Lung, Bladder, and Kidney Cancer Mortality 40 Years After Arsenic Exposure Reduction

Arsenic activated GLUT1-mTORC1/HIF-1α-PKM2 positive feedback networks promote proliferation and migration of bladder epithelial cells

Arsenic (As) is recognized as a potent environmental contaminant associated with bladder carcinogenesis. However, its molecular mechanism remains unclear. Metabolic reprogramming is one of the hallmarks of cancer and is as a central feature of malignancy. Here, we performed the study of cross-talk between the mammalian target of rapamycin complex 1 (mTORC1)/ Hypoxia-inducible factor 1 alpha (HIF-1α) pathway and aerobic glycolysis in promoting the proliferation and migration of bladder epithelial cells treated by arsenic in vivo and in vitro. We demonstrated that arsenite promoted N-methyl-N-nitrosourea (MNU)-induced tumor formation in the bladder of rats and the malignant behavior of human ureteral epithelial (SV-HUC-1) cell. We found that arsenite positively regulated the mTORC1/HIF-1α pathway through glucose transporter protein 1 (GLUT1), which involved in the malignant progression of bladder epithelial cells relying on glycolysis. In addition, pyruvate kinase M2 (PKM2) increased by arsenite reduced the protein expressions of succinate dehydrogenase (SDH) and fumarate hydratase (FH), leading to the accumulation of tumor metabolites of succinate and fumarate. Moreover, heat shock protein (HSP)90, functioning as a chaperone protein, stabilized PKM2 and thereby regulated the proliferation and aerobic glycolysis in arsenite treated SV-HUC-1 cells. Taken together, these results provide new insights into mTORC1/HIF-1α and PKM2 networks as critical molecular targets that contribute to the arsenic-induced malignant progression of bladder epithelial cells.

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence

PURPOSE OF REVIEW

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies.

RECENT FINDINGS

We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

Remediation of arsenic-contaminated soil using nanoscale schwertmannite synthesized by persulfate oxidation with carboxymethyl cellulose stabilization

Schwertmannite (SCH) is a promising material for adsorbing inorganic arsenic (As). We synthesized SCH nanoparticles (nano-SCH) via a modified chemical oxidation method and investigated the application of nano-SCH for the remediation of As-contaminated soils. The production of nano-SCH was successfully prepared using the persulfate oxidation method with carboxymethyl cellulose stabilization. The spherical structure of the nano-SCH particles had an average hydrodynamic diameter of 296 nm with high specific surface areas (108.9 m2/g). Compared with SCH synthesized via the H2O2 oxidation method, the percentage of Fe3+ precipitation in nano-SCH synthesis increased from 63.2% to 84.1%. The inorganic As adsorption capacity of nano-SCH improved by 2.27 times at solution pH = 6. After remediation of heavily As-contaminated soils by using 5% nano-SCH, the leachability of inorganic As rapidly decreased to 0.01% in 30 d. Correspondingly, the immobilization efficiencies of inorganic As in soil reached >99.9%. The inorganic As fractions in treated soil shifted from specifically and nonspecifically bound forms to amorphous and crystalline hydrous oxide-bound fractions. After treatment with 5% nano-SCH for 60 d, soil pH slightly decreased from 5.47 to 4.94; by contrast, soil organic matter content increased by 20.9%. Simultaneously, dehydrogenase concentration in soil decreased by 22.4%-34.7% during the remediation process. These changes in soil properties and As immobilization jointly decreased microbial activity and initiated the re-establishment of bacterial communities in the soil. In summary, this study presents a novel and high-productivity technology for nano-SCH synthesis and confirms the high As immobilization effectiveness of nano-SCH in the remediation of As-contaminated soils.

Reduced burden of Arsenic-Related cancers after water mitigation in Taiwan

BACKGROUND

Epidemiological evidence has demonstrated an association between arsenic in drinking water and increased cancer incidence. This population-based study investigates the impact of a tap water supply system installation in Blackfoot disease-endemic regions of Taiwan on cancer incidence.

METHODS

By using the Taiwan Cancer Registry dataset, we enrolled patients aged 40-84 diagnosed with arsenic-related cancers, including hepatocellular carcinoma, small and squamous cell lung cancer, Bowen's disease, basal and squamous cell skin cancer, urothelial bladder cancer, and upper tract urothelial carcinoma between 1995 and 2019. Random-effects age-period-cohort models were used to estimate the cancer incidence data, and a stabilized kriging method was employed to interpolate incidence rates to more precise spatiotemporal units.

RESULTS

The results showed that the age-standardized incidence rates of all six types of studied cancers were consistently higher in Blackfoot disease-endemic areas than those in other areas from 1995 to 2019. However, the gap in incidence rates between Blackfoot disease-endemic areas and the remaining regions began to narrow approximately after the 1960 birth cohort when the tap water supply system installation commenced. For small and squamous cell lung cancer, Bowen's disease, and urothelial bladder cancer, the excess incidence rates sharply declined to null for those born after the year of arsenic mitigation. For upper tract urothelial carcinoma, the excess incidence rates decreased more gradually for those born after the year of arsenic mitigation. For hepatocellular carcinoma and basal and squamous cell skin cancer, the excess incidence rates remained constant. Spatiotemporal clusters of high incidence rates were identified in the core townships of Blackfoot disease-endemic areas. These clusters began to dissipate mainly after the 1960 birth cohort.

CONCLUSION

Arsenic mitigation from drinking water in Taiwan is associated with a reduced burden of small and squamous cell lung cancers, Bowen's disease, urothelial bladder cancer, and upper tract urothelial carcinoma.

Arsenic in drinking water and lung cancer: A systematic review of 35 years of evidence

The association between higher arsenic concentrations in drinking water and lung cancer is well-established. However, the risk associated with lower levels of arsenic exposure remains uncertain. This systematic review and meta-analysis summarizes the evidence on the relationship between exposure to arsenic in drinking water and lung cancer outcomes as measured over a broad range of exposures, including lower levels. A total of 51 studies were included in the review and 15 met criteria for inclusion in meta-analysis. Risk estimates for lung cancer incidence and mortality were pooled and analyzed separately using Bayesian hierarchical random-effects models with a Gaussian observation submodel for log(Risk), computed using the "brms" R package. For lung cancer incidence, the predicted posterior mean relative risks (RRs) at arsenic concentrations of 10, 50 and 150 μg/L were 1.11 (0.86-1.43), 1.67 (1.27-2.17) and 2.21 (1.61-3.02), respectively, with posterior probabilities of 79%, 100% and 100%, respectively, for the RRs to be >1. The posterior mean mortality ratios at 20, 50 and 150 μg/L were 1.22 (0.83-1.78), 2.10 (1.62-2.71) and 2.41 (1.88-3.08), respectively, with posterior probabilities being above 80%. In addition to observing the dose-response relationship, these findings demonstrate that individuals exposed to low to moderate levels of arsenic (<150 μg/L) were at an elevated risk of developing or dying from lung cancer. Given the widespread exposure to lower levels of arsenic, there is an urgent need for vigilance and potential revisions to regulatory guidelines to protect people from the cancer risks associated with arsenic exposure.

Update of the risk assessment of inorganic arsenic in food

The European Commission asked EFSA to update its 2009 risk assessment on arsenic in food carrying out a hazard assessment of inorganic arsenic (iAs) and using the revised exposure assessment issued by EFSA in 2021. Epidemiological studies show that the chronic intake of iAs via diet and/or drinking water is associated with increased risk of several adverse outcomes including cancers of the skin, bladder and lung. The CONTAM Panel used the benchmark dose lower confidence limit based on a benchmark response (BMR) of 5% (relative increase of the background incidence after adjustment for confounders, BMDL05) of 0.06 μg iAs/kg bw per day obtained from a study on skin cancer as a Reference Point (RP). Inorganic As is a genotoxic carcinogen with additional epigenetic effects and the CONTAM Panel applied a margin of exposure (MOE) approach for the risk characterisation. In adults, the MOEs are low (range between 2 and 0.4 for mean consumers and between 0.9 and 0.2 at the 95th percentile exposure, respectively) and as such raise a health concern despite the uncertainties.

