Application of classic epidemiological studies and proteomics in research of occupational and environmental exposure to lead, cadmium and arsenic

Prenatal exposures to endocrine disrupting chemicals: The role of multi-omics in understanding toxicity

Endocrine disrupting chemicals (EDCs) are a diverse group of toxicants detected in populations globally. Prenatal EDC exposures impact birth and childhood outcomes. EDCs work through persistent changes at the molecular, cellular, and organ level. Molecular and biochemical signals or 'omics' can be measured at various functional levels - including the epigenome, transcriptome, proteome, metabolome, and the microbiome. In this narrative review, we introduce each omics and give examples of associations with prenatal EDC exposures. There is substantial research on epigenomic modifications in offspring exposed to EDCs during gestation, and a growing number of studies evaluating the transcriptome, proteome, metabolome, or microbiome in response to these exposures. Multi-omics, integrating data across omics layers, may improve understanding of disrupted function pathways related to early life exposures. We highlight several data integration methods to consider in multi-omics studies. Information from multi-omics can improve understanding of the biological processes and mechanisms underlying prenatal EDC toxicity.

Metabolomics for exposure assessment and toxicity effects of occupational pollutants: current status and future perspectives

INTRODUCTION

Work-related exposures to harmful agents or factors are associated with an increase in incidence of occupational diseases. These exposures often represent a complex mixture of different stressors, challenging the ability to delineate the mechanisms and risk factors underlying exposure-disease relationships. The use of omics measurement approaches that enable characterization of biological marker patterns provide internal indicators of molecular alterations, which could be used to identify bioeffects following exposure to a toxicant. Metabolomics is the comprehensive analysis of small molecule present in biological samples, and allows identification of potential modes of action and altered pathways by systematic measurement of metabolites.

OBJECTIVES

The aim of this study is to review the application of metabolomics studies for use in occupational health, with a focus on applying metabolomics for exposure monitoring and its relationship to occupational diseases.

METHODS

PubMed, Web of Science, Embase and Scopus electronic databases were systematically searched for relevant studies published up to 2021.

RESULTS

Most of reviewed studies included worker populations exposed to heavy metals such as As, Cd, Pb, Cr, Ni, Mn and organic compounds such as tetrachlorodibenzo-p-dioxin, trichloroethylene, polyfluoroalkyl, acrylamide, polyvinyl chloride. Occupational exposures were associated with changes in metabolites and pathways, and provided novel insight into the relationship between exposure and disease outcomes. The reviewed studies demonstrate that metabolomics provides a powerful ability to identify metabolic phenotypes and bioeffect of occupational exposures.

CONCLUSION

Continued application to worker populations has the potential to enable characterization of thousands of chemical signals in biological samples, which could lead to discovery of new biomarkers of exposure for chemicals, identify possible toxicological mechanisms, and improved understanding of biological effects increasing disease risk associated with occupational exposure.

Multibiomarker approach to assess the magnitude of occupational exposure and effects induced by a mixture of metals

Metals and metalloids including lead (Pb), arsenic (As) and manganese (Mn) can occur as mixtures in occupational contexts, such as mines. These chemicals are all known to be neurotoxic and provoke changes in heme metabolism also known to induce neurotoxicity. The objective of this work was to propose a multi-biomarker (BM) methodology to screen subjects exposed to the mixture of Pb, As and Mn and assess the severity of their exposure/effects, in an individual basis. The urinary levels of the metals, dela-aminolevulinic acid (ALA) and porphyrins were determined in Portuguese miners and in a control group. The combination of Pb and As urinary levels had the highest capability to identify subjects occupationally exposed to this mixture in mines, as evaluated through Receiver Operating Characteristic (ROC) (A = 98.2%; p < 0.05), allowing that 94.2% of 86 studied subjects were properly identified and the generation of an equation indicating the odd of a subject be considered as exposed to the metal mixture. The combination of urinary ALA and porphyrins revealed to be best one to be applied in the assessment of subjects with high, intermediate, and low magnitudes of exposure/effects, with 95.7% of 46 miners classified correctly according to their severity sub-group and allowing to generate equations, which can be applied in new subjects. The proposed methodology showed a satisfactory performance, evaluating in an integrated manner the magnitude of exposure/effects of the exposed workers, may contributing to improve the control of their health.

