Apoptosis of peripheral blood mononuclear cells in children exposed to arsenic and fluoride

Development of the Colorimetric and/or Fluorescent Probes for Detecting Fluoride ions in Aqueous Solution

Fluoride ion is a strong Lewis base and one of the essential trace elements in human body. It plays a very important role in human health and ecological balance. The deficiency or excessive intake of fluoride ions will cause serious health problems, so the development of a sensitive and accurate detection method for fluoride ions is very important. The colorimetric and/or fluorescence sensing method has been a long standing attractive technique with high sensitivity and fast response. To date, most reported probes for fluoride ion are applicable only in organic solvents or organic-containing aqueous solutions. However, the probes for fluoride ion used in aqueous solution are more practically needed in view of environment protection and human health. In this paper, the materials and designing ideas of the colorimetric and/or fluorescent probes for fluoride ion based on different detection mechanisms in recent years were reviewed. Two main categories including formation of hydrogen bonds and formation of coordination covalent bonds were discussed. The latter one is further subdivided into three types, formation of B-F bond, formation of Si-F bond and formation of Mn+-F bond.

Arsenic exposure and prevalence of human papillomavirus in the US male population

Arsenic is a known carcinogen and is naturally available in earth's crust. Inorganic arsenic is an environmental pollutant with immunosuppressive properties. Human papillomavirus (HPV) is considered one of the most common sexually transmitted diseases in the United States. HPV is linked to several types of cancers in males, including oral, anal, and penile cancer. However, limited information is available on the effect of arsenic on HPV in males. The purpose of this study was to examine the association of urinary arsenic species (speciated and total) and the prevalence of HPV infection in the male population. HPV prevalence in males was analyzed using the 2013-2014 and 2015-2016 National Health and Nutrition Examination Survey (NHANES) dataset. Logistic regression analysis was used to examine associations of seven types of urinary arsenic species (arsenous acid, arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), total arsenic acid) with HPV risk for male participants aged 18-59 years (N = 1516). Demographic characteristics were included in the logistic regression model for each arsenic variable. All statistical analyses were conducted by using the software R (version 4.2.0). Increasing DMA was positively associated with the prevalence of low-risk HPV (odds ratio (OR): 1.075, 95% confidence interval (CI): 1.025, 1.128) in addition to the sum of total toxic arsenic species (TUA1) including arsenous acid, arsenic acid, DMA, and MMA (OR: 1.068, 95% CI: 1.022, 1.116). High-risk HPV strains were found to be positively associated with arsenic acid (OR: 1.806, 95% CI: 1.134, 2.876) and total arsenic minus the sum of the two organic arsenic species arsenobetaine and arsenocholine (TUA2) at quartile 3 (Q3) level (OR: 1.523, 95% CI: 1.102, 2.103). The logistic regression models also showed that race and marital status were significant factors related to high-risk HPV. Our study reported that DMA and TUA1 are associated with low-risk HPV and arsenic acid is associated with high-risk HPV infections in males. Future research is required to confirm or refute this finding.

Arsenic: a Culpable Element and a Possible Menace for HIV/AIDS Patients

Arsenic contamination has long been recognized as one of the most harmful environmental pollutants resulting from anthropogenic activity. Apart from being an environmental toxicant or pollutant, this culpable heavy metal also has detrimental effects on human health. People throughout the world are exposed to arsenic (As) mostly through polluted drinking water. Acute inorganic arsenic (iAs) poisoning causes nausea, vomiting, stomach discomfort, and severe diarrhea. As on long-term exposure is a potent carcinogen, characterized by IARC (International Agency for Research on Cancer). As levels are high mainly in Gangetic regions due to which the people living around are suffering the consequences. The carcinogenicity of As is well established but the immunotoxicity caused by it is still unknown. Some animal model supports the toxicity of As in the immune system as well, but in humans, mainly suffering from human immunodeficiency virus (HIV), it is not well established. iAs suppresses the immune system by acting on different targets and exacerbating infections. Although animal studies have demonstrated that arsenic trioxide (As₂O₃) reduces viral rebound and restores CD4 + count in vivo when coupled with antiretroviral medications, elemental AS may have devastating effects on the immune system of HIV patients, making them more prone to opportunistic infections (OIs). It is well known that in later stages of HIV infection, neurological problems also complicate the conditions such as cognitive impairment and AIDS dementia complex (ADC). Along with immunotoxicity, As has the potential to damage HIV patients' brains. This article addresses the immunotoxicity of arsenic and exacerbations caused by it, along with the neurotoxicity, particularly in HIV patients residing near the Gangetic belt.

Dietary contribution to total urinary arsenic in Mexican women

Exposure to inorganic arsenic (iAs) damages health in many ways. The main routes of human exposure are consumption of contaminated water and diet, but evidence regarding the dietary contribution of iAs is limited. The objective of this work was to determine the foods and beverages that contribute to urinary total arsenic levels (TAs). This is a secondary analysis of an original study of breast cancer cases and population controls carried out in northern Mexico during the period 2007-2011, from which 1,462 women without a history of diabetes were selected. We estimated the consumption of the food and beverage groups with a frequency questionnaire. We measured the concentrations of urinary iAs metabolites by high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Total arsenic ranged from 0.5 to 2,360 µg/g creatinine. After adjusting for covariates, we observed a positive association between TAs (with arsenobetaine) with non-bottled drinking water intake, as well as the consumption of root vegetables, vegetables and fruits rich in water, eggs, fish and shellfish. Our findings highlight the relevance of water consumption and some foods for TAs exposure. Food quality monitoring deserves attention in high-risk regions of arsenic contamination.

