Carcinogenic and systemic health effects associated with arsenic exposure--a critical review

Occupational exposure to arsenic and leukopenia risk: Toxicological alert

Arsenic and its inorganic compounds affect numerous organs and systemic functions, such as the nervous and hematopoietic systems, liver, kidneys, and skin. Despite a large number of studies on arsenic toxicity, rare reports have investigated the leukopenia incidence in workers exposed to arsenic. In workplaces, the main source of workers' exposure is the contaminated air by the inorganic arsenic in mines, arsenic or copper smelter industries, and chemical factories. Erythropoiesis inhibition is one of the arsenic effects and it is related to regulatory factor GATA-1. This factor is necessary for the normal differentiation of early erythroid progenitors. JAK-STAT is an important intracellular signal transduction pathway responsible for the mediating normal functions of several cytokines related to cell proliferation and hematopoietic systems development and regulation. Arsenic inactivates JAK-STAT by inhibiting JAK tyrosine kinase and using the IFNγ pathway. The intravascular hemolysis starts after the absorption phase when arsenic binds to the globin of hemoglobin in erythrocytes and is transported into the body, which increases the oxidation of sulfhydryl groups in hemoglobin. So, this article intends to highlight the potential leukopenia risk via inhalation for workers exposed to arsenic and suggests a possible mechanism for this leukopenia through the JAK-signal transducer and activator of transcription (STAT) pathway inhibition.

Alleviation of arsenic-induced neurobehavioral defects with selenium in the larvae of Zaprionus indianus

Selenium is an essential antioxidative micronutrient. This study was conducted to characterize the arsenic toxicity induced on the African fig fly, Zaprionus indianus, and its possible amelioration by selenium. We used computational tools and in vivo experiments to elucidate the mechanism of action of arsenic and selenium on Z. indianus larvae. We conducted experiments to study neurobehavioral parameters including learning and memory ability test and crawling and contraction assays. Our in silico study revealed twelve primary targets of arsenic trioxide. The gene ontology annotation of primary and secondary targets of arsenic trioxide revealed selenocysteine metabolic processes as one of the most reliable targets. To validate our in silico data, we analyzed the effect of arsenic trioxide on larvae of Z. indianus and tested the possible amelioration by sodium selenite supplementation. Our data demonstrated that the arsenic trioxide deteriorated the learning and memory ability of 2nd instar larvae of Z. indianus and such effect was reversed by sodium selenite supplementation. Furthermore, crawling and contraction assay done on 3rd instar larvae showed that there was reduction in both parameters upon arsenic trioxide exposure, which was restored with sodium selenite supplementation. Altogether, our computational and in vivo results strongly indicated that the neurobehavioral defects induced by arsenic trioxide on the larvae of Z. indianus can be successfully alleviated in the presence of sodium selenite.

Source, toxicity and carcinogenic health risk assessment of heavy metals

Heavy metals are chemical elements with unique properties that are toxic even in low concentrations and affect human health with different functions. Agricultural and industrial activities, improper disposal of household solid waste and residues related to industrial producers, discharge of household wastewater and agricultural fertilizers are the most important ways in which toxic heavy metals enter the environment, which harms human health and life. A narrative review of the literature was done from 2000 to 2022 based on searched databases included Google Scholar, PubMed, Springer, Web of Science, and Science Direct (Scopus). All relevant studies published 2000 until 2022 gathered. According to the databases, 820 articles were retrieved. 186 and 50 articles were found and selected based on records identified through database searching and additional records identified through other sources. In the next stage, 97 studies were screened after review and 64 full-text articles entered into the analysis process. Finally, 45 articles were selected in this study. Adverse effects of heavy metals on various conditions in the body depend on a number of factors, including dose, route of exposure and chemical species, as well as age, sex, genetics, nutritional status, and duration of exposure to the heavy metal. The existence of significant relationships between long-term and short-term exposure to toxic heavy metals and their adverse effects, including carcinogenicity, has been extensively studied and proven through numerous experiments. However, the mechanisms associated with this complication have not been properly identified, so in future research, there is a great need for comprehensive studies on the carcinogenicity of heavy metals.

Association between blood heavy metal concentrations and skin cancer in the National Health and Nutrition Examination Survey, 2011-2018

We aimed to evaluate the associations between blood cadmium (Cd), mercury (Hg), lead (Pb), manganese (Mn), and selenium (Se) concentrations and skin cancer. This cross-sectional study was based on National Health and Nutritional Examination Survey (NHANES) data. A binomial logistic regression model was used to analyze the associations between exposure to the metal elements and the risk of skin cancer, and further stratified analyses were conducted by gender, age, body mass index, ethnicity, education, smoking, alcohol drinking, and hypertension. A total of 16,034 participants were included. After fully adjusting for multivariate, the odd ratio (OR)[95% confidence interval (95% CI)] values for skin cancer in those with blood Mn concentrations in the second, third, and fourth quartiles were 0.52 (0.33-0.82), 0.57 (0.36-0.9), and 0.56 (0.35-0.89), respectively, compared with those in the lowest quartile. The ORs (95% CI) for each 1-SD increment in log-transformed values for blood Mn concentrations were 0.79 (0.66-0.94), 0.8 (0.66-0.97), and 0.79 (0.66-0.96), respectively. A significant association between blood Hg and skin cancer was also observed in participants who drank alcohol, with a corresponding OR (95% CI) of 2.61 (1.37-5.00) (p interaction = 0.006). Our study indicated that a higher blood Mn concentration was negatively associated with skin cancer, and blood Hg was positively associated with skin cancer in participants who drank alcohol.

Association between metal(loid)s in serum and leukemia: a systematic review and meta-analysis

Purpose

Heavy metals and metalloids are recognized as environmental threats, which are considered highly toxic and carcinogenic. Epidemiologically, their association with leukemia is under debate. We aim to clarify the association between the heavy metal(loid)s in serum and leukemia via a systematic review and meta-analysis.

Methods

We searched PubMed, Embase, Google Scholar, and CNKI (China National Knowledge Infrastructure) databases for all related articles. The standardized mean difference and its 95% confidence interval was used to evaluate the association of leukemia with heavy metal(loid)s in serum. The statistical heterogeneity among studies was assessed with the Q-test and I 2 statistics.

Results

Among 4,119 articles related to metal(loid)s and leukemia, 21 studies met our inclusion criteria, which are all cross-sectional studies. These 21 studies involved 1,316 cases and 1,310 controls, based on which we evaluate the association of heavy metals/metalloids in serum with leukemia. Our results indicated positive differences for serum chromium, nickel, and mercury in leukemia patients, while a negative difference for serum manganese in acute lymphocytic leukemia (ALL).

Conclusion

Our results suggested an elevated trend of serum chromium, nickel, and mercury concentrations in leukemia patients while descending trend of serum manganese concentration in ALL patients. The result of sensitivity analysis between lead, cadmium, and leukemia and publication bias of association between chromium and leukemia also needed attention. Future research work may focus on the dose-response relationship between any of these elements and the leukemia risks, and further elucidation of how these elements are related to leukemia may shed light on the prevention and treatment of leukemia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-023-00853-2.

