A follow-up study of the development of skin lesions associated with arsenic exposure duration

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.

Maternal Exposure to Arsenic and Its Impact on Maternal and Fetal Health: A Review

Arsenic exposure is a significant public health issue, with harmful effects caused by its use in commercial products such as car batteries, pesticides, and herbicides. Arsenic has three main compounds: inorganic, organic, and arsine gas. Inorganic arsenic compounds in water are highly toxic. The daily intake of arsenic from food and beverages is between 20 and 300 mcg/day. Arsenic is known for its carcinogenic properties and is classified as a human carcinogen by different institutions. Exposure can lead to oxidative stress, DNA damage, and epigenetic deregulation, which can cause endocrine disorders, altered signal transduction pathways, and cell proliferation. In addition, arsenic can easily cross the placenta, making it a critical concern for maternal and fetal health. Exposure can lead to complications such as gestational diabetes, anemia, low birth weight, miscarriage, and congenital anomalies. Female babies are particularly vulnerable to the negative impact of arsenic exposure, with a higher risk of low weight for gestational age and congenital cardiac anomalies. Therefore, it is crucial to monitor and regulate the levels of arsenic in drinking water and food sources to prevent these adverse health outcomes. Further research is necessary to fully understand the impact of arsenic exposure on human health, especially during pregnancy and infancy, by implementing preventative measures and monitoring the levels of arsenic in the environment.

SLC1A5 regulates cell proliferation and self-renewal through β-catenin pathway mediated by redox signaling in arsenic-treated uroepithelial cells

Arsenic exposure increases the risk of bladder cancer in humans, but its underlying mechanisms remain elusive. The alanine, serine, cysteine-preferring transporter 2 (ASCT2, SLC1A5) is frequently overexpressed in cancer cells. The aim of this study was to evaluate the effects of arsenic on SLC1A5, and to determine the role of SLC1A5 in the proliferation and self-renewal of uroepithelial cells. F344 rats were exposed to 87 mg/L NaAsO₂ or 200 mg/L DMA^V for 12 weeks. The SV-40 immortalized human uroepithelial (SV-HUC-1) cells were cultured in medium containing 0.5 μM NaAsO₂ for 40 weeks. Arsenic increased the expression levels of SLC1A5 and β-catenin both in vivo and in vitro. SLC1A5 promoted cell proliferation and self-renewal by activating β-catenin, which in turn was dependent on maintaining GSH/ROS homeostasis. Our results suggest that SLC1A5 is a potential therapeutic target for arsenic-induced proliferation and self-renewal of uroepithelial cells.

Spatiotemporal distribution and probabilistic health risk assessment of arsenic in drinking water and wheat in Northwest China

Drinking water arsenic poisoning has been a health concern, however the importance of dietary arsenic exposure to health also needs to be taken into account. The aim of this study was to conduct a comprehensive health risk assessment of arsenic-contaminated substances in drinking water and wheat-based food intake in the Guanzhong Plain, China. 87 samples of wheat and 150 samples of water were randomly selected from the research region and examined. The level of arsenic in 89.33% of the water samples in the region exceeded the limit for drinking water (10 μg/L), with an average concentration of 29.98 μg/L. The arsenic in 2.13% of the wheat samples exceeded the food limit (0.5 mg/kg) with an average concentration of 0.24 mg/kg. Under the situation of different exposure pathways, two scenarios of deterministic and probabilistic health risk assessments were compared and analyzed. By contrast, the probabilistic health risk assessment can ensure a certain degree of confidence in the assessment results. The findings of this study indicated that the total cancer risk value faced by the population aged 3-79 years, except for those aged 4-6 years, was 1.03E-4-1.21E-3, which exceeded the 10E-6-10E-4 range of thresholds usually used by USEPA as guidance recommendations for determination. And the non-cancer risk experienced by the population aged 6 months to 79 years was higher than the acceptable threshold (1), with children aged 9 months to 1 year having the highest total non-cancer risk of 7.25. The potential health risks of the exposed population were mainly due to the drinking water route, and consumption of arsenic-containing wheat increased both carcinogenic and non-carcinogenic risks. Finally, the sensitivity analysis revealed that the assessment findings were most significantly influenced by exposure time. The amount of intake was the second influencing factor in the health risk assessment from drinking water and dietary intakes of arsenic, and arsenic concentration was the second influencing factor in the health risk assessment due to dermal exposure to arsenic. The findings of this study can aid in understanding the negative health consequences of arsenic pollution to local residents and in adopting focused remediation strategies to alleviate environmental concerns.

