Exposure of children to arsenic in drinking water in the Tharparkar region of Sindh, Pakistan

Environmental Chemical-Induced Reactive Oxygen Species Generation and Immunotoxicity: A Comprehensive Review

Significance: Reactive oxygen species (ROS), the reactive oxygen-carrying chemicals moieties, act as pleiotropic signal transducers to maintain various biological processes/functions, including immune response. Increased ROS production leads to oxidative stress, which is implicated in xenobiotic-induced adverse effects. Understanding the immunoregulatory mechanisms and immunotoxicity is of interest to developing therapeutics against xenobiotic insults. Recent Advances: While developmental studies have established the essential roles of ROS in the establishment and proper functioning of the immune system, toxicological studies have demonstrated high ROS generation as one of the potential mechanisms of immunotoxicity induced by environmental chemicals, including heavy metals, pesticides, aromatic hydrocarbons (benzene and derivatives), plastics, and nanoparticles. Mitochondrial electron transport and various signaling components, including NADH oxidase, toll-like receptors (TLRs), NF-κB, JNK, NRF2, p53, and STAT3, are involved in xenobiotic-induced ROS generation and immunotoxicity. Critical Issues: With many studies demonstrating the role of ROS and oxidative stress in xenobiotic-induced immunotoxicity, rigorous and orthogonal approaches are needed to achieve in-depth and precise understanding. The association of xenobiotic-induced immunotoxicity with disease susceptibility and progression needs more data acquisition. Furthermore, the general methodology needs to be possibly replaced with high-throughput precise techniques. Future Directions: The progression of xenobiotic-induced immunotoxicity into disease manifestation is not well documented. Immunotoxicological studies about the combination of xenobiotics, age-related sensitivity, and their involvement in human disease incidence and pathogenesis are warranted. Antioxid. Redox Signal. 40, 691-714.

Study on arsenic speciation, bioaccessibility, and gut microbiota in realgar-containing medicines by DGT technique and artificial gastrointestinal extraction (PBET) combine with simulated human intestinal microbial ecosystem (SHIME)

It is well-known that several Chinese patent medicines use realgar as a specific component. People are more aware of the health dangers associated with realgar since it includes arsenic. Previous research overstated the arsenic toxicity of realgar-containing Chinese prescription medications because little thought was given to the influence of arsenic bioaccessibility by gut microbiota. In light of this, this study examined the total content, bioaccessibility and speciation of targeted medications while also examining intestinal epithelial transit utilizing the diffusive gradients in thin-films (DGT). All samples contained arsenic, and the bioaccessibilities of the colon, intestine and gastric regions ranged from 0.19% to 1.73%, 0.25-1.88% and 0.21-1.70% respectively. The range of DGT-bioaccessibility is 0.01-0.0018%. Three steps of analysis were conducted on inorganic As(III) and As(V). In health risk assessment, the ADDs and HQs of DGT-bioaccessibility were below the threshold levels when compared to computing average daily intake dose (ADD) and hazard quotient (HQ) by bioaccessibility of gastric, intestinal and colon. Additionally, Proteobacteria and Firmicutes were discovered to be the two predominant kinds of gut microbes in this study. Under arsenic exposure, the abundance of Christensenellaceae, Desulfovibrionaceae and Akkermansiaceae increased, but the quantity of Rikenellaceae decreased. These findings revealed that alterations in gut microbiota had an impact on host metabolism.

An evaluation of arsenic contamination status and its potential health risk assessment in villages of Nadia and North 24 Parganas, West Bengal, India

The present study was conducted to evaluate the arsenic (As) contamination and possible associated health hazards to exposed population in four villages of two districts (Nadia and North 24 Parganas) of West Bengal, India. The study included two villages each from Nadia (Jaguli and Kugacchi) and North 24 Parganas (Chamta and Byaspur) districts. Groundwater, surface water, soil, rice grains and rice-based food samples were collected from these villages. The results revealed the presence of As in high concentrations in groundwater (35.00 to 186.00 µg L^-1), surface water (30.00 to 61.00 µg L^-1), soil (46.17 to 66.00 mg kg^-1), rice grains (0.017 to 1.27 µg g^-1) and rice-based food products (0.012 to 0.40 µg g^-1). The maximum As levels were recorded in all types of samples collected from Kugacchi village. The rice grain samples included high-yielding and local varieties, and the level of As in high-yielding varieties was found to be higher (0.72 to 1.27 µg g^-1) than in local varieties (0.25 to 1.06 µg g^-1). The data of As concentrations was used for understanding the hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) to the As-exposed population, and significant non-carcinogenic and carcinogenic risks were revealed considering consumption of rice grains at 400 g per day. The study demonstrates the severity of As contamination in the surveyed villages, which may pose a hindrance to attainment of sustainable development goals (SDGs) by 2030 and proposes the implementation of requisite safety measures.

