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

Unveiling the interaction and combined effects of multiple metals/metalloids exposure to TNF-α and kidney function in adults using bayesian kernel machine regression and quantile-based G-computation

BACKGROUND

Exposure to multiple metals may cause adverse effects, particularly in the kidneys. However, studies on the combined and interaction effects of metal mixtures on human health remain limited.

OBJECTIVE

The study aims to evaluate the interaction between metals and assess the combined effects of exposure to metal mixtures on tumor necrosis factor-alpha (TNF-α) levels and kidney function METHODS: Particular emphasis has been placed on the impact of various metals, including arsenic (As), cadmium (Cd), lead (Pb), as well as essential trace elements, such as cobalt (Co), copper (Cu), selenium (Se), and zinc (Zn), on human health and their potential collective influence on both TNF-α and kidney function. This cross-sectional study analyzed the data of 421 adults who underwent a health examination. Generalized linear model (GLM), Bayesian kernel machine regression (BKMR), and quantile-based G-computation (qgcomp) were used to evaluate the association and joint effects between the metals and TNF-α, as well as kidney function.

RESULTS

Increased concentrations of As (β = 0.11, 95 % CI = 0.05, 0.17) and Pb (β = 0.30, 95 % CI = 0.23, 0.37) in the blood were associated with elevated levels of TNF-α, while elevated Cu (β = -0.42, 95 % CI = -0.77, -0.07) levels were linked to a significant reduction in TNF-α. The overall effect of metals mixture showed a significant association with a decline in eGFR and an increase TNF-α in the BKMR model. Qgcomp analysis of the metals mixture (β = -0.06, 95 % CI = -0.07, -0.05) indicated that As, Pb, and Zn were the primary contributors to the reduction in eGFR, while As and Pb were the major contributors in metals mixture (β = 0.12, 95 % CI = 0.08, 0.15) to the elevation of TNF-α levels.

CONCLUSION

Exposure to multiple metals could have joint association with the TNF-α levels and kidney function. Furthermore, TNF-α could act as a mediator between metal mixtures and eGFR.

Mediation analysis for TNF-α as a mediator between multiple metal exposure and kidney function

The association between metal mixtures and kidney function has been reported. However, reports on the mechanism of metal toxicity were limited. Oxidative stress was reported as a possible cause. This study aimed to determine the association between of kidney function and metals, such as arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), lead (Pb), selenium (Se), and zinc (Zn), and to explore the possible mediating role of tumor necrosis factor alpha (TNF-α) between metal toxicity and kidney function. In this study, we recruited 421 adults from a health examination. The concentration of blood metals was analyzed using inductively coupled plasma mass spectrometry. We used linear regression models to assess the association between metals and TNF-α. Then, mediation analysis was applied to investigate the relationship between metal exposure, TNF-α, and kidney function. In univariate linear regression, blood As, Cd, Co, Cu, Pb, and Zn levels significantly increased TNF-α and decreased kidney function. Higher blood As and Pb levels significantly increased TNF-α in multivariable linear regressions after adjusting for covariates. We found that blood levels of As (coefficients = -0.021, p = 0.011), Pb (coefficients = -0.060, p < 0.001), and Zn (coefficients = -0.230, p < 0.001) showed a significant negative association with eGFR in the multiple-metal model. Furthermore, mediation analysis showed that TNF-α mediated 41.7 %, 38.8 %, and 20.8 % of blood Cd, As and Pb, respectively. Among the essential elements, TNF-α mediated 24.5 %, 21.5 % and 19.9 % in the effects of blood Co, Cu, and Zn on kidney function, respectively. TNF-α, acting as a mediator, accounted for 20.1 % of the contribution between the WQS score of metal mixtures and the eGFR (p < 0.001). This study suggested that TNF-α may be a persuasive pathway mediating the association between metals and kidney function. Inflammation and kidney injury could be the underlying mechanisms of metal exposure. However, there is still a need to clarify the biochemical mechanism in follow-up studies.

Environmental pollution to kidney disease: an updated review of current knowledge and future directions

Environmental pollution significantly impacts global disease burden. However, the contribution of environmental pollution to kidney disease is often overlooked in nephrology. This review examines the growing body of research demonstrating the significant impacts of environmental pollutants, with a focus on air pollution as a primary factor, and acknowledges the roles of other pollutants, such as heavy metals, in the development and progression of kidney diseases. Short-term exposure to air pollution is linked with an increased risk of kidney disease-related events, including hospital admissions, and death, predominantly occurring in vulnerable populations. In contrast, long-term exposure, even at low to moderate levels, may lead to progressive pathophysiological changes, such as chronic systemic inflammation and oxidative stress, that contribute to the development of kidney disease. In addition, air pollution may exacerbate traditional kidney disease risk factors such as hypertension and diabetes, thereby accelerating disease progression. The review also explores how climate change may interact with various pollutants, including air pollution, influencing kidney disease indirectly. The examined evidence underscores the urgent need for an interdisciplinary approach to research further into environmental kidney disease. Environmental health policies could play a crucial role in the prevention, intervention, and improvement of kidney health worldwide.

