The distribution of arsenic in the body tissues of wood mice and bank voles

Distribution of arsenic species and pathological characteristics of tissues of the mice fed with arsenic-supplemented food simulating rice

The exposure and harm of arsenic have attracted wide attention. Rice is an arsenic-rich crop. The purpose of this study was to learn the distribution of arsenic species and the pathological changes in tissues of mice exposed to arsenic-supplemented food simulating rice. Test groups of mice were orally exposed with prepared arsenic feeds supplemented with four arsenic species (arsenite iAs^III, arsenate iAs^V, monomethylarsonate MMA, and dimethylarsinate DMA) at three doses (total As concentration: 0.91, 9.1 and 30 μg/g), which simulated the arsenic species ratio in rice. After 112 days, the concentrations of the arsenic species in the spleen, thymus, heart, skin and hair were detected, and histopathology of the spleen, heart and skin was observed. Each arsenic species was detected and their total concentration increased in a dose-dependent manner with a few exceptions. One interesting phenomenon is that ratio of the organic arsenic to inorganic arsenic also increased in a dose-dependent manner. For the other, the order of tissues from high to low arsenic concentration was the same in the medium- and high-dose groups. The histopathological sections of the spleen, heart and skin showed dose-dependent debilitating alterations in tissue architecture. Hyperplasia, hyaline degeneration and sclerosis of fibrous connective tissue occurred in the spleen. Myocardial cell atrophy and interstitial edema occurred in the heart. Hyperpigmentation, hyperkeratosis and atypia of basal cells occurred in the skin. In summary, the long-term intake of high arsenic rice has a health risk. Further studies are needed to assess it.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Metal brain bioaccumulation and neurobehavioral effects on the wild rodent Liomys irroratus inhabiting mine tailing areas

Ecotoxicological studies are necessary in order to evaluate the effects of environmental exposure of chemicals on wild animals and their ecological consequences. Particularly, neurobehavioral effects of heavy metal elements on wild rodents have been scarcely investigated. In the present study, we analyzed the effect of metal bioaccumulation (Pb, As, Mg, Ni, and Zn) in the brain and in the liver on exploratory activity, learning, memory, and on some dopaminergic markers in the wild rodent Liomys irroratus living inside mine tailings, at Huautla, Morelos, Mexico. We found higher Pb concentration but lower Zn in striatum, nucleus accumbens, midbrain, and hippocampus in exposed animals in comparison to rodents from the reference site. Exposed rodents exhibited anxious behavior evaluated in the open field, while no alterations in learning were found. However, they displayed slight changes in the memory test in comparison to reference group. The neurochemical evaluation showed higher levels of dopamine and 5-hydroxyindolacetic acid in midbrain, while lower levels of metabolites dihydroxyphenyl acetic acid and homovanillic acid in striatum of exposed rodents. In addition, mRNA expression levels of dopaminergic D2 receptors in nucleus accumbens were lower in animals from the mining zone than in animals from the reference zone. This is the first study that shows that chronic environmental exposure to metals results in behavioral and neurochemical alterations in the wild rodent L. irroratus, a fact that may comprise the survival of the individuals resulting in long-term effects at the population level. Finally, we suggest the use of L. irroratus as a sentinel species for environmental biomonitoring of mining sites.

Heavy metal accumulation and genotoxic effects in levant vole (Microtus guentheri) collected from contaminated areas due to mining activities

Heavy metal contamination is a serious environmental problem commonly monitored in various organisms. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to evaluate the adverse effects of marble and stone quarries on the Levant vole, Microtus guentheri, inhabiting some polluted sites. In this context, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd, and Hg) in the organs (skins, bones, muscles, livers and kidneys) of the biological specimens, and the comet assay revealed DNA damage in blood lymphocytes for the first time. This study was conducted at close to the marble and stone quarries at Korkuteli, Antalya-Turkey during spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all polluted sites (sites 1-5) was significantly higher than that of controls, while in autumn it was higher in samples from three sites (sites 3-5). In terms of heavy metal distribution in organs, we found depositions of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb primarily in the skin with its derivatives, Cu and Cd deposits in the kidney, Cu, Cd and B deposits in the liver, and As and Pb depositions in the bones. The study shows that certain organs (especially skin with its derivatives) and blood lymphocytes of Levant vole can be used as ideal indicators of heavy metal pollution. Our results suggest that the Korkuteli area could already be under the threat of heavy metal pollution.

