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

Heavy metals and elderly kidney health: A multidimensional study through Enviro-target Mendelian Randomization

Chronic Kidney Disease (CKD), closely linked to environmental factors, poses a significant public health challenge. This study, based on 529 triple-repeated measures from key national environmental pollution area and multiple gene-related public databases, employs various epidemiological and bioinformatics models to assess the impact of combined heavy metal exposure (Chromium [Cr], Cadmium [Cd], and Lead [Pb]) on early renal injury and CKD in the elderly. Introducing the novel Enviro-Target Mendelian Randomization method, our research explores the causal relationship between metals and CKD. The findings indicate a positive correlation between increased levels of metal and renal injury, with combined exposure caused renal damage more significantly than individual exposure. The study reveals that metals primarily influence CKD development through oxidative stress and metal ion resistance pathways, focusing on three related genes (SOD2, MPO, NQO1) and a transcription factor (NFE2L2). Metals were found to regulate oxidative stress levels in the body by increasing the expression of SOD2, MPO, NQO1, and decreasing NFE2L2, leading to CKD onset. Our research establishes a new causal inference framework linking environmental pollutants-pathways-genes-CKD, assessing the impact and mechanisms of metal exposure on CKD. Future studies with more extensive in vitro evidence and larger population are needed to validate.

Synergistic susceptibility to environmental lead toxicity in chronic kidney disease

PURPOSE OF REVIEW

While high levels of lead exposure, as occurs accidentally or occupationally, can cause toxicity across multiple organ systems, the hazard of commonly encountered levels of lead in the environment remains unresolved. Challenges to researching the health effects of lead include its complex interplay with renal function, rendering analyses at risk of unaccounted confounding, and the likely small effect size of environmental levels of exposure. While children are known to be disproportionately susceptible to lead toxicity, resulting in appropriately more stringent regulatory surveillance for those under 5 years old, emerging evidence suggests that those with chronic kidney disease (CKD) similarly are at a greater risk. This review summarizes the role of environmental lead toxicity as a potential cause and consequence of CKD.

RECENT FINDINGS

Whether environmental lead exposure causes CKD remains debatable, with little recent research advancing the conflicting, mostly cross-sectional, analyses from years ago. However, an emerging body of evidence suggests that CKD increases the susceptibility to lead toxicity. Higher circulating lead levels and lower urinary excretion result in greater lead accumulation in CKD, with simultaneous greater risk of clinically meaningful disease. Recent studies suggest that levels of lead found commonly in the United States drinking water supply, and currently permissible by the Environmental Protection Agency, associate with hematologic toxicity in those with advanced CKD. Whether environmental lead contamination may have additional negative health impact among this at-risk population, including cardiovascular and neurocognitive disease, warrants further study.

SUMMARY

The underlying pathophysiology of kidney disease synergizes the susceptibility to environmental lead toxicity for those with CKD. Low levels of exposure, as found commonly in the United States water supply, may have adverse health impact in CKD. Further research will be needed to determine if more stringent environmental regulations are warranted to protect the health of all.

Metal concentrations and KIM-1 levels in school-aged children: a cross-sectional study

Environmental exposure to heavy metals and metalloids, originating from sources such as mining and manufacturing activities, has been linked to adverse renal effects. This cross-sectional study assessed children's exposure to these elements and its association with urinary kidney injury molecule-1 (KIM-1). We analyzed data from 99 school-aged children residing in nine localities within the state of Colima, Mexico, during the latter half of 2023. Levels of 23 metals/metalloids and urinary KIM-1 were measured using inductively coupled plasma mass spectrometry (ICP-MS) and enzyme-linked immunosorbent assay, respectively. Detectable levels of these contaminants were found in over 91% of participants, with varied exposure profiles observed across locations ( p = 0.019). After adjusting for confounding factors like gender, age, and locality, higher levels of six metals/metalloids (boron, cadmium, cesium, lithium, selenium, zinc) were significantly associated with increased KIM-1 levels. Tailored mitigation efforts are crucial to protect children from regional pollutant burdens. However, limitations exist, as our study did not capture all potential factors influencing heavy metal/metalloid and KIM-1 levels.

A comprehensive analysis of children's blood lead levels in Latin America and the Caribbean over the last eight years: Progress and recommendations

In 2017 we published a review on blood lead levels (BLL) in children from Latin America and the Caribbean (LAC) for data available up to 14th of March 2014 and recommended the identification and control of "lead hot spots". In the present study, an evaluation of progress toward reducing BLL in the region was carried out. A systematic review of the latest literature on lead exposure in the LAC region held on the PubMed, Web of Science and LILACS databases (January 2014 to March 2022) was conducted using the PRISMA methodology. Only original papers published in peer-reviewed English, Spanish, or Portuguese journals were eligible. A total of 558 papers were retrieved, 77 of which met the selection criteria and 31 (40.25 %) were carried out in Mexico. The prevalence of children with BLL above 10 μg. dL-1 was 22.08 % in the previous review versus 6.78 % in the current study. In the present review, the prevalence of children with BLL above 5 μg. dL-1 was 29.62 %, and only one study reported a BLL prevalence rate between 3.3 and 5 μg. dL-1. The highest BLLs were associated with well-known sources or occupational exposures. The number of countries (n = 13) that published data on BLL in children was lower compared to the previous review (n = 16). Most studies were conducted in areas with known lead exposure sources, similar to the earlier review. The percentage of children at risk of lead poisoning in the region remains unknown because few studies have published data on environmental exposure levels and most samples were relatively small. The recommendation to identify and control sources of lead exposure was maintained, while further suggestions for establishing a systematic public health surveillance system for lead were proposed to help reduce the knowledge gap and inform public health policy-making in LAC.

Systematic Review of Kidney Injury Biomarkers for the Evaluation of CKD of Uncertain Etiology

Introduction

Chronic kidney disease of uncertain etiology (CKDu) is an incompletely defined phenotype of chronic kidney disease (CKD) affecting young individuals mostly in agricultural communities in Central America and South Asia. CKDu is a diagnosis of exclusion made in individuals from endemic regions.

Methods

We conducted a systematic review of the primary literature on urinary and plasma kidney injury biomarkers measured in the setting of CKDu (through February 2023). The literature was identified via a Web of Science search and hand search of the references of previously identified literature. Search terms included "CKDu," "Mesoamerican Nephropathy," "CKD of unknown etiology," "Chronic Interstitial Nephritis in Agricultural Communities," "biomarker," "urin∗," and/or "plasma."

Results

A total of 25 papers were included. The 2 most frequently measured biomarkers were urinary kidney injury molecule-1 (KIM-1) and urinary neutrophil gelatinase-associated lipocalin (NGAL). There was substantial variability in study design, laboratory assay methods, and statistical methodology, which prohibited meta-analysis.

Conclusion

Biomarkers that identify tubulointerstitial disease early and accurately may substantially accelerate progress in the study of CKDu and facilitate public health approaches that eventually lead to its prevention and elimination. To date, the literature is limited by relatively small sample sizes and methodological limitations which should be addressed in future studies.

Associations among environmental exposure to trace elements and biomarkers of early kidney damage in the pediatric population

BACKGROUND

In kidney damage, molecular changes can be used as early damage kidney biomarkers, such as Kidney Injury Molecule-1 and Neutrophil gelatinase-associated lipocalin. These biomarkers are associated with toxic metal exposure or disturbed homeostasis of trace elements, which might lead to serious health hazards. This study aimed to evaluate the relationship between exposure to trace elements and early damage kidney biomarkers in a pediatric population.

METHODS

In Tlaxcala, a cross-sectional study was conducted on 914 healthy individuals. The participants underwent a medical review and a socio-environmental questionnaire. Five early damage kidney biomarkers were determined in the urine with Luminex, and molybdenum, copper, selenium, nickel, and iodine were measured with ICP-Mass.

RESULTS

The eGFR showed a median of 103.75 mL/min/1.73 m2. The median levels for molybdenum, copper, selenium, nickel, and iodine were 24.73 ng/mL, 73.35 ng/mL, 4.78 ng/mL, 83.68 ng/mL, and 361.83 ng/mL, respectively. Except for molybdenum and nickel, the other trace elements had significant associations with the eGFR and the early kidney damage biomarkers. Additionally, we report the association of different exposure scenarios with renal parameters.

DISCUSSION

and Conclusions. Among the explored metals, exposure to Cu and iodine impairs renal function. In contrast, Se may manifest as a beneficial metal. Interactions of Mo-Se and Mo-Iodine seem to alter the expression of NGAL; Mo-Cu for CLU; Mo-Cu, Mo-Se, and Mo-iodine for Cys-C and a-1MG; and Mo-Cu and Mo-iodine for KIM-1; were noticed. Our study could suggest that trace element interactions were associated with early kidney damage biomarkers.