Relief of Cadmium-Induced Intestinal Motility Disorder in Mice by Lactobacillus plantarum CCFM8610

Cadmium (Cd) is a toxic metal inducing a range of adverse effects on organs including liver and kidneys. However, the underlying molecular mechanisms of Cd-induced intestinal toxicity through dietary intake is poorly studied. This study evaluated the toxic effects of Cd on intestinal physiology and confirmed the effectiveness of the protective mechanism of the probiotic Lactobacillus plantarum CCFM8610 against chronic Cd toxicity. After treatment with Cd, the HT-29 cell line was subjected to iTRAQ analysis, which revealed that changes in the proteomic profiles after Cd exposure were related to pathways involved in the stress response and carbohydrate metabolism. The results of an animal trial also indicated that 10 weeks of Cd exposure decreased the fecal water content and contractile response of colonic muscle strips in mice, and delayed the excretion time of the first black feces. L. plantarum CCFM8610 treatment provided protective effects against these Cd-induced intestinal motility dysfunctions by recovering the levels of neurotransmitters, including substance P, acetyl cholinesterase, vasoactive intestinal peptide, 5-hydroxytryptamine, calcitonin gene-related peptide, and nitric oxide, and suppressing the cellular stress response in mice (e.g., the inhibition of mitogen-activated protein kinase pathways). The administration of this probiotic was also observed to reduce Cd levels in the tissues and blood of the mice. Our results suggest a newly identified protective mechanism of probiotics against Cd toxicity that involves the recovery of intestinal motility and increase in fecal cadmium excretion.

Use of an Exposome Approach to Understand the Effects of Exposures From the Natural, Built, and Social Environments on Cardio-Vascular Disease Onset, Progression, and Outcomes

Obesity, diabetes, and hypertension have increased by epidemic proportions in recent years among African Americans in comparison to Whites resulting in significant adverse cardiovascular disease (CVD) disparities. Today, African Americans are 30% more likely to die of heart disease than Whites and twice as likely to have a stroke. The causes of these disparities are not yet well-understood. Improved methods for identifying underlying risk factors is a critical first step toward reducing Black:White CVD disparities. This article will focus on environmental exposures in the external environment and how they can lead to changes at the cellular, molecular, and organ level to increase the personal risk for CVD and lead to population level CVD racial disparities. The external environment is defined in three broad domains: natural (air, water, land), built (places you live, work, and play) and social (social, demographic, economic, and political). We will describe how environmental exposures in the natural, built, and social environments "get under the skin" to affect gene expression though epigenetic, pan-omics, and related mechanisms that lead to increased risk for adverse CVD health outcomes and population level disparities. We also will examine the important role of metabolomics, proteomics, transcriptomics, genomics, and epigenomics in understanding how exposures in the natural, built, and social environments lead to CVD disparities with implications for clinical, public health, and policy interventions. In this review, we apply an exposome approach to Black:White CVD racial disparities. The exposome is a measure of all the exposures of an individual across the life course and the relationship of those exposures to health effects. The exposome represents the totality of exogenous (external) and endogenous (internal) exposures from conception onwards, simultaneously distinguishing, characterizing, and quantifying etiologic, mediating, moderating, and co-occurring risk and protective factors and their relationship to disease. Specifically, it assesses the biological mechanisms and underlying pathways through which chemical and non-chemical environmental exposures are associated with CVD onset, progression and outcomes. The exposome is a promising approach for understanding the complex relationships among environment, behavior, biology, genetics, and disease phenotypes that underlie population level, Black: White CVD disparities.