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 arsenic and health risk of the residents association in contaminated-groundwater area of the urbanized coastal aquifer, Thailand

Determining of arsenic (As) exposure was conducted in 110 residents which divided into two groups using the WHO guidelines for As in drinking water of 10 μg/L. Moreover, questionnaires with face-to-face interviews were used to make a health risk assessment and to determine the associated factors. The median of As in urine was 61.33 μg/L (5.38-600.86 μg/L), accounting for 68.18% of participants who exposed to the contaminated groundwater had obviously high urinary As levels, exceeded the normal value of 50 μg/L of As, as set by the National Health and Nutrition Examination Survey (NHANES). The major factor affecting As in urine was the As contaminated groundwater. Pearson's chi-squared test showed that the urinary As level was influenced on the different groups of As level in groundwater (p-value <0.001). Multiple linear regression confirmed that the actual risk factors of As in urine were the As level in groundwater and the oral exposure route but not the dermal contact. Meanwhile binary logistic regression revealed that all socio-demographic factors were not influenced. Approximately 45.45% of the area had the HI above the risk level of 1, mostly via groundwater drinking pathway. The estimated total cancer risk values, 5.11 × 10^-6 to 2.08 × 10^-3, were higher than the safe level of 10^-6. For long-term exposure, the As concentration and exposure duration were the most variables influencing health risk level. This finding suggests that chronic As exposure should be monitored and also the groundwater should be improved to provide the safe drinking water for the residents.

Characterization and health risk assessment of arsenic in natural waters of the Indus River Basin, Pakistan

The elevated concentrations of arsenic in natural water are one of the major environmental threats to human health. However, the existing characteristics, controlling mechanisms, and associated risks of arsenic in natural waters in the Indus River Basin (IRB), Pakistan, are yet to be unequivocally understood. In this study, a total of 203 samples of surface water (SW), shallow groundwater (SGW), and deep groundwater (DGW) were collected from the IRB to assess the geochemical characteristics of arsenic and its associated health risks, as all three kinds of waters are the main sources of drinking and domestic usage. The results revealed that the arsenic concentrations in the SW, SGW, and DGW were in the ranges of 1.1-26.45, 1.05-44.44, and 0.67-41.09 μg L^-1, respectively. Furthermore, the predominance of As (V) (97 %) over As(III) (3 %) confirmed that the desorption of As in oxidizing environments with elevated pH and Eh is the controlling mechanism. The hazard quotient of 11-45 % and 20-60 % samples and cancer risk of 26-64 % and 26-68 % samples indicated high health risks for the adults and children, respectively, suggesting an immense need for appropriate measures of reducing natural water arsenic concentrations in IRB from the human health perspectives.

Determination of toxic elemental levels in whey milk of different cattle and human using an innovative digestion method: risk assessment for children < 6.0 months to 5 years

In present study, the toxic elements, arsenic (As), cadmium (Cd), and lead (Pb), were determined in whey milk samples obtained from various cattle (cow, goat, buffalo, sheep, camel) and human subjects of different areas of Sindh, Pakistan, based on consuming drinking water (exposed area) and surface water (control/non-exposed area). The whey milk was separated from casein by lowering the pH, and heating in an ultrasonic bath at 60 °C for 5 min and centrifuged. The whey milk samples were treated with deep eutectic solvent, prepared from choline chloride-oxalic acid (ChCl-Ox) at different mole ratio. Effects of different parameters on digestion efficiency of whey milk samples, including time and temperature of electric hot plate, mole ratio, and volumes of deep eutectic solvent were examined. The total levels of all selected toxic elements were also detected in whole milk samples of all exposed and nonexposed cattle and human, after acid digestion method. The validity of the proposed method was established by a conventional acid digestion method of selected whey milk samples and spiked certified standards in replicate real whey milk samples. The resulted elements obtained after proposed and conventional heating system were determined by inductively coupled plasma-optical emission spectrometry. The % of all three toxic elements found in whey milk samples were 24 to 50% of their total content in milk samples of different cattle and human. The As, Cd, and Pb contents in cattle and human milk consumed contaminated groundwater was significantly higher (2- to 3-fold) than those values observed for milk samples of cattle, who receive drinking water from fresh canal water (p < 0.01). Estimating the daily intake, hazard quotient and carcinogenic risk for <6 month to 5 years old children, based on the concentrations of toxic elements in milk samples of different cattle and human..

Human health impact due to arsenic contaminated rice and vegetables consumption in naturally arsenic endemic regions

Rice and vegetables cultivated in naturally arsenic (As) endemic areas are the substantial source of As body loading for persons using safe drinking water. However, tracing As intake, particularly from rice and vegetables by biomarker analysis, has been poorly addressed. This field investigation was conducted to trace the As transfer pathway and measure health risk associated with consuming As enriched rice and vegetables. Purposively selected 100 farmers from five sub-districts of Chandpur, Bangladesh fulfilling specific requirements constituted the subjects of this study. A total of 100 Irrigation water, soils, rice, and vegetable samples were collected from those farmers' who donated scalp hair. Socio-demographic and food consumption data were collected face to face through questionnaire administration. The mean As level in irrigation water, soils, rice, vegetables, and scalp hairs exceeded the acceptable limit, while As content was significant at 0.1%, 5%, 0.1%, 1%, and 0.1% probability levels, respectively, in all five locations. Arsenic in scalp hair is significantly (p ≤ 0.01) correlated with that in rice and vegetables. The bioconcentration factor (BCF) for rice and vegetables is less than one and significant at a 1% probability level. The average daily intake (ADI) is higher than the RfD limit for As. Both grains and vegetables have an HQ (hazard quotient) > 1. Maximum incremental lifetime cancer risk (ILCR) showed 2.8 per 100 people and 1.6 per 1000 people are at considerable and threshold risk, respectively. However, proteinaceous and nutritious food consumption might have kept the participants asymptomatic. The PCA analysis showed that the first principle component (PC1) explains 91.1% of the total variance dominated by As in irrigation water, grain, and vegetables. The dendrogram shows greater variations in similarity in rice and vegetables As, while the latter has been found to contribute more to human body loading compared to grain As.

