Exposure to arsenic and lead of children living near a copper-smelter in San Luis Potosi, Mexico: Importance of soil contamination for exposure of children

Multimetal exposure: Challenges in diagnostics, prevention, and treatment

Extensive use of heavy metals has posed a serious concern for ecosystem and human too. Heavy metals are toxic in nature and their accumulation in human body causes serious disorders such as neurological disease, cardiac disease, gastrointestinal problems, skin disorders, reproductive disease, lungs diseases, and so on. Furthermore, heavy metals not only affect the human health but also have a negative impact on the economy. In the current review, we have elaborated the impact of heavy metal exposure on human health and socioeconomics. We have discussed the molecular mechanism involved in the heavy metal-induced human disorders such as oxidative stress, neuroinflammation, and protein misfolding. Finally, we discussed the preventive measure and treatment strategy that could counter the negative effects of heavy metal intoxications. In conclusion, there is a substantial correlation between heavy metals and the onset and advancement of several health issues. Chelation treatment could be a useful tactic to lessen the toxic metal load and the difficulties that come with it.

Potassium jarosite seeding of soils decreases lead and arsenic bioaccessibility: A path toward concomitant remediation

Soils are common sources of metal(loid) contaminant exposure globally. Lead (Pb) and arsenic (As) are of paramount concern due to detrimental neurological and carcinogenic health effects, respectively. Pb and/or As contaminated soils require remediation, typically leading to excavation, a costly and environmentally damaging practice of removing soil to a central location (e.g., hazardous landfill) that may not be a viable option in low-income countries. Chemical remediation techniques may allow for in situ conversion of soil contaminants to phases that are not easily mobilized upon ingestion; however, effective chemical remediation options are limited. Here, we have successfully tested a soil remediation technology using potted soils that relies on converting soil Pb and As into jarosite-group minerals, such as plumbojarosite (PLJ) and beudantite, possessing exceptionally low bioaccessibility [i.e., solubility at gastric pH conditions (pH 1.5 to 3)]. Across all experiments conducted, all new treatment methods successfully promoted PLJ and/or beudantite conversion, resulting in a proportional decrease in Pb and As bioaccessibility. Increasing temperature resulted in increased conversion to jarosite-group minerals, but addition of potassium (K) jarosite was most critical to Pb and As bioaccessibility decreases. Our methods of K-jarosite treatment yielded <10% Pb and As bioaccessibility compared to unamended soil values of approximately 70% and 60%, respectively. The proposed treatment is a rare dual remediation option that effectively treats soil Pb and As such that potential exposure is considerably reduced. Research presented here lays the foundation for ongoing field application.

Integrating multiple spheres to identify the provenance and risk of urban dust and potentially toxic elements: Case study from central Mexico

This study aims to improve the current method of studying potentially toxic elements (PTEs) in urban dust using direct chemical evidence (from dust, rock, and emission source samples) and robust geochemical methods. The provenance of urban dust was determined using rare earth elements (REEs) and geochemical diagrams (V-Ni-Th*10, TiO2 vs. Zr, and Zr/Ti vs. Nb/Y). The geogenic or anthropogenic source of PTEs was determined using the enrichment factor (EF) and compositional data analysis (CoDA), while a PTE's point emission source was identified using a 3.1*La-1.54*Ce-Zn diagram, mineralogy, and morphology analyses. The spatiotemporal distribution of PTEs was determined using a geographic information system, and their health risk (by inhalation) was estimated using a lung bioaccessibility test and particle size distribution. We collected urban dust (n = 38), rock (n = 4), and zinc concentrate (n = 2) samples and determined PTEs and REEs in a city of 1.25 million inhabitants in central Mexico. Results showed that urban dust derived from the San Miguelito Range. REEs, Sc, and Zr were geogenic, while Mn, Cu, Zn, As, and Pb were anthropogenic. Due to the presente of sphalerite particles, a zinc refinery was identified as the point emission source of Zn, As, and Pb. High concentrations of Zn (5000-20,008 mg/kg), As (120-284 mg/kg), and Pb (350-776 mg/kg) were found in urban dust near the zinc refinery. Additionally, particles of PM2.5 (66-84%), PM5.0 (13-27%), PM10 (3-8%), and PM20 (0-2%) and lung bioaccessibility of Sr (48.5-72.4%), Zn (9.6-28.4%), Cu (10.5-27.0%), Fe (4.5-8.6%), Mn (2.9-9.2%), Cr (38.3%) and Pb (30.6%) demonstrated a latent risk to human health. These approaches improve our understanding of the provenance of urban dust and its PTE emission sources in urban areas.

Immigration and Blood Lead Levels Among Asian Populations in the United States: NHANES 2011-2018

OBJECTIVE

The aim of this study was to explore determinants of high BLLs among the Asian population in the United States.

METHODS

We used the US nationally representative National Health and Nutrition Examination Survey (NHANES), 2011-2018. We conducted stratified analyses to compare the BLLs of US-born and non-US-born Asians. We used adjusted linear regression to find predictors of high BLLs.

RESULTS

Among 12,563 participants in our analysis, the length of stay in the United States is a predictor of the gradual decrease in BLL among Asian immigrants ( P < 0.05). BLLs of immigrants who stayed in the United States for over 50 years were 0.36 μg/dL (95% confidence interval, 0.07 to 0.66) lower than new immigrants, but still higher than their US-born counterparts.

SIGNIFICANCE

Asian population in the US has the highest BLLs among all ethnic groups, and the exposure outside of the US among immigrants is likely the driver.

Baseline concentrations, source apportionment, and probabilistic risk assessment of heavy metals in urban street dust in Northeast Brazil

Heavy metal pollution by accelerating urbanization is an emerging socio-environmental issue that poses a potential risk to human health and the environment. In this scenario, street dust is a primary source of contaminants. Here, the metal concentrations in street dust of one of the biggest Brazilian cities were assessed aiming to identify and quantify the sources of contamination. The metal bioaccessibility and estimated probabilistic (non)-carcinogenic risks to humans were also evaluated. Thirty-six dust samples were collected in the metropolitan region of Recife. Results showed that the traffic governed the distribution and accumulation of metals in street dust. Emissions from vehicles were the primary source (> 70 %) of heavy metals, except for Cd, which had a mixed origin (natural, traffic, and industrial). Moderate to heavy dust contamination by Ba, Cu, Mn, Pb, and Zn were found, with a very high potential ecological risk. The main exposure route depended on the metal. Barium, Cu, and Pb had ingestion rather than dermal contact as the main route of exposure, while inhalation and dermal contact posed the main risks to Mn and Cr, respectively. The risk for children was higher than for adults. The probabilities of unacceptable carcinogenic risk scenarios (TCRI >10-6) for children and adults were 27 and 4 %, respectively, with Cr being the most concerning metal for the health of the urban population.

Pollution Profiles, Source Identification and Health Risk Assessment of Heavy Metals in Soil near a Non-Ferrous Metal Smelting Plant

Heavy metal pollution related to non-ferrous metal smelting may pose a significant threat to human health. This study analyzed 58 surface soils collected from a representative non-ferrous metal smelting area to screen potentially hazardous heavy metals and evaluate their health risk in the studied area. The findings demonstrated that human activity had contributed to the pollution degrees of Cu, Cd, As, Zn, and Pb in the surrounding area of a non-ferrous metal smelting plant (NMSP). Cu, Cd, As, Zn, Pb, Ni, and Co pollution within the NMSP was serious. Combining the spatial distribution and Spearman correlations with principal component analysis (PCA), the primary sources of Cd, As, Pb, and Zn in surrounding areas were related to non-ferrous metal smelting and transportation activities. High non-cancer (THI = 4.76) and cancer risks (TCR = 2.99 × 10^-4) were found for adults in the NMSP. Moreover, heavy metals in the surrounding areas posed a potential cancer risk to children (TCR = 3.62 × 10^-6) and adults (TCR = 1.27 × 10^-5). The significant contributions of As, Pb, and Cd to health risks requires special attention. The construction of a heavy metal pollution management system will benefit from the current study for the non-ferrous metal smelting industry.

