Blood lead and cadmium levels in occupationally exposed workers and their effect on markers of DNA damage and repair

Low-level, chronic ingestion of lead and cadmium: The unspoken danger for at-risk populations

The long-term effects of low-level, chronic exposure to lead and cadmium through ingestion are often overlooked, despite the urgency surrounding the clinical onset and worsening of certain pathologies caused by these metals. This work reviews current legislation, global ingestion levels, and blood levels in the general population to emphasize the need for reactivity towards this exposure, especially in at-risk populations, including patients with early-stage renal and chronic kidney disease. Global data indicates persistent chronic ingestion of lead and cadmium, with no decreasing trend in recent years, and a daily consumption of tens of micrograms worldwide. Moreover, the average blood lead and cadmium levels in the general population are concerning in many countries with some significantly exceeding healthy limits, particularly for children. Technologies developed to cleanse soil and prevent heavy metal contamination in food are not yet applicable on a global scale and remain financially inaccessible for many communities. Addressing this chronic ingestion at the human level may prove more beneficial in delaying the onset of associated clinical pathologies or preventing them all together.

Effects of Cadmium and Lead Co-exposure on Sleep Status in Rural Areas Northwestern China

In this study, we explored how cadmium and lead co-exposure affects sleep status among residents of a polluted area and nature reserve in rural northwestern China. Cadmium and lead levels were measured using blood samples, and sleep status was evaluated using sleep questionnaires, with the main sleep indicators including sleep duration, sleep quality, bedtime, and staying up. Furthermore, cadmium-lead co-exposure levels were divided into three groups: high exposure, medium exposure, and low exposure. Subjects in the contaminated area had significantly higher exposure levels (p < 0.001) and more negative sleep indicators (p < 0.01). Significant differences were found for all four sleep indicators in the high exposure group compared to the low exposure group (p < 0.01). Moreover, the overall evaluation of sleep status with high cadmium-lead co-exposure had a negative impact. Our data suggest that cadmium-lead co-exposure has a negative effect on sleep status and may have a synergistic effect on sleep.

Efficient and safe use of a slow-release Mn material for three sequential crops of rice in Cd-contaminated paddy soils

Traditional passivators reduce the effectiveness of Cd by ion exchange, chemisorption, and complexation in soil. However, traditional passivators have defects such as easy aging and poor durability, which not only reduce the treatment efficiency but also increase the risk of primary soil environmental pollution. For this reason, considering that Mn and Cd have physiological antagonism in rice, sepiolite-supported manganese ferrite (SMF) was prepared in this study to improve passivation persistence. The passivation mechanism, effect and duration of SMF were explored. The results showed that SMF has a dense and small pore structure and that the surface is rough, which provides abundant adsorption sites for Cd2+ adsorption. When the SMF adsorbs Cd2+, ions or functional groups in the material, such as MnOOH*, will exchange with Cd2+ to form Cd(OH)2 and other internal complexes. Indoor pure soil cultivation experiments showed that 0.1 % SMF can reduce the effective Cd content of soil by 41.32 %, demonstrating the efficiency of SMF. The three-crop rice experiments in pots showed that SMF could increase soil pH and continuously increase the content of available Mn in soil. Increasing the content of available Mn reduces the ability of rice to absorb Cd. In addition, the three-cropping rice experiments also indicated that the passivation effect of SMF materials on Cd-contaminated paddy fields was long-lasting and stable and that SMF is a more efficient and safe Cd passivation agent.

Cadmium-chelating ability of the siderophore DHBS secreted by Leclercia adecarboxylata FCH-CR2 and its action mechanism

As one of the most accumulative toxic heavy metals, cadmium (Cd) poses a major threat to human health. Bacterial siderophores, as small molecules with metal-absorbing ability, have great potential activity for Cd-reduction. In this study, the siderophore-producing bacterialstrain FCH-CR2 was isolated from a high-Cd contaminated soil using the CAS method. Leclercia adecarboxylata was identified through 16S rRNA sequence, homology analysis, colony morphology, physiological and biochemical tests. A siderophore, catechol type 2,3-dihydroxy-N-benzoyl-l-serine (DHBS) secreted by FCH-CR2, was purified using RP-HPLC and identified by LC-MS/MS. Intraperitoneal injection of DHBS significantly increased fecal Cd levels, and reduced Cd accumulation in organs. In density flooding theory (DFT) analysis, DHBS may bind to Cd via the hydroxyl site on the benzene ring. Besides, the isothermal titration calorimetry (ITC) assay revealed that the formation of Cd-DHBS is a spontaneous and endothermic reaction with ΔG = -21.4 kJ/mol and ΔH = 1.51 ± 0.142 kJ/mol.