Health effect and risk assessment of the populations exposed to different arsenic levels in drinking water and foodstuffs from four villages in arsenic endemic Gaighata block, West Bengal, India

Health exposure and perception of risk assessment have been evaluated on the populations exposed to different arsenic levels in drinking water (615, 301, 48, 20 µg/l), rice grain (792, 487, 588, 569 µg/kg) and vegetables (283, 187, 238, 300 µg/kg) from four villages in arsenic endemic Gaighata block, West Bengal. Dietary arsenic intake rates for the studied populations from extremely highly, highly, moderately, and mild arsenic-exposed areas were 56.03, 28.73, 11.30, and 9.13 μg/kg bw/day, respectively. Acute and chronic effects of arsenic toxicity were observed in ascending order from mild to extremely highly exposed populations. Statistical interpretation using 'ANOVA' proves a significant relationship between drinking water and biomarkers, whereas "two-tailed paired t test" justifies that the consumption of arsenic-contaminated dietary intakes is the considerable pathway of health risk exposure. According to the risk thermometer (SAMOE), drinking water belongs to risk class 5 (extremely highly and highly exposed area) and 4 (moderately and mild exposed area) category, whereas rice grain and vegetables belong to risk class 5 and 4, respectively, for all the differently exposed populations. The carcinogenic (ILCR) and non-carcinogenic risks (HQ) through dietary intakes for adults were much higher than the recommended threshold level, compared to the children. Supplementation of arsenic-safe drinking water and nutritional food is strictly recommended to overcome the severe arsenic crisis.

Fluoride and arsenic contamination in drinking water due to mining activities and its impact on local area population

Contamination of arsenic and fluoride in drinking water reservoirs is a serious health issue in the Sibi district, Balochistan, Pakistan. The contamination has already been affecting a large population of the district. Dental fluorosis and dermatitis are the most common reported illnesses in the area. This study focused on the evaluation of the root causes and pathway by which it reached to the body. Questioner analysis, simple examination, and pictorial representation were used to study the prevalence of diseases caused by As and F. People of the Sibi district were found to consume both surface and groundwater, which were highly contaminated with arsenic and fluoride. The saturation index, ranging from 1 to 7, showed high enrichment of contaminants in both types of water. Geochemical calculations and the sodium absorption ratio were evaluated. High values of the saturation index of different salts showed high saturation of salts in water. The principal component analysis grouped the data into three clusters, showing that the surface water has no resemblance with the control water. High degree of contamination was observed for most of the samples, whereas, some samples of ground water were closed to the control group; a group of samples within WHO limits. The correlation studies and other calculations also revealed that the F and As reached lethal limits in the drinking water and thus caused severe health damage to the local area population. The diseases found in the area are fluorosis, keratosis, dermatitis, and melanosis.

Assessment of arsenic distribution, bioaccessibility and speciation in rice utilizing continuous extraction and in vitro digestion

Rice, a staple food for half the world's population, easily accumulates arsenic (As). Research on As distribution in rice protein and starch and its relationship with rice As bioaccessibility remains limited. This study investigated As distribution, chemical composition, As bioaccessibility and speciation in rice by continuous extraction and in vitro digestion. Of the total As, 87.5-94.5% was in rice protein and 5.0-9.8% in rice starch. The As amount in different protein fractions decreased as follows: glutelin > globulin > albumin > prolamin. As(V), As(III) and DMA in rice were more bioaccessible in the small intestinal phase than the gastric phase, and almost all As(V) dissolved in the small intestinal phase. Bioaccessible As in gastrointestinal digestive solution and As mass in protein fractions (albumin, globulin, and glutelin) were significantly positively correlated (p < 0.05). These results illuminate the bioaccessibility of As to humans consuming As-contaminated rice and avoid overassessment.

Probabilistic human health risk assessment of arsenic under uncertainty in drinking water sources in Jiangsu Province, China