Nanocurcumin Restores Arsenic-Induced Disturbances in Neuropharmacological Activities in Wistar Rats

The present study was carried out to examine the ameliorative potential of nanocurcumin against arsenic induced (sub-chronic) alterations in central nervous system in male Wistar rats. Nanocurcumin was synthesised and the hydrodynamic diameter, zeta potential and particle size were~76.60 nm, (-) 30 mV and 95nm, respectively. Experimental rats sub-chronically exposed to sodium (meta) arsenite (As; 10 mg.kg-1; 70 days; p.o) induced significant (p<0.05) reduction in superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione and favoured free radical generation and induced lipid peroxidation in brain tissue. The exposure resulted in significant (p<0.05) decrease in voluntary- and involuntary motor activities and enhanced anxiety levels. However, experimental rats receiving nanocurcumin (15 mg.kg-1; p.o) showed significant (p<0.05) recovery in enzymatic - and non-enzymatic antioxidant defence system and restoration of redox balance and overcome arsenic induced depression in motor activities and elevated anxiety levels. Further, Arsenic induced elevation in pro-inflammatory cytokines, cyclooxygenase-2 activity and prostaglandin-E2 in brain and angiotensin-II levels (plasma) was significantly (p<0.05) ameliorated by nanocurcumin. Additionally, quantitative real -time polymerase chain reaction revealed a fivefold decrease in Nox2 expression in brain following nanocurcumin administration. Thus, the study concludes that nanocurcumin can serve as a potential therapeutic candidate to counter arsenic induced redox imbalance and neuropharmacological disturbances and there exists a vast scope to exploit its utility after appropriate clinical modelling.

Long-term impact of the Tyrnyauz tungsten-molybdenum mining and processing factory waste on environmental pollution and children's population

We studied the consequences of the long-term impact of remediated tailing ponds from the Tyrnyauz tungsten-molybdenum mining and processing factory on the environmental pollution and children living in the area. For more than 60 years, the factory has been engaged in the development of tungsten-molybdenum deposits by open-pit and mine methods and the enrichment of the extracted ore. More than 252,771 thousand tons of waste accumulated in its dumps and tailings ponds. This 170-hectare tailing pond contains more than 125 million tons of waste with arsenic, tungsten, molybdenum and other metals. To examine the possible accumulation of potentially toxic elements in children's bodies, we determined the content of heavy metals in drinking water and in the hair of children. An exfoliated buccal micronucleus test was used to determine the cytogenetic status of children. We did not find significant differences in the content of heavy metals inherent of a tailing pond in children's hair from polluted area compared to the control zone. In buccal cells of children living in the vicinity of the tailings pond, the total number of cytogenetic abnormalities was increased by 4.1 times, the total index of proliferation by 1.5 times, early destruction of the nucleus by 2 times and apoptosis by 1.2 times compared to the clean zone. Thus, we identified a genotoxic and cytotoxic effect on children living in the vicinity of the tailing ponds, which led to an increase in the number of children belonging to the medium- and high-risk groups. No correlations were found between the content of heavy metals in children's hair and the frequency of cells with cytogenetic abnormalities. Weak positive correlation was found between the content of manganese, zinc and copper in children's hair and the indicators of buccal epithelial cell proliferation.

Detection of Phenylarsine Oxide in Drinking Water Using an Impedimetric Electrochemical Sensor with Gelatin-Based Solid Electrolyte Enriched with Mercaptoethanol: A Novel Prospective Green Biosensor Methodology

A simple, inexpensive, rapid, and label-free detection of phenylarsine oxide (PAO) in the field is a significant and unmet need because of its fatally acute and chronic effects on human health. A simple, fast, sensitive, and relatively low-cost arsenic detection system with an eco-friendly sensor could fill this gap. To monitor arsenic in situ, a reliable, portable impedimetric electrochemical sensor is the most suitable platform, which is real-time, fast, low-cost, and easy to design and use and has high sensitivity at low detection limits in the nanogram per mL range. The detection system in this study has a patent-applied green sensor with minimum harm to nature and the potential to dissolve in nature. The electrode containing 15 mL of distilled water (DIW) + 2 g gelatin + 1.75 g glycerol was determined to be the most suitable for determining the amount of inorganic arsenic in the range of 1-100 ng/mL using a gelatin-based solid electrochemical sensor enriched with 2-mercaptoethanol. Impedance measurements were performed to analyze the stability of the sensor in both deionized water and drinking water, as well as for arsenic detection. Among the procedures examined, the procedure prepared with 15 mL DIW + 2 g glycerol + 1.75 g gelatin resulted in the best stability in aqueous medium and in sensitivity with resistance changes (-ΔR _ct (%)) of 12% (±0.62%), 26% (±2.3%), and 40% (±3.8%) for the concentrations of 1, 10, and 100 ng/mL PAO in drinking water, respectively. With this detection methodology, there is the potential to detect not only arsenic but also other heavy metals in waters and different biomarkers in human fluids.

Regulation of arsenic methylation: identification of the transcriptional region of the human AS3MT gene

The human enzyme As(III) S-adenosylmethionine methyltransferase (AS3MT) catalyzes arsenic biotransformations and is considered to contribute to arsenic-related diseases. AS3MT is expressed in various tissues and cell types including liver, brain, adrenal gland, and peripheral blood mononuclear cells but not in human keratinocytes, urothelial, or brain microvascular endothelial cells. This indicates that AS3MT expression is regulated in a tissue/cell type-specific manner, but the mechanism of transcriptional regulation of expression of the AS3MT gene is not known. In this study, we define the DNA sequence of the core promoter region of the human AS3MT gene. We identify a GC box in the promoter to which the stress-related transcription factor Sp1 binds, indicating involvement of regulatory elements in AS3MT gene expression.

Melanocytotoxic chemicals and their toxic mechanisms

Melanocyte cell death can lead to various melanocyte-related skin diseases including vitiligo and leukoderma. Melanocytotoxic chemicals are one of the most well-known causes of nongenetic melanocyte-related diseases, which induce melanocyte cell death through apoptosis. Various chemicals used in cosmetics, medicine, industry and food additives are known to induce melanocyte cell death, which poses a significant risk to the health of consumers and industrial workers. This review summarizes recently reported melanocytotoxic chemicals and their mechanisms of toxicity in an effort to provide insight into the development of safer chemicals.

Epigenetics: a new warrior against cardiovascular calcification, a forerunner in modern lifestyle diseases

Arterial and aortic valve calcifications are the most prevalent pathophysiological conditions among all the reported cases of cardiovascular calcifications. It increases with several risk factors like age, hypertension, external stimuli, mechanical forces, lipid deposition, malfunction of genes and signaling pathways, enhancement of naturally occurring calcium inhibitors, and many others. Modern-day lifestyle is affected by numerous environmental factors and harmful toxins that impair our health rather than providing benefits. Applying the combinatorial approach or targeting the exact mechanism could be a new strategy for drug designing or attenuating the severity of calcification. Most of the non-communicable diseases are life-threatening; thus, altering the phenotype and not the genotype may reveal the gateway for fighting with upcoming hurdles. Overall, this review summarizes the reason behind the generation of arterial and aortic valve calcification and its related signaling pathways and also the detrimental effects of calcification. In addition, the individual process of epigenetics and how the implementation of this process becomes a novel approach for diminishing the harmful effect of calcification are discussed. Noteworthy, as epigenetics is linked with genetics and environmental factors necessitates further clinical trials for complete and in-depth understanding and application of this strategy in a more specific and prudent manner.

Urinary heavy metals in residents from a typical city in South China: human exposure and health risks

Although heavy metal pollution has developed into a major global environmental problem, most research has focused on specific elements, especially arsenic (As) and selenium (Se), and on the health risks to people in polluted areas or by occupation. This study investigated the urine of 480 participants from Guangzhou with a population of 18 million and targeted nine heavy metals: As, Se, chromium (Cr), manganese (Mn), nickel (Ni), cadmium (Cd), lead (Pb), antimony (Sb), and mercury (Hg). The heavy metals were widely detected, of which As, Se, Cd, and Pb all exceed 98%. Among the toxicants, As showed the highest concentration, followed by Se with 40.5 and 35.4 μg/L, respectively. The heavy metal levels from suburban subjects were generally higher than those in urban subjects (except for Sb), and the Cd level of males was lower than that of females. Concentrations were related to age, body mass index, alcohol consumption, and smoking. According to the health risk assessment, most subjects experienced potential non-carcinogenic risk from As, Cd, Se, and Hg, which accounted for 38.2%, 8.83%, 8.31%, and 3.38%, respectively. The carcinogenic risk of As and Cd surpassed the risk level of 10^-6, and 90.1% and 35.4% of the subjects, respectively, exceeded 10^-4, an unacceptable risk level. More attention to the high carcinogenic risk from heavy metals and the high detected levels of As and Cd is required.