Health risk assessment in children living in an urban area with hydrofluorosis: San Luis Potosí Mexico case study

BACKGROUND

Fluoride is an inorganic element, which can be found in high concentrations in groundwater. Its consumption and exposure have consequences on human health. The objective of this study was to evaluate fluoride exposure and develop a health risk assessment in children from an urban area with hydrofluorosis in Mexico.

METHODS

Water fluoride levels in active wells were provided by the Water State Agency and divided into three zones: agriculture zone (Zone A), metallurgical zone (Zone B), and industrial zone (Zone C). Urinary fluoride levels were determined by potentiometric method using an ion-selective electrode. Health risk assessment was performed through Monte Carlo model analysis and hazard quotient was calculated.

RESULTS

According to fluoride well concentration, all zones have high concentration especially Zone B (2.55 ± 0.98 mg/L). Urinary fluoride concentrations were highest in children in Zone B (1.42 ± 0.8 mg/L). The estimated median daily intake dose of fluoride was 0.084 mg/Kg-day for the children living in zone B. The highest mean HQ value was to Zone B (1.400 ± 0.980), followed by Zone C (0.626 ± 0.443).

CONCLUSION

The levels of fluoride exposure registered are a potential risk to generate adverse health effects in children in the San Luis Potosi metropolitan area.

Genotoxicity of fluoride subacute exposure in rats and selenium intervention

The aims of this study were to: (i) examine the toxic effects of sodium fluoride (NaF) in blood, liver, spleen, and brain cells of Wistar rats after the subacute exposure; (ii) explore the potential protective properties of selenium (Se) against fluoride toxicity after the simultaneous administration. Twenty male Wistar rats, eight weeks old, weighing approximately 140-190 g, were divided into four experimental groups (n = 5) as follows: I control-tap water; II NaF 150 ppm; III NaF 150 ppm and Se 1.5 mg/L; IV Se 1.5 mg/L, and had available water with solutions ad libitum for 28 days. DNA damage detected by comet assay was confirmed in the liver, spleen, and brain cells, but not in blood. Selenium supplementation together with NaF decreased DNA damage in liver and spleen cells. According to the histological findings, no changes were observed in spleen and brain tissues after NaF administration. Unlike the observed Se protective effect on the DNA level, no significant reduction of liver tissue injury was observed after the NaF and Se treatment, resulting in mild inflammation. Data of this study suggest that DNA damage after NaF subacute exposure at moderately high concentration was reduced in liver and spleen cells due to Se supplementation, but a similar change was not seen in the brain.

Arsenic in waters, soils, sediments, and biota from Mexico: An environmental review

We reviewed over 226 studies dealing with arsenic (As) in water bodies (124 sites or regions; 5,834 samples), soils (44; 2,700), sediments (56; 765), rocks (6; 85), mine waste (25; 582), continental plants (17 (77 species); 571), continental animals (10 (32 species); 3,525) and aquatic organisms (27 (100 species) 2,417) in Mexico. In general, higher As concentrations were associated with specific regions in the states of Hidalgo (21 sites), San Luis Potosi (SLP) (19), Baja California Sur (15), Zacatecas (5), and Morelos (4). High As levels have been detected in drinking water in certain locations of Coahuila (up to 435 μg L^-1) and Sonora (up to 1004 μg L^-1); in continental surficial water in Puebla (up to 780 μg L^-1) and Matehuala, SLP (up to 8684 μg L^-1); in groundwater in SLP (up to 16,000 μg L^-1) and Morelia, Michoacán (up to 1506,000 μg L^-1); in soils in Matehuala, SLP (up to 27,945 μg g^-1) and the Xichú mining area, Guanajuato (up to 62,302 μg g^-1); and in sediments in Zimapán, Hidalgo (up to 11,810 μg g^-1) and Matehuala, SLP (up to 28,600 μg g^-1). In contaminated arid and semi-arid areas, the plants P. laevigata and A. farnesiana exhibit the highest As levels. These findings emphasize the human and environmental risks associated with the presence of As in such regions. A synthesis of the available techniques for the removal of As in water and the remediation technologies for As contaminated soils and sediments is given. The As occurrence, origin (geogenic, thermal, mining and anthropogenic) and evolution in specific regions is summarized. Also, the mobilization and mechanisms to explain the As variability in continental environments are concisely given. For future research, a stratified regional sampling is proposed which prioritizes critical sites for waters, soils and sediments, and biota, considering the subpopulation of foods from agriculture, livestock, and seafood. It is concluded that more detailed and comprehensive studies concerning pollution levels, as well as As trends, transfer, speciation, and toxic effects are still required.

Effect of gene-environment interaction (arsenic exposure - PON1 Q192R polymorphism) on cardiovascular disease biomarkers in Mexican population

Cardiovascular diseases (CVDs) are the primary cause of death worldwide. However, little is known about how the interaction between risk factors affects CVDs. Therefore, the aim of this study was to evaluate the effect of the gene-environment interaction (arsenic exposure x PON1 Q192R polymorphism) on serum levels of CVDs biomarkers in Mexican women. Urinary arsenic levels (UAs) ranged from 5.50-145 μg/g creatinine. The allele frequency was 0.38 and 0.62 for the Q and R alleles, respectively. Moreover, significant associations (p<0.05) were detected between UAs and CVDs biomarkers (ADMA, FABP4, and miR-155). Comparable data were found when CVDs biomarkers were evaluated through PON1 genotype, significant (p<0.05) higher serum concentrations of CVDs biomarkers were identified in R allele carriers compared to levels found in Q allele carriers. Besides, a gene-environment interaction was documented. The results of this study we believe should be of significant interest to regulatory authorities worldwide.