Concentrations of arsenic (As) in 65 drinking water sources in Jiangsu Province of China were analyzed from January 2013 to December 2015. The drinking water sources are classified into five water systems of the Yangze River, the Taihu Lake, the Huai River, the Yishusi River, and other lakes or reservoirs, which are termed as WS-A, WS-B, WS-C, WS-D, and WS-E, respectively. Health risk assessments associated with As in terms of total carcinogenic risk and total hazard index were performed for children (0-5 years), teenagers (6-17 years), and adults (≥ 18 years), respectively. Probabilistic risk assessments were obtained by applying Monte Carlo approach with consideration of uncertainty. The results indicated that in drinking water sources of WS-A, WS-C, and WS-D, maximum concentrations of As were 28 μg/L, 40 μg/L, and 17 μg/L, respectively, which were higher than 10 μg/L recommended by the World Health Organization occurred. Based on the samples investigated in this study, the mean health risks are the highest in drinking water source WS-D and lowest in WS-E for both male and female children, teenagers, and adults. For drinking water source WS-A, the health risks of male children, male teenagers, and female adults are higher than female children and female teenagers, and male adults. However, for drinking water sources WS-B, WS-C, WS-D, and WS-E, the health risks of female children, male teenagers, and female adults are higher than male children, female teenagers, and male adults. The highest health risks occurred in female children consuming drinking water from WS-D. The sensitivity analysis indicated that the concentration of As is the primary factor for carcinogenic risk of all the five water systems. The results obtained can provide meaningful information for risk managers in Jiangsu Province.

Synthesis of novel adsorbent by intercalation of biopolymer in LDH for the removal of arsenic from synthetic and natural water

This study focuses on the synthesis of nanocomposites named CCA and CZA that were prepared by the incorporation of cellulose (CL) in the Ca/Al and Zn/Al layered double hydroxide (LDH), respectively. These materials were then used for the uptake of As(III) and As(V) from aqueous medium. Characterization of both nanocomposites (CCA and CZA) was done using FTIR and Raman analysis to identify the functional groups, N₂ adsorption-desorption isotherms to determine the specific surface area and pore geometry and XPS analysis to obtain the surface atomic composition. Some other characters were investigated using simultaneous TGA and DTA and elemental chemical analysis (CHNS/O). The crystallinity of the prepared nanocomposites was displayed by XRD patterns. Furthermore, the sheet-like structure of the LDHs and the irregularity of surface morphology with porous structure were observed by TEM and SEM microphotographs. Optimization of maximum adsorption capacity was adjusted using different parameters including pH, contact time and adsorbent dosage. The pseudo-second-order model was in good fitting with kinetics results. The adsorption isotherm results showed that CZA exhibits better adsorption capacity for As(III) than CCA and the Langmuir isotherm model described the data well for both nanocomposites. Thermodynamic studies illustrated the endothermic nature of CCA and exothermic nature on CZA, as well as the fact that the adsorption process is spontaneous. A real water sample collected from well located in Gabes (Tunisia), has also been treated. The obtained experimental results were confirmed that these sorbents are efficient for the treatment of hazardous toxic species such as.

Hydrogeochemical controls on arsenic contamination potential and health threat in an intensive agricultural area, northern China

The contamination of ground water with arsenic is a great public health concern. This paper discusses the possible formation mechanism of high As groundwater; identify the main influences of natural and anthropogenic factors on As occurrence in groundwater; and finally estimates As-induced potential health hazards in an intensive agricultural region, Datong Basin (Northern China). Our findings indicate that the predominant controlling factors of As in groundwater can be divided into natural factors and anthropogenic activities. Natural factors can be classified as natural potential source of As, environmental geological characteristics and hydrochemical conditions; anthropogenic activities are manifested in industrial coal mining, domestic coal burning, agricultural irrigation return flow and excessive application of fertilizers, and groundwater exploitation. Microbial and/or chemical reduction desorption of arsenate from Fe-oxide/hydroxide and/or clay minerals, As-bearing Fe-oxide/hydroxide reduction coupled with sulfate reduction, and competition with phosphorus are postulated to be the major process dominating As enrichment in the alkaline and anoxic groundwater. In addition, age-dependent human health risk assessment (HHRS) was performed, and high risk values reveal a high toxic and carcinogenic risk of As contaminate for population who is subject to the continuous and chronic exposure to elevated As.

Elemental imbalance elicited by arsenic and copper exposures leads to oxidative stress and immunotoxicity in chicken gizzard, activating the protective effects of heat shock proteins

Arsenic (As) and copper (Cu) are ubiquitous pollutants that pose a threat to the environment. Our aim is to study the underlying mechanisms by which As and Cu act on the chicken gizzard. In order to detect ionic disorders in chicken gizzard under chronic treatment with As³⁺ and/or Cu²⁺ and whether they can induce oxidative damage as well as immune disorders, 30 mg/kg arsenic trioxide (As₂O₃) and/or 300 mg/kg copper sulfate (CuSO₄) were added to the chicken's basal diet. After 12 weeks of exposure, trace elements were found to have significant interference, accompanied by damage to the antioxidant system. In addition, As³⁺ and/or Cu²⁺ activated the nuclear factor kappa B (NF-κB), inducing severe inflammation. At the same time, damaged structural integrity which might be caused by inflammation was discovered after hematoxylin and eosin (H&E) staining. Moreover, symbolic Th1/Th2 (Th, helper T cell) drift was also observed in treatment groups, meaning that immune function is left to be affected, and the increment in heat shock proteins may be a self-protective mechanism of gizzard. Interestingly, we found that the damage to the gizzard of chicken was aggravated in a time-dependent manner, and the combined exposure was more pathogenic than the single exposure, of which the mechanism needs further exploration. Together, this work helps move us toward a better understanding of the molecular mechanisms that mediate the interactions between Cu excess and As³⁺ exposures and possible health consequences in susceptible species.