Nanomaterials for the Treatment of Heavy Metal Contaminated Water

Nanotechnology finds its application almost in every field of science and technology. At the same time, it also helps to find the solution to various environment-related problems, especially water contamination. Nanomaterials have many advantages over conventional materials, such as high surface area, both polar and non-polar chemistries, controlled and size-tunable, easier biodegradation, which made them ideal candidates for water and environmental remediation as well. Herein, applications of non-carbon nanomaterials, such as layered double hydroxides, iron oxide magnetite nanoparticles, nano-polymer composites, metal oxide nanomaterials and nanomembranes/fibers in heavy metal contaminated water and environmental remediation are reviewed. These non-carbon nanomaterials, due to their tunable unique chemistry and small size have greater potentials for water and environmental remediation applications.

Heavy Metal Contamination of Natural Foods Is a Serious Health Issue: A Review

Heavy metals play an important role in the homeostasis of living cells. However, these elements induce several adverse environmental effects and toxicities, and therefore seriously affect living cells and organisms. In recent years, some heavy metal pollutants have been reported to cause harmful effects on crop quality, and thus affect both food security and human health. For example, chromium, cadmium, copper, lead, and mercury were detected in natural foods. Evidence suggests that these elements are environmental contaminants in natural foods. Consequently, this review highlights the risks of heavy metal contamination of the soil and food crops, and their impact on human health. The data were retrieved from different databases such as Science Direct, PubMed, Google scholar, and the Directory of Open Access Journals. Results show that vegetable and fruit crops grown in polluted soil accumulate higher levels of heavy metals than crops grown in unpolluted soil. Moreover, heavy metals in water, air, and soil can reduce the benefits of eating fruits and vegetables. A healthy diet requires a rational consumption of foods. Physical, chemical, and biological processes have been developed to reduce heavy metal concentration and bioavailability to reduce heavy metal aggregation in the ecosystem. However, mechanisms by which these heavy metals exhibit their action on human health are not well elucidated. In addition, the positive and negative effects of heavy metals are not very well established, suggesting the need for further investigation.

Comparing the concentrations of heavy metals on two bivalve species in Santos Bay, Brazil: Subsidies to understanding the assimilation dynamic of bivalve contaminants

Contaminant substances consist of chemical elements that present the potential to adversely impact the ecology of the environment, thus representing a threat to local fauna and flora. In this context, heavy metals are critical agents that, depending on the nature and level, are potentially toxic to living organisms. In order to evaluate the bioaccumulation of heavy metals in the Santos estuary and to determine the potential influence of salinity gradient on the heavy metal bioconcentration, the present study measured the concentrations of As, Cd, Pb, Cu, Cr, Fe, Ni, and Zn in two bivalve species (Crassostrea rhizophorae and Perna Perna) sampled at different sites of Santos Bay, in the southeastern region of Brazil. Throughout the study, the "sentinel species" used were effective in bioaccumulating contaminants. In oysters, based on the Brazilian legislation, critical limits were exceeded for As, Zn, Cu, and Cr. In the case of mussels, on the other hand, only for As, Zn, and Cr, the critical limits were overcome. In the present study, obtained data suggested salinity as a determinant parameter in As incorporation processes of bivalve mollusks. PRACTITIONER POINTS: The present study presents important results for the development of environmental management policies in estuarine environments. The present study points out differences between different organisms as biomonitors, providing subsidies for the decision of an effective biomonitoring program. The present study discusses values of contaminants as a danger to public health in Santos Bay, which can be extrapolated to other similar environments around the world.

Characterization of Chemical and Bacterial Concentrations in Floor Dust Samples in Southeast Texas Households

Indoor dust can be a major source of heavy metals, nutrients, and bacterial contamination in residential environments and may cause serious health problems. The goal of this research is to characterize chemical and bacterial contaminants of indoor, settled house dust in the Houston Metropolitan region. To achieve this, a total of 31 indoor dust samples were collected, along with household survey data, which were subsequently analyzed for elemental and bacterial concentrations. Microscopic and geospatial analysis was conducted to characterize and map potential hotspots of contamination. Interestingly Cd, Cr, Cu, Pb, and Zn concentrations of all 31 indoor dust samples were significantly enriched and exceeded soil background concentrations. Furthermore, As, Cd, Pb, and Zn concentrations in the dust samples were significantly correlated to the enteric bacterial load concentrations. Human health assessment revealed that cancer risk values via ingestion for Cd, Cr, and Ni were greater than the acceptable range. Of our 31 dust sample isolates, three Gram-negative and 16 Gram-positive pathogenic bacteria were identified, capable of causing a wide range of diseases. Our results demonstrate that both chemical and bacterial characterization of indoor dust coupled with spatial mapping is essential to assess and monitor human and ecological health risks.

Accumulation of Trace Metals in Indigenous Fish Species from the Old Brahmaputra River in Bangladesh and Human Health Risk Implications

In this study, accumulation of the top six most toxic trace metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Nickel (Ni) and Lead (Pb)) were assessed in six indigenous fish species (Barilius barila, Salmostoma acinaces, Gudusia chapra, Labeo bata, Corica soborna, and Sperata aor) collected from the Old Brahmaputra River in Bangladesh. Human health risk associated with these fish consumption was also evaluated. Metals were analyzed in whole body of fish by an atomic absorption spectrometer (AAS). Mean concentrations of metals (μg/g, wet weight) were in the range of As (< 0.02-0.278), Cd (< 0.002-0.005), Cr (0.239-0.761), Hg (0.008-0.057), Ni (< 0.02-0.044), and Pb (< 0.01-0.038). The metal contents varied significantly among the fishes regarding their feeding habits and living habitats. Concentrations of As, Cr, Hg, and Pb were significantly higher in omnivorous species, whereas the benthopelagic species showed significantly higher accumulation of As (p < 0.05). The target hazard quotient (THQ) for noncarcinogenic risk and target cancer risk (TR) for carcinogenic risk were calculated to estimate the probabilities of experiencing these adverse health effects for the fish consumers. Metal-specific THQ values were all below 1 indicating no potential human health risk. Nonetheless, the hazard index (HI) values to estimate the effects from exposure to all metals collectively elucidated chronic noncarcinogenic health risk particularly from G. chapra consumption. The TR values revealed that there was carcinogenic risk from exposure to As through consumption of the fish. This study finally suggests a systematic and continuous monitoring of trace metal contamination in fishes from the river to ensure the fitness of this food item regarding the safety for human health.

Effects of arsenic and heavy metals on metabolic pathways in cells of human origin: Similarities and differences

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There are distinctive overlaps in different heavy metal affected metabolic pathways.

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Affected pathways vary according to the tissue origin and maturity of the cell.

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Arsenic appears to have relatively more pleiotropic effects on metabolic pathways.

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Some of the arsenic affected pathways are associated with diabetes.

