-sectional study found associations between current environmental exposure to (potential) human carcinogens in 14-15-year-old Flemish adolescents and short-term (oxidative) damage to DNA. Prospective follow-up will be required to investigate whether long-term effects may occur due to complex environmental exposures.

Minireview: Endocrine Disruptors: Past Lessons and Future Directions

Within the past few decades, the concept of endocrine-disrupting chemicals (EDCs) has risen from a position of total obscurity to become a focus of dialogue, debate, and concern among scientists, physicians, regulators, and the public. The emergence and development of this field of study has not always followed a smooth path, and researchers continue to wrestle with questions about the low-dose effects and nonmonotonic dose responses seen with EDCs, their biological mechanisms of action, the true pervasiveness of these chemicals in our environment and in our bodies, and the extent of their effects on human and wildlife health. This review chronicles the development of the unique, multidisciplinary field of endocrine disruption, highlighting what we have learned about the threat of EDCs and lessons that could be relevant to other fields. It also offers perspectives on the future of the field and opportunities to better protect human health.

Non-dioxin-like organic toxicant PCB153 modulates sphingolipid metabolism in liver progenitor cells: its role in Cx43-formed gap junction impairment

The non-dioxin-like environmental toxicant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153), member of a group of persistent organic pollutants wide-spread throughout the environment, reduces gap junction intercellular communication (GJIC), an event possibly associated with tumor promotion. Since very few studies have investigated the signaling effectors and mode(s) of action of PCB153, and it is known that the gap junction (GJ) protein Cx43 can be regulated by the bioactive sphingolipid (SL) sphingosine 1-phosphate (S1P), this in vitro study mainly addresses whether SL metabolism is affected by PCB153 in rat liver epithelial WB-F344 cells. PCB153 treatment obtained significant changes in the S1P/ceramide (Cer) ratio, known to be crucial in determining cell fate. In particular, an increase in S1P at 30 min and a decrease of the bioactive lipid at 3 h were observed, whereas Cer level increased at 1 h and 24 h. Notably, a time-dependent modulation of sphingosine kinase (SphK), the enzyme responsible for S1P synthesis, and of its regulators, ERK1/2 and protein phosphatase PP2A, supports the involvement of these signaling effectors in PCB153 toxicity. Electrophysiological analyses, furthermore, indicated that the lipophilic environmental toxicant significantly reduced GJ biophysical properties, affecting both voltage-dependent (such as those formed by Cx43 and/or Cx32) and voltage-independent channels, thereby demonstrating that PCB153 may act differently on GJs formed by distinct Cx isoforms. SphK down-regulation alone induced GJIC impairment, and, when combined with PCB153, the acute effect on GJ suppression was additive. Moreover, after enzyme-specific gene silencing, the SphK1 isoform appears to be responsible for down-regulating Cx43 expression, while being the target of PCB153 at short-term exposure. In conclusion, we provide the first evidence of novel effectors in PCB153 toxic action in rat liver stem-like cells, leading us to consider SLs as potential markers for preventing GJIC deregulation and, thus, the tumorigenic action elicited by this environmental toxicant.