Arsenic contamination, subsequent water toxicity, and associated public health risks in the lower Indus plain, Sindh province, Pakistan

Arsenic (As) contamination in drinking water is a global public health risk. The present study highlighted the geological and anthropogenic causes of As contamination in groundwater (GW) and surface water (SW) and assessment of their potential health risks in Sindh province of Pakistan. Upon analyzing 720 GW and SW samples from 18 different sites, the estimates of As in groundwater and surface water was observed in the range of 0 to 125 and 0 to 35 μg/L with mean values of 46.8 and 15.43 μg/L respectively. Majority of the samples exceeded WHO permissible limit of As (10 μg/L) with higher concentration detected in groundwater samples compared to surface water. Moreover, both of these sample sources were found not potable based on physicochemical characteristics. The results of statistical analysis (correlation analysis, principal component analysis (PCA), and hierarchy cluster analysis (HCA)) indicate that natural mobilization of As in groundwater is believed to be enhanced by the pH-based reductive dissolution of iron hydroxide (FeOH) and competitive sorption of bicarbonate minerals in the presence of microorganisms along with evaporative enrichment while water logging, coal mining, and excessive use of pesticides are believed to be the anthropogenic causes of As enrichment. Furthermore, enormous health risk was associated with As in terms of chronic daily intake (CRI), hazard quotient (HQ), and cancer risk probability (CR) in GW and SW. Mean HQ values in GW were 4.47 mg/kg/day in adults and 3.89 mg/kg/day in children (standard HQ ≤ 1) and was 1.43 and 1.28 mg/kg/day in SW. Mean CR value in both GW and SW was found higher than the safe limit (10^-6) having a mean of 2 × 10^-3 in GW and 7 × 10^-4 (mg/kg/day) in SW. These findings suggest that majority of the sampling sites carry serious public health risk due to high As values and hence demands exigent remedial and management measures.

Identification of hydrochemical genesis and screening of typical groundwater pollutants impacting human health: A case study in Northeast China

Concentrations of common pollutants in groundwater continue to increase, and emerging pollutants are also increasingly found worldwide, thereby increasingly impacting human activities. In this new situation, it is necessary, albeit more difficult, to once again recognize the hydrochemical genesis of groundwater and to subsequently screen the typical pollutants. Taking the groundwater of the Songnen Plain of Northeast China as an example, the hydrochemical genesis was identified using space interpolation, characteristic element ratio and factor analysis methods based on 368 groundwater samples. Subsequently, the typical pollutants with potential impacts on the health of the local residents were screened by the index system method newly established. All the measured hydrochemical compositions show an obvious spatial variation, with a uniform hydrochemical type of HCO₃-Ca in the whole area. Both the major compositions (K, Na, Ca, Mg, HCO₃, Cl and SO₄) and trace compositions (Fe, Mn, Cu, Zn, Pb, As, F, I and Se) are mainly protogenetic in an environment impacted by the lixiviation of groundwater in the migration process in the strata, although these compositions have been impacted by human activities to varying degrees. The mass concentration of NO₃-N has exceeded most of the major compositions except for HCO₃ and Ca, which means the nitrogen pollution problem is already very serious; and this problem is mainly caused by the utilization of fertilizers and the discharge of industrial wastewater and domestic sewage. Human activities have obviously disrupted the natural dynamic balance of these chemicals between the environment and the groundwater, thereby intensifying the release of F, Fe and Mn from the environment. TDS, total hardness, tri-nitrogen, F, Fe, Mn, Pb and As in some parts are found to exceed the standards of groundwater quality to varying degrees. As, Pb, Fe, NO₃-N, NO₂-N, Mn, F and NH₄-N are finally screened as the typical pollutants.

Concentration of Zinc, Copper, Selenium, Manganese, and Cu/Zn Ratio in Hair of Children and Adolescents with Myopia

The aim of this work was to determine the concentration of trace elements, zinc, copper, selenium, manganese, and Cu/Zn ratio, in scalp hair samples of children and adolescents with myopia. The study included 92 children (mean age 14.5 ± 2.5 years) with myopia and 43 healthy persons (mean age 11.8 ± 4.7 years). Each patient had a complete eye examination. Trace element concentrations in hair were determined by atomic absorption spectrometry. Cu/Zn ratio was also calculated. The zinc level in the hair of myopic patients was significantly higher (260 µg/g) in comparison to the control group (130 µg/g). There was a significantly lower Cu/Zn ratio in myopic patients (0.045) compared with controls (0.07). An insignificant difference was observed in the hair level of copper, selenium, and manganese between patients and controls. The results show that trace elements may play a significant role in the pathogenesis of myopia. Further studies should pay more attention to determine the effect of trace element on children myopia.