Various anthropogenic and natural events over the years have gradually increased human exposure to various heavy metals. Several of these heavy metals including cadmium, mercury, nickel, chromium, and the metalloid arsenic among others, have created major public health concerns for their high level of toxicities. Identification of the general as well as the differentially affected cellular metabolic pathways will help understanding the molecular mechanism of different heavy metal-induced toxicities. In this study, we analyzed 25 paired (control vs. treated) transcriptomic datasets derived following treatment of various human cells with different heavy metals and metalloid (arsenic, cadmium, chromium, iron, mercury, nickel and vanadium) to identify the affected metabolic pathways. The effects of these metals on metabolic pathways depend not only on the metals per se, but also on the nature of the treated cells. Tissue of origin, therefore, must be considered while assessing the effects of any particular heavy metal or metalloid. Among the metals and metalloid, arsenic appears to have relatively more pleiotropic influences on cellular metabolic pathways including those known to have association with diabetes. Although only two stem cell derived datasets are included in the current study, effects of heavy metals on these cells appear to be different from other mature cells of similar tissue origin. This study provides useful information about different heavy metal affected pathways, which may be useful in further exploration using wet-lab based techniques.

Multi-element determination of essential and toxic metals in green and roasted coffee beans: A comparative study among different origins using ICP-MS

The aim of this study is to compare the elemental composition among different coffee varieties consumed in Jordan. Levels of different metallic elements in coffee samples; green and roasted coffee beans from five origins; Brazil, Ethiopia, Kenya, Columbia, and India, collected from the Jordanian market were investigated. Twenty-two elements, including essential and toxic elements such as potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), aluminum (Al), manganese (Mn), copper (Cu), barium (Ba), strontium (Sr), zinc (Zn), chromium (Cr), lead (Pb), nickel (Ni), vanadium (V), cobalt (Co), gallium (Ga), uranium (U), cadmium (Cd), silver (Ag), lithium (Li), indium (In), bismuth (Bi), thorium (Th), and thallium (Ti), were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The detected heavy metals and their intake per 1 cup of coffee did not largely contribute to the recommended daily intake (RDI) and tolerable upper limit of daily intake (TULD) in an adult with an average body weight of 80 kg. The ICP-MS versus flame atomic absorption spectrometry (FAAS) results were linearly fitted, and the correlation coefficients (R2 > 0.95) were better than 0.95 for the three checked elements. No significant difference between the results of the two techniques was observed (p > 0.05). The ANOVA results indicated the presence of a significant difference between the levels of Cr, Co, and Zn in green and roasted coffee beans. The results of this study indicated that the coffee consumed in Jordan did not contain toxic levels of heavy elements and is safe for consumption according to health organizations.

The Response of the Associations of Grass and Epichloë Endophytes to the Increased Content of Heavy Metals in the Soil

The rapid development of civilization increases the area of land exposed to the accumulation of toxic compounds, including heavy metals, both in water and soil. Endophytic fungi associated with many species of grasses are related to the resistance of plants to biotic and abiotic stresses, which include heavy metals. This paper reviews different aspects of symbiotic interactions between grass species and fungal endophytes from the genera Epichloë with special attention paid to the elevated concentration of heavy metals in growing substrates. The evidence shows the high resistance variation of plant endophyte symbiosis on the heavy metals in soil outcome. The fungal endophytes confer high heavy metal tolerance, which is the key feature in its practical application with their host plants, i.e., grasses in phytoremediation.

Trace element mass fractions in road dust as a function of distance from road

Road dust particles play an important role in atmospheric pollution and are associated with adverse human health effects. Traffic emissions are a major source of particles in road dust. However, there has been limited information about the relationship between distance from road and traffic-related elements levels in road dust. We investigated the relationships between proximity to the nearest major roadway and trace element mass fractions in PM₁₀ and PM_2.5 re-suspended from the road surface, based on measurements at three different distance ranges. We found that mass fractions of Ba, Cu, Zr, Zn, Cl, Co, Cr, Ca, Ti in PM₁₀ road dust as well as Zr, Cu, Cl, Zn, Cr, Ti, Mn, Ca, Ni, and Fe in PM_2.5 road dust, significantly decreased with distance from major road. Most of these elements are associated with road traffic emissions, including both tailpipe and non-tailpipe emissions. The decrease rates differed among elements due to differences in local traffic contributions. The decreases for elements which are mainly associated with non-tailpipe traffic emissions (e.g., Ba, Zr) were more dramatic. Our results indicate that traffic emissions, especially non-tailpipe emissions, contribute substantially to road dust, suggesting the need for control strategies for non-tailpipe emissions. Implications: We investigated the relationships between road proximity with trace element mass fractions in PM10 and PM2.5 re-suspended from the road surface. We observed significant decrease of traffic-related elements in PM10 and PM2.5 road dust with log distance from major road. We also found that the mass fractions for elements, which mainly come from traffic decrease more sharply compared to elements which come from both traffic and other sources. Our results indicate that traffic emissions contribute substantially to road dust, and imply that the distance to major road can be used as a proxy for ambient exposure.

Linker-Free Magnetite-Decorated Gold Nanoparticles (Fe3O4-Au): Synthesis, Characterization, and Application for Electrochemical Detection of Arsenic (III)

Linker-free magnetite nanoparticles (Fe3O4NPs)-decorated gold nanoparticles (AuNPs) were grown using a new protocol that can be used as a new platform for synthesis of other intact metal-metal oxide nanocomposites without the need for linkers. This minimizes the distance between the metal and metal oxide nanoparticles and ensures the optimum combined effects between the two material interfaces. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of the Fe3O4-Au nanocomposite, without any change in the magnetite phase. Characterization, using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, revealed the composite to consist of AuNPs of 70 ± 10 nm diameter decorated with tiny 10 ± 3 nm diameter Fe3O4NPs in Au:Fe mass ratio of 5:1. The prepared Fe3O4-Au nanocomposite was embedded in ionic liquid (IL) and applied for the modification of glassy carbon electrode (GCE) for the electrochemical detection of As(III) in water. By combining the excellent catalytic properties of the AuNPs with the high adsorption capacity of the tiny Fe3O4NPs towards As(III), as well as the good conductivity of IL, the Fe3O4-Au-IL nanocomposite showed excellent performance in the square wave anodic stripping voltammetry detection of As(III). Under the optimized conditions, a linear range of 1 to 100 μg/L was achieved with a detection limit of 0.22 μg/L (S/N = 3), and no interference from 100-fold higher concentrations of a wide variety of cations and anions found in water. A very low residual standard deviation of 1.16% confirmed the high precision/reproducibility of As(III) analysis and the reliability of the Fe3O4-Au-IL sensing interface. Finally, this proposed sensing interface was successfully applied to analyzing synthetic river and wastewater samples with a 95-101% recovery, demonstrating excellent accuracy, even in complex synthetic river and wastewater samples containing high concentrations of humic acid without any sample pretreatments.

Protective effect of Mucuna pruriens against arsenic-induced liver and kidney dysfunction and neurobehavioral alterations in rats

BACKGROUND AND AIM

Intoxication of arsenic in rats is known to result in neurological effects as well as liver and kidney dysfunction. Mucuna pruriens has been identified for its medicinal properties. The aim of the study was to investigate the protective effect of aqueous seed extract of M. pruriens on sodium arsenite-induced memory impairment, liver, and kidney functions in rats.

MATERIALS AND METHODS

The experiment was divided into short-term treatment (45 days) and long-term treatment (90 days), with each group divided into nine sub-groups consisting of six animals each. Sub-groups 1 and 2 served as normal, and N-acetylcysteine (NAC) controls, respectively. Sub-groups 3-9 received sodium arsenite in drinking water (50 mg/L). In addition, sub-group 4 received NAC (210 mg/kg b.wt) orally once daily, sub-groups 5-7 received aqueous seed extract of M. pruriens (350 mg/kg b.wt, 530 mg/kg b.wt, and 700 mg/kg b.wt) orally once daily and sub-groups 8 and 9 received a combination of NAC and aqueous seed extract of M. pruriens (350 mg/kg b.wt and 530 mg/kg b.wt) orally once daily. Following the treatment, the blood was drawn retro-orbitally to assess the liver (serum alanine transaminase [ALT], serum aspartate transaminase, and serum alkaline phosphatase) and kidney (serum urea and serum creatinine) functions. Learning and memory were assessed by passive avoidance test. Animals were sacrificed by an overdose of ketamine, and their Nissl stained hippocampal sections were analyzed for alterations in neural cell numbers in CA1 and CA3 regions.

