Association of arsenic levels in soil and water with urinary arsenic concentration of residents in the vicinity of closed metal mines

Melatonin alleviates arsenic (As) toxicity in rice plants via modulating antioxidant defense system and secondary metabolites and reducing oxidative stress

The Arsenic (As) load on the environment has increased immensely due to large-scale industrial and agricultural uses of As in several synthetic products, such as fertilizers, herbicides, and pesticides. Melatonin is a plant hormone that has a key role in abiotic stress inhibition, but the mechanism of resilience to As stress remains unexplored in rice plants. In this study, we determined how As affects rice plant and how melatonin facilitate As stress tolerance in rice. Here we investigated that, exogenous melatonin reduced As stress by inducing anthocyanin biosynthesis. Melatonin induced the expression of anthocyanin biosynthesis genes such as PAL, CHS, CHI, F₃H, DFR, and ANS, which resulted in 1659% and 389% increases in cyanidin and delphinidin, respectively. Similarly, melatonin application significantly induced SA and ABA accumulation in response to As stress in rice plant. Application of melatonin also significantly reduced expression of PT-2 and PT-8 (transporter genes) and reduced uptake of As and its translocation to other compartments. Melatonin and As analysis revealed that melatonin application significantly reduced As contents in the melatonin-supplemented plants, suggesting that As uptake is largely dependent on either the melatonin basal level or anthocyanin in rice plants. In this study, we investigated new symptoms on leaves, which can severely damage leaves and impair photosynthesis. However, anthocyanin as a chelating agent, detoxifies As in vacuole and reduces oxidative stress induced by As.

Soil and indoor dust as environmental media of human exposure to As, Cd, Cu, and Pb near a copper smelter in central Chile

In the present study, we assessed the non-carcinogenic and carcinogenic human health risk due to exposure to trace elements in soil and indoor dust in Puchuncaví valley. We also determined the associations between trace element concentration in hair/toenails and the estimated chronic daily intake of trace elements in soil and indoor dust. We found statistically significant association between the trace element concentration in hair/toenails and the estimated chronic daily intake of soil and indoor dust. Indoor dust was more important than soil in terms of human exposure to trace elements in Puchuncaví, due to the high concentration of trace elements on this environmental media and long periods of time that the population spends at their households. With regards to non-carcinogenic risk, we found that there was no health risk associated to soil and indoor dust exposure in the Puchuncaví valley, because none of the hazard quotient values surpassed 1.0. However, carcinogenic risk due to arsenic exposure was above the threshold value of 1.0E-04 in the population of young children (from 1 to 5 years old) in all studied areas, including the control, and in the population of children (from 6 to <18 years old) in the exposed area. Such risk values are classified as unacceptable (US EPA, 2001), requiring some target intervention from the Chilean government.

Mineralogical Controls on the Bioaccessibility of Arsenic in Fe(III)-As(V) Coprecipitates