Metal environmental contamination within different human exposure context- specific and non-specific biomarkers

Exposure to high levels of persistent pollutants, such as metal mixtures, is commonly encountered by the general population especially in industrialized countries. The aim of this work was to evaluate how metal pollution in contaminated areas is reflected in terms of biomarkers (BMs) of exposure and effect in human sub-populations living in distinct non-occupational environmental contexts. Thus, four Portuguese sub-populations living in different areas of Portugal were studied: i- the exposure of each member of these sub-populations to lead (Pb), manganese (Mn) and arsenic (As) was evaluated by determining metal levels in urine; ii- biochemical changes were assessed, establishing the levels of urinary metabolites of heme biosynthesis; iii- the ability of combinations of these BMs to predict the context of exposure of each subject was tested, as to develop a tool to identify adverse health effects in these environmentally exposed populations. Concerning the combinations of BMs, heme precursors in urine (delta-aminolevulinic acid and porphyrins), were predictive of contexts of environmental exposures, with 94.2% of the studied subjects correctly identified as to their sub-population origin. The use of non-specific BMs may affirm the exposure to Pb, Mn and As, also reflecting health effects induced by a chemical environmental mixture. Our studies affirm the difficulty in establishing a metal reference population.

Impairment of learning and memory of mice offspring at puberty, young adulthood, and adulthood by low-dose Cd exposure during pregnancy and lactation via GABAAR α5 and δ subunits

Cadmium (Cd) is a pervasive carcinogen and environmental endocrine disruptor. We studied the changes in learning and memory of offspring mice, whose mothers were exposed to 10 mg Cd/L via the drinking water during pregnancy and lactation period, as well as the changes of testosterone and estrogen levels, serum Cd levels, the histopathological changes and the changes in the mRNA and protein levels of different subunits of γ-aminobutyric acid receptor subtype A subunits (G_ABA_ARs) in the hippocampus at the prepuberty, puberty, young adult, and adult stages. At birth, Cd had no obvious effect on mice offspring as statistically accessed based on their body weight, body length, and tail length (all p > 0.05). After grouped, the serum Cd levels increased in the three exposed groups more than in the normal control group at stages (all p < 0.05). Only serum estradiol of female offspring at age 7 weeks was significantly decreased compared with other groups (all p < 0.05). Histopathological results showed that the arrangement of the cells in hippocampal CA1 area of mice offspring was significantly sparse in the exposed groups compared with the control group. At 5 and 7 weeks, two Cd-exposed groups showed prolonged escape latency and exploring time for the platform compared with the normal group in the Morris water maze (all p < 0.05). Only increased protein expression of GABA_ARα5 was found in the Cd group at these two ages. At age 12 weeks, similar impaired learning and memory of female mice, and decreased protein expression of GABA_ARδ was found in Cd-exposed groups. Collectively, low-dose Cd had no effect on the growth of mice offspring but affected their learning and memory, especially female offspring, at puberty, young adulthood, and adulthood through changed structure in the hippocampal CA1 area and protein expression of GABA_ARα5 and GABA_ARδ.

Low-level lead exposure and cardiovascular disease: the roles of telomere shortening and lipid disturbance

Lead exposure contributing to cardiovascular diseases is known and recognized widely. As the deleterious effects of low lead exposure attained increasing attention over the last decades, there have been numerous studies exploring the association of low levels of lead exposure and cardiovascular diseases. Moreover, it has been observed that lead exposure could cause telomere shortening and lipid disturbance, and that telomere shortening and lipid disturbance are closely related with cardiovascular diseases. Hence, telomere shortening and lipid disturbance might play an important role in the pathophysiological process of chronic low levels of lead exposure contributing to cardiovascular diseases. This review is intended to explore views of the rarely mentioned mechanism, telomere shortening and lipid disturbance, and the cardiovascular effects of low levels of lead exposure.