RESULTS

In the short-term treatment, groups administered with M. pruriens 530 mg/kg b.wt alone and combination of NAC + M. pruriens 350 mg/kg b.wt exhibited a significant improvement in memory retention, less severe neurodegeneration, and decrease in serum ALT levels. In long-term treatment, groups administered with M. pruriens 700 mg/kg b.wt alone and combination of NAC+M. pruriens 350 mg/kg b.wt, respectively, showed better memory retention, decreased neural deficits, and reduced levels of kidney and liver enzymes.

CONCLUSION

The seed extract of M. pruriens showed significant enhancement in memory and learning. The number of surviving neurons in the CA1 and CA3 regions also increased on treatment with M. pruriens. Serum ALT, serum urea, and serum creatinine levels showed significant improvement on long-term treatment with M. pruriens.

Indoor Air Pollution, Related Human Diseases, and Recent Trends in the Control and Improvement of Indoor Air Quality

Indoor air pollution (IAP) is a serious threat to human health, causing millions of deaths each year. A plethora of pollutants can result in IAP; therefore, it is very important to identify their main sources and concentrations and to devise strategies for the control and enhancement of indoor air quality (IAQ). Herein, we provide a critical review and evaluation of the major sources of major pollutant emissions, their health effects, and issues related to IAP-based illnesses, including sick building syndrome (SBS) and building-related illness (BRI). In addition, the strategies and approaches for control and reduction of pollutant concentrations are pointed out, and the recent trends in efforts to resolve and improve IAQ, with their respective advantages and potentials, are summarized. It is predicted that the development of novel materials for sensors, IAQ-monitoring systems, and smart homes is a promising strategy for control and enhancement of IAQ in the future.

Positive Association of Cardiovascular Disease (CVD) with Chronic Exposure to Drinking Water Arsenic (As) at Concentrations below the WHO Provisional Guideline Value: A Systematic Review and Meta-Analysis

To the best of our knowledge, a dose-response meta-analysis of the relationship between cardiovascular disease (CVD) and arsenic (As) exposure at drinking water As concentrations lower than the WHO provisional guideline value (10 µg/L) has not been published yet. We conducted a systematic review and meta-analyses to estimate the pooled association between the relative risk of each CVD endpoint and low-level As concentration in drinking water both linearly and non-linearly using a random effects dose-response model. In this study, a significant positive association was found between the risks of most CVD outcomes and drinking water As concentration for both linear and non-linear models (p-value for trend < 0.05). Using the preferred linear model, we found significant increased risks of coronary heart disease (CHD) mortality and CVD mortality as well as combined fatal and non-fatal CHD, CVD, carotid atherosclerosis disease and hypertension in those exposed to drinking water with an As concentration of 10 µg/L compared to the referent (drinking water As concentration of 1 µg/L) population. Notwithstanding limitations included, the observed significant increased risks of CVD endpoints arising from As concentrations in drinking water between 1 µg/L and the 10 µg/L suggests further lowering of this guideline value should be considered.

Non-Melanoma Skin Cancer in Outdoor Workers: A Study on Actinic Keratosis in Italian Navy Personnel

Occupational exposure to ultraviolet radiation is one of the main risk factors for non-melanoma skin cancer (NMSC) development. The most common variants of NMSC are basal cell carcinomas, squamous cell carcinomas, and actinic keratosis (AK). The latter is nowadays considered by most authors as an early squamous cell carcinoma rather than a precancerous lesion. Outdoor workers have a higher risk of developing NMSC because they spend most of the working day outside. The aim of this descriptive study was to assess the prevalence of skin lesions, especially AK, in a professional category of individuals exposed to ultraviolet (UV) radiation: the Italian Navy. From January to June 2016, a questionnaire and a total skin examination of 921 military personnel were administered by medical specialists (dermatologists) in seven different Italian Navy centres. AK was detected in 217 of 921 (23.5%) workers. Older age, outdoor occupation, longer working life, and fair skin seem to promote the development of AK. Of the 217 workers with AK, 187 (86.2%) had lesions in chronically sun-exposed skin areas. Italian Navy personnel have a high AK prevalence. Further studies are needed to investigate occupational hazards and their health effects among outdoor workers to promote protective behaviour and raise awareness of skin cancer.

Polyamine-stimulation of arsenic-transformed keratinocytes

Tumor promotion is strongly associated with inflammation and increased polyamine levels. Our understanding of relevant mechanisms responsible for arsenic-induced cancer remains limited. Previous studies suggest that arsenic targets and dysregulates stem cell populations that remain dormant in the skin until promoted to be recruited out of the bulge stem cell region, thus giving rise to skin tumors. In this study, we explored a possible mechanism by which increased keratinocyte polyamine biosynthesis promotes tumorsphere formation and invasiveness of arsenic-transformed HaCaT keratinocytes (As-HaCaT). Unlike parental HaCaT cells, As-HaCaT cells were tumorigenic in athymic nude mice, and the CD45negative epithelial tumor cells had enriched expression of Toll-Like Receptor 4 (TLR4), CD34 and CXCR4 as did As-HaCaT tumorsphere cultures compared to As-HaCaT monolayer cultures. Ornithine decarboxylase (ODC) overexpressing keratinocytes (Ker/ODC) release increased levels of the alarmin high mobility group box 1 (HMGB1). Ker/ODC conditioned medium (CM) stimulated As-HaCaT but not parental HaCaT tumorsphere formation, and this was inhibited by glycyrrhizin, an inhibitor of HMGB1, and by TAK242, an inhibitor of the HMGB1 receptor TLR4. Compared to parental HaCaT cells, As-HaCaT cells demonstrated greater invasiveness across a Matrigel-coated filter using either fibroblast CM or SDF-1α as chemoattractants. Addition of Ker/ODC CM or HMGB1 dramatically increased As-HaCaT invasiveness. Glycyrrhizin and TAK242 inhibited this Ker/ODC CM-stimulated invasion of As-HaCaT cells but not HaCaT cells. These results show that polyamine-dependent release of HMGB1 promotes the expansion of stem cell-like subpopulations in arsenic-transformed keratinocytes while also increasing their invasiveness, suggesting that polyamines may be a potential therapeutic target for the prevention and treatment of arsenic-initiated skin cancers.

Metabolic and epigenetic reprogramming in the arsenic-induced cancer stem cells

At present, the belief that genetic mutations control every aspect of tumorigenesis is still very popular. Even for the highly debated "bad luck" theory of cancers, it ascertained that random mutation of genes during the self-renewal of somatic stem cells is responsible for cancer initiation. Logically, most of the new therapeutic strategies so far, from molecular targeting to precision medicine or personalized medicine, are genome-obsessed and focused on identifying and targeting these mutated genes. Accordingly, a rather simplified therapeutic regimen was formulated: cancers with the same mutations, e.g., lung cancer, pancreatic cancer, breast cancer, ovarian cancer, etc, were managed with the same chemo or targeting medicine, whereas for a particular cancer, such as breast cancer or lung cancer, with different mutational spectrums was treated with different, so-called personalized medicine. The outcomes of this strategy, however, are mixed with encouraging and disappointing findings. In this review article, we will address the importance of non-genetic factors, the metabolic and epigenetic reprogramming, during the induction of cancer stem cells in response to arsenic, a major environmental human carcinogen. The information provided may not only advance our understanding of carcinogenic mechanism to a new level but also help in designing new strategies through targeting the metabolic and epigenetic signaling pathways for cancer therapy.