Counteracting arsenic toxicity: Curcumin to the rescue?

Arsenicosis leads to various irreversible damages in several organs and is considered to be a carcinogen. The effects of chronic arsenic poisoning are a result of an imbalance between pro- and antioxidant homeostasis, oxidative stress, as well as DNA and protein damage. Curcumin, the polyphenolic pigment extracted from the rhizome of Curcuma longa, is well-known for its pleiotropic medicinal effects. Curcumin has been shown to have ameliorative effects in arsenic-induced genotoxicity, nephrotoxicity, hepatotoxicity, angiogenesis, skin diseases, reproductive toxicity, neurotoxicity, and immunotoxicity. This review aims to summarize the scientific evidence on arsenic toxicity in various organs and the ameliorative effects of curcumin on the arsenic toxicity.

Probabilistic human health risk assessment associated with fluoride and arsenic co-occurrence in drinking water from the metropolitan area of San Luis Potosí, Mexico

A major public health concern in Mexico is the natural contamination of groundwater with fluoride and arsenic. Therefore, this work aimed to evaluate the magnitude of human health risk after determining fluoride and arsenic concentrations in groundwater samples (n = 50) from the Metropolitan area of the city of San Luis Potosi, Mexico. Fluoride levels in water were determined via a potentiometric method using an ion-selective electrode. Arsenic concentrations in water samples were determined with an Atomic Absorption technique. Subsequently, a probabilistic health risk assessment was developed (Monte Carlo Analysis). Fluoride levels in water ranged from 0.20 to 3.50 mg/L. For arsenic, the mean level found in the assessed water samples was 15.5 ± 5.50 μg/L (range: 2.50-30.0 μg/L). In addition, when the probabilistic health risk assessment was completed, a mean HI (cumulative hazardous index) of higher than 1 was detected, indicating a high NCR (non-carcinogenic risk) for children and adults. According to the results found in this study, exposure protection campaigns are imperative in the Metropolitan area of the city of San Luis Potosí, Mexico, to successfully diminish exposure to arsenic and fluoride and, as a consequence, decrease the NCR in the population living in that region of Mexico.

Updated information on new coronavirus disease 2019 occurrence, drugs, and prediction of a potential receptor

The new coronavirus (COVID‐19) was first reported in Wuhan in China, on 31 December 2019. COVID‐19 is a new virus from the family of coronaviruses that can cause symptoms ranging from a simple cold to pneumonia. The virus is thought to bind to the angiotensin‐converting enzyme 2, as a well‐known mechanism to enter the cell. It then transfers its DNA to the host in which the virus replicates the DNA. The viral infection leads to severe lack of oxygen, lung oxidative stress because of reactive oxygen species generation, and overactivation of the immune system by activating immune mediators. The purpose of this review is to elaborate on the more precise mechanism(s) to manage the treatment of the disease. Regarding the mechanisms of the virus action, the suggested pharmacological and nutritional regimens have been described.

Scenario, perspectives and mechanism of arsenic and fluoride Co-occurrence in the groundwater: A review

Arsenic (As) and fluoride (F^-) are the two most conspicuous contaminants, in terms of distribution and menace, in aquifers around the world. While the majority of studies focus on the individual accounts of their hydro-geochemistry, the current work is an effort to bring together the past and contemporary works on As and F^- co-occurrence. Co-occurrence in the context of As and F^- is a broad umbrella term and necessarily does not imply a positive correlation between the two contaminants. In arid oxidized aquifers, healthy relationships between As and F^- is reported owing desorption based release from the positively charged (hydr)oxides of metals like iron (Fe) under alkaline pH. In many instances, multiple pathways of release led to little or no correlation between the two, yet there were high concentrations of both at the same time. The key influencer of the strength of the co-occurrence is seasonality, environment, and climatic conditions. Besides, the existing primary ion and dissolved organic matter also affect the release and enrichment of As-F^- in the aquifer system. Anthropogenic forcing in the form of mining, irrigation return flow, extraction, recharge, and agrochemicals remains the most significant contributing factor in the co-occurrence. The epidemiological indicate that the interface of these two interacting elements concerning public health is considerably complicated and can be affected by some uncertain factors. The existing explanations of interactions between As-F are indecisive, especially their antagonistic interactions that need further investigation. "Multi-contamination perspectives of groundwater" is an essential consideration for the overarching question of freshwater sustainability.

Prospective cohort study of respiratory effects at ages 14 to 26 following early life exposure to arsenic in drinking water

BACKGROUND

We previously reported chronic respiratory effects in children who were then 7-17 years of age in Matlab, Bangladesh. One group of children had been exposed to high concentrations of arsenic in drinking water in utero and early childhood (average 436 µg/L), and the other group of children were never known to have been exposed to >10 µg/L. The exposed children, both males and females, had marked increases in chronic respiratory symptoms.

METHODS

The current study involves a further follow-up of these children now 14-26 years of age with 463 located and agreeing to participate. They were interviewed for respiratory symptoms and lung function was measured. Data were collected on smoking, body mass index (BMI), and number of rooms in the house as a measure of socioeconomic status.

RESULTS

Respiratory effects were still present in males but not females. In the high exposure group (>400 µg/L in early life) the odds ratio (OR) among male participants for dry cough in the last 12 months was 2.36 (95% confidence interval [CI] = 1.21, 4.63, P = 0.006) and for asthma OR = 2.51 (95% CI = 1.19, 5.29, P = 0.008). Forced vital capacity (FVC) was reduced in males in the early life high-exposure group compared with those never exposed (-95ml, P = 0.04), but not in female participants.