Elucidations of Molecular Mechanism and Mechanistic Effects of Environmental Toxicants in Neurological Disorders

Due to rising environmental and global public health concerns associated with environmental contamination, human populations are continually being exposed to environmental toxicants, including physical chemical mutagens widespread in our environment causing adverse consequences and inducing a variety of neurological disorders in humans. Physical mutagens comprise ionizing and non-ionizing radiation, such as UV rays, IR rays, X-rays, which produces a broad spectrum of neuronal destruction, including neuroinflammation, genetic instability, enhanced oxidative stress driving mitochondrial damage in the human neuronal antecedent cells, cognitive impairment due to alterations in neuronal function, especially in synaptic plasticity, neurogenesis repression, modifications in mature neuronal networks drives to enhanced neurodegenerative risk. Chemical Mutagens including alkylating agents (EMS, NM, MMS, and NTG), Hydroxylamine, nitrous acid, sodium azide, halouracils are the major toxic mutagen in our environment and have been associated with neurological disorders. These chemical mutagens create dimers of pyrimidine that cause DNA damage that leads to ROS generation producing mutations, chromosomal abnormalities, genotoxicity which leads to increased neurodegenerative risk. The toxicity of four heavy metal including Cd, As, Pb, Hg is mostly responsible for complicated neurological disorders in humans. Cadmium exposure can enhance the permeability of the BBB and penetrate the brain, driving brain intracellular accumulation, cellular dysfunction, and cerebral edema. Arsenic exerts its toxic effect by induction of ROS production in neuronal cells. In this review, we summarize the molecular mechanism and mechanistic effects of mutagens in the environment and their role in multiple neurological disorders.

Lead phosphate deposition in porous media and implications for lead remediation

Phosphate addition is commonly applied as an effective method to remediate lead contaminated sites via formation of low solubility lead phosphate solids. However, subsequent transport of the lead phosphate particles may impact the effectiveness of this remediation strategy. Hence, this study investigates the mechanisms involved in the aggregation of lead phosphate particles and their deposition in sand columns as a function of typical water chemistry parameters. Clean bed filtration theory was evaluated to predict the particle deposition behavior, using Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to estimate particle-substrate interactions. The observed particle deposition was not predictable from the primary energy barrier in clean bed filtration models, even in simple monovalent background electrolyte (NaNO3), because weak deposition in a secondary energy minimum prevailed even at low ionic strength, and ripening occurred at ionic strengths of 12.5 mM or higher. For aged (aggregated) suspensions, straining also occurred at 12.5 mM or higher. Aggregation and deposition were further enhanced at low total P/Pb ratios (i.e., P/Pb = 1) and in the presence of divalent cations, such as Ca2+ (≥ 0.2 mM), which resulted in less negative particle surface potentials and weaker electrostatic repulsion forces. However, the presence of 5 mg C/L of humic acid induced strong steric or electrosteric repulsion, which hindered particle aggregation and deposition even in the presence of Ca2+. This study demonstrates the importance of myriad mechanisms in lead phosphate deposition and provides useful information for controlling water chemistry in phosphate applications for lead remediation.

Heavy Metal Contamination of Soil in Preschool Facilities around Industrial Operations, Kuils River, Cape Town (South Africa)

The contamination of soil by heavy metals is a potential health risk, especially among susceptible populations. The aim of this study was to measure the levels of heavy metals, identify the contamination levels and possible sources of heavy metals, and evaluate the health risk caused by heavy metals to the children living in Kuils River. Composite samples of soil were collected at 34 preschools. A portable X-ray fluorescence spectrometer was used to measure the levels of metals. Contamination levels were evaluated using a geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF) and pollution load index (PLI). The spatial distribution of the Igeo contamination levels was assessed using ArcGIS. Sources of heavy metals and the correlation among metals were assessed using factor analysis and Pearson correlation, respectively. The measured concentrations of metals were used to estimate the health risk for children. The average levels of the metals were 16, 4469, 137, 30, 176, 1547 and 232 mg/kg for arsenic (As), iron (Fe), manganese (Mn), lead (Pb), strontium (Sr), titanium (Ti) and zinc (Zn), respectively. According to Igeo, EF, CF and PLI contamination exist in the study area. The health index (HI) for non-carcinogenic effects showed the ingestion route as the main contributor to the total risk, with the accumulative carcinogenic risk exceeding the maximum acceptable level. To protect the affected communities, and children in particular, this study provides evidence of the need for action, including the institution of mandatory buffer zones between pollutant-generating activities and human settlements.

Effects of soil lead exposure and land use characteristics on neurodevelopment among children under 3 years of age in northern Taiwan

Lead (Pb) exposure increases the risks of neurodevelopmental disorders in children. Child-specific activities and land use scenarios may lead to elevated opportunities for Pb exposure through the soil. Therefore, we investigated hair and fingernail Pb concentrations among young children in northern Taiwan, in relation to soil Pb pollution and land use characteristics. We also explored the effect of the Pb exposure burden and land use scenarios on neurobehavioral development. In total, 139 healthy children under 3 years of age were recruited in October 2011 to April 2014. Pb levels in hair and fingernail samples were determined using an inductively coupled plasma/mass spectrometer. Pb concentrations in soils and land use types surrounding the children's homes were accessed by a geographic information system to identify any associations with hair Pb levels. The Bayley Scales of Infant and Toddler Development (Bayley-III) were used to evaluate the cognitive, language, and motor development of the children. A multivariable regression model was performed to assess the effects of soil Pb levels and land-use status on Pb exposure in children, as well as associations of Pb exposure and land-use scenarios with neurodevelopmental abilities. Geometric mean Pb concentrations in hair, fingernails, and soil were 2.9 ± 4.8 μg/g, 0.8 ± 5.1 μg/g, and 20.8 ± 4.3 mg/kg, respectively. The multivariable analysis indicated that soil Pb concentrations and green areas around residences had potential links with Pb exposure among children in northern Taiwan. Hair Pb concentrations were negatively associated with expressive language scores. Soil Pb exposure was positively associated with hair Pb concentrations. Land use types around the children's homes in northern Taiwan were associated with their neurodevelopment. Increased green areas were negatively associated with hair Pb concentrations. Living near a highway may have had negative impacts on gross motor scores. A healthy residence can avoid potential health risks for children during their early life.