Failing kidneys: Hotspots, blind spots and biopolitics of indifference

Chronic kidney disease of non-traditional cause (CKDnt) is commonly associated with monocropping agriculture, heat stress and impoverished working conditions, referred to as CKDnt "hotspots." The condition is also emerging in various sites of environmental contamination, raising questions as to whether multiple variants of the condition exist as a result of different ecologies and different human-environment interactions. This paper examines the emergence of CKDnt around Lake Chapala in Mexico, where we document local efforts to gain recognition and reparation for CKDnt. We follow the ways patients, families and activists have mobilized specific and interlocking infrastructural failures to enact complaint and confront state inaction and neglect of their bodies, communities, and environments. Though their labors have formally achieved little, we discuss how they make visible a biopolitics of indifference, one bound to the production of structural "blindspots."

Update of the risk assessment of inorganic arsenic in food

The European Commission asked EFSA to update its 2009 risk assessment on arsenic in food carrying out a hazard assessment of inorganic arsenic (iAs) and using the revised exposure assessment issued by EFSA in 2021. Epidemiological studies show that the chronic intake of iAs via diet and/or drinking water is associated with increased risk of several adverse outcomes including cancers of the skin, bladder and lung. The CONTAM Panel used the benchmark dose lower confidence limit based on a benchmark response (BMR) of 5% (relative increase of the background incidence after adjustment for confounders, BMDL05) of 0.06 μg iAs/kg bw per day obtained from a study on skin cancer as a Reference Point (RP). Inorganic As is a genotoxic carcinogen with additional epigenetic effects and the CONTAM Panel applied a margin of exposure (MOE) approach for the risk characterisation. In adults, the MOEs are low (range between 2 and 0.4 for mean consumers and between 0.9 and 0.2 at the 95th percentile exposure, respectively) and as such raise a health concern despite the uncertainties.

Threshold effect of urinary chromium on kidney function biomarkers: Evidence from a repeated-measures study

Chronic kidney disease (CKD) is a public health concern worldwide, and chromium exposure may be a risk factor due to its potential nephrotoxicity. However, research on the association between chromium exposure and kidney function especially the potential threshold effect of chromium exposure is limited. A repeated-measures study involving 183 adults (641 observations) was conducted from 2017 to 2021 in Jinzhou, China. Urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were measured as kidney function biomarkers. Generalized mixed models and two-piecewise linear spline mixed models were used to assess the dose-response relationship and potential threshold effect of chromium on kidney function, respectively. Temporal analysis was conducted by the latent process mixed model to depict the longitudinal change of kidney function over age. Urinary chromium was associated with CKD (odds ratio [OR] = 1.29; 95 % confidence interval [CI], 6.41, 14.06) and UACR (Percent change = 10.16 %; 95 % CI, 6.41 %, 14.06 %), and we did not find significant association between urinary chromium and eGFR (Percent change = 0.06 %; 95 % CI, -0.80 %, 0.95 %). The threshold analyses suggested the existence of threshold effects of urinary chromium, with inflection points at 2.74 μg/L for UACR and 3.95 μg/L for eGFR. Furthermore, we found that chromium exposure exhibited stronger kidney damage over age. Our study provided evidence for the threshold effects of chromium exposure on kidney function biomarkers and the heightened nephrotoxicity of chromium in older adults. More attention should be paid to the supervision of chromium exposure concentrations for preventing kidney damage, especially in older adults.

Anthropological perspectives on CKDnt in Mexico: time for a paradigm shift on the social determinants of health

In Mexico, the kidneys of individuals in poor and marginalized communities are failing with little warning and no explanation. Commonly referred to as chronic kidney disease of non-traditional origin (CKDnt), this new variant of kidney disease cannot be accounted for by conventional or discrete etiological explanations, but is instead understood to be a consequence of economic development, environmental degradation and precarious working and living conditions. Drawing on two interconnected ethnographic studies, and the intertwining problems of causation and care, this paper will (1) document the social conditions of disease emergence around Lake Chapala, Central Mexico, and (2) follow the haphazard routes kidney patients take to access resource-intensive biotechnical treatments. Its aim is to both challenge and reconceptualize social determinants as social relations in order to fully account for the profoundly contextual, temporal, and dynamic character of this condition, and to rethink opportunities for care and intervention.

Non-traditional risk factors of progression of chronic kidney disease in adult population: a scoping review

Chronic kidney disease (CKD) has become a public health concern over the last several years. Nowadays developed countries spend around 3% of their annual health-care budget on patients with CKD. According to the scientific community the most remarkable risk factors for CKD are diabetes and hypertension. Unknown CKD etiology has been reported as a global phenomenon including uncommon risk factors such as: dehydration, leptospirosis, heat stress, water quality, and others. This study aims to report non-traditional risk factors for ESRD based on a scoping review methodology. The scoping review methodology described by Arksey and O'Malley was used by performing an extensive review of the information. A total of 46 manuscripts were reviewed. The non-traditional ESRD risk factors are depicted based on six categories. Gender and ethnicity have been considered as risk factors for ESRD. Erythematous systemic lupus (ESL) is reported as an important risk factor for ESRD. Pesticide use has been an significant risk factor due to its effects on human and environmental health. Some compounds commonly used in homes against insects and plants are related to ESRD. Congenital and hereditary diseases in the urinary tract have been studied as a cause of ESRD in children and young adults. End-stage renal disease is a major concern for public health on a global level. As it can be seen, non-traditional risk factors are several and have different etiologies. It is necessary to put the issue on the table and add it to the public agenda in order to find multidisciplinary solutions.

Relationship between urinary biomarkers of early kidney damage and exposure to inorganic toxins in a pediatric population of Apizaco, Tlaxcala, Mexico

BACKGROUND

In recent years, chronic kidney disease has increased in the pediatric population and has been related to environmental factors. In the diagnosis of kidney damage, in addition to the traditional parameters, early kidney damage biomarkers, such as kidney injury molecule 1, cystatin C, and osteopontin, among others, have been implemented as predictors of early pathological processes.

OBJECTIVE

This study aimed to evaluate the relationship between exposure to environmental pollutants and early kidney damage biomarkers.

METHODS

A cross-sectional pilot study was conducted in February 2016 and involved 115 apparently healthy children aged 6-15 residing in Apizaco, Tlaxcala. Participant selection was carried out randomly from among 16,472 children from the municipality of Apizaco. A socio-demographic questionnaire included  age, sex, education, duration of residence in the area, occupation, water consumption and dietary habits, pathological history, and some non-specific symptoms. Physical examination included blood pressure, weight, and height. The urine concentrations of urinary aluminum, total arsenic, boron, calcium, chromium, copper, mercury, potassium, sodium, magnesium, manganese, molybdenum, lead, selenium, silicon, thallium, vanadium, uranium, and zinc, were measured. Four of the 115 participants selected for the study were excluded due to an incomplete questionnaire or lack of a medical examination, leaving a final sample population of 111 participants.

RESULTS

The results showed a mean estimated glomerular filtration rate of 89.1 ± 9.98 mL/min/1.73m2 and a mean albumin/creatinine ratio of 12.9 ± 16.7 mg/g urinary creatinine. We observed a positive and significant correlation between estimated glomerular filtration rate with fluoride, total arsenic and lead, and a correlation of albumin/creatinine ratio with fluoride, vanadium, and total arsenic. There was also a significant correlation between the early kidney damage biomarkers and fluoride, vanadium, and total arsenic, except for cystatin C.

CONCLUSION

In conclusion, our results show that four urinary biomarkers: α1-microglobulin, cystatin C, kidney injury molecule 1, and neutrophil gelatinase-associated lipocalin are related to environmental exposure to urinary fluoride, vanadium, and total arsenic in our pediatric population.

Epidemiological research progress in the effects of metal exposure on kidney

Chronic kidney disease (CKD) is suffered progressive loss of kidney function lasting more than 3 months and is classified according to the degree of kidney damage (level of proteinuria) and the decreased glomerular filtration rate (GFR). The most severe form of CKD is end-stage renal disease. The prevalence of CKD is high with fast growth rate and the disease burden has become increasingly serious. CKD has become an important public health problem threatening human health. The etiology of CKD is complex. In addition to genetic factors, environmental factors are an important cause of CKD. With the development of industrialization, environmental metal pollution has become increasingly severe, and its impact on human health has received widespread attention. A large number of studies have shown that metals such as lead, cadmium, and arsenic can accumulate in the kidney, which can cause damage to the structure and function of the kidney, and play an important role in the development of CKD. Therefore, summarizing the epidemiological research progress in the relationship between arsenic, cadmium, lead, and other metal exposures and kidney diseases can provide new ideas for the prevention and control of kidney diseases caused by metal exposure.