Assessing the health risks of coal-burning arsenic-induced skin damage: A 22-year follow-up study in Guizhou, China

Risk assessment of arsenic-induced skin damage has always received significant global attention. Theories derived from arsenic exposure in drinking water may not be applicable to the coal-burning type to arsenic-exposed area. Furthermore, very few studies have successfully determined the reference value of cumulative arsenic (CA) exposure that leads to specific skin lesions. In this study, we conducted a 22-year follow-up investigation to assess the risk of skin lesions and cancer resulting from long-term, multi-channel arsenic exposure from hazard identification, dose-response assessment, exposure assessment, and risk characterization. The results show that the arsenic exposure can significantly increase the prevalence of skin lesions. For each interquartile range increase of hair arsenic (HA) and CA, the risk of skin damage increased by 1.91 and 3.90 times, respectively. The lower confidence limit of the benchmark dose of HA of arsenic-induced various skin lesions ranged from 0.07 to 0.12 μg·g-1, and 932.57 to 1368.92 mg for CA. The chronic daily intake, lifetime average daily dose in the arsenic-exposed area after the comprehensive prevention and control measures have decreased significantly, but remained higher than the daily baseline level of 3.0 μg·kg-1·d-1. Even as recently as 2020, the hazard quotients and hazard index still exceeded 1, measuring 155.33 and 55.20, and the lifetime excess risk of skin cancer (2.80 × 10-3) remains significantly higher than the acceptable level of 10-6. Our study underscores the effectiveness of comprehensive prevention and control measures in managing high arsenic exposure in coal-burning arsenic poisoning areas. However, it is crucial to acknowledge that the risk of both non-carcinogenic and carcinogenic effects on the skin remains substantially higher than the acceptable level. We recommend setting reference limits for monitoring skin damage among individuals exposed to arsenic, with a recommended upper limit of 0.07 μg·g-1 for HA and a maximum acceptable level of 935.57 mg for CA.

Low-to-Moderate Arsenic Exposure and Urothelial Tract Cancers with a Long Latent Period of Follow-Up in an Arseniasis Area

BACKGROUND

Arsenic exposure can cause adverse health effects. The effects of long-term low-to-moderate exposure and methylations remain unclear.

OBJECTIVE

This study aims to examine the association between low-to-moderate arsenic exposure and urothelial tract cancers while considering the effects of methylation capacity.

METHODS

In this study, 5,811 participants were recruited from an arseniasis area in Taiwan for inorganic arsenic metabolite analysis. This follow-up study was conducted between August 1995 and December 2017. We identified 85 urothelial tract cancers in these participants, including 49 bladder and 36 upper urothelial tract cancer cases. A Cox proportional hazards model was employed.

RESULTS

The analyses revealed a significant association between concentrations of inorganic arsenic in water > 100 ug/L and bladder cancer occurrence, with a hazard ratio (HR) of 4.88 (95% CI 1.35-17.61). A monotonic trend was observed between concentrations of inorganic arsenic in water (from 0 to > 100 ug/L) and the incidence of urothelial tract cancer, including bladder cancer (p < 0.05) and upper urothelial tract cancers (p < 0.05). Participants with a lower primary methylation index or higher secondary methylation index had a prominent effect.

CONCLUSIONS

Rigorous regulations and active interventions should be considered for populations with susceptible characteristics.

Mechanisms Associated with Cognitive and Behavioral Impairment Induced by Arsenic Exposure

Arsenic (As) is a metalloid naturally present in the environment, in food, water, soil, and air; however, its chronic exposure, even with low doses, represents a public health concern. For a long time, As was used as a pigment, pesticide, wood preservative, and for medical applications; its industrial use has recently decreased or has been discontinued due to its toxicity. Due to its versatile applications and distribution, there is a wide spectrum of human As exposure sources, mainly contaminated drinking water. The fact that As is present in drinking water implies chronic human exposure to this metalloid; it has become a worldwide health problem, since over 200 million people live where As levels exceed safe ranges. Many health problems have been associated with As chronic exposure including cancer, cardiovascular diseases, gastrointestinal disturbances, and brain dysfunctions. Because As can cross the blood-brain barrier (BBB), the brain represents a target organ where this metalloid can exert its long-term toxic effects. Many mechanisms of As neurotoxicity have been described: oxidative stress, inflammation, DNA damage, and mitochondrial dysfunction; all of them can converge, thus leading to impaired cellular functions, cell death, and in consequence, long-term detrimental effects. Here, we provide a current overview of As toxicity and integrated the global mechanisms involved in cognitive and behavioral impairment induced by As exposure show experimental strategies against its neurotoxicity.

Gene expression profiles to analyze the anticancer and carcinogenic effects of arsenic in bladder cancer

OBJECTIVES

Arsenic is one of the greatest hazards as an environmental carcinogen. At the same time it is also a promising anticancer agent, that can be used to treat acute promyelocytic leukemia (APL) and some other tumors. Arsenic trioxide (ATO) exerts its therapeutic effect by promoting degradation of an oncogenic protein that drives the growth of APL cells. However, the molecular mechanisms that govern these paradoxical effects of arsenic in bladder cancer remain unclear. We speculate that they share the common mechanism that arsenic binds to the target proteins and subsequently impacts the expression of downstream genes.

METHODS

To address this issue, three Gene Set Enrichments (GSE) were loaded from the Gene Expression Omnibus (GEO) database with four expression matrices. Three of them were mice samples at exposure times of 1, 2, and 12 weeks, and the last was a human urothelial cell (HUC1) sample. Differentially expressed genes (DEGs) from 4 expression groups were identified at iDEP and analyzed at Metascape and Cytoscape for signaling pathway analysis and protein-protein interaction (PPI) analysis. The web-portals UALCAN and GEPIA were used to analyze the role of DEGs in the crosstalk between carcinogenic and anticancer effects. The putative downstream genes of arsenic binding proteins were retrieved using the Cistrome Data Browser. Real-time PCR was used to validate the expression of DEGs.

RESULTS

The signaling pathways referred to lipid metabolism. Responses to various stimuli or hormones were overrepresented in 4 expression matrices. The PPI network emphasized the role of KRAS and TNF signaling in different groups. Furthermore, BDKRB2, FOS, NR4A1, PLAU, SH3BGRL, and F10 played an important role in the crosstalk between carcinogenic and anticancer effects in bladder cancer. Arsenic may impact the activity of ACTB, BACH1, NME2, RBBP4, PARP1, and PML by direct binding, and thus influence the expression of downstream genes such as PAX6, MLLT11, LTBP1, PCSK5, ZFP36, COL8A2, and IL1R2.

CONCLUSION

Arsenic exerted carcinogenic and anticancer functions by altering the expression of crosstalk genes such as BDKRB2, FOS, NR4A1, PLAU, SH3BGRL, and F10, and these were due to arsenic binding proteins.

Alterations of Bax/Bcl-2 ratio contribute to NaAsO2 induced thyrotoxicity in human thyroid follicular epithelial cells and SD rats

The environmental toxicant arsenic causes various human diseases and threatens millions of people worldwide. Recently, a limited number of studies have revealed that exposure to arsenic is associated with thyroid dysfunction, indicating its toxicological impact on the thyroid gland, however, its precise forms of damage and underlying mechanisms remain largely unknown. Here, we sought to observe the thyrotoxicity of sodium arsenite (NaAsO2) on human thyroid follicular epithelial cells (Nthy-ori 3-1) and SD rats, and explore the role of Bax/Bcl-2 ratio in the above process. Our results displayed that NaAsO2 exerted a dose-dependent inhibitory effect on the viability of Nthy-ori 3-1 cells. Alongside the increase doses of NaAsO2 exposure, morphological changes and elevated LDH levels were observed. Furthermore, apoptosis rates increased in a dose- and time-dependent manner, accompanied by a decrease in Bcl-2 and an opposite change in Bax expression. SD rats were treated with 0, 2.5, 5, and 10 mg/kg NaAsO2 for 36 weeks. Our findings revealed that NaAsO2 exposure resulted in arsenic accumulation in thyroid tissue, elevated ratio of Bax/Bcl-2, and histopathological changes of thyroid in rats, which accompanied by the decreased serum T3 and T4 levels and the increased serum TSH level. Furthermore, T3 and T4 levels were negatively correlated with Bax expression, whereas positively correlated with Bcl-2 expression. Collectively, our results suggest that NaAsO2 exposure induces cytotoxicity in Nthy-ori 3-1 cells, causes structural damages and dysfunction of thyroid in SD rats, in which the imbalance of Bax/Bcl-2 ratio may play a significant role.

Genotoxicity and mutagenicity in blood and drinking water induced by arsenic in an impacted gold mining region in Colombia

Arsenic (As) is one of the most dangerous substances that can affect human health and long-term exposure to As in drinking water can even cause cancer. The objective of this study was to investigate the concentrations of total As in the blood of inhabitants of a Colombian region impacted by gold mining and to evaluate its genotoxic effect through DNA damage by means of the comet assay. Additionally, the concentration of As in the water consumed by the population as well as the mutagenic activity of drinking water (n = 34) in individuals were determined by hydride generator atomic absorption spectrometry and the Ames test, respectively. In the monitoring, the study population was made up of a group of 112 people, including inhabitants of four municipalities: Guaranda, Sucre, Majagual, and San Marcos from the Mojana region as the exposed group, and Montería as a control group. The results showed DNA damage related to the presence of As in blood (p < 0.05) in the exposed population, and blood As concentrations were above the maximum allowable limit of 1 μg/L established by the ATSDR. A mutagenic activity of the drinking water was observed, and regarding the concentrations of As in water, only one sample exceeded the maximum permissible value of 10 μg/L established by the WHO. The intake of water and/or food containing As is potentially generating DNA damage in the inhabitants of the Mojana region, which requires surveillance and control by health entities to mitigate these effects.