Assessing Children's Lead Exposure in an Active Mining Community Using the Integrated Exposure Uptake Biokinetic Model

Lead exposure has been shown to be harmful to humans in various settings and there are no safe levels of blood lead in children. At an Alternative Superfund site in Hayden-Winkelman, Arizona, with an active copper smelter and concentrator, lead exceedances in air and soil have been measured in the past 20 years. In this work, the U.S. Environmental Protection Agency's Integrated Exposure Uptake Biokinetic (IEUBK) model was used to estimate Hayden-Winkelman children's (age 6 months-7 years) blood lead levels (BLLs) using site-specific lead concentrations measured in indoor and outdoor air, soil, indoor dust, and drinking water. Values used by a state agency's airborne lead risk forecast program were also evaluated to determine whether their forecasting program is useful in protecting children's public health. Using site-specific values in the model, the results demonstrated that lead ingested via indoor dust was the major contributor to children's BLLs. In addition, the output of the IEUBK model overestimated actual BLLs of children sampled in the community. The IEUBK model was particularly sensitive to high indoor dust levels, and these site-specific measures increased modeled BLL values. This finding is of significance as the IEUBK model is used worldwide in communities with industrial contamination. This study confirmed that the chief contributor to lead exposure in children is household dust. Thus, for lead exposure risk reduction, agencies working at Superfund sites should focus efforts on decontaminating outdoor soil and dust and indoor lead decontamination.

Thallium geochemical fractionation and migration in Tl-As rich soils: The key controls

Thallium (Tl) pollution caused by mining and processing of Tl-enriched ores has become an increasing concern. This study explored the geochemical fractionation and vertical transfer of Tl in a soil profile (200 cm) from a representative Tl-As mineralized area, Southwest China. The results showed that the soils were heavily enriched by Tl and As, with concentration ranging from 3.91-17.3 and 1830-8840 mg/kg (6.79 and 2973 mg/kg in average), respectively. Approximately 50% of Tl occurred in geochemically mobile fractions in the topsoil, wherein the reducible fraction was the most enriched fraction. Further characterization using LA-ICP-MS and TEM revealed that enriched Tl and As in soils were mainly inherited from the weathering of mine tailing piles upstream. XPS characterization indicated that Fe oxides herein may play a critical role in the oxidation of Tl(I) to Tl(III) which provoked further adsorption of Tl onto Fe oxides, thereby facilitating Tl enrichment in the reducible fraction. The findings highlight that the pivotal role of Fe oxides from mineralized area in the co-mobility and migration of Tl and As in the depth profile.

An interlaboratory evaluation of the variability in arsenic and lead relative bioavailability when assessed using a mouse bioassay

Animal bioassays have been developed to estimate oral relative bioavailability (RBA) of metals in soil, dust, or food for accurate health risk assessment. However, the comparability in RBA estimates from different labs remains largely unclear. Using 12 soil and soil-like standard reference materials (SRMs), this study investigated variability in lead (Pb) and arsenic (As) RBA estimates employing a mouse bioassay in 3 labs at Nanjing University, University of Jinan, and Shandong Normal University. Two performances of the bioassay at Nanjing University in 2019 and 2020 showed reproducible Pb and As RBA estimates, but increasing the number of mouse replicates in 2020 produced more precise RBA measurements. Although there were inter-lab variations in diet consumption rate and metal accumulation in mouse liver and kidneys following SRM ingestion due to differences in diet composition, bioassays at 3 labs in 2019 yielded overall similar Pb and As RBA estimates for the 12 SRMs with strong linear correlations between each 2 of the 3 labs for Pb (R² = 0.95-0.98 and slope = 0.85-1.02) and As RBA outcomes (R² = 0.46-0.86 and slope = 0.56-0.79). The consistency in RBA estimates was attributed to the relative nature of the final bioavailability outcome, which might overcome the inter-lab variation in diet consumption and metal uptake in mice. These results increased the confidence of use of mouse bioassays in bioavailability studies.

Bioaccumulation of Toxic Metals in Children Exposed to Urban Pollution and to Cement Plant Emissions

Cement plants located in urban areas can increase health risk. Although children are particularly vulnerable, biomonitoring studies are lacking. Toenail concentration of 24 metals was measured in 366 children (6-10 years), who live and attend school in a city hosting a cement plant. Living addresses and schools were geocoded and attributed to exposed or control areas, according to modeled ground concentrations of PM10 generated by the cement plant. Air levels of PM10 and NO2 were monitored. PM10 levels were higher in the exposed, than in the control area. The highest mean PM10 concentration was recorded close to the cement plant. Conversely, the highest NO2 concentration was in the control area, where vehicular traffic and home heating were the prevalent sources of pollutants. Exposed children had higher concentrations of Nickel (Ni), Cadmium (Cd), Mercury (Hg), and Arsenic (As) than controls. These concentrations correlated each other, indicating a common source. Toenail Barium (Ba) concentration was higher in the control- than in the exposed area. The location of the attended school was a predictor of Cd, Hg, Ni, Ba concentrations, after adjusting for confounders. In conclusion, children living and attending school in an urban area exposed to cement plant emissions show a chronic bioaccumulation of toxic metals, and a significant exposure to PM10 pollution. Cement plants located in populous urban areas seem therefore harmful, and primary prevention policies to protect children health are needed.

Potential environmental pollution from copper metallurgy and methods of management

This paper presents the latest overview of the environmental impact of wastes from the non-ferrous metallurgical industry. Ashes, slags and dusts - by-products from mining and metal processing - are sources of toxic metals, such as Pb, Cd, Hg, As, Al, as well as particulate matter. Physical, chemical and biological processes transform industrial wastes and cause water, soil and air pollution. Improperly protected heaps are subject to wind erosion and rain water leaching. Heavy metals and particulate matter are transported over long distances, contaminating the soil, living areas, watercourses, while in combination with mist they create smog. Water erosion releases heavy metals, which are leached into groundwater or surface runoff. This paper focuses on the range of pollution emissions from non-ferrous metallurgy wastes, hazards, mechanisms of their formation and fallouts, on the current state of technology and technological risk reduction solutions. The impact of pollution on human health and the biosphere, and methods of waste reduction in this industry sector are also presented. A sustainable and modern mining industry is the first step to cleaner production.

Characterization and within-site variation of environmental metal concentrations around a contaminated site using a community-engaged approach

Historic industrial activity led to extensive lead and arsenic contamination within residential areas of East Chicago, Indiana, United States. Although remediation is underway, community concerns about this contamination remain. Therefore, the goal for this analysis was to characterize environmental contamination in soil within and around these areas. A total of 228 samples from 32 different sites (addresses) were collected by community members or study staff. These were analyzed for metals using portable x-ray fluorescence or inductively coupled plasma ̶ optical emission spectroscopy. Concentrations exceeding EPA screening levels were found for 42% of the soil arsenic samples, 35% of the soil lead samples, and 79% of the soil manganese samples; a few samples also contained elevated copper or zinc. Concentrations above EPA screening levels were identified both within and outside of the formally designated contaminated area. Roughly 30% of all sites had at least one sample above and one sample below the screening level for arsenic, lead, and manganese. For sites within the contaminated area, more than 90% (arsenic), 60% (lead) and 60% (manganese) of the samples exceeded EPA screening levels. There was a significant association of proximity to the historic industrial site with elevated soil concentrations of arsenic and lead; a similar association was present for manganese. These results are consistent with existing data for lead and arsenic and we additionally report elevated concentrations of manganese and a high within-site variability of all metal concentrations. These findings should be considered in future remediation efforts.