Butylparaben induced zebrafish (Danio rerio) kidney injury by down-regulating the PI3K-AKT pathway

Butylparaben, a common endocrine disruptor in the environment, is known to be toxic to the reproductive system, heart, and intestines, but its nephrotoxicity has rarely been reported. In order to study the nephrotoxicity and mechanism of butylparaben, we examined the acute and chronic effects on human embryonic kidney cells (HEK293T) and zebrafish. Additionally, we assessed the potential remedial effects of salidroside against butylparaben-induced nephrotoxicity. Our in vitro findings demonstrated oxidative stress and cytotoxicity to HEK293T cells caused by butylparaben. In the zebrafish model, the concentration of butylparaben exposure ranged from 0.5 to 15 μM. An assortment of experimental techniques was employed, including the assessment of kidney tissue morphology using Hematoxylin-Eosin staining, kidney function analysis via fluorescent dextran injection, and gene expression studies related to kidney injury, development, and function. Additionally, butylparaben caused lipid peroxidation in the kidney, thereby damaging glomeruli and renal tubules, which resulted from the downregulation of the PI3K-AKT signaling pathway. Furthermore, salidroside ameliorated butylparaben-induced nephrotoxicity through the PI3K-AKT signaling pathway. This study reveals the seldom-reported kidney toxicity of butylparaben and the protective effect of salidroside against toxicological reactions related to nephrotoxicity. It offers valuable insights into the risks to kidney health posed by environmental toxins.

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.

Lipidomics of children and adolescents exposed to multiple industrial pollutants

BACKGROUND

There are limited studies on the lipidomics of children and adolescents exposed to multiple industrial pollutants.

OBJECTIVES

In this study, we aimed to investigate lipid profile perturbations in 99 children and adolescents (aged 9-15) who lived in a polluted area surrounding the largest petrochemical complex in Taiwan. Previous studies have reported increased risks of acute and chronic diseases including liver dysfunctions and chronic kidney disease (CKD) in residents living in this area.

METHODS

We measured urinary concentrations of 11 metals and metalloids and polycyclic aromatic hydrocarbons (PAHs) metabolite 1-hydroxypyrene (1-OHP) as exposure biomarkers, and urinary oxidative stress biomarkers and serum acylcarnitines as early health effect biomarkers. The association between individual exposure biomarkers and early health effect biomarkers were analyzed using linear regression, while association of combined exposure biomarkers with four oxidative stress biomarkers and acylcarnitines were analyzed using weighted quantile sum (WQS) regression. Lipid profiles were analyzed using an untargeted liquid chromatography mass spectrometry-based technique. "Meet-in-the-middle" approach was applied to identify potential lipid features that linked multiple industrial pollutants exposure with early health effects.

RESULTS

We identified 15 potential lipid features that linked elevated multiple industrial pollutants exposure with three increased oxidative stress biomarkers and eight deregulated serum acylcarnitines, including one lysophosphatidylcholines (LPCs), four phosphatidylcholines (PCs), and two sphingomyelins (SMs) that were up-regulated in high exposure group compared to low exposure group, and two LPCs, four PCs, and two phosphatidylinositols (PIs) down-regulated in high exposure group compared to low exposure group.

CONCLUSION

Our findings could provide information for understanding the health effects, including early indicators and biological mechanism identification, of children and adolescents exposed to multiple industrial pollutants during critical stages of development.

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.

A review of Environmental risks and vulnerability factors of indigenous populations from Latin America and the Caribbean in the face of the COVID-19

Latin America and the Caribbean (LAC) was declared a new epicentre of the coronavirus pandemic by the World Health Organization (WHO) on 22 May 2020. As of 13 January 2021, the numbers of deaths and cases caused by COVID-19 in LAC reported are 552,000 and 17'485,000 respectively. LAC concentrates the largest percentage of indigenous populations throughout the world. In this region, poverty is persistent and particularly rural indigenous peoples hold the steepest barriers to health services and experience profound discrimination based on ethnicity, poverty, and language, compared to their non-indigenous counterparts. The information regarding the health of indigenous populations, in general, is scarce, and this problem is aggravated in the face of the COVID-19 pandemic. Therefore, the main objective of this work is to address the overall scenario of indigenous peoples in the Latin American and Caribbean region from March 2020 to January 2021, in this manner gathering information regarding health problems, economic, social, cultural and environmental factors that make indigenous populations in LAC particularly vulnerable to serious health effects from the COVID-19 pandemic, as well as compiling the mitigation strategies implemented in indigenous communities.

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.

Analysis of urinary metabolites of polycyclic aromatic hydrocarbons in precarious workers of highly exposed occupational scenarios in Mexico

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a risk factor for human health. Workers are a vulnerable group due to their high exposure and therefore require special attention to mitigation measurements; however, some groups of workers are especially vulnerable, precarious workers. The objective of this research was to evaluate mixtures of hydroxylated PAHs (OH-PAHs) in precarious workers in Mexico. The following activities were evaluated: (i) brickmakers (TER), stonemasons (ESC), indigenous workers (TOC) and mercury miners (CAM). Ten OH-PAHS were analyzed: 1-hydroxynaphtalene and 2-hydroxynaphtalene; 2-,3- and 9-hydroxyfluorene; 1-,2-,3- and 4-hydroxyphenanthrene; and 1-hydroxypyrene in urine by GC-MS, chemical fingerprints of the sites were established by multivariate analysis. One hundred forty-nine precarious workers participated in the study. The populations presented total OH-PAHs concentrations of 9.20 (6.65-97.57), 14.8 (9.32-18.85), 15.7 (6.92-195.0), and 101.2 (8.02-134.4) μg/L for CAM, ESC, TER, and TOC, respectively (median (IQR)). The results of the multivariate analysis indicate that the indigenous population presented a different fingerprint compared to the three scenarios. The chemical fingerprints among the brickmakers and mercury mining population were similar. The results of the concentrations were similar and in some metabolites higher than workers in occupations classified as carcinogenic by the IARC; therefore, the control of exposure in these occupations acquires great importance and surveillance through biological monitoring of OH-PAHs should be applied to better estimate exposure in these working populations.

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.