Biological differences underlying sex and gender disparities in bladder cancer: current synopsis and future directions

Sex and gender disparities in bladder cancer have long been a subject of interest to the cancer research community, wherein men have a 4 times higher incidence rate than women, and female patients often present with higher-grade disease and experience worse outcomes. Despite the known differences in disease incidence and clinical outcomes between male and female bladder cancer patients, clinical management remains the same. In this review, we critically analyze studies that report on the biological differences between men and women and evaluate how these differences contribute to sex and gender disparities in bladder cancer. Distinct characteristics of the male and female immune systems, differences in circulating hormone levels and hormone receptor expression, and different genetic and epigenetic alterations are major biological factors that all likely contribute to disparate incidence rates and outcomes for male and female bladder cancer patients. Future preclinical and clinical studies in this area should employ experimental approaches that account for and consider sex and gender disparities in bladder cancer, thereby facilitating the development of precision medicine for the effective treatment of bladder cancer in all patients.

Risk of urinary tract cancers following arsenic exposure and tobacco smoking: a review

Bladder cancer, prostate cancer, and kidney cancer, due to their high morbidity and mortality rates, result in significant economic and health care costs. Arsenic exposure affects the drinking water of millions of people worldwide. Long-term exposure to arsenic, even in low concentrations, increases the risk of developing various cancers. Smoking is also one of the leading causes of bladder, prostate and kidney cancers. Accordingly, this research reviews the relationship between arsenic exposure and smoking with three kinds of urinary tract cancers (bladder cancer, prostate cancer, and kidney cancer) due to their widespread concern for their negative impact on public health globally. In this review, we have gathered the most current information from scientific databases [PubMed, Scopus, Google Scholar, ISI web of science] regarding the relationship between arsenic exposure and tobacco smoking with the risk of bladder, prostate, and kidney cancer. In several studies, a significant relationship was determined between the incidence and mortality rate of the above-mentioned cancers in humans with arsenic exposure and tobacco smoking. The decrease or cessation of smoking and consumption of arsenic-free water significantly declined the incidence of bladder, prostate, and kidney cancers.

An appraisal of the principal concerns and controlling factors for Arsenic contamination in Chile

Although geogenic Arsenic (As) contamination is well-recognized in northern Chile, it is not restricted to this part of the country, as the geological conditions favoring As release to the human environment exist across the country as well, although not at the same level, based on comparatively fewer studies in central and southern Chile. The present work provides a critical evaluation of As sources, pathways, and controls with reports and case studies from across the country based on an exhaustive bibliographic review of its reported geogenic sources and processes that affect its occurrence, systematization, and critical revision of this information. Arc magmatism and associated geothermal activities, identified as the primary As sources, are present across the Chilean Andes, except for the Pampean Flat Slab and Patagonian Volcanic Gap. Metal sulfide ore zones, extending from the country's far north to the south-central part, are the second most important geogenic As source. While natural leaching of As-rich mineral deposits contaminates the water in contact, associated mining, and metallurgical activities result in additional As release into the human environment through mining waste and tailings. Moreover, crustal thickness has been suggested as a principal controlling factor for As release, whose southward decrease has been correlated with lower As values.

ARSENIC IN DRINKING WATER AND URINE AND ITS RELATIONSHIP WITH MALIGNANT TUMORS OF URINARY TRACT IN OSIJEK-BARANJA COUNTY, CROATIA

Increased values of arsenic in potable water in eastern Croatia has been a matter of scientific interest for the past two decades due to numerous health effects, including carcinogenic ones. This study investigated whether prolonged exposure to increased arsenic from water could be detectable through increased arsenic in urine, and whether it influenced the incidence of kidney and bladder cancer in Osijek-Baranja County. Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis of water samples from available water sources (wells, aqueducts). In addition, examinees from Osijek, Našice, Vladislavci, Čepin and Dalj gave their urine samples for analysis. Data on cancer incidence were obtained from the Institute for Public Health Registry and cumulative incidence of kidney and bladder cancer was calculated for the period between January 1, 2000 and December 31, 2018. Elevated arsenic concentration in drinking water was recorded in Vladislavci, Čepin and Osijek area with values above the allowed maximum according to the EU standards (10 µg L-1) and as a result, arsenic levels in urine of the inhabitants were also elevated. Cumulative incidence for bladder cancer showed correlation between increased arsenic in water and urine in the areas affected by increased arsenic in water. Epidemiologic data suggest a conclusion that elevated arsenic could be considered at least as a cofounding factor for urinary tract cancer.

Arsenic in drinking water and kidney cancer: a systematic review

OBJECT

Arsenic as a chemical is found in rock, soil, air and used in various industries and their products, such as colors, hairs, and fertilizers. Humans may be exposed to arsenic mainly through food and drinking water. Due to its adverse health effects, its presence in drinking water has become a public health concern.

METHODS

In this systematic review, we investigated the relationship between arsenic concentration in drinking water and the risk of kidney cancer in humans. For this reason, various electronic databases were searched from 1992 February to November 2021. In this review, three ecological studies, two case-control studies, and four cohort studies were investigated.

RESULTS

High levels of arsenic (100 μg/L) have been reported in many countries such as southwest Taiwan, Niigata, Argentine, and northern Chile. A significant relationship was observed between kidney cancer incidence and its mortality rate with high arsenic levels in drinking water.

CONCLUSIONS

Despite the limitations in some previous studies, reviewing and comparing the data of different regions indicates a scientific relationship between kidney cancer incidence and high concentrations of arsenic in drinking water.

Urinary microbiota and metabolic signatures associated with inorganic arsenic-induced early bladder lesions

Inorganic arsenic (iAs) contamination in drinking water is a global public health problem, and exposure to iAs is a known risk factor for bladder cancer. Perturbation of urinary microbiome and metabolome induced by iAs exposure may have a more direct effect on the development of bladder cancer. The aim of this study was to determine the impact of iAs exposure on urinary microbiome and metabolome, and to identify microbiota and metabolic signatures that are associated with iAs-induced bladder lesions. We evaluated and quantified the pathological changes of bladder, and performed 16S rDNA sequencing and mass spectrometry-based metabolomics profiling on urine samples from rats exposed to low (30 mg/L NaAsO₂) or high (100 mg/L NaAsO₂) iAs from early life (in utero and childhood) to puberty. Our results showed that iAs induced pathological bladder lesions, and more severe effects were noticed in the high-iAs group and male rats. Furthermore, six and seven featured urinary bacteria genera were identified in female and male offspring rats, respectively. Several characteristic urinary metabolites, including Menadione, Pilocarpine, N-Acetylornithine, Prostaglandin B1, Deoxyinosine, Biopterin, and 1-Methyluric acid, were identified significantly higher in the high-iAs groups. In addition, the correlation analysis demonstrated that the differential bacteria genera were highly correlated with the featured urinary metabolites. Collectively, these results suggest that exposure to iAs in early life not only causes bladder lesions, but also perturbs urinary microbiome composition and associated metabolic profiles, which shows a strong correlation. Those differential urinary genera and metabolites may contribute to bladder lesions, suggesting a potential for development of urinary biomarkers for iAs-induced bladder cancer.

Disruption of the tumor suppressor-like activity of aryl hydrocarbon receptor by arsenic in epithelial cells and human lung cancer

As the most classic and extensively studied transcription factor in response to environmental toxic chemicals, the human aryl hydrocarbon receptor (AHR) has been implicated in mediating some oncogenic responses also. Limited information is available, however, on whether arsenic, a widely presented environmental carcinogen, can regulate AHR to exert its carcinogenic activity. Through chromatin immunoprecipitation and sequencing (ChIP-seq), CRISPR-Cas9 gene editing, RNA-seq, and immunohistochemistry (IHC), in this report we provided evidence showing that arsenic enforces TGFβ and other oncogenic signaling pathways in bronchial epithelial cells through disrupting the tumor suppressor-like activity of AHR. AHR is normally enriched on a number of oncogenic genes in addition to the known phase I/II enzymes, such as genes in TGFβ and Nrf2 signaling pathways and several known oncogenes. Arsenic treatment substantially reduced the binding of AHR on these genes followed by an increased expression of these genes. CRISPR-Cas9-based knockout of AHR followed by RNA-seq further demonstrated increased expression of the TGFβ signaling and some oncogenic signaling pathway genes in the AHR knockout cells. IHC studies on human tissue samples revealed that normal human lung tissues expressed high level of AHR. In contrast, the AHR expression was diminished in the lung cancer tissues. Accordingly, the data from this study suggest that AHR has tumor suppressor-like activity for human lung cancer, and one of the carcinogenic mechanisms of arsenic is likely mediated by the inhibition of arsenic on the tumor suppressor-like activity of AHR.