Trace Element Levels in Nails of Residents of Addis Ababa Are Shaped by Social Factors and Geography

The Akaki catchment in Ethiopia is home to Addis Ababa and about five million people. Its watercourses receive a variety of wastes released by the residents and industries. River water is being used for irrigation, livestock watering, and other domestic purposes. This study tested the hypothesis that the river pollution would be reflected in higher levels of trace elements in the nails of residents living in Akaki-Kality Sub-City in the downstream, as compared to those living in Gullele Sub-City in the upstream of the Akaki catchment. Samples were taken and subsequently analysed for metals using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Akaki-Kality were 488 ± 49, 106 ± 10, 5.2 ± 0.3, 13 ± 1.5, 11 ± 8, 2.2 ± 0.3, 0.09 ± 0.01, and 0.16 ± 0.01 μg/g, respectively. Likewise, the concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Gullele were 1035 ± 135, 251 ± 10, 6.6 ± 0.4, 31 ± 3.7, 7.4 ± 1.7, 2.0 ± 0.3, 0.63 ± 0.01, and 0.25 ± 0.01 μg/g, respectively. Co and Cd were not detected. Contrary to the initial hypothesis, higher metal levels were found in nails of residents living in the upstream rather than the downstream area of the catchment. In particular, the concentrations of Fe (p = 0.000), Zn (p = 0.01), and Mn (p = 0.000) were significantly elevated in nails from Gullele and also high in comparison with internationally reported values. Besides, geography and social factors, especially education level, correlated to trace metals in nails. Most of the elements were significantly lower in the nails of individuals with a university degree compared to those who were illiterate or only completed primary school.

Chemical Element Mixtures and Kidney Function in Mining and Non-Mining Settings in Northern Colombia

The exposure to chemical mixtures is a problem of concern in developing countries and it is well known that the kidney is the major target organ for toxic elements. This cross-sectional study aimed to estimate the individual and composite mixture effect of a large number of chemical elements on kidney function in gold-mining and surrounding non-mining populations in northeast Colombia. We measured concentrations of 36 chemical elements in hair as indicators of chronic exposure from 199 adult participants. We estimated the effect of exposure to mixtures of chemical elements on estimated glomerular filtration rate (eGFR) using weighted quantile sum regression (WQS). The WQS index of the mixture was associated with reduced eGFR (Coefficient -2.42; 95%CI: -4.69, -0.16) being Be, Cd, Pb, As, and Mn, the principal contributors of the toxic mixture. Mining activities and Hg concentration were not associated with decreased kidney function. Our results suggest that complex mixtures of chemical elements, mainly heavy metals, act as nephrotoxic in these populations and therefore the analysis of chemical element mixtures is a better approach to identify environmental and occupational chemical risks for kidney damage.

Joint Effect of Multiple Metals on Hyperuricemia and Their Interaction with Obesity: A Community-Based Cross-Sectional Study in China

Metal exposures have been inconsistently related to the risk of hyperuricemia, and limited research has investigated the interaction between obesity and metals in hyperuricemia. To explore their associations and interaction effects, 3300 participants were enrolled from 11 districts within 1 province in China, and the blood concentrations of 13 metals were measured to assess internal exposure. Multivariable logistic regression, restricted cubic spline (RCS), Bayesian kernel machine regression (BKMR), and interaction analysis were applied in the single- and multi-metal models. In single-metal models, five metals (V, Cr, Mn, Co, and Zn) were positively associated with hyperuricemia in males, but V was negatively associated with hyperuricemia in females. Following the multi-metal logistic regression, the multivariate-adjusted odds ratios (95% confidence intervals) of hyperuricemia were 1.7 (1.18, 2.45) for Cr and 1.76 (1.26, 2.46) for Co in males, and 0.68 (0.47, 0.99) for V in females. For V and Co, RCS models revealed wavy and inverted V-shaped negative associations with female hyperuricemia risk. The BKMR models showed a significant joint effect of multiple metals on hyperuricemia when the concentrations of five metals were at or above their 55th percentile compared to their median values, and V, Cr, Mn, and Co were major contributors to the combined effect. A potential interaction between Cr and obesity and Zn and obesity in increasing the risk of hyperuricemia was observed. Our results suggest that higher levels of Cr and Co may increase male hyperuricemia risk, while higher levels of V may decrease female hyperuricemia risk. Therefore, the management of metal exposure in the environment and diet should be improved to prevent hyperuricemia.

Seaweed polysaccharide relieves hexavalent chromium-induced gut microbial homeostasis

Heavy metals released in the environment pose a huge threat to soil and water quality, food safety and public health. Additionally, humans and other mammals may also be directly exposed to heavy metals or exposed to heavy metals through the food chain, which seriously threatens the health of animals and humans. Chromium, especially hexavalent chromium [Cr (VI)], as a common heavy metal, has been shown to cause serious environmental pollution as well as intestinal damage. Thus, increasing research is devoted to finding drugs to mitigate the negative health effects of hexavalent chromium exposure. Seaweed polysaccharides have been demonstrated to have many pharmacological effects, but whether it can alleviate gut microbial dysbiosis caused by hexavalent chromium exposure has not been well characterized. Here, we hypothesized that seaweed polysaccharides could alleviate hexavalent chromium exposure-induced poor health in mice. Mice in Cr and seaweed polysaccharide treatment group was compulsively receive K2Cr2O7. At the end of the experiment, all mice were euthanized, and colon contents were collected for DNA sequencing analysis. Results showed that seaweed polysaccharide administration can restore the gut microbial dysbiosis and the reduction of gut microbial diversity caused by hexavalent chromium exposure in mice. Hexavalent chromium exposure also caused significant changes in the gut microbial composition of mice, including an increase in some pathogenic bacteria and a decrease in beneficial bacteria. However, seaweed polysaccharides administration could ameliorate the composition of gut microbiota. In conclusion, this study showed that seaweed polysaccharides can restore the negative effects of hexavalent chromium exposure in mice, including gut microbial dysbiosis. Meanwhile, this research also lays the foundation for the application of seaweed polysaccharides.

Absence of significant association of trace elements in nails with urinary KIM-1 biomarker among residents of Addis Ababa in Upper Awash Basin, Ethiopia: a cross-sectional study

The Akaki River in the Upper Awash Basin, which flows through Addis Ababa, the capital city of Ethiopia, has been highly polluted by sewage from factories and residential areas. A population-based cross-sectional study was used to assess the association between trace elements and kidney injury from residents living in polluted areas downstream (Akaki-Kality) versus upstream (Gullele) in Sub-Cities of Addis Ababa. A total of 95 individuals (53 from Akaki-Kality and 42 from Gullele) were included in the study. Kidney injury molecule 1 (KIM-1), lead, arsenic, cadmium, cobalt, lead, manganese, zinc, iron, copper, chromium and nickel were evaluated in residents' urine and nail samples. A large proportion (74%) of the sample population contained KIM-1, including 81% residents in Akaki-Kality and 64% residents in Gullele. KIM-1 was, however, not significantly different (p = 0.05) between the two Sub-Cities, with median of 0.224 ng/mL in Akaki-Kality and 0.152 ng/mL in Gullele. Most of the analyzed elements, except Pb, As, Cd and Co, were found in all of the nail samples, with median (µg/g) in the range of 442‒714 Fe, 97.0‒246 Zn, 11.6‒24.1 Mn, 4.49‒5.85 Cu, 1.46‒1.66 Cr and 1.22‒1.41 Ni. The high incidence of KIM-1 indicates a potential for long term renal tubular damage among residents of the Sub-Cities. The concentrations of the elements in nails were, however, not significantly associated (p = 0.05) with the corresponding levels of KIM-1 in urine. Hence, the observed KIM-1 might be related to exposure to toxic substances or factors other than those included in this study.

Prenatal Metal Exposures and Associations with Kidney Injury Biomarkers in Children

Prenatal exposure to arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) may be nephrotoxic, yet limited studies have examined subclinical kidney injury biomarkers in children. We assessed whether metal exposure in the second trimester (2T), a crucial time of kidney development, is associated with altered urine kidney injury and function biomarkers in preadolescent children. Analyses included 494 children participating in a birth cohort study in Mexico City. Concentrations of As, Cd, and Pb were measured from pregnant women in 2T blood and urine, and Hg in urine only. Kidney biomarkers were measured from children in urine at age 8-12 years. We assessed the associations between individual metals and (1) kidney biomarkers using linear regression and (2) a multi-protein kidney mixture using weighted quantile sum (WQS) regression. Associations of separate urine and blood metal mixtures with individual kidney biomarkers were assessed via WQS. Within the multi-protein mixture, the association with increased urinary As was predominated by urine alpha-1-microglobulin (A1M), interferon gamma-induced protein 10 (IP10), and fatty acid binding protein 1; the association with increased urinary Cd was predominated by A1M, clusterin, and albumin. The urine metal mixture was associated with increased albumin (0.23 ng/mL; 95% confidence interval (CI): 0.10, 0.37), IP10 (0.15 ng/mL; 95% CI: 0.02, 0.28), and cystatin C (0.17 ng/mL; 95% CI: 0.04, 0.31); these associations were mainly driven by urinary As and Cd. We observed null associations between prenatal blood or urine metal mixtures and estimated glomerular filtration rate. Higher prenatal urinary metals, individually and as a mixture were associated with altered kidney injury biomarkers in children. Further research and longer participant follow-up are required to ascertain the risk of kidney disease later in life.