Metabolic Changes and Their Associations with Selected Nutrients Intake in the Group of Workers Exposed to Arsenic

Arsenic (As) exposure causes numerous adverse health effects, which can be reduced by the nutrients involved in the metabolism of iAs (inorganic As). This study was carried out on two groups of copper-smelting workers: WN, workers with a urinary total arsenic (tAs) concentration within the norm (n = 75), and WH, workers with a urinary tAs concentration above the norm (n = 41). This study aimed to analyze the association between the intake level of the nutrients involved in iAs metabolism and the signal intensity of the metabolites that were affected by iAs exposure. An untargeted metabolomics analysis was carried out on urine samples using liquid chromatography-mass spectrometry, and the intake of the nutrients was analyzed based on 3-day dietary records. Compared with the WN group, five pathways (the metabolism of amino acids, carbohydrates, glycans, vitamins, and nucleotides) with twenty-five putatively annotated metabolites were found to be increased in the WH group. In the WN group, the intake of nutrients (methionine; vitamins B2, B6, and B12; folate; and zinc) was negatively associated with six metabolites (cytosine, D-glucuronic acid, N-acetyl-D-glucosamine, pyroglutamic acid, uridine, and urocanic acid), whereas in the WH group, it was associated with five metabolites (D-glucuronic acid, L-glutamic acid, N-acetyl-D-glucosamine, N-acetylneuraminic acid, and uridine). Furthermore, in the WH group, positive associations between methionine, folate, and zinc intake and the signal intensity of succinic acid and 3-mercaptolactic acid were observed. These results highlight the need to educate the participants about the intake level of the nutrients involved in iAs metabolism and may contribute to further considerations with respect to the formulation of dietary recommendations for people exposed to iAs.

Inorganic arsenic promotes apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway

Chronic exposure to high-dose inorganic arsenic through groundwater, air, or food remains a major environmental public health issue worldwide. Apoptosis, a method of cell death, has recently become a hot topic of research in biology and medicine. Previous studies have demonstrated that extracellular signal-regulated kinase (ERK) is related to arsenic-induced apoptosis. However, the reports are contradictory, and the knowledge of the above-mentioned mechanisms and their mutual regulation remains limited. In this study, the associations between the TGF-β1/ERK signaling pathway and arsenic-induced cell apoptosis were confirmed using the HaCaT cell model. The relative expressions of the indicators of the TGF-β1/ERK signaling pathway, apoptosis-related genes (cytochrome C, caspase-3, caspase-9, cleaved caspase-3, cleaved caspase-9, and Bax), the mitochondrial membrane potential, and the total apoptosis rate were significantly increased (P < .05), while the expression of the antiapoptosis gene Bcl-2 was significantly decreased (P < .05) in cells of the group exposed to arsenic. Moreover, the results demonstrated that the ERK inhibitor (PD98059) and TGF-β1 inhibitor (LY364947) could inhibit the activation of the ERK signaling pathway, thereby reducing the mitochondrial membrane potential, the total apoptosis rate, and the expression of pro-apoptosis-related genes in the cells, while the expression of the antiapoptosis gene Bcl-2 was significantly increased (P < .05). By contrast, the recombinant human TGF-β1 could promote apoptosis of the HaCaT cells by increasing the activation of the ERK signaling pathway (P < .05). These results indicate that inorganic arsenic promotes the apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway.

Assessing the Association of Element Imbalances With Arsenism and the Potential Application Value of Rosa roxburghii Tratt Juice