Wing membrane and fur samples as reliable biological matrices to measure bioaccumulation of metals and metalloids in bats

There is a growing conservation concern about the possible consequences of environmental contamination in the health of bat communities. Most studies on the effects of contaminants in bats have been focused on organic contaminants, and the consequences of bat exposure to metals and metalloids remain largely unknown. The aim of this study was to evaluate the suitability of external biological matrices (fur and wing membrane) for the assessment of exposure and bioaccumulation of metals in bats. The concentration of arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, selenium and zinc was measured in internal organs (liver, heart, brain), internal (bone) and external tissues (wing membrane, fur) collected from bat carcasses of four species (Hypsugo savii, Nyctalus leisleri, Pipistrellus pipistrellus, Pipistrellus pygmaeus) obtained in windfarm mortality searches. With the exception of zinc (P = 0.223), the results showed significant differences between the concentrations of metals in the analyzed tissues for all metals (P < 0.05). Significant differences were also found between organs/tissues (P < 0.001), metals (P < 0.001) and a significant interaction between organs/tissues and metals was found (P < 0.001). Despite these results, the patterns in terms of metal accumulation were similar for all samples. Depending on the metal, the organ/tissue that showed the highest concentrations varied, but fur and wing had the highest concentrations for most metals. The variability obtained in terms of metal concentrations in different tissues highlights the need to define standardized methods capable of being applied in monitoring bat populations worldwide. The results indicate that wing membrane and fur, biological matrices that may be collected from living bats, yield reliable results and may be useful for studies on bats ecotoxicology, coupled to a standardized protocol for large-scale investigation of metal accumulation.

Exposure of low-concentration arsenic-initiated inflammation and autophagy in rat lungs

Chronic arsenic exposure through water intake is a worldwide issue, which has caused many diseases. Lungs are the first target organ of arsenic and lung inflammation, autophagy, and even the onset of tumors can be induced by arsenic exposure. Here, we tested the outcome of low-concentration arsenic exposure in rat lungs. Tissue changes, inflammation, autophagy, and other physiological responses were observed in this study. Results showed that low-concentration exposure of arsenite through water intake could initiate autophagy and inflammation in lungs but high concentration exposure produced a weak autophagy response and accentuated inflammation with the possibility of a chronic inflammation environment emerging followed by tumorigenesis.

Quantification and feed to food transfer of total and inorganic arsenic from a commercial seaweed feed

Seaweed has a long-associated history of use as a supplemented livestock feed, providing nutrients and vitamins essential to maintaining animal health. Some species of seaweed, particularly the fucoids, are well-known accumulators of the metalloid arsenic (As). Arsenic toxicity to humans is well established even at low exposure levels and is considered a class 1 human carcinogen. As mankind's appetite for livestock produce continues to grow unabated, there is a concern that consumption of livestock produce reared on a diet supplemented with seaweed animal feed (SAF) may pose a threat to the human population due to potentially high levels of As present in seaweed. To address this concern and provide end users, including industry, consumers, policymakers and regulators with information on the exposure associated with As in commercial seaweed animal feed, the estimated daily intake (EDI) of As was calculated to evaluate potential human exposure levels. Using As data from a commercially available seaweed meal over a five-year period (2012-2017) a population exposure assessment was carried out. A Monte Carlo simulation model was developed to characterise the feed to food transfer of As from animal feed to animal produce such as beef, milk, chicken, and eggs. The model examined initial levels in seaweed, inclusion rate in animal feed, animal feeding rates and potential transfer to food produced from a supplemented diet of SAF. The analysis of seaweed animal feed showed that inorganic As was a small fraction of the total As found in seaweed meal (80:1). Statistical analysis found significant differences in the concentration of As in seaweed animal feed depending on the grain size (p < 0.001), with higher As concentrations in smaller sized grain fractions. Due to several detoxification steps and subsequent rapid excretion from the bodies of livestock, a very low carryover rate of As compounds from seaweed animal feed into livestock produce was observed. The EDI calculated in this study for the livestock produce evaluated at the 95th confidence interval was <0.01% of suggested safe levels of inorganic As intake. The threat to the general population as a result of consumption of livestock products reared on a diet consisting of SAF is found to be negligible.