Heavy metal pollution of street dust in the largest city of Mexico, sources and health risk assessment

In large industrialized cities, tons of particles containing heavy metals are released into the environment and accumulate on street surfaces. Such particles cause a potential risk to human health due to their composition and size. The heavy metal contamination levels, main emission sources, and human health risks were identified in 482 samples of street dust. Heavy metal concentrations were obtained by microwave-assisted acid digestion and ICP-OES. The results indicated that street dust in Mexico City is contaminated mainly with Pb, Zn, and Cu, according to the contamination factor and the geoaccumulation index. The pollution load index of the street dust was made with the concentrations of Pb, Zn, Cu, Cr, and Ni. The main sources of Pb, Zn, Cu, and Cr are anthropic, probably due to vehicular traffic. The highest levels of Cr and Pb in urban dust represent a health risk for children. Contamination limits were proposed for heavy metals in street dust of Mexico City. These limits might be useful to generate and apply public policies to decrease anthropic emissions of the heavy metals studied, particularly Cr and Pb.

Long-Term Manure Application Changes Bacterial Communities in Rice Rhizosphere and Arsenic Speciation in Rice Grains

Bioavailability and speciation of arsenic (As) are impacted by fertilization and bacteria in the rice rhizosphere. In this study, we investigated the effects of long-term manure application on As bioavailability, microbial community structure, and functional genes in a rice paddy field. The results showed that manure application did not affect total As in the soil but increased soluble As forms by 19%, increasing arsenite (As(III)) accumulation in rice grains and roots by 34 and 64% compared to a control. A real-time quantitative polymerase chain reaction (qPCR) and high-throughput sequencing analysis demonstrated that manure application increased the relative abundance of Rhizobium, Burkholderia, Sphingobium, and Sphingomonas containing arsenate reductase genes (arsC) in the rhizosphere soil, consistent with the 529% increase in arsC, which may have promoted arsenate (As(V)) reduction and increased As availability in pore water. In addition, manure application significantly altered the iron (Fe)-plaque microbial community structure and diversity. The microbes, particularly, Bradyrhizobium, Burkholderia, and Ralstonia, were mostly associated with As, Fe, and sulfur (S) cycles. This result was consistent with changes in the functional genes related to As, Fe, and S transformation. Although manure application promoted As(V) reduction (arsC) in Fe-plaque by 682%, it inhibited Fe and S reduction by decreasing Fe^III reduction bacteria (Geobacteraceae) and the sulfate-reducing gene (dsrA) abundance. Further, manure application changed the composition of the microbial community that contained the arsC gene. In short, caution needs to be excised even in the soil with a low As concentration as manure application increased As(III) accumulation in rice grains.

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

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

Toxic metal(loid)s contamination and potential human health risk assessment in the vicinity of century-old copper smelter, Karabash, Russia

Active smelters release high concentration of multiple toxic metal(loid)s into the environment, degrading the soil cover and posing high risks to human health. The present study investigates Cu along with other metal(loids) such as As, Cd, Hg, Co, Mn, Pb and Zn in the soil collected from the vicinity of Cu smelter, Karabash, Russia, and potential health risks to local children and adults were assessed. The average concentrations of Cu, Zn, Pb, As, Cd, and Hg in the exposed soil were 2698, 1050, 702, 392, 9 and 2 mg kg^-1, respectively, which was significantly (p < 0.05) much higher than reference soil: Cu(107), As(18), Cd(0.3), Hg(0.2), Pb(54) and Zn(125) mg kg^-1. The enrichment factor (EF) for Cu, Hg, Pb and Zn showed significant enrichment, whereas very high enrichment was recorded for As (20.0) and Cd (27.6) suggesting the soil was severely affected by smelting activities. The pollution load index was tenfold higher than the acceptable level of one, whereas potential ecological risk factor showed very high potential risks of Cd and Hg, along with a considerable ecological risk of As and Cu. Very high ecological risk index of 1810 indicates severe degradation of environmental ecosystem. The results of EF, Pearson correlation and principle component analysis were complementary and suggest the anthropogenic source of contamination for Cu, As, Pb, Hg and Cd. The present result suggests As > Pb > Cu in the exposed soil were the major contributors for the health risks and account for 81%, 12% and 5%, and 77%, 12% and 8% of hazard quotient for children and adults, respectively. Noticeably, the health risks to local children dwelling in the vicinity of Cu smelter were 12 and 20 times higher than to adult and the acceptable level of one, respectively. Therefore, in order to reduce the health risk due to metal(loid)s, mitigation measures are needed to remediate the pollution of the exposed soil.

Design and synthesis of biopolymer-derived porous graphitic carbon covered iron-organic frameworks for depollution of arsenic from waters

A series of alginate-derived porous graphitic carbon (PGC) wrapped iron-based organic frameworks (Fe-MIL-88B) composites were synthesized and checked their ability for the removal of arsenite (As(III)) and arsenate (As(V)) from water. Various amounts of PGC (5, 10, 20, and 50 wt/wt %) were utilized as a wrapping material for the development of composites with Fe-MIL-88B@PGCx% and optimized for As(III)/As(V) adsorption. The chemical functionalities, structure, morphology, porous properties and bonding nature of the adsorbents were analyzed using FTIR, PXRD, SEM, BET, and XPS, respectively. Fe-MIL-88B@PGC20% composite was explored to have maximum removal efficiency and fastest adsorption kinetics for As(III)/As(V), of all Fe-MIL-88B@PGCx% composites and pristine Fe-MIL-88B studied here. The developed adsorbents are highly pH dependent and selective in common co-existing anions except for F^-, PO₄^3- and humic acid. The Langmuir isotherm studies of As(III) and As(V) adsorption suggest maximum adsorption capacities of 1.6853 and 2.2636 mmol/g, at pH of 3.0 and 9.2, respectively. The XPS analysis of As(III)-sorbed Fe-MIL-88B@PGC20% composite reveals that a portion of As(III) has been oxidized into As(V) during the adsorption process. The continuous flow-bed column study indicates that bed volumes of 249.6 and 452.8 mL of As(III) and As(V) contaminated water was treated, respectively, also reduced the concentration of As(III)/As(V) to less than WHO standards (<10 μg/L).

Integrated probabilistic risk assessment in sites contaminated with arsenic and lead by long-term mining liabilities in San Luis Potosi, Mexico

Mining environmental liabilities (MEL) in San Luis Potosi are the result of more than 450 years of mining activity, which has contaminated the soil mainly with arsenic (As) and lead (Pb) in several areas. Risk assessments are used to estimate the possibility of the occurrence of adverse effects on human health or on ecological receptors; and the most accessible way of performing them is through probabilistic estimates such as the Latin Hypercube Sampling (LHS) model. Therefore, the aim of this study was to carry out an Integrated Probabilistic Environmental Risk Assessment (IPERA) for the estimation of health risks in infants and rodents. The mean concentrations of As and Pb in soil were significantly higher (p<0.05) in all contaminated sites than in their respective reference sites. Villa de la Paz was the site with the highest mean concentration of As (1374 mg/kg), while Charcas was the one with the highest level of Pb (12,929 mg/kg). The Hazard Quotient (HQ) was calculated and Villa de la Paz had the highest values of As in both rodents (11.994) and children (39.32), and Charcas showed the highest values of Pb in both (24.971 and 31.668 for rodents and children respectively). The cumulative hazard Index (HI) reveals there is a very significant health risk due to As and Pb exposure for both rodents and children in contaminated areas of these mining communities.