Contamination assessment and health risk of arsenic exposure to stairway dust in the zinc smelting district, Northeast China

Stairway dust samples were collected from residential communities in Huludao city to investigate population health risk of arsenic (As) exposure through stairway dust. ArcGIS software was used to analyze As spatial distribution in Huludao city. Hazard index was applied to assess health risk due to exposure to As in stairway dust. The results were that As concentrations ranged from 13.26 to 237.58 mg kg^-1, and the mean value was 59.64 mg kg^-1, which was seven times as high as the background value of Liaoning Province. The pattern of spatial distribution was concentric rings as the center of Huludao zinc plant, with the extension to the northeast and southwest. The average value of I_geo was 2.176, which fell into moderately polluted level. For non-carcinogenic risk, the hazard indexes were less than 1, indicating that there was almost no health risk for residents exposed to stairway dust. But population risk exposure to dust would increase rapidly with exposure time in stairway. The highest contribution to the overall figure of non-carcinogenic risk and carcinogenic risk appeared to be ingestion of substrate particles followed by inhalation pathway and dermal absorption of As in dust samples. And for carcinogenic risk, the risk values were lower than the threshold range of EPA's safe limits (1 × 10^-6 and 1 × 10^-4), suggesting that potential cancer risk of As due to exposure to stairway dust can be acceptable.

Interplay between elemental imbalance-related PI3K/Akt/mTOR-regulated apoptosis and autophagy in arsenic (III)-induced jejunum toxicity of chicken

Arsenic trioxide (As₂O₃), the most toxic form of arsenic found in foodstuffs, is considered a carcinogen for human and animal. But many of the events that occur during its passage through the gastrointestinal tract are uncharted in birds. This study assesses the toxic effect on the jejunum of chicken which subchronically exposed to diets that contain As₂O₃ (0, 0.625, 1.25, 2.5 mg/kg body weight) for 90 days. Electron microscopy, TdT-mediated dUTP nick-end labeling (TUNEL), qPCR, and Western blot were performed. The results showed that mitochondrial fusion and apoptosis inhibiting genes had degressive trends, whereas mitochondrial fission and apoptosis activating genes presented heightened expressions in the treatment group compared with the control (P < 0.05). Subsequently, significant inhibition in PI3K/AKT/mTOR signaling was observed. Moreover, the expression of autophagy markers (LC3-II/LC3-I, Beclin-1) increased time and dose-dependently. Additionally, metabolic disorders of trace elements were detected evidenced by their significant decreases (aluminum, silicon, calcium, manganese, strontium, titanium, lithium, boron, cobalt, mercury, chromium) and increases (arsenic, cadmium, selenium, lead, nickel) on 90 days using inductively coupled plasma mass spectrometer (ICP-MS). It is possible that the changes of trace elements have a hand in the come on and development of arsenism. Taken together, we conjectured that, in chicken jejunum, arsenic led to redistribution of trace elements, promoting apoptosis via regulating mitochondrial dynamics, leading to autophagy through PI3K/AKT/mTOR signal pathways.

Challenges and Patterns of Seeking Primary Health Care in Slums of Karachi: A Disaster Lurking in Urban Shadows

This study aimed to evaluate the challenges and patterns of seeking primary health care services in slums of Karachi, where about 60% of the population lives in various informal settlements. We surveyed 8 largest slums of the metropolitan, and analyzed the data both descriptively and inferentially to evaluate the factors associated with health care seeking behavior. Significantly positive association of quality health care seeking behavior and various socioeconomic indicators were found. In addition, substantial insights about the conditions of slum dwellers and health challenges of the population, such as low immunization and low vaccinations, among others, were reported. Thus, the role of policymakers is emphasized to strategize for the inclusion of these people in national health plans and to develop health infrastructure near these communities. Furthermore, there is a strong need to increase awareness of the population about hygiene practices, importance of immunization, and importance of utilizing appropriate health care services.

The evaluation of arsenic contamination potential, speciation and hydrogeochemical behaviour in aquifers of Punjab, Pakistan

In this study, we tested 123 groundwater wells from five different areas of Punjab, Pakistan for arsenic (As) contamination level and species, as well as delineated hydrogeochemical behaviour of As in aquifers. Results revealed that 75% and 41% of the groundwater wells exceeded the safe As limit of World Health Organisation (WHO, 10 μg L^-1) and Pakistan-EPA (50 μg L^-1), respectively. Arsenite (As(III)) and arsenate (As(V)) spanned 0-80% and 20-100% of total As (1.2-206 μg L^-1), respectively. The mean As content (5.2 μg L^-1) of shallow wells at 9-40 m depth did not exceed the WHO safe limit, representing a safe aquifer zone for pumping of groundwater compared to deeper wells at 41-90 m (51 μg L^-1) and >90 m (23 μg L^-1) depths. Piper-plot elucidated that the aqueous chemistry was dominated with Na-SO₄, Na-Ca-SO₄, Na-Mg-SO₄ type saline water. Principal component analysis grouped As concentration with well depth, pH, salinity, Fe and CO₃, exhibiting that these hydrogeochemical factors could have potential role in controlling As release/sequestration into the aquifers of study area. Geochemical modeling showed positive saturation indices only for iron (Fe) oxide-phases, indicating Fe oxides as the major carriers of As. Overall, this study provides insights to tackle emerging As threat to the communities in Punjab, Pakistan, as well as help develop suitable management/mitigation strategies - based on the baseline knowledge of As levels/species and factors governing As contamination in the study area.