Chronic lead exposure enhances the sympathoexcitatory response associated with P2X4 receptor in rat stellate ganglia

Chronic lead exposure causes peripheral sympathetic nerve stimulation, including increased blood pressure and heart rate. Purinergic receptors are involved in the sympathoexcitatory response induced by myocardial ischemia injury. However, whether P2X4 receptor participates in sympathoexcitatory response induced by chronic lead exposure and the possible mechanisms are still unknown. The aim of this study was to explore the change of the sympathoexcitatory response induced by chronic lead exposure via the P2X4 receptor in the stellate ganglion (SG). Rats were given lead acetate through drinking water freely at doses of 0 g/L (control group), 0.5 g/L (low lead group), and 2 g/L (high lead group) for 1 year. Our results demonstrated that lead exposure caused autonomic nervous dysfunction, including blood pressure and heart rate increased and heart rate variability (HRV) decreased. Western blotting results indicated that after lead exposure, the protein expression levels in the SG of P2X4 receptor, IL-1β and Cx43 were up-regulated, the phosphorylation of p38 mitogen-activated protein kinase (MAPK) was activated. Real-time PCR results showed that the mRNA expression of P2X4 receptor in the SG was higher in lead exposure group than that in the control group. Double-labeled immunofluorescence results showed that P2X4 receptor was co-expressed with glutamine synthetase (GS), the marker of satellite glial cells (SGCs). These changes were positively correlated with the dose of lead exposure. The up-regulated expression of P2X4 receptor in SGCs of the SG maybe enhance the sympathoexcitatory response induced by chronic lead exposure.

Trace element levels in blood and associated factors in adults living in the metropolitan area of São Paulo, Brazil

This study evaluated blood arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), copper (Cu) and manganese (Mn) levels in a group of residents (n=374) in the metropolitan area of São Paulo (MASP) and investigated the association between trace element levels in blood and sociodemographic and lifestyle factors. Trace elements were measured in specimens by inductively coupled plasma mass spectrometry (ICP-MS). Geometric means were 3.6μg/L, 0.13μg/L, 23.9μg/L, 1.4μg/L, 999μg/L, and 12.5μg/L for As, Cd, Pb, Hg, Cu, and Mn, respectively. As, Pb and Hg levels were associated with education level. Men presented higher blood lead levels (PbB) and lower blood copper levels (CuB) than women. Fish consumption was primarily related to increased blood Hg levels (HgB). Smokers exhibited 1.8 times more blood cadmium levels (CdB) than non-smokers. Only 4% of the study samples exceeded the Pb reference values for the MASP population, and 12% had Hg levels higher than the German HBM-I value (5μg/L for adults).The study group showed slightly higher exposure to As, Hg and Mn and lower Cd than those of European and North American studies.

Urinary arsenic, cadmium, manganese, nickel, and vanadium levels of schoolchildren in the vicinity of the industrialised area of Asaluyeh, Iran

Asaluyeh is one of the most heavily industrialised areas in the world where gas, petrochemical, and many downstream industries are located. This study aims to survey the biomonitoring of four metals and one metalloid in children living in the vicinity of Asaluyeh area. To do this, we analysed the creatinine-adjusted urinary levels of arsenic (As), cadmium (Cd), vanadium (V), manganese (Mn), and nickel (Ni) in 184 elementary schoolchildren (99 boys and 85 girls) living in Asaluyeh and compared them with a reference population. The comparisons were done for two seasons (spring and fall). The results showed that in the case area (Asaluyeh), the levels of As, V, Mn, and Ni were significantly higher and that of Cd was not significantly higher than the reference city for both seasons. The mean concentration of metal(loid)s in Asaluyeh (case) and Sadabad (reference) area as μg g^-1 creatinine was As 2.90 and 2.24, V 0.06 and 0.03, Mn 0.28 and 0.25, Ni 0.54 and 0.29, and Cd 0.31 and 0.28 in spring and As 3.08 and 2.28, V 0.07 and 0.03, Mn 0.30 and 0.26, Ni 0.91 and 0.30, and Cd 0.36 and 0.31 in the fall. Seasonal variations played a key role in determining urinary metal(loid) concentration, as we saw the significant level of As, Cd, V, and Ni in fall than in spring. With regard to the impact of gender on the absorption and accumulation of urinary metal(loid)s, boys showed higher levels of the studied elements, especially for As, than girls as outdoor activities are more popular among boys. Due to the values being lower than those reported in literature, more research is needed on various population groups and other exposure sources in order to judge whether living in the vicinity of the gas and petrochemical industries in Asaluyeh is a threat to nearby residents.