New insights into the role of plasmids from probiotic Lactobacillus pentosus MP-10 in Aloreña table olive brine fermentation

In silico analysis of Lactobacillus pentosus MP-10 plasmids (pLPE-1 to pLPE-5) suggests that plasmid-borne genes mediate the persistence of lactobacilli during olive fermentation and enhance their probiotic properties and their competitiveness in several ecological niches. The role of plasmids in the probiotic activities of L. pentosus MP-10 was investigated by plasmid-curing process which showed that plasmids contribute in increased metal tolerance and the biosequestration of several metals such as iron, aluminium, cobalt, copper, zinc, cadmium and mercury. Statistically significant differences in mucin adhesion were detected between the uncured and the cured L. pentosus MP-10, which possibly relied on a serine-rich adhesin (sraP) gene detected on the pLPE-2 plasmid. However, plasmid curing did not affect their tolerance to gastro-intestinal conditions, neither their growth ability under pre-determined conditions, nor auto-aggregation and pathogen co-aggregation were changed among the cured and uncured L. pentosus MP-10. These findings suggest that L. pentosus MP-10 plasmids play an important role in gastro-intestinal protection due to their attachment to mucin and, thus, preventing several diseases. Furthermore, L. pentosus MP-10 could be used as a bioquencher of metals in the gut, reducing the amount of these potentially toxic elements in humans and animals, food matrices, and environmental bioremediation.

Exposure to mixtures of mercury, cadmium, lead, and arsenic alters the disposition of single metals in tissues of Wistar rats

Humans throughout the world are exposed regularly to mixtures of environmental toxicants. Four of the most common heavy metal toxicants in the environment are mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As). Numerous studies have assessed the effects and disposition of individual metals in organ systems; however, humans are usually exposed to mixtures of toxicants or metals rather than to a single toxicant. Therefore, the purpose of the current study was to test the hypothesis that exposure to a mixture of toxic heavy metals alters the disposition of single metals in target organs. Wistar rats (Rattus norvegicus) were exposed to Hg, Cd, Pb, or As as a single metal or as a mixture of metals. Rats were injected intravenously for three days, following which kidneys, liver, brain, and blood were harvested. Samples were analyzed for content of Hg, Cd, Pb, and As via inductively coupled plasma mass spectrometry. In general, exposure to a mixture of metals reduced accumulation of single metals in target organs. Interestingly, exposure to mixtures of metals with Pb and/or As increased the concentration of these metals specifically in the liver. The findings from this study indicate that exposure to mixtures of toxic heavy metals may alter significantly the distribution and accumulation of these metals in target organs and tissues.

Genetic mechanisms of arsenic detoxification and metabolism in bacteria

Arsenic, distributed pervasively in the natural environment, is an extremely toxic substance which can severely impair the normal functions of living cells. Research on the genetic mechanisms of arsenic metabolism is of great importance for remediating arsenic-contaminated environments. Many organisms, including bacteria, have developed various strategies to tolerate arsenic, by either detoxifying this harmful element or utilizing it for energy generation. This review summarizes arsenic detoxification as well as arsenic respiratory metabolic pathways in bacteria and discusses novel arsenic resistance pathways in various bacterial strains. This knowledge provides insights into the mechanisms of arsenic biotransformation in bacteria. Multiple detoxification strategies among bacteria imply possible functional relationships among different arsenic detoxification/metabolism pathways. In addition, this review sheds light on the bioremediation of arsenic-contaminated environments and prevention of antibiotic resistance.

The Structure of an As(III) S-Adenosylmethionine Methyltransferase with 3-Coordinately Bound As(III) Depicts the First Step in Catalysis

Arsenic is a ubiquitous environmental toxic substance and a Class 1 human carcinogen. Arsenic methylation by the enzyme As(III) S-adenosylmethionine (SAM) methyltransferase (ArsM in microbes or AS3MT in animals) detoxifies As(III) in microbes but transforms it into more toxic and potentially more carcinogenic methylated species in humans. We previously proposed a reaction pathway for ArsM/AS3MT that involves initial 3-coordinate binding of As(III). To date, reported structures have had only 2-coordinately bound trivalent arsenicals. Here we report a crystal structure of CmArsM from Cyanidioschyzon sp.5508 in which As(III) is 3-coordinately bound to three conserved cysteine residues with a molecule of the product S-adenosyl-l-homocysteine bound in the SAM binding site. We propose that this structure represents the first step in the catalytic cycle. In a previously reported SAM-bound structure, a disulfide bond is formed between two conserved cysteine residues. Comparison of these two structures indicates that there is a conformational change in the N-terminal domain of CmArsM that moves a loop to allow formation of the 3-coordinate As(III) binding site. We propose that this conformational change is an initial step in the As(III) SAM methyltransferase catalytic cycle.

HPLC-ICP-MS speciation analysis and risk assessment of arsenic in Cordyceps sinensis

BACKGROUND

Cordyceps sinensis, one of the most valued traditional herbal medicines in China, contains high amount of arsenic. Considering the adverse health effects of arsenic, this is of particular concern. The aim of this study was to determine and analyze arsenic speciation in C. sinensis, and to measure the associated human health risks.

METHODS

We used microwave extraction and high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry to determine and analyze the arsenic content in C. sinensis, and measured the associated human health risks according to the hazard index (HI), lifetime cancer risk (CR), and target hazard quotient (THQ).

RESULTS

The main arsenic speciation in C. sinensis were not the four organic arsenic compounds, including dimethyl arsenic, monomethyl arsenic, arsenobetaine, and arsenocholine, but comprised inorganic arsenic and other unknown risk arsenic compounds. HI scores indicated that the risk of C. sinensis was acceptable. CR results suggested that the cancer risk was greater than the acceptable lifetime risk of 10-5, even at low exposure levels. THQ results indicated that at the exposure level < 2.0 months/year, the arsenic was not likely to harm human health during a lifetime; however, if the exposure rate was > 3.0 months/year, the systemic effects of the arsenic in C. sinensis was of great concern.

CONCLUSION

The arsenic in C. sinensis might not be free of risks. The suggested C. sinensis consumption rate of 2.0 months/year provided important insights into the ways by which to minimize potential health risks. Our study not only played the role of "cast a brick to attract jade" by which to analyze arsenic speciation in C. sinensis but also offered a promising strategy of risk assessment for harmful residues in traditional herbal medicines.

Road dust and its effect on human health: a literature review

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words "road dust" and "health" or "fugitive dust" and "health" in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Road dust and its effect on human health: a literature review

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words “road dust” and “health” or “fugitive dust” and “health” in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Arsenic hyperaccumulation in Pityrogramma calomelanos L. (Link): adaptive traits to deal with high metalloid concentrations

Pityrogramma calomelanos is interestingly the single non-Pteris arsenic (As)-hyperaccumulating fern. It has been pointed as a potential species for phytoremediation and a model plant to study the As toxicity and its mechanisms of action. In order to investigate the morphoanatomical traits associated to As tolerance, P. calomelanos plants were exposed to different As concentrations in hydroponic solution. At low As dose (1 mM As), 90% of the As accumulated in plants was allocated in shoots, and no symptoms of As stress were observed in fronds and roots. Under higher As exposure (10 and 30 mM As), 81-74% of the total As in plants was present in shoots, and apical and marginal necroses on pinnae were observed. Anatomical observations showed that As induces damages mainly in the secondary veins and adjacent cells. High amounts of phenols were observed in pinna tissues of control and treated plants. In the roots, As promoted slight alterations as detachment of border-like cells and accumulation of granular substances in cortical cells. The high root-to-shoot As translocation and the constitutive presence of phenols and border-like cells protecting the root tips showed to be adaptive traits that allow P. calomelanos to survive in contaminated sites.