Carcinogenic and non-carcinogenic risk assessments of arsenic contamination in drinking water of Ardabil city in the Northwest of Iran

Based on the environmental health assessment framework of the United State Environmental Protection Agency, a quantitative health risk assessment of arsenic in contaminated drinking water in a city in the northwest of Iran has been carried out. In the exposure assessment step, arsenic concentrations in drinking water were determined during four seasons. In addition, the water ingestion rate for different age groups in this region was determined. The concentration of arsenic in 163 collected samples from different locations during four seasons ranged from 0 to 99 μg L^-1. Furthermore, a high percentage of the samples manifested higher levels than the permissible limit of 10 μg L^-1. The total daily water intake rates of four age groups 1 to <2 (group 1), 2 to <6 (group 2), 6 to <16 (group 3), and ≥16 years (group 4) were estimated as 0.86, 1.49, 2.00, and 2.33 L day^-1, respectively. Calculating the lifetime average daily dose of arsenic indicated that adults (group 4) had the highest and children (group 1) had the lowest daily intake of arsenic in their entire life. The results of risk characteristic showed that the order of excess lifetime cancer risk via arsenic exposure in the four groups was 4 > 3 > 2 > 1. The estimated risks for all age groups were higher than the acceptable range (1E-6 to 1E-4). The hazard quotient values for all of the classified groups were lower than the recommended limit values (<1), but it cannot be concluded that potential non-carcinogenicity risks are non-existent since the possible exposure to arsenic via food and skin may also pose the risk.

Cadmium induces BNIP3-dependent autophagy in chicken spleen by modulating miR-33-AMPK axis

Cadmium (Cd), a widespread environmental pollutant, has toxic effects on organs including spleen. However, the underlying mechanisms of Cd induced spleen toxicity and the roles of micro-RNA (miRNA) in this process remain poorly understood. To investigate this, cadmium chloride (CdCl₂, 10 mg/kg) was administered in the diet of chickens for 90 days. Electron microscopy, qPCR and Western blot were performed. Results showed that Cd exposure suppressed miR-33-5q which increased the levels of AMPK. Subsequently, significant decrease in AKT/mTOR signaling and HSP70 were observed. Concurrently, levels of NF-κB, p-JNK/JNK increased significantly. Moreover, the expression of BNIP3 and other autophagy markers (LC3-I, LC3-II, Beclin-1) increased significantly. Additionally, the levels of ions (Ca, Cr, Se, Sr, Sn, Ba) and (Na, Mg, V, Fe, Mo, Cu, Zn, Cd) significantly decreased and increased, respectively. Taken together, we conclude that Cd induced the deregulation of miR-33-AMPK axis led to BNIP3-dependent autophagy in chicken spleen through AKT/mTOR and HSP70-NF-κB/JNK signal pathways. In-addition Cd could affect ion homeostasis in chicken spleen.

NF-κB-mediated inflammation correlates with calcium overload under arsenic trioxide-induced myocardial damage in Gallus gallus

Arsenic is a known environmental pollutant and highly hazardous toxin to human health. Due to the biological accumulation, arsenic produces a variety of cardiovascular diseases. However, the exact mechanism is still unclear. Here, our objective was to evaluate myocardial damage and determine the potential mechanism under arsenic exposure in chickens. Arsenic trioxide (As₂O₃) (1.25 mg/kg BW, corresponding 15 mg/kg feed) was administered as basal diet to male Hy-line chickens (one-day-old) for 4, 8 and 12 weeks. The results showed that As₂O₃-induced histological and ultrastructural damage in heart accompanied with significantly Ca²⁺ overload and increased the activities of myocardial enzymes. Moreover, As₂O₃ exposure significantly increased (P < 0.05) the mRNA levels of ITPR3, PMCA, TRPC1, TRPC3, STIM1, ORAI1 and pro-inflammatory genes, while the mRNA levels of ITPR1, ITPR2, RyR1, RyR3, SERCA, SLC8A1, CACNA1S and interleukin-10 were decreased (P < 0.05) by As₂O₃ exposure at 4, 8 and 12 weeks as compared with the corresponding control group. Western blot results showed that As₂O₃ exposure decreased the expression of SERCA and SLC8A1 protein, while the expression of TNF-α, NF-κB, iNOS and PMCA1 increased compared with the corresponding control group. Additionally, correlation analysis and protein-protein interaction prediction shown that NF-κB-mediated inflammatory response have a function correlation with calcium (Ca) regulation-related genes. In conclusion, this study indicated that As₂O₃-induced inflammatory response might dependent on Ca overload in myocardial damage of chickens. Our work has implications for the development of potential therapeutic approaches by resisting Ca overload for arsenic-induced myocardial damage.

Extensive arsenic contamination in high-pH unconfined aquifers in the Indus Valley

Arsenic-contaminated aquifers are currently estimated to affect ~150 million people around the world. However, the full extent of the problem remains elusive. This is also the case in Pakistan, where previous studies focused on isolated areas. Using a new data set of nearly 1200 groundwater quality samples throughout Pakistan, we have created state-of-the-art hazard and risk maps of arsenic-contaminated groundwater for thresholds of 10 and 50 μg/liter. Logistic regression analysis was used with 1000 iterations, where surface slope, geology, and soil parameters were major predictor variables. The hazard model indicates that much of the Indus Plain is likely to have elevated arsenic concentrations, although the rest of the country is mostly safe. Unlike other arsenic-contaminated areas of Asia, the arsenic release process in the arid Indus Plain appears to be dominated by elevated-pH dissolution, resulting from alkaline topsoil and extensive irrigation of unconfined aquifers, although pockets of reductive dissolution are also present. We estimate that approximately 50 million to 60 million people use groundwater within the area at risk, with hot spots around Lahore and Hyderabad. This number is alarmingly high and demonstrates the urgent need for verification and testing of all drinking water wells in the Indus Plain, followed by appropriate mitigation measures.