DNA damage resulting from human endocrine disrupting chemical exposure: Genotoxicity, detection and dietary phytochemical intervention

In recent years, exposure to endocrine disrupting chemicals (EDCs) has posed an increasing threat to human health. EDCs are major risk factors in the occurrence and development of many diseases. Continuous DNA damage triggers severe pathogenic consequences, such as cancer. Beyond their effects on the endocrine system, EDCs genotoxicity is also worthy of attention, owing to the high accessibility and bioavailability of EDCs. This review investigates and summarizes nearly a decade of DNA damage studies on EDC exposure, including DNA damage mechanisms, detection methods, population marker analysis, and the application of dietary phytochemicals. The aims of this review are (1) to systematically summarize the genotoxic effects of environmental EDCs (2) to comprehensively summarize cutting-edge measurement methods, thus providing analytical solutions for studies on EDC exposure; and (3) to highlight critical data on the detoxification and repair effects of dietary phytochemicals. Dietary phytochemicals decrease genotoxicity by playing a major role in the detoxification system, and show potential therapeutic effects on human diseases caused by EDC exposure. This review may support research on environmental toxicology and alternative chemo-prevention for human EDC exposure.

Long-term cadmium exposure induces chronic obstructive pulmonary disease-like lung lesions in a mouse model

Accumulating evidences demonstrate that long-term exposure to atmospheric fine particles and air pollutants elevates the risk of chronic obstructive pulmonary disease (COPD). Cadmium (Cd) is one of the important toxic substances in atmospheric fine particles and air pollutants. In this study, we aimed to establish a mouse model to evaluate whether respiratory Cd exposure induces COPD-like lung injury. Adult male C57BL/6 mice were exposed to CdCl₂ (10 mg/L, 4 h per day) by inhaling aerosol for either 10 weeks (short-term) or 6 months (long-term). The mean serum Cd concentration was 6.26 μg/L in Cd-exposed mice. Lung weight and coefficient were elevated in long-term Cd-exposed mice. Pathological scores and alveolar destructive indices were increased in long-term Cd-exposed mouse lungs. Mean linear intercept and airway wall thickness were accordingly elevated in Cd-exposed mice. Inflammatory cell infiltration was obvious and inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, IL-10 and TGF-β, were up-regulated in Cd-exposed mouse lungs. α-SMA, N-cadherin and vimentin, epithelial-mesenchymal transition markers, and extracellular matrix collagen deposition around small airway, determined by Masson's trichrome staining, were shown in Cd-exposed mouse lungs. COPD-characteristic lung function decline was observed in long-term Cd-exposed mice. These outcomes show that long-term respiratory exposure to Cd induces COPD-like lung lesions for the first time.

The Protective Role of Ozone Therapy in Kidney Disease: A Review

Ozone (O3) is a reactive oxygen species (ROS) that can interact with cellular components and cause oxidative stress. Following said logic, if O3 induces such a stressful milieu, how does it exert antioxidant functions? This is mediated by controlled toxicity produced by low concentrations of O3, which enhance the cell’s suppliance of antioxidant properties without causing any further damage. Therapeutic concentrations vary extensively, although 50 µg/mL is commonly used in experimental and clinical procedures, given that augmented concentrations might work as germicides or cause endogenous damage. O3 therapy has been shown to be effective when applied before or after traumatic renal procedures, whether caused by ischemia, xenobiotics, chronic damage, or other models. In this review, we focus on discussing the role of O3 therapy in different models of kidney damage associated with fibrosis, apoptosis, oxidative stress, and inflammation. We integrate and report knowledge about O3 in renal therapy, debunking skepticism towards unconventional medicine, explaining its proven therapeutic properties, and thus providing background for its use in further research as well as in clinical settings.