Black Tea Extract, via Modulation of TGF-β Pathway, Prevents Inorganic Arsenic-induced Development of Squamous Cell Carcinoma of the Skin in Swiss Albino Mice

Chronic exposure to inorganic arsenic (iAs) elevates reactive oxygen species (ROS) generation and up-regulates TGF-β signalling. This promotes induction of epithelial to mesenchymal transition (EMT) and causes the development of squamous cell carcinoma (SCC) of skin. Black tea is a popular beverage worldwide and an effective antioxidant. Chemopreventive potential of black tea extract (BTE) against iAs induced carcinogenicity has been explored here. The study aims to investigate the role of BTE in prevention of iAs-induced SCC of skin in Swiss albino mice via the modulation of TGF-β signalling and EMT. Mice were divided into (1) control, (2) iAs, (3) iAs+BTE, and (4) BTE groups and were administered iAs and BTE alone, or in combination for 330 days. Histological studies were performed to assess development of SCC. ROS generation was estimated by flowcytometry. Expression of TGF-β and downstream proteins belonging to suppressor of mothers against decapentaplegic (Smad), phosphoinositide-3-kinase (PI3K)-protein kinase B (AKT) and mitogen-activated protein kinase (MAPK) pathways was assessed by immunoblotting. Expression of EMT markers was evaluated by immunoblotting, immunohistochemistry and semi-quantitative reverse transcriptase-PCR. After 330 days of iAs treatment, development of invasive SCC of skin probably due to excess ROS generation, elevation of TGF-β, downregulation of the Smad pathway, upregulation of PI3K-AKT and MAPK signalling molecules and induction of EMT was observed. All these modulations were found to be reversed by BTE, which inhibits iAs induced SCC of skin by quenching excess ROS, promoting Smad mediated TGF-β signalling, downregulating signalling intermediates of PI3K-AKT and MAPK pathways and inhibiting EMT.

Arsenic causing gallbladder cancer disease in Bihar

In recent times Gallbladder cancer (GBC) incidences increased many folds in India and are being reported from arsenic hotspots identified in Bihar. The study aims to establish association between arsenic exposure and gallbladder carcinogenesis. In the present study, n = 200 were control volunteers and n = 152 confirmed gallbladder cancer cases. The studied GBC patient's biological samples-gallbladder tissue, gallbladder stone, bile, blood and hair samples were collected for arsenic estimation. Moreover, n = 512 gallbladder cancer patients blood samples were also evaluated for the presence of arsenic to understand exposure level in the population. A significantly high arsenic concentration (p < 0.05) was detected in the blood samples with maximum concentration 389 µg/L in GBC cases in comparison to control. Similarly, in the gallbladder cancer patients, there was significantly high arsenic concentration observed in gallbladder tissue with highest concentration of 2166 µg/kg, in gallbladder stones 635 µg/kg, in bile samples 483 µg/L and in hair samples 6980 µg/kg respectively. Moreover, the n = 512 gallbladder cancer patient's blood samples study revealed very significant arsenic concentration in the population of Bihar with maximum arsenic concentration as 746 µg/L. The raised arsenic concentration in the gallbladder cancer patients' biological samples-gallbladder tissue, gallbladder stone, bile, blood, and hair samples was significantly very high in the arsenic exposed area. The study denotes that the gallbladder disease burden is very high in the arsenic exposed area of Bihar. The findings do provide a strong link between arsenic contamination and increased gallbladder carcinogenesis.

Prenatal arsenic exposure induces immunometabolic alteration and renal injury in rats

Arsenic (As) exposure is progressively associated with chronic kidney disease (CKD), a leading public health concern present worldwide. The adverse effect of As exposure on the kidneys of people living in As endemic areas have not been extensively studied. Furthermore, the impact of only prenatal exposure to As on the progression of CKD also has not been fully characterized. In the present study, we examined the effect of prenatal exposure to low doses of As 0.04 and 0.4 mg/kg body weight (0.04 and 0.4 ppm, respectively) on the progression of CKD in male offspring using a Wistar rat model. Interestingly, only prenatal As exposure was sufficient to elevate the expression of profibrotic (TGF-β1) and proinflammatory (IL-1α, MIP-2α, RANTES, and TNF-α) cytokines at 2-day, 12- and 38-week time points in the exposed progeny. Further, alteration in adipogenic factors (ghrelin, leptin, and glucagon) was also observed in 12- and 38-week old male offspring prenatally exposed to As. An altered level of these factors coincides with impaired glucose metabolism and homeostasis accompanied by progressive kidney damage. We observed a significant increase in the deposition of extracellular matrix components and glomerular and tubular damage in the kidneys of 38-week-old male offspring prenatally exposed to As. Furthermore, the overexpression of TGF-β1 in kidneys corresponds with hypermethylation of the TGF-β1 gene-body, indicating a possible involvement of prenatal As exposure-driven epigenetic modulations of TGF-β1 expression. Our study provides evidence that prenatal As exposure to males can adversely affect the immunometabolism of offspring which can promote kidney damage later in life.

Hyperphosphorylation of EGFR/ERK signaling facilitates long-term arsenite-induced hepatocytes epithelial-mesenchymal transition and liver fibrosis in sprague-dawley rats

Arsenic is a well known environmental hazardous material, chronic arsenic exposure results in different types of liver damage. Among them, liver fibrosis has become a research hotspot because of its reversibility, while the underlying mechanism is still unclear. Previous studies revealed that EGFR/ERK signaling appears to play an important role in fibrosis diseases. In this study, sprague-dawley rats were exposed to different doses of arsenite for 36 weeks to investigate the roles of EGFR/ERK signaling on arsenite-induced liver fibrogenesis. Our results showed that long-term arsenite exposure induced liver fibrosis, accompanied by hepatic stellate cells (HSCs) activation, excessive serum secretion of extracellular matrix (ECM), and hepatocytes epithelial-mesenchymal transformation (EMT). In addition, arsenite exposure caused hyperphosphorylation of EGFR/ERK signaling in liver tissue of rats, indicating that EGFR/ERK signaling may be involved in arsenite-induced liver fibrosis. Indeed, erlotinib (a specific phosphorylation inhibitor of EGFR) intervention significantly decreased arsenite induced hyperphosphorylation of EGFR/ERK signaling, thereby suppressed hepatocytes EMT process and alleviated liver fibrogenesis in arsenite exposed rats. In summary, the present study provides evidences showing that hyperphosphorylation of EGFR/ERK signaling facilitates long-term arsenite-induced hepatocytes EMT and liver fibrosis in rats, which brings new insights into the pathogenesis of arsenic-induced liver injury.

miRNAs and arsenic-induced carcinogenesis

Arsenic-induced carcinogenesis is a worldwide health problem. Identifying the molecular mechanisms responsible for the induction of arsenic-induced cancers is important for developing treatment strategies. MicroRNA (miRNA) dysregulation is known to affect development and progression of human cancer. Several studies have identified an association between altered miRNA expression in cancers from individuals chronically exposed to arsenic and in cell models for arsenic-induced carcinogenesis. This chapter provides a comprehensive review for miRNA dysregulation in arsenic-induced cancer.

The dark side of NRF2 in arsenic carcinogenesis

Arsenic is an environmental toxicant that significantly enhances the risk of developing disease, including several cancers. While the epidemiological evidence supporting increased cancer risk due to chronic arsenic exposure is strong, therapies tailored to treat exposed populations are lacking. This can be accredited in large part to the chronic nature and pleiotropic pathological effects associated with prolonged arsenic exposure. Despite this fact, several putative mediators of arsenic promotion of cancer have been identified. Among these, the critical transcription factor NRF2 has been shown to be a key mediator of arsenic's pro-carcinogenic effects. Importantly, the dependence of arsenic-transformed cancer cells on NRF2 upregulation exposes a targetable liability that could be utilized to treat arsenic-promoted cancers. In this chapter, we briefly introduce the "light" vs "dark" side of the NRF2 pathway. We then give a brief overview of arsenic metabolism, and discuss the epidemiological and experimental evidence that support arsenic promotion of different cancers, with a specific emphasis on mechanisms mediated by chronic, non-canonical activation of NRF2 (i.e., the "dark" side). Finally, we briefly highlight how the non-canonical NRF2 pathway plays a role in other arsenic-promoted diseases, as well as research directions that warrant further investigation.

Drinking water and the implications for gender equity and empowerment: A systematic review of qualitative and quantitative evidence

BACKGROUND

Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE).

METHODS

A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and clinicaltrials.gov). Drinking water studies with an all-female cohort or disaggregated findings according to gender were included.

RESULTS

A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men.

CONCLUSION

This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy.