Assessment of Children's Metal Exposure via Hand Wipe, Outdoor Soil and Indoor Dust and Their Associations with Blood Biomarkers

The soil environment contributes considerably to human exposure to metals. This study aimed to comprehensively compare children's exposure to soil metals using different sampling approaches (i.e., hand wipe, indoor dust and outdoor soil) and assessment strategies, combing the method of external exposure evaluation and the correlation with internal biomarkers. Environmental exposure samples (hand wipe, outdoor soil and indoor dust), blood samples and child-specific exposure factors were simultaneously collected for 60 children aged 3 to 12 years from an area of northwestern China. Eight typical toxic metals were analyzed. Results showed that metal levels in hand wipes were associated with children's age, years of residency and the ground types of the play areas. Hand-to-mouth contact was an important pathway for children's metal exposure, with the corresponding oral exposure cancer risk to Cr already exceeding the maximum acceptable level. In comparison, metal concentrations in hand wipes were one to seven times higher than those in outdoor soil and indoor dust. Even greater discrepancies were found for the estimated exposure dose, which could lead to differences of several to dozens of times. In addition, Pb, Mn and Cr in hand wipes were significantly correlated with those in blood, whereas no relationships were found with soil and dust. This study indicates that the selection of different sampling and assessing strategies could lead to great differences in children metal exposure outcomes. It also suggests that hand wipe, which could reflect the true and integrated exposure level and the individual difference, serves as a better matrix to assess children's metal exposure compared to soil and dust. Further studies should standardize the sampling method for hand wipes and verify its applicability for other age groups.

Prenatal and early childhood critical windows for the association of nephrotoxic metal and metalloid mixtures with kidney function

INTRODUCTION

As renal development and maturation processes begin in utero and continue through early childhood, sensitive developmental periods arise during which metal exposures can program subclinical nephrotoxicity that manifests later in life. We used novel dentine biomarkers of established nephrotoxicants including arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr), and lithium (Li), and their mixtures, to identify critical windows of exposure-associated kidney function alterations in preadolescents.

METHODS

Participants included 353 children in the Programming Research in Obesity Growth, Environment and Social Stressors (PROGRESS) longitudinal birth cohort study based in Mexico City. Estimated glomerular filtration rate (eGFR) was assessed in 8-12 year old children using serum cystatin C measures. Pre- and postnatal metal(loid) concentrations were assessed in weekly increments by analyzing deciduous teeth with laser ablation-inductively coupled plasma-mass spectrometry. We used reverse distributed lag models (rDLMs) and lagged Weighted Quantile Sum (L-WQS) regression to examine time-varying associations between weekly perinatal metal(loid) exposure or metal(loid) mixtures and preadolescent eGFR while adjusting for age, sex, BMI z-score, SES and prenatal tobacco smoke exposure.

RESULTS

We identified a critical window of susceptibility to Pb exposure, in the late 3rd trimester (5 weeks prior to birth) during which higher Pb exposure was associated with children's increased eGFR. When all elements were assessed as a mixture, we identified late 2nd/early 3rd trimester (weeks 8-17 of gestation) as a window of vulnerability associated with decreased eGFR, with Li and Cr contributing the greatest weights to the association. When stratified by sex, we observed stronger effects among boys than girls.

CONCLUSIONS

Using tooth-matrix biomarkers, we identified discrete developmental exposure windows wherein Pb and metal(loid) mixtures were associated with altered preadolescent kidney function.

Nephrotoxic Biomarkers with Specific Indications for Metallic Pollutants: Implications for Environmental Health

Environmental and occupational exposure to heavy metals and metalloids is a major global health risk. The kidney is often a site of early damage. Nephrotoxicity is both a major consequence of heavy metal exposure and potentially an early warning of greater damage. A paradigm shift occurred at the beginning of the 21st century in the field of renal medicine. The medical model of kidney failure and treatment began to give way to a social model of risk factors and prevention with important implications for environmental health. This development threw into focus the need for better biomarkers: markers of exposure to known nephrotoxins; markers of early damage for diagnosis and prevention; markers of disease development for intervention and choice of therapy. Constituents of electronic waste, e-waste or e-pollution, such as cadmium (Cd), lead (Pb), mercury (HG), arsenic (As) and silica (SiO₂) are all potential nephrotoxins; they target the renal proximal tubules through distinct pathways. Different nephrotoxic biomarkers offer the possibility of identifying exposure to individual pollutants. In this review, a selection of prominent urinary markers of tubule damage is considered as potential tools for identifying environmental exposure to some key metallic pollutants.

Arsenic Exposure through Dietary Intake and Associated Health Hazards in the Middle East

Dietary arsenic (As) contamination is a major public health issue. In the Middle East, the food supply relies primarily on the import of food commodities. Among different age groups the main source of As exposure is grains and grain-based food products, particularly rice and rice-based dietary products. Rice and rice products are a rich source of core macronutrients and act as a chief energy source across the world. The rate of rice consumption ranges from 250 to 650 g per day per person in South East Asian countries. The source of carbohydrates through rice is one of the leading causes of human As exposure. The Gulf population consumes primarily rice and ready-to-eat cereals as a large proportion of their meals. Exposure to arsenic leads to an increased risk of non-communicable diseases such as dysbiosis, obesity, metabolic syndrome, diabetes, chronic kidney disease, chronic heart disease, cancer, and maternal and fetal complications. The impact of arsenic-containing food items and their exposure on health outcomes are different among different age groups. In the Middle East countries, neurological deficit disorder (NDD) and autism spectrum disorder (ASD) cases are alarming issues. Arsenic exposure might be a causative factor that should be assessed by screening the population and regulatory bodies rechecking the limits of As among all age groups. Our goals for this review are to outline the source and distribution of arsenic in various foods and water and summarize the health complications linked with arsenic toxicity along with identified modifiers that add heterogeneity in biological responses and suggest improvements for multi-disciplinary interventions to minimize the global influence of arsenic. The development and validation of diverse analytical techniques to evaluate the toxic levels of different As contaminants in our food products is the need of the hour. Furthermore, standard parameters and guidelines for As-containing foods should be developed and implemented.

Mechanistic understanding of the toxic effects of arsenic and warfare arsenicals on human health and environment

Worldwide, more than 200 million people are estimated to be exposed to unsafe levels of arsenic. Chronic exposure to unsafe levels of groundwater arsenic is responsible for multiple human disorders, including dermal, cardiovascular, neurological, pulmonary, renal, and metabolic conditions. Consumption of rice and seafood (where high levels of arsenic are accumulated) is also responsible for human exposure to arsenic. The toxicity of arsenic compounds varies greatly and may depend on their chemical form, solubility, and concentration. Surprisingly, synthetic organoarsenicals are extremely toxic molecules which created interest in their development as chemical warfare agents (CWAs) during World War I (WWI). Among these CWAs, adamsite, Clark I, Clark II, and lewisite are of critical importance, as stockpiles of these agents still exist worldwide. In addition, unused WWII weaponized arsenicals discarded in water bodies or buried in many parts of the world continue to pose a serious threat to the environment and human health. Metabolic inhibition, oxidative stress, genotoxicity, and epigenetic alterations including micro-RNA-dependent regulation are some of the underlying mechanisms of arsenic toxicity. Mechanistic understanding of the toxicity of organoarsenicals is also critical for the development of effective therapeutic interventions. This review provides comprehensive details and a critical assessment of recently published data on various chemical forms of arsenic, their exposure, and implications on human and environmental health.

Cadmium toxicity symptoms and uptake mechanism in plants: a review

Cadmium (Cd) is one of non-essential heavy metals which is released into environment naturally or anthropogenically. It is highly persistent toxic metals that are exceptionally distressing industrial and agriculture activities by contaminating soil, water and food. Its long-duration endurance in soil and water results in accumulation and uptake into plants, leading to the food chain. This becomes a serious global problem threatening humans and animals as food chain components. Living organisms, especially humans, are exposed to Cd through plants as one of the main vegetative food sources. This review paper is concentrated on the symptoms of the plants affected by Cd toxicity. The absorption of Cd triggers several seen and unseen symptoms by polluted plants such as stunted growth, chlorosis, necrosis and wilting. Apart from that, factors that affect the uptake and translocation of Cd in plants are elaborated to understand the mechanism that contributes to its accumulation. By insight of Cd accumulation, this review also discussed the phytoremediation techniques-phytoextraction, phytostimulation, phytostabilization, phytovolatization and rhizofiltration in bioremediating the Cd.