Transcriptional Regulatory Network of Plant Cadmium Stress Response

Cadmium (Cd) is a non-essential heavy metal with high toxicity to plants. Plants have acquired specialized mechanisms to sense, transport, and detoxify Cd. Recent studies have identified many transporters involved in Cd uptake, transport, and detoxification. However, the complex transcriptional regulatory networks involved in Cd response remain to be elucidated. Here, we provide an overview of current knowledge regarding transcriptional regulatory networks and post-translational regulation of the transcription factors involved in Cd response. An increasing number of reports indicate that epigenetic regulation and long non-coding and small RNAs are important in Cd-induced transcriptional responses. Several kinases play important roles in Cd signaling that activate transcriptional cascades. We also discuss the perspectives to reduce grain Cd content and improve crop tolerance to Cd stress, which provides a theoretical reference for food safety and the future research of plant varieties with low Cd accumulation.

Cadmium exposure and DNA damage (genotoxicity): a systematic review and meta-analysis

Existing literature suggests an association between chronic cadmium (Cd) exposure and the induction of DNA damage and genotoxicity. However, observations from individual studies are inconsistent and conflicting. Therefore current systematic review aimed to pool evidence from existing literature to synthesize quantitative and qualitative corroboration on the association between markers of genotoxicity and occupational Cd exposed population. Studies that evaluated markers of DNA damage among occupationally Cd-exposed and unexposed workers were selected after a systematic literature search. The DNA damage markers included were chromosomal aberrations (chromosomal, chromatid, sister chromatid exchange), Micronucleus (MN) frequency in mono and binucleated cells (MN with condensed chromatin, lobed nucleus, nuclear buds, mitotic index, nucleoplasmatic bridges, pyknosis, and karyorrhexis), comet assay (tail intensity, tail length, tail moment, and olive tail moment), and oxidative DNA damage (8-hydroxy-deoxyguanosine). Mean differences or standardized mean differences were pooled using a random-effects model. The Cochran-Q test and I² statistic were used to monitor heterogeneity among included studies. Twenty-nine studies with 3080 occupationally Cd-exposed and 1807 unexposed workers were included in the review. Cd among the exposed group was higher in blood [4.77 μg/L (-4.94-14.48)] and urine samples [standardized mean difference 0.47 (0.10-0.85)] than in the exposed group. The Cd exposure is positively associated with higher levels of DNA damage characterized by increased frequency of MN [7.35 (-0.32-15.02)], sister chromatid exchange [20.30 (4.34-36.26)], chromosomal aberrations, and oxidative DNA damage (comet assay and 8OHdG [0.41 (0.20-0.63)]) compared to the unexposed. However, with considerable between-study heterogeneity. Chronic Cd exposure is associated with augmented DNA damage. However, more extensive longitudinal studies with adequate sample sizes are necessary to assist the current observations and promote comprehension of the Cd's role in inducing DNA damage.Prospero Registration ID: CRD42022348874.

Associations between DNA methylation and genotoxicity among lead-exposed workers in China

Studies have shown that lead (Pb) exposure caused genotoxicity, however, the underlying mechanisms remain unclear. A mechanism may be via DNA methylation which is one of the most widely studied epigenetic regulations for cellular activities. Whether this is involved in Pb-induced genotoxicity has rarely been studied. Our study aimed to examine whether DNA methylation was associated with Pb exposure and genotoxicity, and to explore its potential mediating roles. A total of 250 Pb-exposed workers were enrolled. Blood lead levels (BLLs) and genotoxic biomarkers (Micronuclei and Comet) were analyzed. Methylation levels at CpG sites of LINE1 and Alu and promoter region of P53, BRCA1, TRIM36 and OGG1 were measured by pyrosequencing. Generalized linear model (GLM) combined with restricted cubic splines (RCS) were used to analyze relationships between Pb exposure, DNA methylation and genotoxicity. Mediation effect was used to explore mediating roles of DNA methylation. The distribution of BLLs was right-skewed and showed wide ranges from 23.7 to 636.2 μg/L with median (P₂₅, P₇₅) being 218.4 (106.1, 313.9) μg/L among all workers. Micronuclei frequencies showed Poisson distribution [1.94 ± 1.88‰] and Comet tail intensity showed normal distribution [1.69 ± 0.93%]. GLM combined with RCS showed that Alu methylation was negatively associated with BLLs, while P53 and OGG1 methylation were positively associated with BLLs. Micronuclei were negatively associated with Alu and TRIM36 methylation but positively with P53 methylation. Comet was positively associated with P53 and BRCA1 methylation. Mediation effect showed that Alu methylation mediated 7% effects on association between Pb exposure and micronuclei, whereas, P53 methylation mediated 14% and BRCA1 mediated 9% effects on association between Pb exposure and Comet. Our data show that Pb exposure induced changes of global and gene-specific DNA methylation which mediated Pb-induced genotoxicity.