Endemic arsenism caused by coal burning is a unique type of biogeochemical disease that only exists in China, and it is also a disease of element imbalances. Previous studies have shown that element imbalances are involved in the pathogenesis of arsenic; however, the interaction between the various elements and effective preventive measures have not been fully studied. This study first conducted a cross-sectional study of a total of 365 participants. The results showed that arsenic exposure can increase the content of elements (Al, As, Fe, Hg, K, and Na) in the hair (p < 0.05), but the content of other elements (Ca, Co, Cu, Mn, Mo, P, Se, Sr, V, and Zn) was significantly decreased (p < 0.05). Also, the high level of As, Fe, and Pb and the low level of Se can increase the risk of arsenism (p < 0.05). Further study found that the combined exposure of Fe–As and Pb–As can increase the risk of arsenism, but the combined exposure of Se–As can reduce the risk of arsenism (p < 0.05). In particular, a randomized, controlled, double-blind intervention study reveals that Rosa roxburghii Tratt juice (RRT) can reverse the abovementioned element imbalances (the high level of Al, As, and Fe and the low level of Cu, Mn, Se, Sr, and Zn) caused by arsenic (p < 0.05). Our study provides some limited evidence that the element imbalances (the high level of As, Fe, and Pb and the low level of Se) are the risk factors for the occurrences of arsenism. The second major finding was that RRT can regulate the element imbalances, which is expected to improve arsenism. This study provides a scientific basis for further understanding a possible traditional Chinese health food, RRT, as a more effective detoxication of arsenism.

Assessing the Potential Value and Mechanism of Kaji-Ichigoside F1 on Arsenite-Induced Skin Cell Senescence

Chronic exposure to inorganic arsenic is a major environmental public health issue worldwide affecting more than 220 million of people. Previous studies have shown the correlation between arsenic poisoning and cellular senescence; however, knowledge regarding the mechanism and effective prevention measures has not been fully studied. First, the associations among the ERK/CEBPB signaling pathway, oxidative stress, and arsenic-induced skin cell senescence were confirmed using the HaCaT cell model. In the arsenic-exposed group, the relative mRNA and protein expressions of ERK/CEBPB signaling pathway indicators (ERK1, ERK2, and CEBPB), cell cycle-related genes (p21, p16^INK4a), and the secretion of SASP (IL-1α, IL-6, IL-8, TGF-β1, MMP-1, MMP-3, EGF, and VEGF) and the lipid peroxidation product (MDA) were significantly increased in cells (P < 0.05), while the activity of antioxidant enzyme (SOD, GSH-Px, and CAT) was significantly decreased (P < 0.05), and an increased number of cells accumulated in the G1 phase (P < 0.05). Further Kaji-ichigoside F1 intervention experiments showed that compared to that in the arsenic-exposed group, the expression level of the activity of antioxidant enzyme was significantly increased in the Kaji-ichigoside F1 intervention group (P < 0.05), but the indicators of ERK/CEBPB signaling pathway, cell cycle-related genes, and SASP were significantly decreased (P < 0.05), and the cell cycle arrest relieved to a certain extent (P < 0.05). Our study provides some limited evidence that the ERK/CEBPB signaling pathway is involved in low-dose arsenic-induced skin cell senescence, through regulating oxidative stress. The second major finding was that Kaji-ichigoside F1 can downregulate the ERK/CEBPB signaling pathway and regulate the balance between oxidation and antioxidation, alleviating arsenic-induced skin cell senescence. This study provides experimental evidence for further understanding of Kaji-ichigoside F1, a natural medicinal plant that may be more effective in preventing and controlling arsenic poisoning.

Associations between and risks of trace elements related to skin and liver damage induced by arsenic from coal burning

Long-term exposure to high levels of arsenic has been documented to induce skin and liver damage, affecting hundreds of millions of people. While arsenic-induced skin and liver damage and trace element alterations have been studied, their correlations and risks have not been explained. Based on the above premise, this study included a total of 172 subjects from a coal-burning arsenic poisoning area. The levels of 18 trace elements in hair and six liver function indices in serum were detected, and the associations between and risks of trace elements related to skin and liver damage were analyzed. Finally, the receiver operating characteristic (ROC) curve and areas under the curve (AUC) were used to analyze the diagnostic values of certain trace elements for arsenic-induced skin and liver damage. The results found that a decrease in Se was a risk factor for arsenic-induced skin and liver damage (OR = 8.33 and 1.92, respectively). Furthermore, increases in Al and V were risk factors for arsenic-induced skin damage (OR = 1.05) and liver damage (OR = 13.16), respectively. In addition, the results found that Se and Al possessed certain diagnostic values for arsenic-induced skin damage (AUC = 0.93, 0.80), that Se possessed a diagnostic value for liver damage (AUC = 0.93), and that the combination of Se and Al increased the diagnostic value for skin damage (AUC = 0.96). This study provides an important research basis for further understanding the reasons for arsenic-induced skin and liver damage, for screening and identifying candidate diagnostic biomarkers, and for improving prevention and control strategies for arsenism.