Dual Roles of Oxidative Stress in Metal Carcinogenesis

It has been well established that environmental and occupational exposure to heavy metal causes cancer in several organs. Although the exact mechanism of heavy metal carcinogenesis remains elusive, metal-generated reactive oxygen species (ROS) are essential. ROS can play two roles in metal carcinogenesis; two stages in the process of metal carcinogenesis differ in the amounts of ROS activating a dual redox-mediated mechanism. In the early stage of metal carcinogenesis, ROS acts in an oncogenic role. However, in the late stage of metal carcinogenesis, ROS plays an antioncogenic role. Similarly, NF-E2-related factor 2 (Nrf2) also has two different roles, which makes it a key molecule for separating metal carcinogenesis into two different stages. In the early stage, inducible Nrf2 fights against elevated ROS to decrease cell transformation by its antioxidant protection property. In the late stage, constitutively activated Nrf2 manipulates reduced ROS to perform a comfortable environment for apoptosis resistance through an oncogenic role. Interestingly, a cunning carcinogenic mechanism takes advantage of the dual role of Nrf2 to implement the dual role of ROS through a series of redox adaption mechanisms. In this review, we discuss the paradox in the rationales behind the two opposite ROS roles and focus on their potential pharmacological application. The dual role of ROS represents a 'double-edged sword' with many possible novel ROS-mediated strategies in cancer therapy in metal carcinogenesis.

Dietary intake of heavy metals from eight highly consumed species of cultured fish and possible human health risk implications in Bangladesh

Concentrations of five heavy metals (Pb, Cd, Cr, As and Hg) in eight highly consumed cultured fish species (Labeo rohita, Clarias gariepinus, Hypophthalmichthys molitrix, Cyprinus capio, Puntius sarana, Oreochromis mossambicus, Pangasius pangasius and Anabas testudineus) collected from four wholesale markets of Dhaka city, Bangladesh (Karwan Bazar, Mohammadpur Town Hall, Newmarket and Mirpur-1) were measured using atomic absorption spectrometry (AAS) in order to evaluate the potential human health risks from the consumption of fish. The estimated daily intake (EDI) of all the studied heavy metals calculated on the basis of mean fish consumption of 49.5 g person^-1 d^-1 by Bangladeshi households indicated that no risk to people's health with respect to the EDI of investigated heavy metals through the consumption of the fish samples. From the human health point of view, the estimation of non-carcinogenic risk indicated that intake of individual heavy metal through the consumption of fish was safe for human health, whereas, consumption of combined heavy metals suggested potential health risk to highly exposed consumers. However, the estimation of carcinogenic risk of arsenic due to the consumption of fish indicated that consumers remain at risk of cancer.

Effect of arsenic acid withdrawal on hepatotoxicity and disruption of erythrocyte antioxidant defense system

We investigated the effects of withdrawal from Sodium arsenite (NaAsO₂) on the hepatic and antioxidant defense system in male Wistar rats using a before and after toxicant design. Rats were orally gavaged daily with varying doses of NaAsO₂ for a period of 4 weeks. One half of the population was sacrificed and the remaining half had the toxicant withdrawn for another further 4 weeks. Biochemical and immunohistochemical techniques were used to assess the impact of withdrawal on the erythrocyte and hepatic systems. Exposure of Wistar rats to NaASO₂ led to a significant (p < 0.05) increase in hepatic and erythrocyte markers of oxidative stress (malondialdehyde, thiol contents and hydrogen peroxide generation). Concurrently, there was a significant (p < 0.05) increase in hepatic and erythrocyte antioxidant enzymes (glutathione-S-transferase, glutathione peroxidase and superoxide dismutase) following exposure. Withdrawal from NaAsO₂ exposure led to a decline in both erythrocyte and hepatic markers of oxidative stress and together with a significant improvement in antioxidant defense system. Histopathology and immunohistochemistry revealed varying degrees of recovery in hepatocyte ultrastructure alongside increased expression of the pro-survival protein Kinase B (Akt/PKB) after 4 weeks of NaAsO₂ withdrawal. Conclusively, withdrawal from exposure led to a partial recovery from oxidative stress-mediated hepatotoxicity and derangements in erythrocyte antioxidant system through Akt/PKB pathway.

Environmental Arsenic Contamination and its Effect on Dental Caries Experience in School Children

Aims and Objectives:

To assess the effect of exposure to arsenic by drinking water and caries prevalence in children.

Material and Methods:

A total of 200 children between 10 to 14 years of age, 100 each from study village (Hutti, Raichur district, Karnataka) and control village (Sanduru, Bellary district, North Karnataka) were included in the study. Water samples from both the villages were analyzed for arsenic levels. Arsenic levels were determined in the hair and nail samples from the subjects to assess chronic arsenic exposure. Caries experience was measured by the DMFT/deft index and the severity of caries was measured by modified ICDAS-II index.

Results:

The mean concentration of arsenic in the study group was found to be 2.44 ppm in the hair samples and 2.72 ppm in the nail samples as compared to 0.12 ppm in both hair and nail samples in the control group. These values were statistically significant ( p < 0.001). The mean DMFT score in the control group was 0.99 and in the study group was 2.45, which was statistically significant ( p < 0.05) using SPSS version 21.

Conclusion:

Chronic arsenic exposure could be a possible cause for the increased caries experience in children in the study group.

Identification of novel loci for the generation of reporter mice

Deciphering the etiology of complex pathologies at molecular level requires longitudinal studies encompassing multiple biochemical pathways (apoptosis, proliferation, inflammation, oxidative stress). In vivo imaging of current reporter animals enabled the spatio-temporal analysis of specific molecular events, however, the lack of a multiplicity of loci for the generalized and regulated expression of the integrated transgenes hampers the creation of systems for the simultaneous analysis of more than a biochemical pathways at the time. We here developed and tested an in vivo-based methodology for the identification of multiple insertional loci suitable for the generation of reliable reporter mice. The validity of the methodology was tested with the generation of novel mice useful to report on inflammation and oxidative stress.

A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water

Arsenic (As) is an extremely toxic element that exists in the environment in different chemical forms. The detection of arsenic in potable water remains a challenging task. This study presents a highly sensitive enzymatic catalysis system for trace sensing of inorganic arsenic in water. This is the first enzyme-catalyzed fluorescence assay capable of detecting arsenic at concentrations below the allowable level adopted by the World Health Organization (10 ppb in drinking water). The enzyme catalytically produces fluorescent NADH in the presence of arsenate, which enables facile detection of arsenate at concentrations in the 0-200 ppb range. Calibration curves made at a set time interval allow accurate determination of unknown arsenic samples. This method holds potential for interfacing with automated analytical sampling systems to allow arsenic determinations in environmental health applications.

Differential toxicity of arsenic on renal oxidative damage and urinary metabolic profiles in normal and diabetic mice

Diabetes is a common metabolic disease, which might influence susceptibility of the kidney to arsenic toxicity. However, relative report is limited. In this study, we compared the influence of inorganic arsenic (iAs) on renal oxidative damage and urinary metabolic profiles of normal and diabetic mice. Results showed that iAs exposure increased renal lipid peroxidation in diabetic mice and oxidative DNA damage in normal mice, meaning different effects of iAs exposure on normal and diabetic individuals. Nuclear magnetic resonance (NMR)-based metabolome analyses found that diabetes significantly changed urinary metabolic profiles of mice. Oxidative stress-related metabolites, such as arginine, glutamine, methionine, and β-hydroxybutyrate, were found to be changed in diabetic mice. The iAs exposure altered amino acid metabolism, lipid metabolism, carbohydrate metabolism, and energy metabolism in normal and diabetic mice, but had higher influence on metabolic profiles of diabetic mice than normal mice, especially for oxidative stress-related metabolites and metabolisms. Above results indicate that diabetes increased susceptibility to iAs exposure. This study provides basic information on differential toxicity of iAs on renal toxicity and urinary metabolic profiles in normal and diabetic mice and suggests that diabetic individuals should be considered as susceptible population in toxicity assessment of arsenic.