X-ray amorphous Fe(III)-As(V) coprecipitates are common initial products of oxidative As- and Fe-bearing sulfide weathering, and often control As solubility in mine wastes or mining-impacted soils. The formation conditions of these solids may exert a major control on their mineralogical composition and, hence, As release in the gastric tract of humans after incidental ingestion of As-contaminated soil. Here, we synthesized a set of 35 Fe(III)-As(V) coprecipitates as a function of pH (1.5-8) and initial molar Fe/As ratio (0.8-8.0). The solids were characterized by synchrotron X-ray diffraction, FT-IR spectroscopy, and electrophoretic mobility measurements, and their As bioaccessibility (BA_As) was evaluated using the gastric-phase Solubility/Bioavailability Research Consortium in vitro assay (SBRC-G). The coprecipitates contained 1.01-4.51 mol kg^-1 As (molar Fe/As_solid: 1.00-8.29) and comprised varying proportions of X-ray amorphous hydrous ferric arsenates (HFA_am) and As(V)-adsorbed ferrihydrite. HFA_am was detected up to pH 6 and its fraction decreased with increasing pH and molar Fe/As ratio. Bioaccessible As ranged from 2.9 to 7.3% of total As (x̅ = 4.8%). The BA_As of coprecipitates formed at pH ≤ 4 was highest at formation pH 3 and 4 and controlled by the intrinsically high solubility of the HFA_am component, possibly enhanced by sorbed sulfate. In contrast, the BA_As of coprecipitates dominated by As(V)-adsorbed ferrihydrite was much lower and controlled by As readsorption and/or surface precipitation in the gastric fluid. Bioaccessible As increased up to 95% with increasing liquid-to-solid ratio, indicating an enhanced solubility of these solids due to interactions between Fe and the glycine buffer. We conclude (i) that natural Fe(III)-As(V) coprecipitates exhibit a particularly high solubility in the human gastric tract when formed at pH ∼ 3-4 in the presence of sulfate, and (ii) that the in vitro bioaccessibility of As in Fe(III)-As(V) coprecipitates as assessed by tbe SBRC-G assay depends critically on their solid-phase concentration in As-contaminated soil and mine-waste materials.

Water Consumption as Source of Arsenic, Chromium, and Mercury in Children Living in Rural Yucatan, Mexico: Blood and Urine Levels

Studies investigating the correlation between metal content in water and metal levels in children are scarce worldwide, but especially in developing nations. Therefore, this study investigates the correlation between arsenic, chromium, and mercury concentrations in drinking and cooking water and in blood and urine samples collected from healthy and supposedly non-exposed children from a rural area in Yucatan, Mexico. Mercury in water shows concentrations above the recommended World Health Organization (WHO) value for drinking and cooking water. Also, 25% of the children show mercury in urine above the WHO recommended value. Multivariate analyses show a significant role for drinking and cooking water as a vector of exposure in children. Also, the factor analysis shows chronic exposure in the case of arsenic, as well as an ongoing detoxification process through urine in the case of mercury. Further studies should be done in order to determine other potential metal exposure pathways among children.

Urinary arsenic species concentration in residents living near abandoned metal mines in South Korea

BACKGROUND

Arsenic is a carcinogenic heavy metal that has a species-dependent health effects and abandoned metal mines are a source of significant arsenic exposure. Therefore, the aims of this study were to analyze urinary arsenic species and their concentration in residents living near abandoned metal mines and to monitor the environmental health effects of abandoned metal mines in Korea.

METHODS

This study was performed in 2014 to assess urinary arsenic excretion patterns of residents living near abandoned metal mines in South Korea. Demographic data such as gender, age, mine working history, period of residency, dietary patterns, smoking and alcohol use, and type of potable water consumed were obtaining using a questionnaire. Informed consent was also obtained from all study subjects (n = 119). Urinary arsenic species were quantified using high performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP/MS).

RESULTS

The geometric mean of urinary arsenic (sum of dimethylarsinic acid, monomethylarsonic acid, As³⁺, and As⁵⁺) concentration was determined to be 131.98 μg/L (geometric mean; 95% CI, 116.72-149.23) while urinary inorganic arsenic (As³⁺ and As⁵⁺) concentration was 0.81 μg/L (95% CI, 0.53-1.23). 66.3% (n = 79) and 21.8% (n = 26) of these samples exceeded ATSDR reference values for urinary arsenic (>100 μg/L) and inorganic arsenic (>10 μg/L), respectively. Mean urinary arsenic concentrations (geometric mean, GM) were higher in women then in men, and increased with age. Of the five regions evaluated, while four regions had inorganic arsenic concentrations less than 0.40 μg/L, one region showed a significantly higher concentration (GM 15.48 μg/L; 95% CI, 7.51-31.91) which investigates further studies to identify etiological factors.

CONCLUSION

We propose that the observed elevation in urinary arsenic concentration in residents living near abandoned metal mines may be due to environmental contamination from the abandoned metal mine.