CONCLUSIONS

By the age range 14-26, there was little remaining evidence of chronic respiratory effects in females but pronounced effects persisted in males. Mechanisms for the marked male female differences warrant further investigation along with further follow-up to see if respiratory effects continue in males.

Health effects of arsenic exposure in Latin America: An overview of the past eight years of research

Studies conducted over the past eight years in Latin America (LA) have continued to produce new knowledge regarding health impacts of arsenic (As) in drinking water. We conducted a systematic review of 92 peer-reviewed English articles published between 2011 and 2018 to expand our understanding on these health effects. Majority of the LA studies on As have been conducted in Chile and Mexico. Additional data have emerged from As-exposed populations in Argentina, Bolivia, Brazil, Colombia, Ecuador, and Uruguay. The present review has documented recent data on the biomarkers of As exposure, genetic susceptibility and genotoxicity, and risk assessment to further characterize the health effects and exposed populations. Some recent findings on the associations of As with bladder and lung cancers, reproductive outcomes, and declined cognitive performance have been consistent with what we reported in our previous systematic review article. We have found highly convincing evidence of in utero As exposure as a significant risk factor for several health outcomes, particularly for bladder cancer, even at moderate level. New data have emerged regarding the associations of As with breast and laryngeal cancers as well as type 2 diabetes. We observed early life As exposure to be associated with kidney injury, carotid intima-media thickness, and various pulmonary outcomes in children. Other childhood effects such as low birth weight, low gestational age, anemia, increased apoptosis, and decreased cognitive functions were also reported. Studies identified genetic variants of As methyltransferase that could determine susceptibility to As related health outcomes. Arsenic-induced DNA damage and alteration of gene and protein expression have also been reported. While the scope of research is still vast, the substantial work done on As exposure and its health effects in LA will help direct further large-scale studies for more comprehensive knowledge and plan appropriate mitigation strategies.

Environmental exposure of arsenic and fluoride and their combined toxicity: A recent update

Environmental exposure to arsenic (As) and fluoride (F) in the recent year has been increased because of excessive use of naturally contaminated ground water. Surface water is also regularly contaminated with these elements in various industrial areas. Arsenicosis and fluorosis upon individual exposure of As and F are reported in many studies. A syndrome of endemic As poisoning and fluorosis occurs during concurrent exposure of As and F. Previous reports showed synergistic, antagonistic and independent effects of these two compounds, although few recent reports also revealed antagonistic effects after co-exposure. Interaction during intestinal absorption and influence of F on As metabolism might be the cause of antagonism. The synergism/antagonism is thought to depend on the dose and duration of the co-exposure. However, the detailed mechanism is still not fully understood and needs further studies. Removal technologies of As and F from contaminated water is available but removal of such contaminants from food is yet to be developed. Antioxidants are useful to mitigate the toxic effects of As and F. This review focused on the effect of co-exposure, amelioration as well as removal techniques of As and F.

The use of urinary fluoride excretion to facilitate monitoring fluoride intake: A systematic scoping review

BACKGROUND

As a recognised effective and economical agent for dental caries prevention, fluoride has been used in many different fluoridation schemes implemented across the world. Considering the narrow 'dose-gap' between the benefit of caries reduction and the risk of dental fluorosis, it is recommended that fluoride intake is monitored by measuring urinary fluoride excretion. The aim of this scoping review is to map the current literature/evidence on fluoride intake and excretion studies in relation to the study population, settings, type of study design, methodology, and analytical approach.

METHODS

Embase/Ovid, MEDLINE/Ovid, CINAHL/EBSCO, Scopus/Elsevier were searched for relevant articles until April 2018. Studies were included if they reported intake and excretion of fluoride in healthy humans of all age groups. Findings were explored using a narrative synthesis to summarise studies characteristics and outcome measures.

RESULTS

Removal of duplicates from the originally 2295 identified records yielded 1093 studies of which 206 articles were included. Only 21.6% of the studies were conducted in children (<8-year-olds). Most studies (38.8%) used drinking water concentration as a proxy for fluoride intake, whereas only 11.7% measured fluoride intake from all sources. Of the 72 studies that measured dietary fluoride intake, only 10 reported the validity of the employed dietary assessment method. Only 14 studies validated the urine sample collection methods. No information on the validity of the employed analytical method was reported by the majority (64.6%) of studies. Only a small proportion (8.7%) of the included studies investigated the association between fluoride intake and excretion.

CONCLUSION

The findings reveal much variability in terms of conducting the studies and reporting the findings, illustrating a high heterogeneity in data collection across settings and populations. Future studies should provide more detail on sampling technique, measurement protocols (including validation), and on clearly defining the relationship between intake and urinary excretion of fluoride.

Simultaneous removal of fluoride and arsenic from well water by electrocoagulation

The co-occurrence of fluoride and arsenic in groundwater presents a problem in many, mostly arid, regions of Latin America and the world. These pollutants cause significant health problems and are difficult to remove simultaneously from drinking water. In this study, the electrocoagulation process for the simultaneous removal of fluoride and arsenic was evaluated in well from the state of Durango, Mexico, in order to both solve the local problem and determine how to apply the method generally. Tests were carried out with different times, concentrations, initial pH values, and electric current densities, with iron and aluminum as electrode materials. The removal efficiencies in simultaneous presence were 85.68% for fluoride and approximately 100% for arsenic. The final concentrations for both pollutants were below the drinking water limits established by the World Health Organization (WHO) and Mexican regulations. The optimum conditions of the electrocoagulation process found were a current density of 4.5 mA/cm², an initial pH of 5, and a treatment time of 15 min, considering initial fluoride and arsenic concentrations of 5 mg/L and 80 μg/L, respectively.