A perspective of chronic low exposure of arsenic on non-working women: Risk of hypertension

The relationship between arsenic (As) exposure and hypertension risk are extensively studied. The As content in scalp hair has been used as a reliable indicator of population for long-time exposure from different sources. Therefore, we investigated the association between hair As concentration and hypertension risk, as well as the potential modifying effects of single nucleotide polymorphisms (SNPs) related to phase II metabolism enzyme genes. We recruited 398 non-working women in Shanxi Province, northern China, from Aug 2012 to May 2013, including 163 subjects with hypertension (cases) and 235 healthy controls. Scalp hair and blood samples were collected from each subject. We analyzed the As concentrations of ~24-cm-long strands of hair representing the two most recent years of growth and SNPs of three genes (epoxide hydrolase 1, N-acetyltransferase 2, and glutathione S-transferase P1) in each subject. The results revealed that the hair As concentration of this population was significantly lower than in populations living near high As polluted sources in China and other countries. The median As concentration (inter-quartile range) of hair in the cases (i.e. 0.211 [0.114-0.395] μg/g hair) was higher than in the controls (i.e. 0.101 [0.048-0.227] μg/g hair). Higher hair As concentrations were associated with an elevated hypertension risk, with an adjusted odds ratio of 2.55 [95% confidence interval: 1.55-4.20]. No interaction effects between hair As concentration and SNPs related to phase II metabolism enzymes on hypertension risk were observed. It was concluded that chronic low exposure level of As might be associated with hypertension risk among the study subjects.

The effects of arsenic contaminated drinking water of livestock on its total levels in milk samples of different cattle: Risk assessment in children

This work was carried out to evaluate the arsenic (As) levels in milk samples of different milch animals, sheep, goats, cows, buffaloes and camels in Tharparkar, Pakistan. The concentration of As in the milk samples of cows, buffalos, sheep, goats and camels were observed in the range of 15.1-18.4, 2.6-7.7, 25.7-33.2, 10.5-37.3 and 6.6-13.7 μg/L, respectively. The levels of As in livestock drinking water of each farms/flocks was found in the range of 238-2000 μg L^-1. A positive correlation with Pearson correlation coefficients, ranged as, 0.926-0.974 (p = 0.001-0.011) was observed between the As concentration in milk samples of cattle and in corresponding drinking water of farms/flocks. The high bio-transfer factor of As was occurred in the milk samples of sheep. The content of As in scalp hair of children was observed to be elevated, who consumed milk of lower cattle (sheep and goat) than cow and camel. The As content in scalp hair directly proportional to the age of children. The hazardous quotient value of As due to consumption of milk was observed in decreasing order as, sheep > goats > camels > cows. The total hazardous quotient or noncarcinogenic risk values for children consuming the milk of sheep, goat, cow and camels were found >1 of reference dose for As, creates adverse effects on health in childhood stage. The children of all three age group have higher carcinogenic risk factor who are consuming milk of goat and sheep than larger cattle.

Human Arsenic exposure via dust across the different ecological zones of Pakistan

The present study aims to assess the arsenic (As) levels into dust samples and its implications for human health, of four ecological zones of Pakistan, which included northern frozen mountains (FMZ), lower Himalyian wet mountains (WMZ), alluvial riverine plains (ARZ), and low lying agricultural areas (LLZ). Human nail samples (N=180) of general population were also collected from the similar areas and all the samples were analysed by using ICP-MS. In general the higher levels (p<0.05) in paired dust and human nail samples were observed from ARZ and LLZ than those of other mountainous areas (i.e., WMZ and FMZ), respectively. Current results suggested that elevated As concentrations were associated to both natural, (e.g. geogenic influences) and anthropogenic sources. Linear regression model values indicated that As levels into dust samples were associated with altitude (r(2)=0.23), soil carbonate carbon density (SCC; r(2)=0.33), and population density (PD; r(2)=0.25). The relationship of paired dust and nail samples was also investigated and associations were found for As-nail and soil organic carbon density (SOC; r(2)=0.49) and SCC (r(2)=0.19) in each studied zone, evidencing the dust exposure as an important source of arsenic contamination in Pakistan. Risk estimation reflected higher hazard index (HI) values of non-carcinogenic risk (HI>1) for children populations in all areas (except FMZ), and for adults in LLZ (0.74) and ARZ (0.55), suggesting that caution should be paid about the dust exposure. Similarly, carcinogenic risk assessment also highlighted potential threats to the residents of LLZ and ARZ, as in few cases (5-10%) the values exceeded the range of US-EPA threshold limits (10(-6)-10(-4)).