HER2 overexpression triggers the IL-8 to promote arsenic-induced EMT and stem cell-like phenotypes in human bladder epithelial cells

Arsenic is a natural chemical element that is strongly associated with bladder cancer. Understanding the underlying mechanisms behind the association between arsenic and bladder cancer as well as identifying effective preventive interventions will help reduce the incidence and mortality of this disease. The epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) properties play key roles in cancer development and progression. Here, we reported that chronic exposure to arsenic resulted in EMT and increased levels of the CSC marker CD44 in human uroepithelial cells. Furthermore, IL-8 promoted a mesenchymal phenotype and upregulated CD44 by activating the ERK, AKT and STAT3 signaling. Phosphorylation of the human epidermal growth factor receptor 2 (HER2) was key for arsenic-induced IL-8 overexpression and depended on the simultaneous activation of the MAPK, JNK, PI3K/AKT and GSK3β signaling pathways. We also found that genistein inhibited arsenic-induced HER2 phosphorylation and downregulated its downstream signaling pathways, thereby inhibiting progression of EMT, and reducing CD44 expression levels. These results demonstrate that the HER2/IL-8 axis is related to the acquisition of an EMT phenotype and CSCs in arsenic-treated cells. The inhibitory effects of genistein on EMT and CSCs provide a new perspective for the intervention and potential chemotherapy against arsenic-induced bladder cancer.

Arsenic induced redox imbalance triggers the unfolded protein response in the liver of zebrafish

Inorganic arsenic (iAs) is one of the most endemic toxicants worldwide and oxidative stress is a key cellular pathway underlying iAs toxicity. Other cellular stress response pathways, such as the unfolded protein response (UPR), are also impacted by iAs exposure, however it is not known how these pathways intersect to cause disease. We optimized the use of zebrafish larvae to identify the relationship between these cellular stress response pathways and arsenic toxicity. We found that the window of iAs susceptibility during zebrafish development corresponds with the development of the liver, and that even a 24-h exposure can cause lethality if administered to mature larvae, but not to early embryos. Acute exposure of larvae to iAs generates reactive oxygen species (ROS), an antioxidant response, endoplasmic reticulum (ER) stress and UPR activation in the liver. An in vivo assay using transgenic larvae expressing a GFP-tagged secreted glycoprotein in hepatocytes (Tg(fabp10a:Gc-EGFP)) revealed acute iAs exposure selectively decreased expression of Gc-EGFP, indicating that iAs impairs secretory protein folding in the liver. The transcriptional output of UPR activation is preceded by ROS production and activation of genes involved in the oxidative stress response. These studies implicate redox imbalance as the mechanism of iAs-induced ER stress and suggest that crosstalk between these pathways underlie iAs-induced hepatic toxicity.

Assessing potential mechanisms of arsenic-induced skin lesions and cancers: Human and in vitro evidence

Environmental exposure to arsenic is a major public health challenge worldwide. In detailing the hallmark signs of chronic arsenic exposure, previous studies have shown that epigenetic and immune dysfunction are associated with arsenic-induced skin lesions; however, knowledge regarding interactions between the mechanisms listed above is limited. In this study, a total of 106 skin samples were collected over the past 20 years. Based on the presence or absence of high arsenic exposure, the participants were divided into arsenic exposure (72) and reference (34) groups. Additionally, the arsenic exposure group was further divided into the non-cancer group (31, including skin hyperpigmentation and hyperkeratosis) and the skin cancer group (41, including Bowen's disease, basal cell carcinoma and squamous cell carcinoma) according to a skin histopathological examination. First, the associations among miR-155, NF-AT1 with immunological dysfunction and arsenic-induced skin lesions and carcinogenesis were confirmed using these skin samples. In the arsenic-exposed group, miR-155-5p, keratin 1(Krt1), keratin 10 (Krt10), and keratin 6c (Krt6c) were significantly increased in the skin (p < 0.05), while NF-AT1, interleukin-2 (IL-2), and interferon-γ (IFN-γ) were significantly decreased (p < 0.05). Clear correlations were observed among these factors (p < 0.05). In immortalized human keratinocytes, silencing and overexpression of NF-AT1 could alter the expression and secretion of immunological dysfunction indicators (IL-2 and IFN-γ) that are induced by arsenic exposure (p < 0.05); however, miR-155-5p levels did not change significantly (p > 0.05). The miR-155-5p mimic and inhibitor could regulate the NF-AT1-mediated immunological dysfunction caused by arsenic (p < 0.05). Our study provides some limited evidence that miR-155-5p regulates the NF-AT1-mediated immunological dysfunction that is involved in the pathogenesis and carcinogenesis of arsenic. The second major finding was that Krt1 and Krt10 are markers of hyperkeratosis caused by arsenic, and Krt6c is a potential biomarker that can reflect arsenic carcinogenesis.