Histopathology related to cadmium and lead bioaccumulation in chronically exposed wood mice, Apodemus sylvaticus, around a former smelter

The ceasing of industrial activities often reduces the emission of pollutants but also often leaves disturbed areas without remediation and with persistent pollutants that can still be transferred along the food chain. This study examines the potential relationships between non-essential trace metals and histopathology in target tissues of wood mice (Apodemus sylvaticus) collected along a gradient of contamination around the former smelter, Metaleurop Nord (northern France). Cadmium and lead concentrations were measured, and histological alterations attributable to chronic trace metal exposure were assessed in the liver and the kidneys of 78 individuals. Metal concentrations quantified in the present study were among the highest observed for this species. Some histological alterations significantly increased with Cd or Pb concentrations in the soil and in the organs. Sixteen mice from polluted sites were considered at risk for metal-induced stress because their Cd and/or Pb tissue concentrations exceeded the LOAELs for single exposure to these elements. These mice also exhibited a higher severity of histological alterations in their organs than individuals with lower metal burdens. These results indicate that the Metaleurop smelter, despite its closure in 2003, still represents a threat to the local ecosystem because of the high levels and high bioavailability of Cd and Pb in the soil. However, among the mice not considered at risk for metal-induced stress based on the metal levels in their tissues, a large percentage of individuals still exhibited histological alterations. Thus, the present study suggests that the evaluation of toxic effects based only on the LOAELs for single metal exposure may result in the underestimation of the real risks when specimens are exposed to multiple stressors.

An approach to the arsenic status in cardiovascular tissues of patients with coronary heart disease

Among non-cancer effects of arsenic, cardiovascular diseases have been well documented; however, few are known about the arsenic fate in cardiovascular tissues. We studied the analytic bioinorganic arsenic behaviour in cardiovascular tissues from an arsenic exposure coronary heart disease patient group from Antofagasta-Chile against a small unexposed arsenic coronary heart patient group. Total arsenic concentrations were measured in pieces of cardiovascular tissues of the arsenic-exposed and unexposed coronary heart patient groups by hydride generation atomic absorption spectrometry (HG-AAS); speciation analysis was made by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Pieces of auricle (AU), mammary artery (MAM), saphenous vein (SAP) and fat residuals (FAT) were considered in this study. The arsenic concentrations in AU and MAM tissues were significantly different between both groups of patients. Also, it was demonstrated that the AU is an 'As(3+) target tissue.' Otherwise, linking of the total concentrations of arsenic with conditional variables and variables related to medical geology factors allowed us to infer that the latter are more important for the cardiovascular risk of arsenic exposure in the Antofagasta region. Knowledge of total arsenic and the prevalence of the trivalent ion (As(3+)) in the AU of patients could contribute to understanding the effect of arsenic on cardiovascular diseases.

Arsenic in the hair of the individuals in Santana-AP-Brazil: significance of residence location

The concentration of arsenic in the hair of the individuals living in Santana city was measured. 121 donors in urban and the periphery area were studied. The periphery of the city shows the highest levels of arsenic (5.94 +/- 6.54 mg kg(-1) - mean; 0.27-23.85 mg kg(-1)). 47.83% in the urban area showed arsenic concentrations of less than 1.00 mg kg(-1), while in the periphery only 11.22% had results below this value. The results showing the influence of residence location. The Principal Component Analysis showed that the variable residence location were responsible for the correct formation of the periphery group.

Bioavailability and bioaccessibility of arsenic in a soil amended with drinking-water treatment residuals

Earlier incubation and greenhouse studies in our laboratory confirmed the effectiveness of drinking-water treatment residual (WTR) in decreasing soil arsenic (As) bioaccessibility as determined with in vitro tests, which led us to hypothesize a similar outcome if animal studies were to be conducted. Our objective was to evaluate the potential of WTR in lowering soil As bioavailability by conducting in vivo experiments and compare the in vitro to the in vivo As data. This study was performed using 6-week-old male BALB/c mice that were fed with an As-contaminated soil slurry using the gavage method. Blood and stomach contents were collected at 1 and 24 h after feeding. Urine and excreta were collected at time 0 (before feeding) and 24 h after feeding. Relative As bioavailability (RBA) values calculated from the blood samples of mice fed with WTR and WTR-amended soil samples ranged from 13% to 24% and from 25% to 29%, respectively; both were significantly (p < 0.001) lower than that of the unamended (no-WTR) soil (approximately 100% RBA). Absolute As bioavailability (ABA) in the gastric phase was significantly (p < 0.001) lowered, to 7-16%, in the WTR-amended soil compared with that of the unamended control (26%). A significant (p < 0.001) linear correlation (r = 0.94) was observed between the in vitro (stomach-phase) and the in vivo RBA data. Percentage recovery of As obtained from four mice tissue compartments (i.e., blood, stomach, urine, and fecal matter) after oral and intramuscular administrations was 63-80%. Results illustrate the effectiveness of in situ WTR amendment in decreasing in vivo soil As bioavailability, thereby lowering the potential cancer risk via an oral ingestion pathway.