Occupational exposure to respirable crystalline silica and chronic non-malignant renal disease: systematic review and meta-analysis

Background

While occupational exposure to respirable silica is known to lead to lung disease, most notably silicosis, its association with chronic kidney disease is unclear.

Objectives

This review explores the association between occupational exposure to respirable silica and chronic non-malignant renal disease such as glomerulonephritis. The evidence has been collected and compiled. Possible sources of bias are thoroughly discussed.

Methods

Cohort studies with silica exposure and case–control studies of renal disease were searched in PubMed until January 2015. Two authors independently abstracted data; any disagreement was resolved by consulting a third reviewer. A meta-analysis was performed to evaluate the association to silica exposure.

Results

A total of 23 cohort and four case–control studies were included in the analysis. The meta-analysis of cohort studies yielded elevated overall SMRs for renal disease. Some studies, however, included dose–response analyses, most of which did not show a positive trend. The approaches and results of the case–control studies were very heterogeneous.

Conclusions

While the studies of cohorts exposed to silica found elevated SMRs for renal disease, no clear evidence of a dose–response relationship emerged. The elevated risk may be attributed to diagnostic and methodological issues. In order to permit a reliable estimation of a possible causal link, exposed cohorts should be monitored for renal disease, as the information from mortality studies is hardly reliable in this field.

Electronic supplementary material

The online version of this article (doi:10.1007/s00420-017-1219-x) contains supplementary material, which is available to authorized users.

Retrospective mining of toxicology data to discover multispecies and chemical class effects: Anemia as a case study

Predictive toxicity models rely on large amounts of accurate in vivo data. Here, we analyze the quality of in vivo data from the U.S. EPA Toxicity Reference Database (ToxRefDB), using chemical-induced anemia as an example. Considerations include variation in experimental conditions, changes in terminology over time, distinguishing negative from missing results, observer and diagnostic bias, and data transcription errors. Within ToxRefDB, we use hematological data on 658 chemicals tested in one or more of 1738 studies (subchronic rat or chronic rat, mouse, or dog). Anemia was reported most frequently in the rat subchronic studies, followed by chronic studies in dog, rat, and then mouse. Concordance between studies for a positive finding of anemia (same chemical, different laboratories) ranged from 90% (rat subchronic predicting rat chronic) to 40% (mouse chronic predicting rat chronic). Concordance increased with manual curation by 20% on average. We identified 49 chemicals that showed an anemia phenotype in at least two species. These included 14 aniline moiety-containing compounds that were further analyzed for their potential to be metabolically transformed into substituted anilines, which are known anemia-causing chemicals. This analysis should help inform future use of in vivo databases for model development.

A review of heavy metals in indoor dust and its human health-risk implications

Indoor dust acts as a media for heavy metal deposition. Past studies have shown that heavy metal concentration in indoor dust is affected by local human activities and atmospheric transport can have harmful effects on human health. Additionally, children are more sensitive to heavy metals due to their hand-to-mouth behaviour and rapid body development. However, limited information on health risks were found in past dust studies as these studies aimed to identify heavy metal concentrations and sources of indoor dust. The objective of this review is to discuss heavy metal concentration and sources influencing its concentration in indoor dust. Accordingly, high lead (Pb) concentration (639.10 μg/g) has been reported in heavy traffic areas. In addition, this review paper aims to estimate the health risk to children from heavy metals in indoor dust via multiple exposure pathways using the health-risk assessment (HRA). Urban areas and industrial sites have revealed high heavy metal concentration in comparison to rural areas. Hazard index (HI) values found in arsenic (As), chromium (Cr) and Pb were 21.30, 1.10 and 2.40, respectively, indicate that non-carcinogenic elements are found in children. Furthermore, most of the past studies have found that carcinogenic risks for As, cadmium (Cd), Cr and Pb were below the acceptable total lifetime cancer risk (TLCR) range (1×10-6-1×10-4). The results of health risk assessment in this review show that carcinogenic risk exists among children. Hence, this proves that future studies need to focus on children's carcinogenic risk in indoor dust studies in order to find out the sources of heavy metals in indoor dust. This review highlights the importance of having the HRA application using bioavailable heavy metal concentration as it provides more accurate health-risk estimation. Moreover, this review is also useful as a reference for policy decision making in protecting children's health.

Reproductive and Developmental Toxicity of Arsenic in Rodents: A Review

Arsenic is a recognized reproductive toxicant in humans and induces malformations, especially neural tube defects, in laboratory animals. Early studies showed that murine malformations occurred only when a high dose of inorganic arsenic was given by intravenous or intraperitoneal injection in early gestation. Oral gavage of inorganic arsenic at maternally toxic doses caused reduced fetal body weight and increased resorptions. Recently, arsenic reproductive and developmental toxicity has been studied in situations more similar to human exposures and using broader endpoints, such as behavioral changes and gene expression. For the general population, exposure to arsenic is mostly oral, particularly via drinking water, repeated and prolonged over time. In mice and rats, methylated or inorganic arsenic via drinking water or by repeated oral gavage induced male and female reproductive and developmental toxicities. Furthermore, at nonmaternally toxic levels, inorganic arsenic given to pregnant dams via drinking water affected fetal brain development and postnatal behaviors. However, arsenic given by repeated oral gavage to pregnant mice and rats was not morphologically teratogenic. In this review of arsenic reproductive and developmental toxicity in rats and mice, the authors summarize recent in vivo studies and discuss possible underlying mechanisms. The influences of folate, selenium, zinc, and arsenic methylation on arsenic reproductive and developmental toxicity are also discussed.

Chemical Characterization and Cytoprotective Effect of the Hydroethanol Extract from Annona coriacea Mart. (Araticum)

INTRODUCTION

Annona coriacea Mart. (araticum) is a widely distributed tree in the cerrado. Its value is attributed principally to the consumption of its fruit which possesses a large nutritive potential. The objective was to identify the chemical profile and evaluate the antimicrobial and cytoprotective activity of the hydroethanol extract of A. coriacea Mart. (HEAC) leaves against the toxicity of mercury chloride.

MATERIALS AND METHODS

The characterization of components was carried out using high-performance liquid chromatography (HPLC). The minimum inhibitory concentration (MIC) was determined by microdilution method in broth with strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. For evaluation of the modulatory and cytoprotective activity of aminoglycoside antibiotics (gentamicin and amikacin) and mercury chloride (HgCl2), the substances were associated with the HEAC at subinhibitory concentrations (MIC/8).

RESULTS AND DISCUSSION

The HPLC analysis revealed the presence of flavonoids such as Luteolin (1.84%) and Quercetin (1.19%) in elevated concentrations. The HEAC presented an MIC ≥512 μg/mL and significant antagonistic action in aminoglycosides modulation, and it also showed cytoprotective activity to S. aureus (significance P < 0.0001) and E. coli (significance P < 0.05) bacteria against the mercury chloride heavy metal with significance, this action being attributed to the chelating properties of the flavonoids found in the chemical identification.

CONCLUSIONS

The results acquired in this study show that the HEAC presents cytoprotective activity over the tested strains in vitro and can also present antagonistic effect when associated with aminoglycosides, reinforcing the necessity of taking caution when combining natural and pharmaceutical products.

SUMMARY

The hydroalcoholic extract of A. coriacea Mart. presents in vitro cytoprotective activity against the toxic effect of Hg. Abbreviations Used: HPLC-DAD: High-performance liquid chromatography with a diode array detector; MIC: Minimum inhibitory concentration; DMSO: Dimethyl sulfoxide.