Impact of arsenic exposure on clinical biomarkers indicative of cardiovascular disease risk in Mexican women

An appropriate and precise identification of high-risk individuals to develop cardiovascular diseases (CVD) is of high importance to reduce these kinds of diseases, a major health concern worldwide. Therefore, the aim of this research was to evaluate prognostic CVD biomarkers in Mexican women exposed to inorganic arsenic via drinking water. Then, a cross-sectional study including 190 women was achieved. Urinary arsenic (UAs) levels were analyzed as exposure biomarker to that metalloid. While, plasma asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin levels, hypertriglyceridemic waist (HW) phenotype, atherogenic index of plasma (AIP), and Framingham risk score (FRS) were assessed as prognostic CVD biomarkers. Mean UAs level detected in the evaluated urinary samples was 45.0 ± 40.0 μg/g creatinine. In addition, mean plasma ADMA, FABP4, chemerin and adiponectin levels were 0.68 µmol/L, 20.3 ng/mL, 12.5 μg/mL, and 255 ng/mL, correspondingly. Approximately, 54% of women participants displayed an HW phenotype. Regarding AIP and FRS values, 0.12 ± 0.15 and 7.50 ± 8.00 were found, respectively. Besides, strong and significant associations (p < 0.05) between UAs and AIP, ADMA, and FABP4 were distinguished. Also, after a multivariate analysis, the association between those variables persisted after adjustment for traditional risk factors of CVD. In conclusion, according to the results found in this research, the most sensible CVD biomarkers distinguished in this study were AIP, ADMA, and FABP4. Nevertheless, more studies are necessary to confirm the results found in this investigation.

Sodium arsenite exposure impairs B cell proliferation and enhances vascular inflammation in Plasmodium berghei mouse model

Arsenic exposure has been linked to an impaired immune response and inflammation. Our study investigated the effects of sodium arsenite on host immune response and vascular inflammation during malarial infection. Mice were divided into three groups: control (C), Plasmodium berghei infection (I) and sodium arsenite exposure with Plasmodium berghei infection (As-I). The results showed that splenocyte proliferation stimulated by lipopolysaccharide (LPS) and pokeweed mitogen (PWM) was suppressed in the I group, and the suppression was more pronounced in the As-I group, suggesting that acquired immunity in infected mice was worsening following arsenic exposure. ICAM-1, an adhesion protein involved in parasite-infected red blood cell (iRBC) binding to endothelium, and HIF-1α, a hypoxia marker protein in the descending aorta, were increased in the As-I group compared to the I group. Collectively, our results suggest that arsenic may increase host susceptibility to malaria through suppression of B cell proliferation and enhancement of adhesion between iRBC and endothelium by increasing ICAM-1.

Long-term exposure to low level of fluoride induces apoptosis via p53 pathway in lymphocytes of aluminum smelter workers

Long-term occupational exposure to low level of fluoride can induce oxidative stress and apoptosis in many cells, including lymphocyte. However, the underlying mechanism remains unclear. Hence, this study was designed to explore the potential oxidative stress and apoptosis of long-term occupational exposure to low level of fluoride in aluminum smelter workers. A total of 120 aluminum smelter workers were recruited in control, low-, middle-, and high-fluoride exposure groups with 30 workers for each group. The peripheral blood samples were collected, centrifuged, and isolated to obtain serum and lymphocyte suspensions. The air and serum fluoride concentrations were detected by fluoride ion-selective electrode method. The lymphocytic apoptosis rate, DNA damage, oxidative stress, and mRNA levels of p53, Bcl-2, and Bax were assessed by Annexin V/PI staining, comet assay, attenuated total reflectance Fourier transform infrared spectroscopy and real-time polymerase chain reaction, respectively. Results showed that the air and serum fluoride concentrations of fluoride-exposed groups were higher than those of the control group (p < 0.05). Fluoride exposure might induce apoptosis, DNA damage and oxidative stress in a dose-dependent manner in lymphocytes (p < 0.05). The expression levels of p53 and Bax were increased with fluoride exposure in lymphocytes (p < 0.05), whereas the Bcl-2 expression was decreased but not significantly. Taken together, these observations indicate that long-term occupational exposure to low level of fluoride may lead to oxidative stress and induce apoptosis through the p53-dependent pathway in peripheral blood lymphocytes of aluminum smelter workers. Serum fluoride level may be the potential biomarker of fluoride exposure.

Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children

BACKGROUND

Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited.

METHODS

We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism.

RESULTS

Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 μg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 μg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 μg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested.

CONCLUSIONS

An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.

Evaluation of epigenetic alterations (mir-126 and mir-155 expression levels) in Mexican children exposed to inorganic arsenic via drinking water

Recently, a great number of epidemiological studies have shown evidence that exposure to inorganic arsenic could have harmful effects on the cardiovascular system of humans. However, the underlying mechanisms through which arsenic induces cardiovascular toxic effects remain unclear. In this regard, epigenetic mechanisms have emerged as a probable connection between environment and disease phenotypes, including cardiovascular diseases. Therefore, this study aimed to evaluate epigenetic changes related to cardiotoxicity (miR-126 and miR-155 expression levels) in children from San Luis Potosi, Mexico exposed to inorganic arsenic. From 2014 to 2015, in a cross-sectional study, children (aged 6-12 years; n = 73) attending public schools at the studied sites were enrolled to take part in this study. Urinary arsenic was used as an exposure biomarker and analyzed by an atomic absorption spectrophotometry technique. On the other hand, miR-126 and miR-155 expression levels were evaluated by qRT-PCR. A mean urinary arsenic level of 30.5 ± 25.5 μg/g of creatinine was found. Moreover, the data showed a significant negative association (p < 0.05) between urinary arsenic concentrations and plasma miR-126 levels. However, an association between urinary arsenic concentrations and plasma miR-155 levels was not found (p > 0.05). In this regard, some investigations have shown an association between diminished plasma miR-126 levels and cardiovascular illnesses. The results found in this study are of concern. However, more similar studies including a larger sample size are necessary in order to clarify the real significance of the data.