Water reclamation during drinking water treatments using polyamide nanofiltration membranes on a pilot scale

The aim of this study was to investigate the performances of polyamide nanofiltration membranes during water reclamation. The study was conducted using nanofiltration concentrates obtained from two different nanofiltration drinking water treatment plants placed in the northern part of Serbia (Kikinda and Zrenjanin). Used nanofiltration concentrates contained high concentrations of arsenic (45 and 451 μg/L) and natural organic matter (43.1 and 224.40 mgKMnO4/L). Performances of polyamide nanofiltration membranes during water reclamation were investigated under various fluxes and transmembrane pressures in order to obtain drinking water from nanofiltration concentrates and, therefore, reduce the amount of produced concentrates and minimize the waste that has to be discharged in the environment. Applied polyamide nanofiltration membranes showed better removal efficiency during water reclamation when the concentrate with higher content of arsenic and natural organic matter was used while the obtained permeates were in accordance with European regulations. This study showed that total concentrate yield can be reduced to ~5 % of the optimum flux value, in both experiments. The obtained result for concentrate yield under the optimum flux presents considerable amount of reclaimed drinking water and valuable reduced quantity of produced wastewater.

Metal mixture (As-Cd-Pb)-induced cell transformation is modulated by OLA1

Environmental pollutants are complex mixtures in which metals are ubiquitous. Metal mixtures of arsenic, cadmium and lead are present in the occupational environment and generate health effects such as cardiovascular, renal and cancer diseases. Cell transformation induced by metal mixtures that depend on reactive oxygen species (ROS) generation, cell viability maintenance and avoidance of senescence was previously reported by our group. The aim of the present study was to explore the role of a Obg-like ATPase1 (OLA1) in the cell transformation of BALB/c 3T3 A31-1-1 clonal cells induced by a metal mixture (2 µM NaAsO2, 2 µM CdCl2 and 5 µM Pb(C2H3O2)2 3H2O) through ROS generation. The interest in OLA1 is justified because this protein has been proposed to be a negative regulator of the cellular antioxidant response. Small interfering RNA (siRNA) was used to knockdown OLA1 before the initiation stage of the transformation assay. We evaluated (ROS) and OLA1 protein expression throughout the initiation and promotion stages of transformation. OLA1 knockdown modulated metal mixture-induced cell transformation more strongly when the metal mixture was an initiator stimulus than when it was a promoter. The ability of the metal mixture to initiate cell transformation was diminished by OLA1 knockdown, an effect that depended on intracellular ROS levels. The effect of OLA1 was synergistic with N-Acetyl-l-cysteine (NAC) co-treatment. Oxidative stress-associated transcription factors Egr1 and Smad were also down-regulated by the OLA1 knockdown, contributing to the rescue of metal mixture cell transformation.

G.I.S. Surveillance of Chronic Non-occupational Exposure to Heavy Metals as Oncogenic Risk

INTRODUCTION

The potential oncogenic effect of some heavy metals in people occupationally and non-occupationally exposed to such heavy metals is already well demonstrated. This study seeks to clarify the potential role of these heavy metals in the living environment, in this case in non-occupational multifactorial aetiology of malignancies in the inhabitants of areas with increased prevalent environmental levels of heavy metals.