Assessment of biomarkers of early kidney damage and exposure to pollutants in artisanal mercury mining workers from Mexico

Artisanal mercury mining (AMM) is an informal economic activity that employs low technology and limited protection, and poses a risk to workers and their families; due to the extraction process, these scenarios involve exposure to complex mixtures of pollutants that synergistically aggravate the health of miners and people living near the site. Although mercury is the predominant pollutant, there are others such as polycyclic aromatic hydrocarbons (PAHs), toluene, arsenic, and lead which have been classified as nephrotoxic pollutants. Therefore, the purpose of this research was to evaluate the association between exposure to a complex mixture of pollutants (mercury, lead, arsenic, PAHs, and toluene) and kidney damage in artisanal Hg mining workers through early kidney damage proteins (KIM-1, OPN, RBP-4, NGAL, and Cys-C). The results demonstrate the presence of OH-PAHs at concentrations of 9.21 (6.57-80.63) μg/L, hippuric acid as a biomarker of exposure to toluene, As and Pb (655. 1 (203.8-1231) mg/L, 24.05 (1.24-42.98) g/g creatinine, and 4.74 (2.71-8.14) g/dL, respectively), and urinary Hg (503.4 (177.9-878.7) g/g creatinine) in the study population. As well as biomarkers of kidney damage, NGAL and RPB-4 were found in 100% of the samples, KIM-1 and Cys-C in 44.1%, and OPN in 41% of the miners. Significant correlations were found between several of the evaluated pollutants and early kidney damage proteins. Our results demonstrate the application of the early kidney damage biomarkers for the assessment of damage caused by the exposure to mixtures of pollutants and, therefore, the urgent need for monitoring in AMM areas.

Pollution characteristics and human health risk assessments of toxic metals and particle pollutants via soil and air using geoinformation in urbanized city of Pakistan

Toxic metals and particle pollutants in urbanized cities have significantly increased over the past few decades mainly due to rapid urbanization and unplanned infrastructure. This research aimed at estimating the concentration of toxic metals and particle pollutants and the associated risks to public health across different land-use settings including commercial area (CA), urban area (UA), residential area (RA), and industrial area (IA). A total of 47 samples for both soil and air were collected from different land-use settings of Faisalabad city in Pakistan. Mean concentrations of toxic metals such as Mn, Zn, Pb, Ni, Cr, Co, and Cd in all land-use settings were 92.68, 4.06, 1.34, 0.16, 0.07, 0.03, and 0.02 mg kg^-1, respectively. Mean values of PM₁₀, PM_2.5, and Mn in all land-use settings were found 5.14, 1.34, and 1.9 times higher than the World Health Organization (WHO) guidelines. Mn was found as the most hazardous metal in terms of pollution load index (PLI) and contamination factor (CF) in the studied area. Health risk analysis for particle pollutants using air quality index (AQI) and geoinformation was found in the range between good to very critical for all the land-use settings. The hazard quotient (HQ) and hazard index (HI) were higher for children in comparison to adults, suggesting that children may be susceptible to potentially higher health risks. However, the cancer risk (CR) value for Pb ingestion (1.21 × 10^-6) in children was lower than the permissible limit (1 × 10^-4 to 1 × 10^-6). Nonetheless, for Cr inhalation, CR value (1.09 × 10^-8) was close to tolerable limits. Our findings can be of valuable assistance toward advancing our understanding of soil and air pollutions concerning public health in different land-use settings of the urbanized cities of Pakistan.

Arsenic exposure and non-carcinogenic health effects

Inorganic arsenic (iAs) exposure is a serious health problem that affects more than 140 million individuals worldwide, mainly, through contaminated drinking water. Acute iAs poisoning produces several symptoms such as nausea, vomiting, abdominal pain, and severe diarrhea, whereas prolonged iAs exposure increased the risk of several malignant disorders such as lung, urinary tract, and skin tumors. Another sensitive endpoint less described of chronic iAs exposure are the non-malignant health effects in hepatic, endocrine, renal, neurological, hematological, immune, and cardiovascular systems. The present review outlines epidemiology evidence and possible molecular mechanisms associated with iAs-toxicity in several non-carcinogenic disorders.

Evaluation of hydroxylated metabolites of polycyclic aromatic hydrocarbons and biomarkers of early kidney damage in indigenous children from Ticul, Yucatán, Mexico

Polycyclic aromatic hydrocarbons (PAHs) are environmental persistent chemicals, produced by the incomplete combustion of solid fuels, found in smoke. PAHs are considered carcinogenic, teratogenic, and genotoxic. Children are susceptible to environmental pollutants, particularly those living in high-exposure settings. Therefore, the main objective of this study was to evaluate the exposure to PAHs through hydroxylated metabolites of PAHs (OH-PAHs), 1-hydroxynaphtalene (1-OH-NAP), and 2-hydroxynaphtalene (2-OH-NAP); 2-,3-, and 9-hydroxyfluorene (2-OH-FLU, 3-OH-FLU, 9-OH-FLU); 1-,2-,3-, and 4-hydroxyphenanthrene (1-OH-PHE, 2-OH-PHE, 3-OH-PHE, 4-OH-PHE); and 1-hydroxypyrene (1-OH-PYR), as well as kidney health through biomarkers of early kidney damage (osteopontin (OPN), neutrophil gelatinase-associated lipocalin (NGAL), α1-microglobulin (α1-MG), and cystatin C (Cys-C)) in children from an indigenous community dedicated to footwear manufacturing and pottery in Ticul, Yucatán, Mexico. The results show a high exposure to PAHs from the found concentrations of OH-PAHs in urine in 80.5% of the children in median concentrations of 18.4 (5.1-71.0) μg/L of total OH-PAHs, as well as concentrations of kidney damage proteins in 100% of the study population in concentrations of 4.8 (3-12.2) and 7.9 (6.5-13.7) μg/g creatinine of NGAL and Cys-C respectively, and 97.5% of the population with concentrations of OPN and α1-MG at mean concentrations of 207.3 (119.8-399.8) and 92.2 (68.5-165.5) μg/g creatinine. The information provided should be considered and addressed by the health authorities to establish continuous biomonitoring and programs to reduce para-occupational exposure in the vulnerable population, particularly children, based on their fundamental human right to health.

Cadmium promotes apoptosis and inflammation via the circ08409/miR-133a/TGFB2 axis in bovine mammary epithelial cells and mouse mammary gland

Cadmium is a common environmental heavy metal pollutant that can accumulate over long periods of time and cause disease. Thus, analysis of the molecular mechanisms affected by cadmium in the body could be of great significance for the prevention and treatment of cadmium-related diseases. In this study, flow cytometry, immunofluorescence, transmission electron microscopy, H&E (Hematoxylin Eosin) staining and TUNEL (TdT-mediated dUTP Nick-End Labeling) assays were used to verify that cadmium induced apoptosis and immune responses in bovine mammary epithelial cells (BMECs) and in mouse mammary gland. Isolated BMECs cultured with or without cadmium were collected to screen miRNA (microRNA) using high-throughput sequencing. There were 42 differentially-expressed miRNAs among which 27 were upregulated and 15 downregulated including bta-miR-133a, bta-miR-23b-5p, bta-miR-29e, bta-miR-365-5p, bta-miR-615, bta-miR-7, bta-miR-11975, bta-miR-127, and bta-miR-411a. Among those, miR-133a (which can specifically target TGFB2 (Recombinant Transforming Growth Factor Beta 2) was the most significantly downregulated with a fold-change of 5.27 in BMECs cultured with cadmium. Application of the double luciferase reporter system, western blotting, and qRT-PCR (Quantitative Real-time PCR) revealed that circ08409 can directly bind to miR-133a. Experiments demonstrated that circRNA-08409 could adsorb bta-miR-133a. Both circ08409 and TGFB2 significantly increased apoptosis and altered expression level of a series of inflammatory factors in BMECs. In contrast, miR-133a decreased significantly apoptosis and inflammation in the cells. Compared with cultures receiving only cadmium, the miR-133a+cadmium cultures exhibited significant reductions in the occurrence of late apoptosis. Overall, results indicated that circ08409 could relieve the inhibitory effect of miR-133a on TGFB2 expression by combining with miR-133a and subsequently modulating cell proliferation, apoptosis and inflammation. Overall, the data suggested that the circ08409/miR-133a/TGFB2 axis might play a role in mediating the effect of cadmium on BMECs. As such, data provide novel insights into controlling hazards that cadmium could induce in the mammary gland.