Arsenic and fluoride co-contamination in shallow aquifers from agricultural suburbs and an industrial area of Punjab, Pakistan: Spatial trends, sources and human health implications

Release of arsenic (As) and fluoride (F^-) species into groundwater is a serious health concern around the world. The present study was the first systematic baseline study conducted in Rahim Yar Khan district, Punjab, focusing on As and F^- contamination in groundwater. A total of 51 representative groundwater samples comprising of 44 samples from agricultural suburbs and 7 from an industrial base were analysed. Statistical parameters, principal component analysis-multiple linear regression (PCA-MLR) and health risk assessment model were used to investigate the hydro geochemistry, spatial patterns, interrelation, source contribution and associated health risks of high As and F^- in groundwater of the study area. Results showed high risk of F^- exposure to people of the study area, with all samples exceeding the WHO standard of 1.5 mg/L, and for As, 32.5% of the studied groundwater samples exceeded the WHO standard (10 µg/L). The maximum As (107.23 µg/L) and F^- (26.4 mg/L) levels were observed in samples close to the agricultural and smelting areas, implicating the frequent use of fertilizers and influence of industrial effluents in the study area. The PCA-MLR receptor model quantitatively illustrates that the majority of As and F^- comes from natural sources, while, among anthropogenic sources, industrial and agricultural activities contributed the most. Health risk assessment revealed a high risk of As and F^- contamination to the exposed population; therefore, detailed control strategies and policies are required in order to mitigate the health risks.

Co-occurrence perspective of arsenic and fluoride in the groundwater of Diphu, Assam, Northeastern India

Considerable lacunae exists in As and F(-) co-contamination investigation in the Brahmaputra and Gangetic floodplains. Therefore we selected Diphu a township in the Karbi Plateau rising from the Brahmaputra floodplains for evaluation of As and F co-occurrence, correlation with coexisting ions of the aquifer system and elucidation of potential processes for releasing As and F(-) in the groundwater. Our initial appraisal used generic plots for identification of hydro geochemical processes and major water types. Subsequently, As and F(-) co-occurrence with pH, depth, HCO3(-), SO4(2-), Ca(2+) and Fe were probed for possible correlation followed by hierarchical cluster analyses to identify key processes for co-occurrence. Finally, saturation indices of groundwater minerals were calculated using MINTEQA2 to elucidate prospective As and F(-) release into groundwater. Results indicate F(-) and As presence in Ca-HCO3 rich water along with positive correlation between Ca(2+) and F(-) possibly due to limestone reserves in adjoining areas. Multivariate analyses suggest the presence of high concentrations of PO4(3-), and H4SiO4 either individually or in combination can enhance the mobility of both As and F(-) and possibly abet conditions conducive for co-contamination of aquifers. Initial release of As and F(-) from the parent rock seems driven by the anthropogenic activities while mobilization depends on chemical interactions and individual affinities of the elements. The results of speciation highlight further mobilization of As and F(-) into the groundwater which in turn require regular attention for sustainable management of scarce water resource present in the area.

Exposure Assessment to Environmental Chemicals in Children from Ciudad Juarez, Chihuahua, Mexico

It has been demonstrated that the human biomonitoring of susceptible populations is a valuable method for the identification of critical contaminants. Therefore, the purpose of this study was to assess the exposure profile for arsenic (As), lead (Pb), mercury (Hg), 1-hydroxypyrene (1-OHP), 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) in children living in Ciudad Juarez, Chihuahua, Mexico (a major manufacturing center in Mexico). In 2012, we evaluated a total of 135 healthy children living in Ciudad Juarez since birth. The total PBDEs levels ranged from nondetectable (< LOD) to 215 ng/g lipid, with a mean total PBDEs level of 29.5 ± 53.0 ng/g lipid (geometric mean ± standard deviation). The mean total PCBs level in the study participants was 29.0 ± 10.5 ng/g lipid (range 4.50-50.0 ng/g lipid). The mean concentration of total DDT (DDT + DDE) was 11.9 ± 6.70 ng/g lipid (range 3.00-26.0 ng/g lipid). The mean 1-OHP levels was 1.2 ± 1.1 µmol/mol creatinine (range <LOD to 3.90 µmol/mol creatinine). Regarding heavy metals levels, the mean urinary As levels was 19.5 ± 3.07 µg/g creatinine, for urinary mercury the levels ranged from <LOD to 11.5 µg/L, with a mean value of 2.10 µg/L, and finally, the mean blood lead level was 4.20 ± 3.80 µg/dL. In conclusion, our data indicate high exposure levels to chemicals analyzed in the children living in the study community. Therefore, a biomonitoring program for the surveillance of the child population in Ciudad Juarez is necessary.