Occupational exposure of lead and cadmium on adolescent and adult workers of battery recycling and welding workshops: Adverse impact on health

The occupational exposure of toxic metals is an important concern, because of its potential accumulation in living organisms, leading to long term toxic effects. The occupational and environmental contacts of toxic metals, cadmium (Cd) and lead (Pb) have been evaluated by determination of them in biological samples (blood and scalp hair) of adolescent and adults, workers of battery recycling and welding workshops. The age matched adolescent and adult residing in nonindustrial areas were also selected, termed as referent/control subjects. The blood and scalp hair samples of workers and controls were analyzed for Cd and Pb using graphite furnace atomic absorption spectrometry previously decomposed the matrices using acid mixture. The biochemical parameters of workers of both age groups were also evaluated. The average concentrations of Cd and Pb in blood and scalp hair samples of adolescent workers were three fold higher as compared with control subjects. The drinking water in containers of both workshops contained Pb and Cd in two to four and five to thirteen folds, respectively, higher than recommended permissible limits of WHO. The significant correlations between the blood lead levels and hemoglobin (%) in adolescent (r = -0.78). The positive correlation was observed among incidence of blood pressure with Pb and Cd concentrations in biological samples of workers (adults) (r = 0.65 to 0.83). These findings suggest that occupational exposure of toxic metals might be created adverse impacts on workers due to ill management of workshops.

Biomonitoring of Metals in Children Living in an Urban Area and Close to Waste Incinerators

The impact of waste incinerators is usually examined by measuring environmental pollutants. Biomonitoring has been limited, until now, to few metals and to adults. We explored accumulation of a comprehensive panel of metals in children free-living in an urban area hosting two waste incinerators. Children were divided by georeferentiation in exposed and control groups, and toenail concentrations of 23 metals were thereafter assessed. The percentage of children having toenail metal concentrations above the limit of detection was higher in exposed children than in controls for Al, Ba, Mn, Cu, and V. Exposed children had higher absolute concentrations of Ba, Mn, Cu, and V, as compared with those living in the reference area. The Tobit regression identified living in the exposed area as a significant predictor of Ba, Ni, Cu, Mn, and V concentrations, after adjusting for covariates. The concentrations of Ba, Mn, Ni, and Cu correlated with each other, suggesting a possible common source of emission. Exposure to emissions derived from waste incinerators in an urban setting can lead to body accumulation of specific metals in children. Toenail metal concentration should be considered a noninvasive and adequate biomonitoring tool and an early warning indicator which should integrate the environmental monitoring of pollutants.

Trace element biomonitoring in hair and blood of occupationally unexposed population residing in polluted areas of East Kazakhstan and Pavlodar regions

INTRODUCTION

Eastern and North-Eastern regions of Kazakhstan are considered to be environmentally disadvantaged due to industrial pollution and activity of the former Semipalatinsk Nuclear Test Site. Ferrous metallurgy is represented by the world's largest ferroalloy plant located in Aksu. In addition to a ferroalloy plant, Aksu is the home for the largest thermal power plant in Kazakhstan.

OBJECTIVE

Biomonitoring of 31 hair and blood trace elements (Ag, Ba, Be, Bi, Cs, Co, Ce, Cr, Cu, Eu, Gd, Hf, In, La, Li, Mn, Mo, Nb, Nd, Pb, Sc, Sn, Tl, Th, U, V, W, Y, Yb, Zn, and Zr) in non-occupationally exposed population residing in polluted areas of East Kazakhstan and Pavlodar regions.

METHODS

Five case groups, residing in the vicinity to the former Semipalatinsk Nuclear Test Site (Akzhar, Borodulikha, and Karaul) or in proximity to industrial plants (Aksu and Ust-Kamenogorsk) have been assessed vs. controls from a rural settlement in Kurchum. In total, 204 hair and blood samples were analyzed by inductively coupled plasma mass spectrometry.

RESULTS

The observed blood concentrations of trace elements were in agreement with earlier studies on residents of industrially polluted areas. Elevated levels of blood Ba, Mn, Pb, V, and Zn were detected in residents of Aksu and Ust-Kamenogorsk. The elemental composition of head hair was characterized by greater stability between the study sites.

CONCLUSION

Residency near the former Semipalatinsk Test Site could be considered as safe, while the environmental status of industrial settlements appears to be rather adverse.

Assessing the contributions of metals in environmental media to exposure biomarkers in a region of ferroalloy industry

Residential proximity to ferroalloy production has been associated with increased manganese exposure, which can adversely affect health, particularly among children. Little is known, however, about which environmental samples contribute most to internal levels of manganese and other ferroalloy metals. We aimed to characterize sources of exposure to metals and evaluate the ability of internal biomarkers to reflect exposures from environmental media. In 717 Italian adolescents residing near ferromanganese industry, we examined associations between manganese, lead, chromium, and copper in environmental samples (airborne particles, surface soil, indoor/outdoor house dust) and biological samples (blood, hair, nails, saliva, urine). In multivariable regression analyses adjusted for child age and sex, a 10% increase in soil Mn was associated with increases of 3.0% (95% CI: 1.1%, 4.9%) in nail Mn and 1.6% (95% CI: -0.2%, 3.4%) in saliva Mn. Weighted-quantile-sum (WQS) regression estimated that higher soil and outdoor dust Mn accounted for most of the effect on nail Mn (WQS weights: 0.61 and 0.22, respectively, out of a total of 1.0). Higher air and soil Mn accounted for most of the effect on saliva Mn (WQS weights: 0.65 and 0.29, respectively). These findings can help inform biomarker selection in future epidemiologic studies and guide intervention strategies in exposed populations.

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.

Prevalence and Factors Associated with High Levels of Aluminum, Arsenic, Cadmium, Lead, and Mercury in Hair Samples of Well-Nourished Thai Children in Bangkok and Perimeters

Toxic element exposure increases risk of neurodevelopmental disorders. However, hair element profiles of well-nourished urban resident children were largely unknown. We identified prevalence and the contributing factors of high hair aluminum (Al), arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) levels in 111 Thai children (aged 3-7 years old). Most participants were well-nourished with high socioeconomic status. Since ROC curve of hair element data showed inadequate sensitivity for cutoff set-up, US reference hair levels were used to categorize high and low level groups. Nevertheless, compared to the current reference at 5 μg/dL, blood lead cutoff at 2.15 μg/dL provided more consistent results with that of hair lead levels. High As and Pb levels were the first and second most prevalent element, while Al was the element found in highest amount in hair. High hair Al (12% prevalence) levels were associated with being male regardless of age or nutritional status. High hair As levels were associated with living in Bangkok (OR = 6.57) regardless of school type. High hair Pb levels were associated with being under 5 years old and living in Bangkok (OR = 3.06). However, no associations were found between blood Pb, hair Cd, Hg, and tested factors. These findings suggested that under 5-year-old boys living in capital city like Bangkok may be at risk of exposure to multiple toxic elements. Future studies in these children are warranted to identify their exposure sources and proper risk management strategies.

A comprehensive review on current status, mechanism, and possible sources of arsenic contamination in groundwater: a global perspective with prominence of Pakistan scenario

Arsenic(As)-mediated contamination of groundwater resources in different parts of the world is a consequence of natural or anthropogenic sources, leading to adverse effects on the environment and human health. Millions of people from different countries are unfortunately consuming groundwater contaminated with alarming levels of As. Exposure to the high concentration of As for an extended period of time can cause devastating effects on human health such as skin lesions, cardiac disorders, discolouration and cancer. Until 2018, about 11 districts of Sindh and Punjab provinces in Pakistan had been found with As contamination in groundwater beyond the national defined permissible level, i.e. 50 µg/L. Tharparkar and Hyderabad (in Sindh province) along Indus river and Lahore and Kasur (in Punjab province) are well-known hotspots sites of natural geogenic As contamination in groundwater. Higher levels of Sulfates (SO₄^2-), Chloride (Cl^-) and Carbonate (CO₃^2-) along with the elevated values of electrical conductivity and basic pH, as well as augmented presence of "As V" species, were all an indication of oxidizing condition in groundwater, and these oxidizing conditions are identified as the primary mechanism of As contamination into aquifers of Pakistan via oxidative dissolution. The main aim of this review is to summarize and discuss the current contamination status of As in groundwater water globally with a special focus on Pakistan scenario, isotopic evidence to track sources of groundwater recharge and its effects on As contamination in groundwater with various redox conditions prevailing in Pakistan. In addition, public health consequences of As contamination and mitigation strategies for As removal from water resources have been also highlighted. In this review, the data were extracted from various cutting edge studies published in national and international journals.