Drinking water heavy metal toxicity and chronic kidney diseases: a systematic review

Heavy metals in drinking water can threat human health and may induce several diseases. The association between heavy metals exposure and chronic kidney disease (CKD) has been indicated by few epidemiological studies. We conducted a systematic review of the epidemiologic publications of the association between exposure to heavy metals through drinking water and CKD. Keywords related to heavy metals and kidney diseases on MeSH were identified and searched in PubMed, Google Scholar, Scopus, Ovid-Medline and Web of Science until July 2020. 14 publications met our inclusion criteria and included in the current review. The included articles were conducted on the association between arsenic, cadmium, lead and chromium in drinking water and CKD. Our study could not find strong evidence between heavy exposure to through drinking water and CKD, except for arsenic. The negative association was found between arsenic and lead and glomerular filtration rate (eGFR). The positive correlation was observed between cadmium exposure and urinary N-acetyl-β-d-glucosaminidase (NAG) concentrations, and also arsenic and chromium exposure and kidney injury molecule (KIM-1). Assessment of studies showed an association between arsenic, cadmium, lead and chromium and albuminuria and proteinuria, without CKD outcomes. Current systematic study showed few evidence for exposure to arsenic, cadmium, lead and chromium through drinking water and incidence of kidney problems. However, more epidemiological studies are required to confirm this association.

Micro RNA (miRNA) Differential Expression and Exposure to Crude-Oil-Related Compounds

This review summarizes studies on miRNA differential regulation related to exposure to crude oil and 20 different crude oil chemicals, such as hydrocarbons, sulphur, nitrogen, and metal- containing compounds. It may be interesting to explore the possibility of using early post-transcriptional regulators as a potential novel exposure biomarker.

Crude oil has been defined as a highly complex mixture of solids, liquids, and gases. Given the toxicological properties of the petroleum components, its extraction and elaboration processes represent high-risk activities for the environment and human health, especially when accidental spills occur. The effects on human health of short-term exposure to petroleum are well known, but chronic exposure effects may variate depending on the exposure type (i.e., work, clean-up activities, or nearby residence).

As only two studies are focused on miRNA differential expression after crude-oil exposure, this review will also analyse the bibliography concerning different crude-oil or Petroleum-Related Compounds (PRC) exposure in Animalia L. kingdom and how it is related to differential miRNA transcript levels. Papers include in vitro, animal, and human studies across the world.

A list of 10 miRNAs (miR-142-5p, miR-126-3p, miR-24-3p, miR-451a, miR-16-5p, miR-28-5p, let-7b-5p, miR-320b, miR-27a-3p and miR-346) was created based on bibliography analysis and hypothesised as a possible “footprint” for crude-oil exposure. miRNA differential regulation can be considered a Big-Data related challenge, so different statistical programs and bioinformatics tools were used to have a better understanding of the biological significate of the most interesting data.

Biomarkers of effect as determined in human biomonitoring studies on hexavalent chromium and cadmium in the period 2008-2020

A number of human biomonitoring (HBM) studies have presented data on exposure to hexavalent chromium [Cr(VI)] and cadmium (Cd), but comparatively few include results on effect biomarkers. The latter are needed to identify associations between exposure and adverse outcomes (AOs) in order to assess public health implications. To support improved derivation of EU regulation and policy making, it is of great importance to identify the most reliable effect biomarkers for these heavy metals that can be used in HBM studies. In the framework of the Human Biomonitoring for Europe (HBM4EU) initiative, our study aim was to identify effect biomarkers linking Cr(VI) and Cd exposure to selected AOs including cancer, immunotoxicity, oxidative stress, and omics/epigenetics. A comprehensive PubMed search identified recent HBM studies, in which effect biomarkers were examined. Validity and applicability of the markers in HBM studies are discussed. The most frequently analysed effect biomarkers regarding Cr(VI) exposure and its association with cancer were those indicating oxidative stress (e.g., 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), glutathione (GSH)) and DNA or chromosomal damage (comet and micronucleus assays). With respect to Cd and to some extent Cr, β-2-microglobulin (B2-MG) and N-acetyl-β-D-glucosaminidase (NAG) are well-established, sensitive, and the most common effect biomarkers to relate Cd or Cr exposure to renal tubular dysfunction. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule (KIM)-1 could serve as sensitive biomarkers of acute kidney injury in response to both metals, but need further investigation in HBM studies. Omics-based biomarkers, i.e., changes in the (epi-)genome, transcriptome, proteome, and metabolome associated with Cr and/or Cd exposure, are promising effect biomarkers, but more HBM data are needed to confirm their significance. The combination of established effect markers and omics biomarkers may represent the strongest approach, especially if based on knowledge of mechanistic principles. To this aim, also mechanistic data were collected to provide guidance on the use of more sensitive and specific effect biomarkers. This also led to the identification of knowledge gaps relevant to the direction of future research.

Exposure to polycyclic aromatic hydrocarbon mixtures and early kidney damage in Mexican indigenous population

The traditions and habits of indigenous communities in México include the use of wood and biomass burning to cook their food, which generates large amounts of smoke and therefore pollution inside the households. This smoke is composed of a complex mixture of polycyclic aromatic hydrocarbons (PAHs) which at high levels of exposure cause carcinogenic, genotoxic effects and some chronic pulmonary and cardiovascular diseases; however, few studies relate kidney health with exposure to PAHs. Thus, the aim of this study was the evaluation of 10 hydroxylated metabolites of PAHs (OH-PAHs), and their correlation with biomarkers of early kidney damage renal (cystatin-C (Cys-C)), osteopontin (OPN), retinol-binding protein-4 (RPB-4), and neutrophil gelatinase-associated lipocalin (NGAL) in the indigenous population of the Huasteca Potosina in Mexico. The results demonstrate the presence of the OH-PAHs and kidney damage biomarkers in 100% of the study population. The OH-PAHs were shown in the following order of frequency, 1-OH-PYR > 4-OH-PHE > 2-OH-NAP > 1-OH-NAP > 9-OH-FLU > 3-OH-FLU > 2-OH-FLU > 3-OH-PHE and with the following percentages of detection 97.6, 87.8, 78, 73.2, 68.3, 31.7, 14.6, and 12.2%, respectively. NGAL and RBP-4 were present in above 85% of the population, with mean concentrations of 78.5 ± 143.9 and 139.4 ± 131.7 ng/g creatinine, respectively, OPN (64%) with a mean concentration of 642.6 ± 723.3 ng/g g creatinine, and Cys-C with a mean concentration of 33.72 ± 44.96 ng/g creatinine. Correlations were found between 1-OH-NAP, 2-OH-NAP, 9-OH-FLU, and 4-OH-PHE and the four biomarkers of early kidney damage. 3-OH-FLU with OPN and 1-OH-PYR correlated significantly with NGAL, OPN, and RPB-4.

Lead (Pb) exposure is associated with changes in the expression levels of circulating miRNAS (miR-155, miR-126) in Mexican women

The environmental contamination with lead (Pb) is considered a critical issue worldwide. Therefore, this study aimed to evaluate the expression levels of circulating miRNAs (miR-155, miR-126, and miR-145) in Mexican women exposed to Pb. Blood lead levels (BLL) were assessed in enrolled women (n = 190) using an atomic absorption method. Also, serum miRNAs expression levels were quantified through a real-time PCR assay. A mean BLL of 10.5 ± 4.50 μg/dL was detected. Overexpression of miR-155 was detected in highly exposed women. Besides, a significant simple positive relationship (p < 0.05) was found between BLL and serum miR-155 expression levels. Additionally, a significant inverse correlation (p < 0.05) was determined between BLL and serum miR-126 expression levels, as downregulation of miR-126 expression levels was observed in highly exposed women. The findings in this study are the concern, as epigenetic changes detected may represent a connection between health illnesses and Pb exposure.

Occupational Paraquat and Glyphosate Exposure May Decline Renal Functions among Rural Farming Communities in Sri Lanka

Extensive use of herbicides is common among rural agricultural workers in Sri Lanka. Recent studies have postulated their role in the development of chronic kidney disease of unknown etiology (CKDu). Paraquat and glyphosate are leading herbicides used by sugarcane farmers (SF), hence occupational exposure is inevitable. This study examined the expression of urinary paraquat, glyphosate and biomarkers among residential SF in CKDu emerging regions, Warunagama (WA) and Rahathangama (RH), in the Uva Province with non-endemic Matara (MA) in the Southern Province of Sri Lanka. Urinary glyphosate, Paraquat, kidney injury molecule -1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL) and β2-microglobulin (B2M) were determined using enzyme-linked immunosorbent assays (ELISA). Urinary creatinine, microalbumin, serum creatinine (SCr), serum cystatin C, estimated glomerular filtration rate (eGFR), and albumin creatinine ratio (ACR) were also assessed. Generally, herbicide residues and kidney injury biomarkers were higher in SF compared to the non-endemic MA. Creatinine-adjusted urinary glyphosate and paraquat levels were significantly higher in WA compared to MA. ACR in RH (median 14.9; IQR 5.4-393.1 mg/g) and WA (23.7; 11.5-64.6) was significantly higher than MA (4.3; 2.2-6.7). This study reports 39 individuals with impaired kidney function among SF in Sri Lanka for the first time. Urinary NGAL levels were significantly higher in both WA (median 2.14; IQR 1.28-6.15 ng/mg Cr) and RH (3.09; 1.15-9.09) compared to MA (1.28; 0.56-2.81). However, urinary KIM-1 levels in RH (3.2; 1.29-106.1 ng/g Cr) and WA (3.6; 1.94-115.1) were not significantly higher in MA (1.74; 0.76-116.9). Urinary NGAL (r = 0.493), eGFR (r = -0.147) and ACR (r = 0.171) significantly correlated with urinary glyphosate, but not with urinary paraquat levels. Urinary KIM-1 levels did not correlate with either urinary glyphosate or paraquat, while urinary B2M and serum cystatin C levels showed significant correlation with urinary glyphosate levels. The current study reports higher urinary herbicide levels among sugarcane farmers in WA and RH, and that is potentially linked to the subsequent decline in kidney function, as indicated by ACR, eGFR, and NGAL. We posit that these indicators may serve as markers to detect renal injury among herbicide-exposed SF in Rural Sri Lanka.