DNA damage in Mexican children living in high-risk contaminated scenarios

The aim of this study was to evaluate the deoxyribonucleic acid (DNA) damage (as a biomarker of biological effects) in children living in areas at high risk of contamination in Mexico using the comet assay. The alkaline comet assay was performed in order to assess DNA damage levels in blood cells of 276 children living in eleven communities in four states of Mexico. Moreover, levels of arsenic and 1-hydroxypyrene (1-OHP) in urine and lead and total DDT [sum of 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE) and 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT)] in blood were quantified. We found urinary 1-OHP levels between <LOD and 14.5 μmol/mol creatinine; for arsenic, the urinary levels were 3.5-180 μg/g creatinine (range). Lead levels in blood ranged from 0.5 to 24 μg/dL and finally, the levels of total DDT (DDE and DDT) ranged from <LOD to 32,000 ng/g lipid. Regarding DNA damage (comet assay), the most important finding in our study was that children exposed to a chemical mixture [high levels of exposure to polycyclic aromatic hydrocarbons (PAHs) and DDT were found] had the significant highest DNA damage level (p<0.05) in their blood cells (olive tail moment=7.5±3.5), when compared with DNA damage levels in children living in the other scenarios assessed in this work. Finally, significant correlations were observed between urinary arsenic levels (r=0.32, p<0.05); urinary 1-OHP levels (r=0.65, p<0.01); total DDT in blood levels (r=0.59, p<0.01) and DNA damage. In conclusion, the data indicates that children living in areas which are at high risk of contamination showed high levels of biomarkers of exposure in urine or blood. Moreover, the exposure levels contribute to DNA damage and suggest an increased health risk in studied sites at risk of great pollution.

Arsenite selectively inhibits mouse bone marrow lymphoid progenitor cell development in vivo and in vitro and suppresses humoral immunity in vivo

It is known that exposure to As⁺³ via drinking water causes a disruption of the immune system and significantly compromises the immune response to infection. The purpose of these studies was to assess the effects of As⁺³ on bone marrow progenitor cell colony formation and the humoral immune response to a T-dependent antigen response (TDAR) in vivo. In a 30 day drinking water study, mice were exposed to 19, 75, or 300 ppb As⁺³. There was a decrease in bone marrow cell recovery, but not spleen cell recovery at 300 ppb As⁺³. In the bone marrow, As⁺³ altered neither the expression of CD34+ and CD38+ cells, markers of early hematopoietic stem cells, nor CD45−/CD105+, markers of mesenchymal stem cells. Spleen cell surface marker CD45 expression on B cells (CD19+), T cells (CD3+), T helper cells (CD4+) and cytotoxic T cells (CD8+), natural killer (NK+), and macrophages (Mac 1+) were not altered by the 30 day in vivo As⁺³ exposure. Functional assays of CFU-B colony formation showed significant selective suppression (p<0.05) by 300 ppb As⁺³ exposure, whereas CFU-GM formation was not altered. The TDAR of the spleen cells was significantly suppressed at 75 and 300 ppb As⁺³. In vitro studies of the bone marrow revealed a selective suppression of CFU-B by 50 nM As⁺³ in the absence of apparent cytotoxicity. Monomethylarsonous acid (MMA⁺³) demonstrated a dose-dependent and selective suppression of CFU-B beginning at 5 nM (p<0.05). MMA⁺³ suppressed CFU-GM formation at 500 nM, a concentration that proved to be nonspecifically cytotoxic. As⁺⁵ did not suppress CFU-B and/or CFU-GM in vitro at concentrations up to 500 nM. Collectively, these results demonstrate that As⁺³ and likely its metabolite (MMA⁺³) target lymphoid progenitor cells in mouse bone marrow and mature B and T cell activity in the spleen.

Arsenic and fluoride co-exposure affects the expression of apoptotic and inflammatory genes and proteins in mononuclear cells from children

Humans may be exposed to arsenic (As) and fluoride (F) through water consumption. However, the interaction between these two elements and gene expression in apoptosis or inflammatory processes in children has not been thoroughly investigated. Herein, the expression of cIAP-1, XIAP, TNF-α, ENA-78, survivin, CD25, and CD40 was evaluated by RT-PCR. Additionally, the surface expression of CD25, CD40, and CD40L on peripheral blood mononuclear cells was analyzed by flow cytometry, and TNF-α was measured by Western blotting. This study examined 72 children aged 6-12 years who were chronically exposed to As (154.2μg/L) and F (5.3mg/L) in drinking water and in food cooked with the same water. The urine concentrations of As (6.9-122.4μg/L) were positively correlated with the urine concentrations of F (1.0-8.8mg/L) (r(2)=0.413, p<0.0001). The CD25 gene expression levels and urine concentrations of As and F were negatively correlated, though the CD40 expression levels were negatively correlated only with the As concentration. Age and height influenced the expression of cIAP-1, whereas XIAP expression was correlated only with age. Additionally, there was a lower percentage of CD25- and CD40-positive cells in the group of 6- to 8-year-old children exposed to the highest concentrations of both As and F when compared to the 9- to 12-year-old group (CD25: 0.7±0.8 vs. 1.1±0.9, p<0.0014; CD40: 16.0±7.0 vs. 21.8±5.8, p<0.0003). PHA-stimulated lymphocytes did not show any changes in the induction of CD25, CD69, or CD95. In summary, high concentrations of As and F alter the expression patterns of CD25 and CD40 at both the genetic and protein levels. These changes could decrease immune responses in children exposed to As and F.