Polyadenylation of canonical histone H3.1 in carcinogenesis

Canonical histone messenger RNAs (mRNAs) are transcribed during S phase and do not terminate with a poly(A) tail at the 3' end. Instead, the histone mRNAs display a stem-loop structure at their 3-end. Stem-loop-binding protein (SLBP) binds the stem-loop and regulates canonical histone mRNA metabolism. We previously demonstrated that exposure to arsenic, an environmental carcinogen, induces polyadenylation of canonical histone H3.1 mRNA, causing transformation of human cells in vitro. Arsenic decreased cellular levels of SLBP by inducing its proteasomal degradation and inhibiting SLBP transcription via epigenetic mechanisms. Similarly, we also reported that nickel and arsenic have similar effects on canonical histone mRNA transcription and translation. Most recently, we further demonstrated that bisphenols' exposure increased polyadenylation of canonical histone H3.1 mRNA possibly through down-regulation of SLBP expression. This facilitates the abnormal stability of at least one canonical histone isoform (H3.1), and also increases H3 protein levels. Excess expression of canonical histones have been shown to increase sensitivity to DNA damage as well as increase the frequency of missing chromosomes and induce genomic instability. Thus, polyadenylation of canonical histone mRNA following arsenic, nickel and bisphenols exposure may contribute to metal and bisphenol-induced carcinogenesis.

Genome-wide DNA methylation pattern in whole blood of patients with coal-burning arsenic poisoning

Exposure to coal-burning arsenic leads to an increased risk of cancer, multi-systems damage and chronic diseases, with DNA methylation one potential mechanism of arsenic toxicity. There are few studies on genome-wide methylation in the coal-burning arsenic poisoning population. Illumina 850 K methylation beadchip is the most suitable technology for DNA methylation of epigenome-wide association analysis. This study used 850 K to detect changes in Genome-wide DNA methylation in whole blood samples of 12 patients with coal-burning arsenic poisoning ( Arsenic poisoning group) and four healthy control participants (Healthy control group). There is clearly abnormal genome-wide DNA methylation in coal-burning arsenic poisoning, with 647 significantly different methylation positions, 524 different methylation regions and 335 significantly different methylation genes in arsenic poisoning patients compared with healthy controls. Further functional analysis of Gene ontology (GO) and Kyoto encyclopedia of genes (KEGG) found 592 GO items and 131 KEGG pathways between patients of coal-burning arsenic poisoning and healthy control. Then, analysis of gene degree and combined-score identified NAPRT1, NT5C3B, NEDD4L, SLC22A3 and RAB11B as target genes. Further validation by qRT-PCR indicates that mRNA expression of five genes changes significantly in the arsenic poisoning group (n = 72) compared to the healthy control group (n = 72). These results showed the genome-wide methylation pattern and highlighted five critical genes within the coal-burning arsenic poisoning population that involve Nicotinate and nicotinamide metabolism, Choline metabolism in cancer, and Ubiquitin mediated proteolysis. Next, the methylation profile of coal burning arsenic poisoning will be further excavation and the mechanism of coal burning arsenic poisoning will be further explored from five genes related pathways and functions.

Synergy of arsenic with smoking in causing cardiovascular disease mortality: A cohort study with 27 follow-up years in China

Background

To explore the patterns of the exposure-response relationship between arsenic exposure and cardiovascular disease (CVD) mortality and investigate the effect of cigarette smoking on the association.

Methods

Seven thousand seven hundred thirty-five tin miners with at least 10 years of arsenic exposure were enrolled since 1992 and followed up for 27 years. Each individual's air arsenic exposure at workplace was calculated by time weighted average arsenic concentration × exposure months. Detailed information on smoking was collected at baseline, and information on smoking status was collected for five consecutive years from 1992 to 1996. Hazard ratio (HR) and 95% confidence interval (CI) for the risk of CVD were estimated using Cox proportional hazards models.

Results

A total of 1,046 CVD deaths occurred in this cohort over 142,287.7 person-years of follow up. We firstly reported that for equal cumulative exposure, participants exposed to higher concentrations over shorter duration had a higher risk of CVD mortality than those exposed to lower concentration over longer duration. The HR and 95% CI were 1.38 (95%CI: 1.03-1.85) in participants exposed to arsenic concentration (45.5-99.5 mg/m³), 1.29 (95%CI: 1.02-1.67) in 99.5-361.0 mg/m³. Further, participants with age at first exposure <18 years had a significantly higher risk of morality from CVD, cerebrovascular and heart diseases than those with ≥18 years. Finally, all synergy indices were greater than 1 (range, 1.11-2.39), indicating that the joint effect of arsenic exposure and cigarette smoking on CVD mortality was greater than the sum of their individual effect.

Conclusions

Exposure to air arsenic at workplace is adversely associated with mortality from CVD, especially among smokers younger than 18 years and smokers.

Heavy metal and phthalate contamination and labeling integrity in a large sample of US commercially available cannabidiol (CBD) products

BACKGROUND

The demand and availability of commercially available cannabidiol (CBD) products has grown substantially, which is of particular interest among medically vulnerable people. Because the cannabis plant is recognized as a bioaccumulator, which is highly effective at absorbing and retaining contaminants (e.g., heavy metals) in soil, it is important to characterize the degree of contamination in CBD products and their label accuracy to better estimate potential health benefits and risks associated with consumption.

METHODS

Levels of lead, cadmium, arsenic, mercury, four phthalates, and CBD labeling accuracy were quantified in a selection of commercially available CBD products in the US. Heavy metal concentrations were quantified by inductively coupled plasma-mass spectrometry. Phthalates were quantified by liquid chromatography-tandem mass spectrometry. CBD labeling accuracy was determined by extracting samples into a suitable organic solvent and analyzing using liquid chromatography with diode array detection.

RESULTS

Lead was detected in 42 %, cadmium in 8 %, arsenic in 28 %, and mercury in 37 % of 121 edible CBD products. Four edible CBD products exceeded the California Proposition 65 threshold for daily lead consumption of 0.5μg in two servings. The percentage of edible products with detectable phthalate concentrations varied between 13 % and 80 % across the four phthalates, with DEHP being most prevalent. Among all products tested for CBD labeling accuracy (topicals, edibles, N = 516), 40 % contained <90 % of the CBD indicated on the product label, 18 % contained >110 %, and only 42 % of products fell within ±10 % of the CBD claimed on the manufacturer label. Concentrations of heavy metals and phthalates were not associated with CBD potency.

CONCLUSIONS

Low-level contamination of edible CBD products with heavy metals and phthalates is pervasive. There is substantial discrepancy between the product label claims for CBD potency and the amount measured in both edible and topical products, underscoring the need for tight regulations for CBD product label integrity to protect consumers.

Health and economic gain attributable to the introduction of the World Health Organization's drinking water standard on arsenic level in Hungary: A nationwide retrospective study on cancer occurrence and ischemic heart disease mortality

The World Health Organization (WHO) estimates that 140 million individuals are at risk from consumption of drinking water containing arsenic at concentrations above the WHO guideline value of 10 μg/l. Arsenic mitigation is considered to be the most effective way to prevent arsenic related diseases. After joining the European Union, Hungary implemented a Drinking Water Quality Improvement Programme (DWQIP) to reduce levels of arsenic in drinking water below the WHO guideline value. But what impact did this have on health? We estimated the change in lifetime excess skin, lung, and bladder cancer risks and mortality from ischaemic heart disease (IHD) associated with chronic arsenic intake among those exposed before (2004-2007) and after (2014-2017) the implementation of DWQIP. A population-based risk assessment approach was used to assess lifetime excess cancer risk applying two scenarios for lung and bladder cancers. The economic benefits of the DWQIP were estimated by the combination of cost of illness and value per statistical life methods. Compared to the period before the DWQIP, its implementation was associated with a significant reduction in arsenic in drinking water [median: 3.0 μg/l interquartile range (IQR): 1.5-12.0 μg/l to median: 2.15 μg/l IQR: 1.0-5.79 μg/l]. The two scenarios were estimated to be associated with 225.2 and 35.9 fewer cancer cases each year. The number of annually prevented IHD deaths was estimated to be 88.9. It was estimated that the benefits of the DWQIP will outweigh its costs. We conclude that reducing arsenic levels in drinking water to 10.0 μg/l resulted in significant health and economic benefits. Our study goes beyond the existing research, offering both new insights into the impact of arsenic mitigation and providing a methodological template for similar studies in the many parts of the world that have yet to reduce arsenic exposure.