Effect of embedded metal fragments on urinary metal levels and kidney biomarkers in the Sprague-Dawley rat

BACKGROUND

Wounds with embedded metal fragments are an unfortunate consequence of armed conflicts. In many cases the exact identity of the metal(s) and their long-term health effects, especially on the kidney, are not known.

AIM OF STUDY

The aim of this study was to quantitate the urinary levels of metals solubilized from surgically implanted metal pellets and to assess the effect of these metals on the kidney using a battery of biomarker assays.

MATERIALS AND METHODS

Using a rodent model system developed in our Institute to simulate embedded fragment injuries, eight metals considered likely components of an embedded fragment wound were individually implanted into the gastrocnemius muscle of male Sprague-Dawley rats. The rats were followed for 12 months post-implantation with urine collected prior to surgery then at 1-, 3-, 6-, 9-, and 12-months post-implantation to provide a within-subjects cohort for examination. Urinary metal levels were determined using inductively coupled plasma-mass spectrometry and urinary biomarkers assessed using commercially available kits to determine metal-induced kidney effects.

RESULTS

With few exceptions, most of the implanted metals rapidly solubilized and were found in the urine at significantly higher levels than in control animals as early as 1-month post-implantation. Surprisingly, many of the biomarkers measured were decreased compared to control at 1-month post-implantation before returning to normal at the later time points. However, two metals, iron and depleted uranium, showed increased levels of several markers at later time points, yet these levels also returned to normal as time progressed.

CONCLUSION

This study showed that metal pellets surgically implanted into the leg muscle of Sprague-Dawley rats rapidly solubilized with significant levels of the implanted metal found in the urine. Although kidney biomarker results were inconsistent, the changes observed along with the relatively low amounts of metal implanted, suggest that metal-induced renal effects need to be considered when caring for individuals with embedded metal fragment wounds.

Concentrations of selected arsenic species in urine across various stages of renal function including hyperfiltration

Data (N = 10,590) from National Health and Nutrition Examination Survey for 2005-2016 for US adults aged ≥ 20 years were analyzed to study how concentrations of arsenobetaine (UAB), monomethylarsonic acid (UMMA), dimethylarsenic acid (UDMA), and total arsenic (UAS) in urine vary across the stages of renal function (RF). Data were analyzed over RF-1A (eGFR > 110 mL/min/1.73 m²), RF-1B (eGFR between 90 and 110 mL/min/1.73 m²), RF-2 (eGFR between 60 and 90 mL/min/1.73 m²), RF-3A (eGFR between 45 and 60 mL/min/1.73 m²), and RF-3B/4 (eGFR between 15 and 45 mL/min/1.73 m²). Adjusted geometric mean (AGM) concentrations of the total population, males, and females for UAS, UAB, and UDMA were observed to follow inverted U-shaped distributions with points of inflection located at RF-3A. For example, adjusted concentrations for the total population for UAS were 8.8, 8.8, 9.5, 11.7, and 9.6 μg/L for those in RF-1A, RF-1B, RF-2, RF-3A, and RF-3B/4 respectively. While statistically significant differences were only occasionally observed, males, in general, had lower AGMs than females for UAS and UDMA, but females had lower AGMs than males for UAB. Among the various racial/ethnic groups, non-Hispanic whites had the lowest adjusted concentrations of all four arsenic variables. Adjusted levels of all four arsenic variables were observed to decrease over survey years of 2005-2006 through 2015-2016. However, statistical significance was not necessarily reached for all RF stages. Smoking was associated with reduced levels of four arsenic variables over RF-1A through RF-2. Diabetes was associated with increased levels of UMMA and UDMA at RF-2.

Effects of Untreated Drinking Water at Three Indigenous Yaqui Towns in Mexico: Insights from a Murine Model

Background: Reports in a northwestern Mexico state linked arsenic (As) in drinking water to DNA damage in people from indigenous communities. However, this correlation remains under discussion due to unknown variables related to nutrition, customs, and the potential presence of other metal(oid)s. Methods: To determine this association, we sampled water from three Yaqui towns (Cócorit, Vícam, and Pótam), and analyzed the metals by ICP-OES. We exposed four separate groups, with five male CD-1 mice each, to provide further insight into the potential effects of untreated drinking water. Results: The maximum concentrations of each metal(oid) in µg·L⁻¹ were Sr(819) > Zn(135) > As(75) > Ba(57) > Mo(56) > Cu(17) > Al(14) > Mn(12) > Se(19). Histological studies revealed brain cells with angulation, satellitosis, and reactive gliosis with significant statistical correlation with Mn and As. Furthermore, the liver cells presented hepatocellular degeneration. Despite the early response, there is no occurrence of both statistical and significative changes in hematological parameters. Conclusions: The obtained results provide experimental insights to understand the potential effects of untreated water with low As and Mn contents in murine models. This fact is noteworthy because of the development of histological changes on both the brain and liver at subchronic exposure.

Urinary MicroRNAs in Environmental Health: Biomarkers of Emergent Kidney Injury and Disease

PURPOSE OF REVIEW

There is a critical need for sensitive biomarkers of renal disease and progression. Micro(mi)RNAs are attractive as next-generation biomarkers in kidney disease, particularly as urine miRNAs can inform kidney function and cellular integrity. This review summarizes recent epidemiologic and toxicologic advances using urinary miRNAs and exosomal miRNAs as novel biomarkers of chemical exposure and of kidney damage and disease.

RECENT FINDINGS

Urine miRNA biomarkers offer improved stability over protein in stored samples, relative ease of collection and quantitation, and conserved sequence homology across species. Particularly in the case of emergent environmental health threats such as chronic kidney disease of unknown origin, urinary miRNAs hold promise as biomarkers of disease and/or exposure. We present evidence to address scientific knowledge gaps, comment on the relevance of urine-derived miRNAs in environmental health research, and discuss limitations and recommendations for future directions needed to advance miRNA biomarker strategies.

Exposure to an Extended-Interval, High-Dose Gentamicin Regimen in the Neonatal Period Is Not Associated With Long-Term Nephrotoxicity

Objectives: To assess the association between gentamicin exposure and subclinical signs of nephrotoxicity in school children who were exposed to a high-dose gentamicin regimen in the neonatal period. Methods: Children receiving three or more doses (6 mg/kg) of gentamicin as neonates were invited to a follow-up in school age. We evaluated potential signs of subclinical nephrotoxicity with four validated urine biomarkers: protein-creatinine ratio (PCR), albumin-creatinine ratio (ACR), kidney injury molecule-1 (KIM-1), and N-acetyl-beta-D-glucosaminidase (NAG) normalized for urine creatinine (NAG-Cr). In addition, blood pressure was measured. The measures of gentamicin exposure were cumulative dose (mg/kg) and highest trough plasma concentration (TPC) in mg/L. We used logistic and linear regression and non-parametric kernel regression to analyze the relationship between gentamicin exposure and the urine biomarkers. Results: A total of 222 gentamicin exposed children were included. As neonates, the children were exposed to a median (interquartile range-IQR) cumulative gentamicin dose of 36 (26-42) mg/kg and the median (IQR) TPC was 1.0 (0.7-1.3) mg/L. At follow-up, 15 children (6.8%) had either one abnormal urine biomarker value (13 children) or two abnormal urine biomarker values (2 children). These 17 biomarker values were all marginally above the suggested upper cutoff, and included the following markers; KIM-1 (n = 2), NAC-Cr (n = 5), ACR (n = 6), and PCR (n = 4). All other 207 children had normal sets of all four urine biomarkers. One child had hypertension. There were no differences in gentamicin exposure, gestational age (GA) at birth or birth weight between the group of 15 children with one or two abnormal urine biomarker values compared to the other 207 children who had normal biomarker values. Using different regression analyses, we did not find any association between gentamicin exposure (cumulative dose and/or TPC) and the urine biomarker values. Conclusions: Exposure to an extended-interval, high-dose gentamicin regimen in the neonatal period was not associated with signs of subclinical nephrotoxicity in schoolchildren. We therefore suggest that the gentamicin treatment regimen evaluated in this study is safe in terms of long-term nephrotoxicity. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT03253614.