Developmental Immunotoxicity, Perinatal Programming, and Noncommunicable Diseases: Focus on Human Studies

Developmental immunotoxicity (DIT) is a term given to encompass the environmentally induced disruption of normal immune development resulting in adverse outcomes. A myriad of chemical, physical, and psychological factors can all contribute to DIT. As a core component of the developmental origins of adult disease, DIT is interlinked with three important concepts surrounding health risks across a lifetime: (1) the Barker Hypothesis, which connects prenatal development to later-life diseases, (2) the hygiene hypothesis, which connects newborns and infants to risk of later-life diseases and, (3) fetal programming and epigenetic alterations, which may exert effects both in later life and across future generations. This review of DIT considers: (1) the history and context of DIT research, (2) the fundamental features of DIT, (3) the emerging role of DIT in risk of noncommunicable diseases (NCDs) and (4) the range of risk factors that have been investigated through human research. The emphasis on the human DIT-related literature is significant since most prior reviews of DIT have largely focused on animal research and considerations of specific categories of risk factors (e.g., heavy metals). Risk factors considered in this review include air pollution, aluminum, antibiotics, arsenic, bisphenol A, ethanol, lead (Pb), maternal smoking and environmental tobacco smoke, paracetamol (acetaminophen), pesticides, polychlorinated biphenyls, and polyfluorinated compounds.

The combined effects of fluorine and arsenic on renal function in a Chinese population

Chronic exposure to combined fluoride and arsenic continues to be a major public health problem worldwide, affecting thousands of people. The results clearly show that the combined effect of fluoride and arsenic on renal function is mainly antagonism at these exposure levels.

In utero arsenic exposure and infant infection in a United States cohort: a prospective study

Arsenic (As), a ubiquitous environmental toxicant, has recently been linked to disrupted immune function and enhanced infection susceptibility in highly exposed populations. In drinking water, as levels above the EPA maximum contaminant level occur in our US study area and are a particular health concern for pregnant women and infants. As a part of the New Hampshire Birth Cohort Study, we investigated whether in utero exposure to As affects risk of infant infections. We prospectively obtained information on 4-month-old infants (n=214) using a parental telephone survey on infant infections and symptoms, including respiratory infections, diarrhea and specific illnesses, as well as the duration and severity of infections. Using logistic regression and Poisson models, we evaluated the association between maternal urinary As during pregnancy and infection risks adjusted for potentially confounding factors. Maternal urinary As concentrations were related to total number of infections requiring a physician visit (relative risk (RR) per one-fold increase in As in urine=1.5; 95% confidence interval (CI)=1.0, 2.1) or prescription medication (RR=1.6; 95% CI=1.1, 2.4), as well as lower respiratory infections treated with prescription medication (RR=3.3; 95% CI=1.2, 9.0). Associations were observed with respiratory symptoms (RR=4.0; 95% CI=1.0, 15.8), upper respiratory infections (RR=1.6; 95% CI=1.0, 2.5), and colds treated with prescription medication (RR=2.3; 95% CI=1.0, 5.2). Our results provide initial evidence that in utero As exposure may be related to infant infection and infection severity and provide insight into the early life impacts of fetal As exposure.

Arsenic immunotoxicity: a review

Exposure to arsenic (As) is a global public health problem because of its association with various cancers and numerous other pathological effects, and millions of people worldwide are exposed to As on a regular basis. Increasing lines of evidence indicate that As may adversely affect the immune system, but its specific effects on immune function are poorly understood. Therefore, we conducted a literature search of non-cancer immune-related effects associated with As exposure and summarized the known immunotoxicological effects of As in humans, animals and in vitro models. Overall, the data show that chronic exposure to As has the potential to impair vital immune responses which could lead to increased risk of infections and chronic diseases, including various cancers. Although animal and in vitro models provide some insight into potential mechanisms of the As-related immunotoxicity observed in human populations, further investigation, particularly in humans, is needed to better understand the relationship between As exposure and the development of disease.

In utero arsenic exposure is associated with impaired thymic function in newborns possibly via oxidative stress and apoptosis

Prenatal arsenic exposure is associated with increased infant morbidity and reduced thymus size, indicating arsenic-related developmental immunotoxicity. We aimed to evaluate effects of prenatal arsenic exposure on thymic function at birth and related mechanisms of action. In a Bangladeshi cohort, arsenic was measured in urine (U-As, gestational week (GW) 8 and 30) and blood (B-As, GW14) in 130 women. Child thymic index was measured by sonography at birth and thymic function by signal-joint T-cell receptor-rearrangement excision circles (sjTRECs) in cord blood mononuclear cells (CBMC). In a subsample (n = 44), sjTRECs content in isolated CD4(+) and CD8(+) T cells, expression of oxidative-stress defense and apoptosis-related genes in CBMC, arsenic concentrations (urine, placenta, and cord blood), and oxidative stress markers in placenta and cord blood were measured. In multivariable-adjusted regression, ln U-As (GW8) was inversely associated with ln sjTRECs in CBMC (B = -0.25; 95% confidence interval [CI] -0.48 to -0.01). Using multivariable-adjusted spline regression, ln U-As (GW30) and ln B-As (GW14) were inversely associated with ln sjTRECs in CBMC (B = -0.53; 95% CI -0.93 to -0.13 and B = -1.27; 95% CI -1.89 to -0.66, respectively) below spline knots at U-As 150 µg/l and B-As 6 µg/kg. Similar inverse associations were observed in separated CD4(+) and CD8(+) T cells. Arsenic was positively associated with 8-hydroxy-2'-deoxyguanosine in cord blood (B = 0.097; 95% CI 0.05 to 0.13), which was inversely associated with sjTRECs in CD4(+) and CD8(+) T cells. In conclusion, prenatal arsenic exposure was associated with reduced thymic function, possibly via induction of oxidative stress and apoptosis, suggesting subsequent immunosuppression in childhood.