Heavy metals in food crops: Health risks, fate, mechanisms, and management

Food security is a high-priority issue for sustainable global development both quantitatively and qualitatively. In recent decades, adverse effects of unexpected contaminants on crop quality have threatened both food security and human health. Heavy metals and metalloids (e.g., Hg, As, Pb, Cd, and Cr) can disturb human metabolomics, contributing to morbidity and even mortality. Therefore, this review focuses on and describes heavy metal contamination in soil-food crop subsystems with respect to human health risks. It also explores the possible geographical pathways of heavy metals in such subsystems. In-depth discussion is further offered on physiological/molecular translocation mechanisms involved in the uptake of metallic contaminants inside food crops. Finally, management strategies are proposed to regain sustainability in soil-food subsystems.

Sources of lead exposure in various countries

This review evaluates the sources of lead exposure worldwide. Studies from searches relating to sources of lead exposure in various countries within different regional zones were reviewed. Results indicated that in Nigeria, exposure sources include electronic waste, paint and batteries. In Mexico exposure sources include glazed ceramics, lead contaminated utensils and lead contaminated water, for India lead sources include cosmetics and traditional medicines. Sources of lead exposure in China include e-waste, traditional medicines and industrial emissions. In France, exposure sources included lead paint from older homes, imported ceramics and cosmetics and industrial emissions. Australia's exposure sources include paint, dust, imported toys and traditional medicines. Finally, in the United States exposure sources included paint, the industrial legacy of lead exposure and batteries. In high-income countries (HICs) the legacy of lead exposure keeps populations continuously exposed. In lower- and middle-income countries (LMICs), in addition to the legacy of lead exposure, lack of regulations or the inability to enforce regulations keeps populations exposed. In all, evidence suggests that lead exposure remains an issue of public health significance in both HIC and LMIC.

Heavy metal contamination and health risk assessment for children near a large Cu-smelter in central China

Nonferrous metallurgy is causing significant concerns due to its emissions of heavy metals into environment, degrading environmental quality, and consequently posing high risks to human health. In this study, the concentration levels of Cadmium (Cd), Copper (Cu), Lead (Pb), and Arsenic (As) were investigated in soil, crop, well water, and fish samples collected around the Daye Copper Smelter in Hubei province, China, and the potential health risks were assessed for local children. The results showed that soils near the smelter were heavily polluted by Cd, Cu, Pb, and As, with the mean concentrations of 4.87, 195.26, 92.65, and 35.84 mg/kg, respectively, which were significantly higher than the values of soil Cd (0.18 mg/kg), Cu (32.84 mg/kg), Pb (28.46 mg/kg), and As (13.65 mg/kg) in the reference area (p < 0.001). The concentrations of Cd and As in vegetable samples collected from smelter-affected area exceeded the maximum permissible level (MPL) for food in China by 82% and 39%, respectively. The concentrations of Cd and Pb in rice grain harvested from smelter-affected area were 9.35 and 1.35 times higher than the corresponding MPL, respectively. The concentrations of Cd, As, and Cu in fish muscle from smelter-affected area exceeded the national MPL by 72%, 41%, and 24% of analyzed samples, respectively. The concentrations of Cd (p < 0.05) and As (p < 0.01) in well water were significantly higher in the smelter-affected area than those in the reference area, respectively. The health risks to local children in the smelter-affected area were 30.25 times higher than the acceptable level of 1, and most of the risks were resulted from Cd (46%), As (27%) and Pb (20%). The intake of crops was a major source (78%) to health risks for local children.

Environmental and take-home lead exposure in children living in the vicinity of a lead battery smelter in Serbia

Blood lead levels (BLLs) have been falling steadily worldwide due to restricted use of lead (Pb) and its compounds. although they remain above preindustrial Pb levels. Elevated BLL can still be found in children living near secondary Pb smelters that represent around 50% of Pb production. There have been no studies on Pb exposure in children living in Serbia ever since the 1980s. The aim of this study was to evaluate the BLLs in children living in two villages in Serbia (Zajača, the location of a secondary lead smelter, and Paskovac, 5 km away), identify the primary determinants of children's BLLs, and investigate the impact of BLLs on children's health symptoms and school achievement. The study was conducted in 2011 on 127 children, aged 1-18 years, whose BLLs were measured using inductively coupled argon plasma mass spectrometry (ICP-MS). The median BLL in children was 12 μg/dl, with a significantly higher value of 17.5 μg/dl in Zajača, compared to 7.6 μg/dl in Paskovac. Only 1 out of 75 and 12 out of 52 children from Zajača and Paskovac, respectively, had BLLs below the CDC recommended 5 μg/dl level. Living near the smelter resulted in 19 times, and having a father who works in the plant 4 times higher odds of elevated BLLs. No significant effects of elevated BLLs health symptoms were seen in this study. BLLs of children living near a battery recycling plant in Serbia, an upper-middle income European country, were in the range and even higher than those of children living in developing countries. For the first time, the contribution of environmental and take-home lead exposure was quantified using mixed-effect modeling, and our results indicate a contribution of 25-40% of the take-home lead exposure to the BLLs of children living in the vicinity of a secondary lead smelter.

Impact of inorganic ions and natural organic matter on arsenates removal by ferrate(VI): Understanding a complex effect of phosphates ions

Arsenic compounds are carcinogenic to humans and are typically removed from contaminated water using various sorbents. The ionic composition plays a significant role in arsenate removal efficiency during the process of water remediation. Here, we quantify the effects of natural ions (chlorides, nitrates, carbonates, sulfates, and phosphates) and humic acid on the removal of arsenates by ferrate(VI) at pH = 6.6. In the experiments, the initial concentration of arsenates was 10 mg L^-1 (as As) and the concentrations of ions varied in the range from 5 to 100 mg L^-1 of element in ionic form and humic acid. The achieved results show that only phosphate ions had principle influence on the efficiency of arsenate removal by ferrate(VI). The effect of phosphates was elucidated by applying transmission electron microscopy, energy-dispersive X-ray spectroscopy, and low temperature in-field ⁵⁷Fe Mössbauer spectroscopy to solid samples, prepared under different weight ratios of ferrate(VI), arsenates, and phosphates. These results show three crucial effects of phosphates on the arsenate removal mechanisms. At low P:As weight ratio (up to 1:1), the incorporation of arsenate ions into the crystalline structure of γ-Fe₂O₃/γ-FeOOH nanoparticles was found to be suppressed by the presence of phosphates. Thus, arsenates were mainly adsorbed onto the surface of γ-Fe₂O₃/γ-FeOOH nanoparticles. Further increase in the P:As weight ratio (more than 1:1) resulted in the competition between arsenates and phosphates sorption. With the increased concentration of phosphate ions, the number of arsenates on the surface of γ-Fe₂O₃/γ-FeOOH nanoparticles was reduced. Finally, the complexation of iron(III) ions with phosphate ions occurred, leading to a decrease in the arsenates removal efficiency, which resulted from a lower content of precipitated γ-Fe₂O₃/γ-FeOOH nanoparticles. All these aspects need to be considered prior to application of ferrate(VI) for arsenates removal in real natural waters.