METHODS

Using a multidisciplinary approach throughout a complex epidemiological study, we investigated the potential oncogenic role of non-occupational environmental exposure to some heavy metals [chrome (Cr), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb) and arsenic (As)-in soil, drinking water, and food, as significant components of the environment] in populations living in areas with different environmental levels (high vs. low) of the above-mentioned heavy metals. The exposures were evaluated by identifying the exposed populations, the critical elements of the ecosystems, and as according to the means of identifying the types of exposure. The results were interpreted both epidemiologically (causal inference, statistical significance, mathematical modelling) and by using a GIS approach, which enabled indirect surveillance of oncogenic risks in each population.

RESULTS

The exposure to the investigated heavy metals provides significant risk factors of cancer in exposed populations, in both urban and rural areas [ χ2 test (p < 0.05)]. The GIS approach enables indirect surveillance of oncogenic risk in populations.

CONCLUSIONS

The role of non-occupational environmental exposure to some heavy metals in daily life is among the more significant oncogenic risk factors in exposed populations. The statistically significant associations between environmental exposure to such heavy metals and frequency of neoplasia in exposed populations become obvious when demonstrated on maps using the GIS system. Environmental surveillance of heavy metals pollution using GIS should be identified as an important element of surveillance, early detection, and control of neoplastic risks in populations, at the level of a single locality, but even on a wider geographical scale.

Metabonomic analysis of serum of workers occupationally exposed to arsenic, cadmium and lead for biomarker research: a preliminary study

Environmental metabonomics is the application of metabonomics to characterize the interactions of organisms with their environment. Metabolic profiling is an exciting addition to the armory of the epidemiologist for the discovery of new disease risk biomarkers and diagnostics. This work is a continuation of research searching for preclinical serum markers in a group of 389 healthy smelter workers exposed to lead, cadmium and arsenic. Changes in the metabolic profiles were studied using Proton Nuclear Magnetic Resonance Spectroscopy on pooled serum samples from both the metal exposed and control groups. These multivariate metabonomic datasets were analyzed with Principal Component Analysis and Partial Least Squares Discriminant Analysis. Analysis of metabolic profiles of people exposed to heavy metals suggests energy metabolism disturbance induced by heavy metals. Changes in lipid fraction (very-low-density lipoprotein - VLDL, low-density lipoprotein - LDL), unsaturated lipids and in the level of amino acids suggest perturbation of the metabolism of lipids and amino acids. This study illustrated the high reliability of NMR-based metabonomic profiling on the study of the biochemical effects induced by the mixture of heavy metals. This approach is capable of identifying intermediate biomarkers of response to toxicants at environmental/occupational concentrations, paving the way to its use in a monitoring of smelter workers exposed to low doses of lead, cadmium and arsenic.

Cadmium induced pathophysiology: prophylactic role of edible jute (Corchorus olitorius) leaves with special emphasis on oxidative stress and mitochondrial involvement

The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against CdCl₂ intoxication. In vitro bioassay on isolated mice hepatocytes confirmed dose dependent cytoprotective effect of AECO. The CdCl₂ (30 μM) exhibited a significantly increased levels of lipid peroxidation, protein carbonylation along with the reduction of antioxidant enzymes and reduced glutathione levels in hepatocytes. AECO (200 and 400 μg/ml) + CdCl₂ (30 μM) could significantly restore the aforementioned oxidation parameters in hepatocytes. Beside this, AECO could significantly reduce Cd-induced increase in Bad/Bcl-2 ratio and the over-expression of NF-κB, caspase 3 and caspase 9. In in vivo assay, CdCl₂ (4 mg/kg body weight, for 6 days) treated rats exhibited a significantly increased intracellular Cd accumulation, oxidative stress and DNA fragmentation in the organs. In addition, the haematological parameters were significantly altered in the CdCl₂ treated rats. Simultaneous administration of AECO (50 and 100 mg/kg body weight), could significantly restore the biochemical, antioxidant and haematological parameters near to the normal status. Histological studies of the organs supported the protective role of jute leaves. Presence of substantial quantity of phenolic compounds and flavonoids in extract may be responsible for overall protective effect.