Comparative Biomonitoring of Arsenic Exposure in Mothers and Their Neonates in Comarca Lagunera, Mexico

Multiple comorbidities related to arsenic exposure through drinking water continue to be public problems worldwide, principally in chronically exposed populations, such as those in the Comarca Lagunera (CL), Mexico. In addition, this relationship could be exacerbated by an early life exposure through the placenta and later through breast milk. This study conducted a comparative analysis of arsenic levels in multiple biological samples from pregnant women and their neonates in the CL and the comparison region, Saltillo. Total arsenic levels in placenta, breast milk, blood, and urine were measured in pregnant women and their neonates from rural areas of seven municipalities of the CL using atomic absorption spectrophotometry with hydride generation methodology. The average concentrations of tAs in drinking water were 47.7 µg/L and 0.05 µg/L in the exposed and non-exposed areas, respectively. Mean levels of tAs were 7.80 µg/kg, 77.04 µg/g-Cr, and 4.30 µg/L in placenta, blood, urine, and breast milk, respectively, in mothers, and 107.92 µg/g-Cr in neonates in the exposed group, which were significantly higher than those in the non-exposed area. High levels of urinary arsenic in neonates were maintained 4 days after birth, demonstrating an early arsenic exposure route through the placenta and breast milk. In addition, our study suggested that breastfeeding may reduce arsenic exposure in infants in arsenic-contaminated areas. Further studies are necessary to follow up on comorbidities later in life in neonates and to provide interventions in this region.

Structural, Optical, and Arsenic Removal Properties of Sol-Gel Synthesized Fe-Doped TiO2 Nanoparticles

Pure and Fe-doped TiO₂ nanoparticles were synthesized by the sol-gel method. The samples were characterized by X-ray diffraction, Raman spectroscopy, BET, UV-vis diffuse reflectance spectroscopy, and scanning electron microscopy. The results show a dependence between the crystallite size and the amount of dopant, which decreases from 13.02 to 12.81 nm. The same behavior was observed in the optical properties, where the band gap decreased from 3.2 to 2.86 eV. The arsenic (V) adsorption was tested in aqueous solution containing 5 mg/L of arsenic and 0.5 g/L of adsorbent at pH 7 and in dark conditions. The results indicate that the TiO₂-B sample shows a higher arsenic removal, reaching 88% arsenic removal from the water at pH 7. Thus, it is also shown that the best performance occurs at pH 5, where it reaches an arsenic removal of 94%. Ion competition studies show that arsenic removal capacity is slightly affected by chloride, carbonate, nitrate, and sulfate ions. According to the results, the synthesized samples are a promising material for treating arsenic-contaminated water.

Inorganic arsenic exposure-induced premature senescence and senescence-associated secretory phenotype (SASP) in human hepatic stellate cells

Exposure to inorganic arsenic has been known to induce cancers in various organs, however, the underlying mechanisms remain unclear. Premature senescence refers to the irreversible growth arrest induced by stress stimuli. The senescence-associated secretory phenotype (SASP), particularly in fibroblasts, has been shown to promote cancer development. In this study, we examined whether arsenite exposure causes premature senescence and induction of SASP in liver fibroblasts using the human hepatic stellate cell line, LX-2. Exposure of LX-2 cells to 5 or 7.5 μM of sodium arsenite for 144 h induced the features of senescence in the cells, including morphological changes, growth inhibition, increased senescence-associated β-galactosidase activity, increased P21 gene expression, and decreased LAMINB1 gene expression. The mRNA expressions of SASP factors, such as MMP1, MMP3, IL-8, IL-1β, and CXCL1, were also highly upregulated. The wound healing assay revealed that the conditioned medium from LX-2 cells with arsenite-induced senescence increased the migration activity of cells of the human hepatoma cell line, Huh-7. Gene expression data of liver cancer samples from the Human Protein Atlas showed that high expression levels of the SASP factors that were upregulated in the cells with arsenite-induced senescence were strongly associated with a poor prognosis. In addition, the cellular levels of γ-H2AX, a DNA double-strand break marker, were increased by arsenite exposure, suggesting that DNA damage could contribute to premature senescence induction. These results show that arsenite exposure induces premature senescence in hepatic stellate cells and suggest that the SASP factors from the senescent cells promote hepatic carcinogenesis.

Developmental arsenic exposure induces dysbiosis of gut microbiota and disruption of plasma metabolites in mice

Arsenic is a notorious environmental pollutant. Of note, developmental arsenic exposure has been found to increase the risk of developing a variety of ailments later in life, but the underlying mechanism is not well understood. Many elements of host health have been connected to the gut microbiota. It is still unclear whether and how developmental arsenic exposure affects the gut microbiota. In the present study, we found that developmental arsenic exposure changed intestinal morphology and increased intestinal permeability and inflammation in mouse pups at weaning. These alterations were accompanied by a significant change in gut microbiota, as evidenced by considerably reduced gut microbial richness and diversity. In developmentally arsenic-exposed pups, the relative abundance of Muribaculaceae was significantly decreased, while the relative abundance of Akkermansia and Bacteroides was significantly enhanced at the genus level. Metabolome and pathway enrichment analyses indicated that amino acid and purine metabolism was promoted, while glycerophospholipid metabolism was inhibited. Interestingly, the relative abundance of Muribaculaceae and Akkermansia showed a strong correlation with most plasma metabolites significantly altered by developmental arsenic exposure. These data indicate that gut microbiota dysbiosis may be a critical link between developmental arsenic exposure and metabolic disorders and shed light on the mechanisms underlying increased susceptibility to diseases due to developmental arsenic exposure.

Assessment of Arsenic in Hair of the Inhabitants of East Croatia—Relationship to Arsenic Concentrations in Drinking Water

The problem of elevated arsenic concentrations in water and environment is an increasing public health concern. The aim of the study was to assess the arsenic content in human hair in selected areas of eastern Croatia and to compare them with measured values after installation of a new water supply system. The hair samples were taken in the areas of wider Osijek and Vinkovci area and analyzed using the ICP–MS method. These data were also compared with data for Vinkovci previously published in 2004. Depending on the investigated area, the median concentrations ranged from 0.02 to 0.9 µg g−1, whereby this last value exceeded the upper range of the reference value (0.319 µg g−1). The arsenic concentrations from the Našice, Osijek and Vinkovci areas were within or slightly above the maximum allowed reference range. The highest median values in hair samples were detected in Čepin, with arsenic-contaminated potable water, while in areas where the water source was changed, the values were significantly lower. The results add to the conclusion that there has been significant reduction in hair arsenic concentrations in the population that was given access to clean, uncontaminated water from other regional sources.

Associations and Interactions between Heavy Metals with White Blood Cell and Eosinophil Count

The accumulation of heavy metals in the body has been associated with an elevated immune response. The aim of this study was to investigate the associations among heavy metals and white blood cell (WBC) and eosinophil count in the general population in southern Taiwan. We also explored the interactions and synergetic effects of heavy metals on WBC and eosinophil count. We conducted a health survey in the general population living in southern Taiwan between June 2016 and September 2018. Seven heavy metals were measured: blood lead (Pb), and urine cadmium (Cd), copper (Cu), nickel, arsenic (As), chromium and manganese (Mn). A total of 2,447 participants were enrolled. In multivariable analysis, high concentrations of Pb (log per 1 mg/L; coefficient β, 0.332; p = 0.005) and Cu (log per 1 μg/dL; coefficient β, 0.476; p < 0.001) were significantly associated with a high WBC count. In addition, high concentrations of Pb (log per 1 mg/L; coefficient β, 0.732; p < 0.001), As (log per 1 μg/L; coefficient β, 0.133; p = 0.015), Cu (log per 1 μg/dL; coefficient β, 0.181; p = 0.018), and Cd (log per 1 μg/L; coefficient β, 0.139; p = 0.002) were significantly associated with a high eosinophil count. Further, the effect of interactions between Pb and As (coefficient β, 0.721; p = 0.029) and Mn and Cu (coefficient β, 0.482; p = 0.018) on WBC count, and As and Cu (unstandardized coefficient β, 0.558; p = 0.002) on eosinophil count were statistically significant. In conclusion, the heavy metals Pb, As, Cu, and Cd were associated with WBC and eosinophil count. In addition, synergistic effects of heavy metal poisoning on the association with WBC and eosinophil count were also observed.

Arsenic, tobacco use, and lung cancer: An occupational cohort with 27 follow-up years

BACKGROUND

We explored the shape of the exposure-response relationship of arsenic-related lung cancer and the interaction between arsenic and tobacco use.

METHODS

A total of 3278 tin miners with at least 10 years of arsenic exposure were enrolled since 1992 and followed up for 27 years. After excluding radon-exposed miners and former smokers, 1620 miners were included into the sub-cohort. Lung cancer risks were estimated by modeling total exposure and intensity of arsenic exposure.

RESULTS

The cohort experienced 73,866 person-years and 414 lung cancer cases. Firstly, the ERR/mg/m3-year was 0.0033 (95% CI: 0.0014-0.0045) in arsenic concentration <3 mg/m³ and 0.0056 (95% CI: 0.0035-0.0073) in arsenic concentration ≥3 mg/m³. After adjusting for cumulative arsenic exposure, and the ERR/mg/m³ increased with increasing intensity (0.129 (95% CI: 0.039, 0.189)). Secondly, an unique aspect of this population was the early age at first arsenic exposure for workers. Results showed that lung cancer incidence risk from exposed in childhood (<13 years) was non-significantly greater than those in other age groups (13-17 and ≥ 18 years). Finally, the most likely joint effects of inhaled arsenic and tobacco use was sub-multiplicative.