Assessment of arsenic exposure by drinking well water and associated carcinogenic risk in peri-urban areas of Vehari, Pakistan

Arsenic (As) is a highly toxic and carcinogenic element. It has received considerable consideration worldwide in recent years due to its highest toxicity to human, and currently, high concentrations observed in the groundwater. Some recent media and research reports also highlighted possible As contamination of groundwater systems in Pakistan. However, there is a scarcity of data about As contents in groundwater in different areas/regions of the country. Consequently, the current study estimated the As concentration in the groundwater used for drinking purpose in 15 peri-urban sites of district Vehari, Pakistan. In total, 127 groundwater samples were collected and examined for As contents in addition to physicochemical characteristics such as temperature, electrical conductivity, pH, total soluble salts, chloride, carbonates, bicarbonates, sodium, potassium, lithium, calcium and barium. Results indicated that the groundwater samples were not fully fit for drinking purposes with several parameters, especially the alarming levels of As (mean As: 46.9 µg/L). It was found that 83% groundwater samples of peri-urban sites in district Vehari have As concentration greater than WHO lower permissible limit (10 µg/L). The risk assessment parameters (mean hazard quotient: 3.9 and mean cancer risk: 0.0018) also showed possible carcinogenic and non-carcinogenic risks associated with ingestion of As-contaminated groundwater at peri-urban sites. Based on the findings, it is anticipated that special monitoring and management of groundwater is necessary in the studied area in order to curtail the health risks associated with the use of As-contaminated drinking water. Moreover, appropriate remediation and removal of As from groundwater is also imperative for the study area before being used for drinking purpose to avoid As exposure and related risks to the local community.

Exposure assessment for the abandoned metal mine area contaminated by arsenic

Among the results of community health impact assessments completed in 2014, residents of the Indae abandoned metal mine area showed high average urinary concentrations of harmful arsenic (As), at 148.9 µg/L. The concentration of harmful As was derived as the sum of As(V), As(III), MMA, and DMA concentrations known to be toxic. In this area, mining hazard prevention work was not carried out and the pollution source was neglected, and the health effect of the residents due to arsenic exposure was concerned. We re-assessed As exposure levels and tried to identify exposure factors for residents of this area. Analysis of the soil, sediment, and river water to assess the association between the soil of the Indae abandoned metal mine area and the soil in residential areas confirmed a correlation between Pb and As concentrations in the soil. Since Pb and As behave similarly, the use of the stable Pb isotope ratio for assessment of the pollution source tracking was validated. In the 3-isotope plot (207/206Pb vs. 208/206Pb) of soil samples in this area, a stable Pb isotope ratio was located on the same trend line, which confirmed that the soil in the residential area was within the area of influence of the Indae abandoned metal mine. Therefore, we judged that the pollution source of As was the Indae abandoned metal mine. The results by As species were As (III) 1.45 μg/L, As (V) 0.74 μg/L, monomethylarsonic acid (MMA) 2.43 μg/L, dimethylarsinic acid (DMA) 27.63 μg/L, and arsenobetaine 88.62 μg/L. The urinary harmful As was 31.92 μg/L, much lower than the 148.9 μg/L reported in a 2014 survey, due to the implementation of a multi-regional water supply in November 2014 that restricted As exposure through drinking river water. However, concerns remain over chronic exposure to As because As in river water used for farming and in agricultural soil still exceeds environmental standards; thus, ongoing work to address hazards from former mining areas and continued environmental monitoring is necessary.