Exposure to Mixtures of Pollutants in Mexican Children from Marginalized Urban Areas

Background:

Exposure to contaminant mixtures in developing countries is an important public health issue. Children are identified as the most susceptible group to adverse health effects due to the exposure.

Objective:

The aim of this study was to conduct a screening for mixture pollutants in Mexican children in urban marginalized communities.

Methods:

We analyzed children (aged 6–12 years old) who resided in four urban marginalized communities in San Luis Potosi, Mexico: i) Bellas Lomas (BEL), a site with vehicular traffic; ii) Tercera Chica (TC), a site with brick kilns; Iii) Rincon de San Jose (SJR), a site with a hazardous waste landfill; and (iv) Morales (MOR) a metallurgical zone with copper-arsenic and electrolytic zinc smelters. Polycyclic Aromatic Hydrocarbons (1-hydroxypyrene (1-OHP)), benzene (trans, trans-muconic acid (t,t-MA), manganese, arsenic and fluoride were quantified in urine and lead in blood samples.

Findings:

Our results indicate that median exposures to manganese were 4.4, 5.2, 5.8 and 6.3 µg/L for BEL, TC, SJR and MOR, respectively. For BEL, fluoride was present at a higher concentration with 2.3 mg/L followed by MOR, TC and SJR with 1.7, 1.5 and 1.2 mg/L respectively. The highest concentrations of arsenic that were found were 11 µg/L in MOR and lead concentration was reported between 4.2 and 6.8 µg/dL, in BEL, TC and MOR. 1-OHP and t,t-MA were higher in TC (0.23 µmol/mol creatinine (cr), 429.7 µg/g cr, respectively) followed by SJR (0.09 µmol/mol cr, 427.4 µg/g cr), MOR (0.03 µmol/mol cr, 258.6 µg/g cr) and BEL (0.06 µmol/mol cr, 220.6 µg/g cr).

Conclusion:

Considering the large number of people, especially children, exposed to multiple pollutants, it is important to design effective intervention programs that reduce exposure and the resultant risk in the numerous urban marginalized communities in Mexico.

Influence of diet in urinary levels of metals in a biomonitoring study of a child population of the Valencian region (Spain)

Pollution by trace elements and its possible effect on organisms has become a worldwide concern due to the increasing presence of trace elements in the environment and especially in the food chain. Exposure to chemicals has traditionally been measured using environmental samples, however, human biomonitoring brings a different perspective, in which all sources and exposure pathways are integrated. The objective of this paper is to discern the possible relationship between children's diet and the metals found in children urine. With this aim in mind, a total of 120 voluntaries participated in a diet survey carried out in a school-aged population (age 6-11) from the Valencian region. In addition, twenty trace elements were analysed in children urine (arsenic, antimony, barium, beryllium, caesium, cadmium, cobalt, copper, lead, manganese, mercury, molybdenum, nickel, platinum, selenium, thallium, thorium, uranium, vanadium and zinc). Results permitted to compare metal levels in urine with metal levels of other biomonitoring studies to conclude that values, including ours, were similar in most studies. On the other hand, children who ate more vegetables had the highest values in cadmium, copper, molybdenum, antimony, thallium, vanadium, and zinc, while those who ate more fish reached higher values in mercury. Finally, children who ate more cereals and baked products had higher values in total arsenic.

Whole blood and hair trace elements and minerals in children living in metal-polluted area near copper smelter in Karabash, Chelyabinsk region, Russia

The primary aim of the study is assessment of hair and whole blood trace element and mineral levels in children living in a polluted area near a copper smelter (Karabash) and two control locations (Varna, Tomino) using inductively coupled plasma mass spectrometry. The obtained data indicates that both blood and hair As, Pb, and Fe levels in children living in Karabash significantly exceeded the control values. Whole blood levels of copper in children living in Varna exceeded that in Tomino (p = 0.155) and Karabash (p < 0.001) by 16 %. Oppositely, hair concentration of Cu was maximal in children from Karabash. Blood Ca and Mg content in children from Varna exceeded the respective values from Tomino and Karabash by 32 % (p = 0.021) and 42 % (p < 0.001), and 19 % (p < 0.001) and 9 % (p < 0.001), respectively. Similar differences were observed in hair mineral content. Oppositely, children living in Tomino and Karabash were characterized by 10 (p = 0.002) and 23 % (p < 0.001) higher levels of blood phosphorus. At the same time, hair P content was maximal in a polluted area. Therefore, children living in a polluted area near a copper smelter had significantly higher values of heavy metals and decreased Mg and Ca content in biosamples. It is supposed that adverse health effects in persons living near a copper smelter may be associated not only with toxic metal overexposure but also with altered mineral homeostasis.

Low blood lead levels impair intellectual and hematological function in children from Cartagena, Caribbean coast of Colombia

Lead produces numerous biochemical and physiological changes in humans, including hematological disorders, toxic effects on the central nervous system and in the function of several organs. The aim of this study was to determine blood lead levels (BLL) in children from Cartagena, Colombia, associating those with hematological and liver damage markers, the intelligence quotient (IQ), as well as with gene expression of the aminolevulinate dehydratase (ALAD), superoxide dismutase 1 (SOD1), gamma interferon (INF-γ), tumor necrosis factor (TNF) and tumor protein (p53). To achieve this purpose, 118 blood samples were collected from children 5-16 years old, with their respective informed consent from their parents. BLL was measured by atomic absorption; hematological parameters were obtained with automated systems; plasma was utilized to analyze hepatic toxicity markers, alanine aminotransferase (ALT), gamma-glutamyltransferase (γ-GT) and alkaline phosphatase (ALP); the Kaufman Brief Intelligence Test (K-BIT) was administered to measure the IQ; and gene expression was quantified from blood RNA. The mean BLL was 1.7±0.3μg/dL. A low proportion of the children (3.4%) had BLL above the CDC recommended limit (5μg/dL). BLL were correlated weakly, but negatively with child age, weight, height, body mass index, platelets wide distribution, mean platelet volume, γ-GT and IQ. There were not significant changes in the expression of evaluated genes. These results support the hypothesis that BLL below 5μg/dL may still be a detrimental factor on children's cognitive abilities, development and hematology, in line with recent concerns that there is no safe level of pediatric lead exposure.

Diversity and arsenic-tolerance potential of bacterial communities from soil and sediments along a gold tailing contamination gradient

Gold tailings often release arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on the diversity of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected at various distances from tailings in the Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes. The membrane transport proteins ArsB and (or) ACR3 pump As(III) out of the cell to resist As toxicity. We studied the abundance and phylogeny of ArsB and ACR3 using PCR-based clone libraries and quantitative PCR. The bacterial community was divided into 10 phyla and 59 genera. The transformation from As(V) to As(III) was predominant, which was coupled with denitrification. Both ArsB and ACR3 likely evolved from different orders of Proteobacteria. The arsB gene seems to be more stable in bestowing bacteria with the capability to respond to the As concentration. Moreover, As with iron, manganese, and total organic carbon also influenced the clustering relationships of samples and bacterial distribution.