CONCLUSION

This study enlightened us that for fixed cumulative arsenic exposure, higher concentration over shorter duration might be more deleterious than lower concentration over longer duration. Substantial reductions in the lung cancer burden of smokers exposed to arsenic could be achieved by reductions in either exposure.

Up-regulation of PUMA caused the activation of p53 phosphorylation and acetylation, enhancing the interaction between PUMA and Bcl-X and mediating arsenic-induced apoptosis

Arsenic is a toxic metalloid vastly dispersed all over the occupational environments, manifesting multiple adverse health issues related to apoptosis. PUMA (p53 up-regulated modulator of apoptosis) is a crucial member of the Bcl-2 protein family and plays a key role in pro-apoptosis. The purpose of this work was to determine whether inorganic arsenic (NaAsO₂) and its metabolites influenced the expression of PUMA in vivo and vitro, followed by investigating the mechanisms. RNA was extracted from serum and used to determine the expression of PUMA in vivo. The urine samples performed arsenic speciation analysis. This trial tested three-dose proportions in two cell lines (A549: 20, 40, 60 μM/L; 16HBE: 1.5, 3.0, 4.5 μM/L), respectively. According to the results of qRT-PCR and western blotting, NaAsO₂ caused the overexpression of PUMA, not its metabolites. Furthermore, NaAsO₂ induced phosphorylation of p53 at Ser315, 376, 392, and Thr55, and acetylation of p53 at K370, 382 with a dose-response relationship, suggesting the contribution of PUMA up-regulation to p53 phosphorylation and acetylation. CCK-8, JC-1 (5, 5', 6, 6'-tetrachloro-1, 1', 3, 3'-tetramethylbenzimi-dazolylcarbocyanine iodide), Hoechst33342/PI and the caspase3 and PARP1 blots were utilized to reveal apoptosis responding to NaAsO₂ exposure. The co-immunoprecipitation assay showed that the interaction between PUMA and Bcl-X enhanced in intensity responding to NaAsO₂ exposure, disrupting the complexes of Bcl-X with other pro-survival Bcl-2-related proteins. To our knowledge, we first reported that NaAsO₂ activated phosphorylation of p53 at Ser315, 376, and Thr55, as well as acetylation of p53 at K370.

Aggregated cumulative county arsenic in drinking water and associations with bladder, colorectal, and kidney cancers, accounting for population served

BACKGROUND

Many studies neglect to account for variation in population served by community water systems (CWSs) when aggregating CWS-level contaminant concentrations to county level.

OBJECTIVE

In an ecological epidemiologic analysis, we explored two methods-unweighted and weighted (proportion of CWS population served by county population)-to account for population served by CWS in association between arsenic and three cancers to determine the impact of population served on aggregated measures of exposure.

METHODS

CWS arsenic concentration data for 19 states were obtained from Centers for Disease Control and Prevention (CDC) National Environmental Public Health Tracking Network for 2000-10, aggregated to county level, and linked to county-level cancer data for 2011-5 from National Cancer Institute and CDC State Cancer Profiles. Negative binomial regression models estimated adjusted risk ratios (aRR) and 95% confidence intervals (CI) between county-level bladder, colorectal, and kidney cancers and quartiles of aggregated cumulative county-level arsenic concentration (ppb-years).

RESULTS

We observed positive associations between the highest quartile of exposure, compared to the lowest, of aggregated cumulative county-level arsenic concentration (ppb-year) for bladder [weighted aRR: 1.89(1.53, 2.35)], colorectal [1.64(1.33, 2.01)], and kidney [1.69(1.37, 2.09)] cancers. We observed stronger associations utilizing the weighted exposure assessment method. However, inferences from this study are limited due to the ecologic nature of the analyses and different analytic study designs are needed to assess the utility that the weighted by CWS population served metric has for exposure assessment.

SIGNIFICANCE

Weighting by CWS population served accounts for some potential exposure assignment error in epidemiologic analysis.

Urinary arsenic and relative telomere length in 5-7 year old children in Bangladesh

BACKGROUND

Telomere length has been associated with the occurrence and progression of common chronic and age-related diseases, and in younger populations, may represent a biomarker of disease susceptibility. Early childhood is a critical period for telomere biology as this period is characterized by a rapid decline in telomere length due to a large turnover of highly proliferative cells and may represent a period of unique sensitivity to environmental insults. Arsenic (As) exposure has been associated with both telomere lengthening and shortening in adults and children and some evidence suggests the effects may differ by level and timing of exposure.

OBJECTIVES

Given the lack of clarity across studies, we investigated the association between urinary As and leukocyte telomere length among 476 five- to seven-year-old children enrolled in the Bangladesh Environmental Research in Children's Health (BiRCH) cohort.

METHODS

In a series of multivariable models, adjusted for key covariates, we examined associations between urinary As and relative telomere length (RTL) of whole blood DNA.

RESULTS

We observed small but consistent, negative associations between urinary As and RTL, such that a doubling of urinary As was associated with a -0.017 (95% CI: -0.030, -0.005; p = 0.0056) decrease in RTL, in fully adjusted models. We also observed a somewhat stronger inverse relationship between urinary As concentration and RTL among children born to fathers ≥ 30 years of age at the time of birth, than those < 30 years; however, we did not observe a statistically significant interaction.

DISCUSSION

Our study suggests that As influences RTL, with detectable associations in early to mid-childhood. Further studies are needed to confirm our findings and investigate the potential long-term impacts of telomere shortening in childhood on later life health outcomes. Additional studies exploring how dose and timing of exposure may relate to RTL are critical to understanding As's relationship to telomere length.

The pharmacokinetics of therapeutic arsenic trioxide in acute promyelocytic leukemia patients

Arsenic trioxide (ATO) treats Acute Promyelocytic Leukemia (APL). ATO is converted from inorganic arsenic (iAs) to methylated (MAs) and dimethylated (DMAs) metabolites, which are excreted in the urine. Methylation of iAs is important in detoxification, as iAs exposure is deleterious to health. We examined ATO metabolism in 25 APL patients, measuring iAs, MAs, and DMAs. Plasma total iAs increased after ATO administration, followed by a rapid decline, reaching trough levels by 4-6 h. We identified two patterns of iAs metabolism between 6 and 24 h after infusion: in Group 1, iAs increased and were slowly converted to MAs and DMAs, whereas in Group 2, iAs was rapidly metabolized. These patterns were associated with smoking and different treatments: ATO with all-trans retinoic acid (ATRA) alone vs. ATO preceded by ATRA and chemotherapy. Our data suggest that smoking and prior chemotherapy exposure may be associated with ATO metabolism stimulation, thus lowering the effective blood ATO dose.

Quality and human health risk assessment of uranium and other heavy metals in drinking water from Kwale County, Kenya

Heavy metal contamination in drinking water is a global health concern. Anthropogenic and geogenic activities exacerbate the concentrations of these metals in surface and groundwater. In this study, we sampled drinking water sourced from surface and groundwater resources at the environs of Mrima Hill and the Kwale heavy minerals sand deposit, Kwale County, Kenya. The concentrations of Cr, Ni, Cu, As, Cd, Pb, and U were measured using the inductively coupled plasma mass spectrometer. The water quality indices were evaluated using the weighted arithmetic index method, while the human health risks due to exposure to these heavy metals through the ingestion pathway were assessed using deterministic and probabilistic techniques. The concentrations of Cr and Cd in samples from both study areas exceeded the national and international maximum contaminant levels in drinking water. The concentration levels of Ni, Cu, As, and U in all samples from both study areas were within the recommended values in drinking water. Therefore, the quality of water from both study areas was unsuitable for human consumption due to Cd and Cr contamination. The non-carcinogenic risk assessment also showed that the hazard indices (HI) evaluated for both children and adults at the study areas were higher than unity. In addition, the estimated carcinogenic risks of both population groups were more than the recommended value of 10-4. This study shows that the residents near Mrima Hill and the Kwale heavy minerals sand deposit remain susceptible to carcinogenic and non-carcinogenic health risks emanating from exposure to these heavy metals in drinking water.

Paradoxical effects of arsenic in the lungs

High levels (> 100 ug/L) of arsenic are known to cause lung cancer; however, whether low (≤ 10 ug/L) and medium (10 to 100 ug/L) doses of arsenic will cause lung cancer or other lung diseases, and whether arsenic has dose-dependent or threshold effects, remains unknown. Summarizing the results of previous studies, we infer that low- and medium-concentration arsenic cause lung diseases in a dose-dependent manner. Arsenic trioxide (ATO) is recognized as a chemotherapeutic drug for acute promyelocytic leukemia (APL), also having a significant effect on lung cancer. The anti-lung cancer mechanisms of ATO include inhibition of proliferation, promotion of apoptosis, anti-angiogenesis, and inhibition of tumor metastasis. In this review, we summarized the role of arsenic in lung disease from both pathogenic and therapeutic perspectives. Understanding the paradoxical effects of arsenic in the lungs may provide some ideas for further research on the occurrence and treatment of lung diseases.