TRIAL REGISTRATION

Not Applicable (We do not have health care intervention on human participants).

Environment and Health: Not Only Cancer

The Hippocratic tradition emphasized environmental causes of diseases and the need for harmony between the individual and the natural environment as the right philosophy to maintain a good health status. Public awareness and scientific attention concerning environmental pollution is usually focused on the consequent increased risk of developing cancer. Air pollution has been recognized by the World Health Organization (WHO) to cause cardiovascular and respiratroy diseases, as well as lung cancer, after acute/chronic exposure to fine particulates (PM2.5 and PM10) even at concentrations which are 50% lower than those accepted as legal limits in many developed countries. An increase of 10 µg/m³ of PM2.5 produces a +4%-6% of overall mortality, a +10% of cardiovascular disease prevalence (arithmyas, acute myocardial infarctions, and heart failure) and a +22% of lung cancer prevalence. In addition to these chronic effects, acute hospitalizations are also affected, especially among susceptible populations such as children and diabetic patients. Water and soil contamination also have an additional detrimental effect on people's health. Other issues concerning environment contamination and human health include male/female fertility, metabolic and thyroid conditions, but also professional exposures resulting in occupational diseases. Moreover, in the perspective of "gender medicine", different acute or chronic effects of environmental pollution should be specifically assessed both in men and in women. This special issue on "Environmental Diseases" is aimed at providing a global overview about different threats to human health possibily originating from environmental contamination.

Urinary arsenic levels influenced by abandoned mine tailings in the Southernmost Baja California Peninsula, Mexico

Gold has been mined at San Antonio-El Triunfo, (Baja California Sur, Mexico) since the 18th century. This area has approximately 5,700 inhabitants living in the San Juan de Los Planes and El Carrizal hydrographic basins, close to more than 100 abandoned mining sites containing tailings contaminated with potentially toxic elements such as arsenic. To evaluate the arsenic exposure of humans living in the surrounding areas, urinary arsenic species, such as inorganic arsenic (iAs) and the metabolites mono-methylated (MMA) and di-methylated arsenic acids (DMA), were evaluated in 275 residents (18-84 years of age). Arsenic species in urine were analyzed by hydride generation-cryotrapping-atomic absorption spectrometry, which excludes the non-toxic forms of arsenic such as those found in seafood. Urinary samples contained a total arsenic concentration (sum of arsenical species) which ranged from 1.3 to 398.7 ng mL(-1), indicating 33% of the inhabitants exceeded the biological exposition index (BEI = 35 ng mL(-1)), the permissible limit for occupational exposure. The mean relative urinary arsenic species were 9, 11 and 80% for iAs, MMA and DMA, respectively, in the Los Planes basin, and 17, 10 and 73%, respectively, in the El Carrizal basin. These data indicated that environmental intervention is required to address potential health issues in this area.

Health effects of chronic arsenic exposure

Arsenic is a unique element with distinct physical characteristics and toxicity whose importance in public health is well recognized. The toxicity of arsenic varies across its different forms. While the carcinogenicity of arsenic has been confirmed, the mechanisms behind the diseases occurring after acute or chronic exposure to arsenic are not well understood. Inorganic arsenic has been confirmed as a human carcinogen that can induce skin, lung, and bladder cancer. There are also reports of its significant association to liver, prostate, and bladder cancer. Recent studies have also suggested a relationship with diabetes, neurological effects, cardiac disorders, and reproductive organs, but further studies are required to confirm these associations. The majority of research to date has examined cancer incidence after a high exposure to high concentrations of arsenic. However, numerous studies have reported various health effects caused by chronic exposure to low concentrations of arsenic. An assessment of the health effects to arsenic exposure has never been performed in the South Korean population; thus, objective estimates of exposure levels are needed. Data should be collected on the biological exposure level for the total arsenic concentration, and individual arsenic concentration by species. In South Korea, we believe that biological exposure assessment should be the first step, followed by regular health effect assessments.