Exploring Mexican adolescents' perceptions of environmental health risks: a photographic approach to risk analysis

The objective of this study was to explore Mexican adolescents' perceptions of environmental health risks in contaminated urban areas, and to test the environmental photography technique as a research tool for engaging adolescents in community-based health research. The study was conducted with 74 adolescents from two communities in the city of San Luis Potosi, Mexico. Participants were provided with disposable cameras and asked to take photographs of elements and situations which they believed affected their personal health both at home and outside their homes. They were also asked to describe each photograph in writing. Photographs and written explanations were analyzed by using quantitative and qualitative content analysis. Risk perception plays a crucial role in the development of Risk Communication Programs (RCPs) aimed at the improvement of community health. The photography technique opens up a promising field for environmental health research since it affords a realistic and concise impression of the perceived risks. Adolescents in both communities perceived different environmental health risks as detrimental to their well-being, e.g. waste, air pollution, and lack of hygiene. Yet, some knowledge gaps remain which need to be addressed.

Manganese and Developmental Neurotoxicity

Manganese (Mn) is an essential metal that plays a fundamental role for brain development and functioning. Environmental exposure to Mn may lead to accumulation in the basal ganglia and development of Parkinson-like disorders. The most recent research is focusing on early-life overexposure to Mn and the potential vulnerability of younger individuals to Mn toxicity also in regard to cognitive and executive functions through the involvement of the frontal cortex.Neurodevelopmental disturbances are increasing in the society, and understanding the potential role of environmental determinants is a key for prevention. Therefore, assessing the environmental sources of Mn exposure and the mechanisms of developmental neurotoxicity and defining appropriate biomarkers of exposure and early functional alterations represent key issues to improve and address preventive strategies. These themes will be reviewed in this chapter.

The Adverse Effects of Heavy Metals with and without Noise Exposure on the Human Peripheral and Central Auditory System: A Literature Review

Exposure to some chemicals in the workplace can lead to occupational chemical-induced hearing loss. Attention has mainly focused on the adverse auditory effects of solvents. However, other chemicals such as heavy metals have been also identified as ototoxic agents. The aim of this work was to review the current scientific knowledge about the adverse auditory effects of heavy metal exposure with and without co-exposure to noise in humans. PubMed and Medline were accessed to find suitable articles. A total of 49 articles met the inclusion criteria. Results from the review showed that no evidence about the ototoxic effects in humans of manganese is available. Contradictory results have been found for arsenic, lead and mercury as well as for the possible interaction between heavy metals and noise. All studies found in this review have found that exposure to cadmium and mixtures of heavy metals induce auditory dysfunction. Most of the studies investigating the adverse auditory effects of heavy metals in humans have investigated human populations exposed to lead. Some of these studies suggest peripheral and central auditory dysfunction induced by lead exposure. It is concluded that further evidence from human studies about the adverse auditory effects of heavy metal exposure is still required. Despite this issue, audiologists and other hearing health care professionals should be aware of the possible auditory effects of heavy metals.

DNA methylation changes in Mexican children exposed to arsenic from two historic mining areas in San Luis potosí

Arsenic is a carcinogen and epimutagen that threatens the health of exposed populations worldwide. In this study, we examined the methylation status of Alu and long interspersed nucleotide elements (LINE-1) and their association with levels of urinary arsenic in 84 Mexican children between 6 and 12 years old from two historic mining areas in the State of San Luis Potosí, Mexico. Urinary arsenic levels were determined by atomic absorption spectrophotometry and DNA methylation analysis was performed in peripheral blood leukocytes by bisulfite-pyrosequencing. The geometric mean of urinary arsenic was 26.44 µg/g Cr (range 1.93-139.35). No significant differences in urinary arsenic or methylation patterns due to gender were observed. A positive correlation was found between urinary arsenic and the mean percentage of methylated cytosines in Alu sequences (Spearman correlation coefficient r = 0.532, P < 0.001), and a trend of LINE-1 hypomethylation was also observed (Spearman correlation coefficient r = -0.232, P = 0.038) after adjustment for sex and age. A linear regression model showed an association with log-normalized urinary arsenic for Alu (β = 1.05, 95% CI: 0.67; 1.43, P < 0.001) and LINE-1 (β = -0.703, 95% CI: -1.36; -0.38, P = 0.038). Despite the low-level arsenic exposure, a subtle epigenetic imbalance measured as DNA methylation was detected in the leukocytes of Mexican children living in two historic mining areas. Environ. Mol. Mutagen. 57:717-723, 2016. © 2016 Wiley Periodicals, Inc.

Environmental exposure to arsenic and chromium in children is associated with kidney injury molecule-1

Environmental hazards from natural or anthropological sources are widespread, especially in the north-central region of Mexico. Children represent a susceptible population due to their unique routes of exposure and special vulnerabilities. In this study we evaluated the association of exposure to environmental kidney toxicants with kidney injury biomarkers in children living in San Luis Potosi (SLP), Mexico. A cross-sectional study was conducted with 83 children (5-12 years of age) residents of Villa de Reyes, SLP. Exposure to arsenic, cadmium, chromium, fluoride and lead was assessed in urine, blood and drinking water samples. Almost all tap and well water samples had levels of arsenic (81.5%) and fluoride (100%) above the permissible levels recommended by the World Health Organization. Mean urine arsenic (45.6ppb) and chromium (61.7ppb) were higher than the biological exposure index, a reference value in occupational settings. Using multivariate adjusted models, we found a dose-dependent association between kidney injury molecule-1 (KIM-1) across chromium exposure tertiles [(T1: reference, T2: 467pg/mL; T3: 615pg/mL) (p-trend=0.001)]. Chromium upper tertile was also associated with higher urinary miR-200c (500 copies/μl) and miR-423 (189 copies/μL). Arsenic upper tertile was also associated with higher urinary KIM-1 (372pg/mL). Other kidney injury/functional biomarkers such as serum creatinine, glomerular filtration rate, albuminuria, neutrophil gelatinase-associated lipocalin and miR-21 did not show any association with arsenic, chromium or any of the other toxicants evaluated. We conclude that KIM-1 might serve as a sensitive biomarker to screen children for kidney damage induced by environmental toxic agents.

Bioaccessibility of Cd and Pb in tailings from a zinc smelting in Brazil: implications for human health

Soils and wastes enriched with heavy metals may present ecological and human health risks. A considerable number of mining areas exist in Brazil, where high levels of metals have been found. However, studies of bioaccessibility of metals in soils/tailings from these areas are scarce, despite their potential informational contribution concerning exposure risks of residents near these areas. This study evaluated tailings collected from four sites of a zinc smelting area located in Brazil with aims to: (1) evaluate the presence of metals of potential concern; (2) investigate Cd and Pb bioaccessibility; and (3) determine the desorption kinetics of Cd and Pb. High concentrations of total Cd and Pb (up to 1743 mg Cd kg(-1) and 8675 mg Pb kg(-1)) and great variability were found in the tailings, indicating the importance of adequate planning for their final disposal, in order to avoid contamination in the surrounding environment. Cadmium and Pb bioaccessibility percentages in the intestinal phase were less than 47 and 4 %, respectively, which represents significant fractions not available for absorption in the intestinal tract. However, this material has to be monitored since its bioaccessibility may increase with eventual physicochemical changes, releasing Cd and Pb. Desorption kinetics experiments revealed that Pb in the samples remained in less labile fractions, whereas Cd was found in more labile fractions, which is in accordance with the bioaccessibility results.