Effect of gene-environment interaction (arsenic exposure - PON1 Q192R polymorphism) on cardiovascular disease biomarkers in Mexican population

Cardiovascular diseases (CVDs) are the primary cause of death worldwide. However, little is known about how the interaction between risk factors affects CVDs. Therefore, the aim of this study was to evaluate the effect of the gene-environment interaction (arsenic exposure x PON1 Q192R polymorphism) on serum levels of CVDs biomarkers in Mexican women. Urinary arsenic levels (UAs) ranged from 5.50-145 μg/g creatinine. The allele frequency was 0.38 and 0.62 for the Q and R alleles, respectively. Moreover, significant associations (p<0.05) were detected between UAs and CVDs biomarkers (ADMA, FABP4, and miR-155). Comparable data were found when CVDs biomarkers were evaluated through PON1 genotype, significant (p<0.05) higher serum concentrations of CVDs biomarkers were identified in R allele carriers compared to levels found in Q allele carriers. Besides, a gene-environment interaction was documented. The results of this study we believe should be of significant interest to regulatory authorities worldwide.

Probabilistic human health risk assessment associated with fluoride and arsenic co-occurrence in drinking water from the metropolitan area of San Luis Potosí, Mexico

A major public health concern in Mexico is the natural contamination of groundwater with fluoride and arsenic. Therefore, this work aimed to evaluate the magnitude of human health risk after determining fluoride and arsenic concentrations in groundwater samples (n = 50) from the Metropolitan area of the city of San Luis Potosi, Mexico. Fluoride levels in water were determined via a potentiometric method using an ion-selective electrode. Arsenic concentrations in water samples were determined with an Atomic Absorption technique. Subsequently, a probabilistic health risk assessment was developed (Monte Carlo Analysis). Fluoride levels in water ranged from 0.20 to 3.50 mg/L. For arsenic, the mean level found in the assessed water samples was 15.5 ± 5.50 μg/L (range: 2.50-30.0 μg/L). In addition, when the probabilistic health risk assessment was completed, a mean HI (cumulative hazardous index) of higher than 1 was detected, indicating a high NCR (non-carcinogenic risk) for children and adults. According to the results found in this study, exposure protection campaigns are imperative in the Metropolitan area of the city of San Luis Potosí, Mexico, to successfully diminish exposure to arsenic and fluoride and, as a consequence, decrease the NCR in the population living in that region of Mexico.

Cohort profile: health effects monitoring programme in Ndilǫ, Dettah and Yellowknife (YKHEMP)

PURPOSE

The Yellowknife Health Effects Monitoring Programme (YKHEMP) was established to examine the relationship of exposure to arsenic and other chemicals of potential concern such as antimony, cadmium, lead, manganese and vanadium and health outcomes.

PARTICIPANTS

A total of 2037 individuals were recruited, including children (age 3-19) and adults (age 20+), residing in Dettah, Ndilǫ and Yellowknife, in the Northwest Territories, Canada, in two waves in Fall 2017 and Spring 2018. In Yellowknife, there were 891 (675 adults, 216 children), randomly selected participants with a participation rate of 64%. In addition, we also recruited a total of 875 (669 adults, 206 children) volunteer participants. A total of 225 (137 adults, 88 children) of the Yellowknives Dene First Nation (YKDFN), and 46 (33 adults, 13 children) of the North Slave Métis Alliance participated in the study. Each participant answered a lifestyle questionnaire as well as provided toenail clippings and urine for contaminant testing and saliva samples for testing of genetic polymorphisms associated with arsenic metabolism. Participants also provided consent to have their medical records reviewed by the research team for the past 5 years to allow for the investigation between exposure and health outcomes.

FINDINGS TO DATE

The adult YKHEMP participants had lower urinary total arsenic but the children had higher inorganic arsenic than the general Canadian population. There was no difference in urinary total arsenic concentrations between adults and children, however, urinary inorganic arsenic concentrations were generally higher in children than in adults in all four YKHEMP sampling groups. The adult YKDFN participants had lower urinary total arsenic and inorganic arsenic concentrations compared with the random selected and volunteer participants.

FUTURE PLANS

YKHEMP is designed as a prospective cohort study; the children participants will be re-examined in 2022 and both adult and children participants in 2027.

Assessment of kidney health and exposure to mixture pollutants in the Mexican indigenous population

The indigenous population is one of the most vulnerable to suffer from contaminated environments. One of the target organs to suffer early deterioration from exposure to toxins is the kidney. The objective of this article was to evaluate biomarkers of exposure to organic and inorganic toxins and biomarkers of early kidney damage in urine from an indigenous Tenek population in Mexico. The biomarkers of exposure were Li, Be, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Sn, Ba, and Pb evaluated by ICP-MS and hippuric acid for toluene exposure evaluated by UV-coupled with liquid chromatography; the biomarkers of kidney damage were cystatin C (Cys-C), osteopontin (OPN), retinol-binding protein-4 (RPB-4), and neutrophil gelatinase-associated lipocalin (NGAL). Thirty-one urine samples were obtained from indigenous people; 16, 42, 45.1, and 45.2% of the population exceeded the reference values for Pb, Zn, As, and hippuric acid respectively. Our results demonstrate significant correlations between the metals tested and the proteins associated with renal damage; Cys-C, OPN, and RPB4 showed a significant correlation with Li, B, and Mo, as well as hippuric acid in the case of Cys-C and Zn in OPN and RPB-4; NGAL did not present significant correlations with any of the pollutants of the study. This pilot study contributes to the evidence of great inequity in health associated to environmental pollution matters faced by indigenous people and addresses the need of initiatives for mitigation under the perspective that health is a fundamental human right.

Effects of oral exposure to arsenite on arsenic metabolism and transport in rat kidney

Nephrotoxicity is within the recognized toxic effects of arsenic. In this study we assessed the effect of arsenite on the renal capacity to metabolize and handle arsenicals in rats exposed to drinking water with 0, 1, 5, or 10 ppm sodium arsenite for ten days. Arsenite treatment did not affect the gene expression of the main enzyme catalyzing methylation of arsenite, As3mt, while it reduced the expression of GSTO1 mRNA and protein. Arsenite decreased the expression of Aqp3, Mrp1, Mrp4, and Mdr1b (i.e., transporters and channels used by arsenic), but not that of Aqp7, Glut1, Mrp2, and Mdr1a. The protein abundance of AQP3 was also reduced by arsenite. Arsenite increased urinary NGAL and FABP3 and decreased Klotho plasma levels, without alteration of creatinine, which evidenced early tubular damage. Renal Klotho mRNA and protein expressions were also downregulated, which may exacerbate renal damage. No effect was observed in selected miRNAs putatively associated with renal injury. Plasma PTH and FGF23 were similar between groups, but arsenite decreased the renal expression of Fgfr1 mRNA. In conclusion, exposure to arsenite alters the gene expression of proteins involved in the cellular handling of arsenical species and elicits tubular damage.

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.

Renal bioaccumulation of trace elements in urban and rural Sri Lankan populations: A preliminary study based on post mortem tissue analysis

INTRODUCTION

Environmental pollution, especially by toxic trace elements, is a global health concern. Heavy metals such as Cadmium (Cd), Arsenic (As) and Lead (Pb) are associated with numerous disorders and are considered by some as an aetiological factor for the Chronic Kidney Disease (CKDu1) epidemic in Sri Lanka. This study explores patterns of bioaccumulation of six trace elements in kidneys obtained during forensic autopsies from urban and rural regions in Sri Lanka.

METHODS

Kidney samples obtained from one urban district (n = 13) and three rural districts (n = 18) were lyophilized, microwave digested and profiled by ICP-MS techniques.

RESULTS AND DISCUSSION

The mean age of the sampled population was 47.9 ± 11.3 yrs. Median (IQR) for Cd, As, Pb, Cr, Zn and Se were, 14.67(8.04-22.47) μg/g, 0.44(0.29-0.56) μg/g, 0.11(0.07-0.30) μg/g, 0.15(0.1096-0.3274), 25.55(17.24-39.35) μg/g and 0.52(0.37-0.84) μg/g, respectively. Cd, Zn and Se levels were significantly higher (p < 0.05) among the urban samples compared to that of the rural group. Zn and Se levels were higher among younger age groups. As, Pb and Cr did not show any significant differences between the two cohorts nor any correlations with age.

CONCLUSION

This population-specific baseline study provides an insight into the differences in exposure to toxic trace elements and essential elements between urban and rural populations. Residents in CKDu affected rural districts did not appear to be at risk of toxic heavy metal exposure, however their renal bioaccumulation of nephroprotective essential elements was lower than urban residents.