ATF3 inhibits arsenic-induced malignant transformation of human bronchial epithelial cells by attenuating inflammation

Arsenic is a naturally occurring metalloid strongly associated with the incidence of lung cancer. Understanding the mechanisms of arsenic-induced carcinogenesis favors the development of effective interventions to reduce the incidence and mortality of lung cancer. In this study, we investigated the role of activating transcription factor 3 (ATF3) in arsenic-induced transformation of human bronchial epithelial cells. ATF3 was upregulated during chronic exposure to 0.25 μM arsenic, and loss of ATF3 promoted arsenic-induced transformation. Moreover, arsenic-transformed ATF3 knockout (ATF3 KO-AsT) cells exhibited more aggressive characteristics, including acceleration in proliferation, resistance to chemotherapy and increase in migratory capacity. RNA-seq revealed that pathways involved in inflammation, cell cycle, EMT and oncogenesis were affected due to ATF3 deficiency during chronic arsenic exposure. Further experiments confirmed the overproduction of IL-6, IL-8 and TNFα as well as enhanced phosphorylation of AKT and STAT3 in ATF3 KO-AsT cells. Our results demonstrate that ATF3 upregulated by chronic low-dose arsenic exposure represses cell transformation and acquisition of malignant characteristics through inhibiting the production of proinflammatory cytokines and activation of downstream proteins AKT and STAT3, providing a new strategy for the prevention of carcinogen-induced lung cancer.

Seven potential sources of arsenic pollution in Latin America and their environmental and health impacts

This review presents a holistic overview of the occurrence, mobilization, and pathways of arsenic (As) from predominantly geogenic sources into different near-surface environmental compartments, together with the respective reported or potential impacts on human health in Latin America. The main sources and pathways of As pollution in this region include: (i) volcanism and geothermalism: (a) volcanic rocks, fluids (e.g., gases) and ash, including large-scale transport of the latter through different mechanisms, (b) geothermal fluids and their exploitation; (ii) natural lixiviation and accelerated mobilization from (mostly sulfidic) metal ore deposits by mining and related activities; (iii) coal deposits and their exploitation; (iv) hydrocarbon reservoirs and co-produced water during exploitation; (v) solute and sediment transport through rivers to the sea; (vi) atmospheric As (dust and aerosol); and (vii) As exposure through geophagy and involuntary ingestion. The two most important and well-recognized sources and mechanisms for As release into the Latin American population's environments are: (i) volcanism and geothermalism, and (ii) strongly accelerated As release from geogenic sources by mining and related activities. Several new analyses from As-endemic areas of Latin America emphasize that As-related mortality and morbidity continue to rise even after decadal efforts towards lowering As exposure. Several public health regulatory institutions have classified As and its compounds as carcinogenic chemicals, as As uptake can affect several organ systems, viz. dermal, gastrointestinal, peptic, neurological, respiratory, reproductive, following exposure. Accordingly, ingesting large amounts of As can damage the stomach, kidneys, liver, heart, and nervous system; and, in severe cases, may cause death. Moreover, breathing air with high As levels can cause lung damage, shortness of breath, chest pain, and cough. Further, As compounds, being corrosive, can also cause skin lesions or damage eyes, and long-term exposure to As can lead to cancer development in several organs.

Protective effects of curcumin on ATO-induced nephrotoxicity in ducks in relation to suppressed autophagy, apoptosis and dyslipidemia by regulating oxidative stress

Arsenic trioxide (ATO) has been known as common environmental pollution, and is deemed to a threat to global public health. Curcumin (Cur) is a phytoconstituent, which has been demonstrated to have antioxidant effects. In the current experiment, we investigated the efficacy of Cur against ATO-induced kidney injury and explored the potential molecular mechanisms that have not yet been fully elucidated in ducks. The results showed that treatment with Cur attenuated ATO-induced body weight loss, reduced the content of ATO in the kidney, and improved ATO-induced kidney pathological damage. Cur also remarkably alleviated the ascent of ATO-induced MDA level and activated the Nrf2 pathway. Using the TEM, we found Cur relieved mitochondrial swelling, autolysosomes generating and nuclear damage. Simultaneously, Cur was found that it not only significantly reduced autophagy-related mRNA and protein levels (mTOR, LC3-Ⅰ, LC3-Ⅱ, Atg-5, Beclin1, Pink1 and Parkin) and but also decreased apoptosis-related mRNA and protein expression levels (cleaved caspase-3, Cytc, p53 and Bax). Furthermore, through nontargeted metabolomics analysis, we observed that lipid metabolism balance was disordered by ATO exposure, while Cur administration alleviated the disturbance of lipid metabolism. These results showed ATO could induce autophagy and apoptosis by overproducing ROS in the kidney of ducks, and Cur might relieve excessive autophagy, apoptosis and disturbance of lipid metabolism by regulating oxidative stress. Collectively, our findings explicate the potential therapeutic value of Cur as a new strategy to a variety of disorders caused by ATO exposure.

Analyzing liver protein-bound DMAV by using size exclusion and ion exchange HPLC combined with ICP-MS and MRM mode in rats exposed to AS4S4

Long-term exposure to high levels of arsenic (As) will result in damage to organs. Compared with free arsenic, protein-bound arsenic are more difficult to be excreted from the bodies due to their complexation with biological macromolecules. We developed a method of size exclusion chromatography (SEC) and ion exchange chromatography (IEC) combined with inductively coupled plasma-mass spectrometry (ICP-MS) and multiple reaction monitoring (MRM) mode, which was used to determine bound-arsenic species. DMA^V was identified as bound arsenic species in rat livers after As4S4 overexposure. Subsequent proteomics analysis showed the potential binding partners included hemoglobin, glutathione S-transferases, superoxide dismutase [Cu-Zn] & [Mn], thiosulfate sulfurtransferase, and metallothionein-2. The method developed here was sensitive, repeatable, and conducive to arsenic analysis, especially for toxicity evaluation of arsenic-containing substances in vivo.

Blood Arsenic Levels as a Marker of Breast Cancer Risk among BRCA1 Carriers

An important group of breast cancers is those associated with inherited susceptibility. In women, several predisposing mutations in genes involved in DNA repair have been discovered. Women with a germline pathogenic variant in BRCA1 have a lifetime cancer risk of 70%. As part of a larger prospective study on heavy metals, our aim was to investigate if blood arsenic levels are associated with breast cancer risk among women with inherited BRCA1 mutations. A total of 1084 participants with pathogenic variants in BRCA1 were enrolled in this study. Subjects were followed from 2011 to 2020 (mean follow-up time: 3.75 years). During that time, 90 cancers were diagnosed, including 67 breast and 10 ovarian cancers. The group was stratified into two categories (lower and higher blood As levels), divided at the median (<0.85 µg/L and ≥0.85 µg/L) As level among all unaffected participants. Cox proportional hazards models were used to model the association between As levels and cancer incidence. A high blood As level (≥0.85 µg/L) was associated with a significantly increased risk of developing breast cancer (HR = 2.05; 95%CI: 1.18-3.56; p = 0.01) and of any cancer (HR = 1.73; 95%CI: 1.09-2.74; p = 0.02). These findings suggest a possible role of environmental arsenic in the development of cancers among women with germline pathogenic variants in BRCA1.

Nutrition, one-carbon metabolism and arsenic methylation

Exposure to arsenic (As) is a major public health concern globally. Inorganic As (InAs) undergoes hepatic methylation to form monomethyl (MMAs)- and dimethyl (DMAs)-arsenical species, facilitating urinary As elimination. MMAsIII is considerably more toxic than either InAsIII or DMAsV, and a higher proportion of MMAs in urine has been associated with risk for a wide range of adverse health outcomes. Efficiency of As methylation differs substantially between species, between individuals, and across populations. One-carbon metabolism (OCM) is a biochemical pathway that provides methyl groups for the methylation of As, and is influenced by folate and other micronutrients, such as vitamin B12, choline, betaine and creatine. A growing body of evidence has demonstrated that OCM-related micronutrients play a critical role in As methylation. This review will summarize observational epidemiological studies, interventions, and relevant experimental evidence examining the role that OCM-related micronutrients have on As methylation, toxicity of As, and risk for associated adverse health-related outcomes. There is fairly robust evidence supporting the impact of folate on As methylation, and some evidence from case-control studies indicating that folate nutritional status influences risk for As-induced skin lesions and bladder cancer. However, the potential for folate to be protective for other As-related health outcomes, and the potential beneficial effects of other OCM-related micronutrients on As methylation and risk for health outcomes are less well studied and warrant additional research.