Evaluation of some sources of variability in using small mammals as pollution biomonitors

In the present study the effects of gender, age and nutritional status on tissue concentrations of some trace elements (Zn, Cu, Mn, and Cr) in wood mouse (Apodemus sylvaticus), Spanish shrew (Sorex granarius), and great white-toothed shrew (Crocidura russula) were investigated. Four sampling stations were selected for the study: a restored mine dump, an area characterised by ultrabasic soil and two sites in oak woods in the vicinity of a power plant. Gender had no effect on the tissue concentrations of the metals studied, except for the concentration of Zn in brain tissue from C. russula. The relative age of the individuals was estimated on the basis of crystalline lens weight in mice and dental abrasion in shrews, as body weight was considered a poor indicator of age because of the strong interindividual overlap in the populations. Age was only significantly (and negatively) correlated with the concentration of Cr in livers of mice from one station, a finding that may indicate physiological stress on growth at this site. The nutritional status was estimated from the body mass index; the relationships between this index and metal concentrations for both A. sylvaticus and C. russula were negative, which can be attributed to the weight-specific metabolic rate that leads to a relatively low uptake of metals per unit of body weight. As there was no relation between duration of exposure and concentrations of metals in the organs analysed, age should not be included as a variable factor in the condition index.

Comparison of transfer and effects of Cd on rats exposed in a short experimental snail-rat food chain or to CdCl2 dosed food

Transfer and toxic effects of two cadmium (Cd) forms, inorganic (CdCl2 dosed rat food) or organic (contaminated snail-based rat food) were studied in Wistar rat. Cd concentrations in rat food were 0 and 2.5 microg Cd g(-1) for both inorganic and organic forms and a high concentration of 100 microg Cd g(-1) was also tested for the inorganic form. Rats were exposed for four weeks to contaminated food. Both forms of Cd were bioavailable to rats, with a percentage of transfer from food to rats of around 1% for all contaminated groups. Cd concentrations in rat tissues increased with increasing Cd concentrations in the food. Rats fed with organic form of Cd accumulated significantly more Cd in the main organ for Cd toxicity, the kidney, than those eating the inorganic form. Survival was not affected for any rat group but a decrease in growth and food consumption was observed for the inorganic form. As a defence system against Cd toxicity, rats increased their metallothionein (MT) synthesis at the highest Cd concentration in the target organs (kidney, liver and small intestine) and even did the same at low Cd concentrations (2.5 microg Cd g(-1)) in the kidney. At this low Cd concentration, MT induction was lower in the small intestine of rats ingesting organic Cd than those ingesting inorganic Cd. Bioavailability of organic and inorganic forms of Cd was similar, but subsequent Cd distribution within organs was different. This quantification of the trophic transfer of both inorganic and organic forms of a toxicant is a basis for a better assessment of the fate and effects of chemicals in food webs.

Non-destructive pollution exposure assessment by means of wood mice hair

Concentrations of cadmium, copper, lead and zinc were measured in hair, kidney, liver, lung and muscle tissue of wood mice captured along a pollution gradient. We found positive relationships between cadmium concentrations in hair and all internal tissues. Hair lead concentrations were positively correlated with lead contents in kidney and liver. Age had a significant effect on cadmium accumulation in all tissues and hair. Apart from a very weak relationship between zinc concentrations in hair and liver, no significant relation between copper or zinc content in hair and any of the internal organs was observed. In summary, our observations suggest that hair of wood mice can be used for monitoring exposure to non-essential metals like cadmium and lead, but not to homeostatically regulated metals such as copper or zinc.

Mammalian glucose permease GLUT1 facilitates transport of arsenic trioxide and methylarsonous acid

Arsenic exposure is associated with hypertension, diabetes, and cancer. Some mammals methylate arsenic. Saccharomyces cerevisiae hexose permeases catalyze As(OH)(3) uptake. Here, we report that mammalian glucose transporter GLUT1 catalyzes As(OH)(3) and CH(3)As(OH)(2) uptake in yeast or in Xenopus laevis oocytes. Expression of GLUT1 in a yeast lacking other glucose transporters allows for growth on glucose. Yeast expressing yeast HXT1 or rat GLUT1 transport As(OH)(3) and CH(3)As(OH)(2). The K(m) of GLUT1 is to 1.2mM for CH(3)As(OH)(2), compared to a K(m) of 3mM for glucose. Inhibition between glucose and CH(3)As(OH)(2) is noncompetitive, suggesting differences between the translocation pathways of hexoses and arsenicals. Both human and rat GLUT1 catalyze uptake of both As(OH)(3) and CH(3)As(OH)(2) in oocytes. Thus GLUT1 may be a major pathway uptake of both inorganic and methylated arsenicals in erythrocytes or the epithelial cells of the blood-brain barrier, contributing to arsenic-related cardiovascular problems and neurotoxicity.