Plasma microRNA expression and immunoregulatory cytokines in an Indian population occupationally exposed to cadmium

Following its accumulation in the body, cadmium (Cd) exposure is associated with devastating effects on multiple organ system of the human body. The immune system is one of the sensitive targets for Cd-induced toxicity. Recently, studies have demonstrated a significant role of Cd in inducing epigenetic alterations. With this background, the present study was planned to study the changes in candidate microRNA (miRNA) expression associated with immune regulation in occupationally Cd-exposed workers. One hundred individuals involved in welding and metal handicraft manufacturing, while 80 apparently healthy subjects without any prior history of occupational exposure were recruited for the study. Blood Cd level was determined by atomic absorption spectrometry. Serum cytokine levels were measured using an enzyme-linked immunosorbent assay and serum miRNA expression of candidate miRNAs (miR-146a, miR-210, and miR-222) were determined by real-time polymerase chain reaction. The median Cd level (2.40 μg/L) in the occupationally exposed workers was significantly higher than the nonexposed subjects (0.90 μg/L). Among the cytokines, interleukin-4 (IL-4), and tumor necrosis factor-alpha (TNF-α) were significantly higher while IL-2 and IL-10 were significantly lower in the exposed. The expression level of miR-146a and miR-222 were significantly different between the groups with the former showing downregulation and later showing upregulation. Correlation analysis revealed a positive and negative association of miR-222 and miR-146a with blood cadmium level, IL-17 as well as TNF-α, respectively. Furthermore, the in-silico analysis revealed a significant role of the studied miRNAs in various cellular and genetic pathways. The findings of the present study demonstrate significant involvement of Cd-induced alteration in miRNAs in varied immune regulatory changes in exposed individuals.

Bats and pollution: Genetic approaches in ecotoxicology

Environmental pollution drives the decline of species and, as flying mammals, bats can be considered to be excellent indicators of environmental quality, and the analysis of genetic biomarkers in these animals can provide important parameters for the assessment of environmental health. This review verifies the trends in pollution research, in particular, the use of genetic markers in the study of bats, based on a literature search of the Web of Science and Scopus platforms. Sixteen publications were identified during the search, which focused on the timeframe between 1996 and March 2022, including investigations of the effects of heavy metals, agricultural pesticides, and radiation. The studies were based primarily on the application of biomarkers for genotoxic analysis, including the comet assay, micronucleus test, and the Polymerase Chain Reaction (PCR). Only 55 bat species have been investigated up to now, that is, 4% of the 1447 currently recognized. In general, bats exposed to polluted environments presented a higher frequency of genotoxic and mutagenic damage than those sampled in clean environments. Given the importance of the diverse ecological functions provided by bats, including pest control, pollination, and seed dispersal, it is increasingly necessary to investigate the damage caused to the health of these animals exposed to areas with high concentrations of contaminants. Although genetic biomarkers have been used to investigate physiological parameters in bats for more than two decades, then, many knowledge gaps remain, worldwide, in terms of the number of species and localities investigated.

Oxidative stress and DNA damage resulting from welding fumes exposure among professional welders: A systematic review and meta-analysis

The present systematic review aimed to evaluate the associations between welding fumes exposure and changes in oxidative stress [superoxide dismutase (SOD) and malondialdehyde (MDA)] and DNA damage [8-hydroxy-2'-deoxyguanosine (8-OHdG) and DNA-protein crosslink (DPC)] markers in professional welders (PROSPERO CRD42022298115). Six electronic bibliographic databases were searched from inception through September 2021 to identify observational epidemiological studies evaluating the association between welding fumes exposures and changes in oxidative stress and DNA damage in professional welders. Two reviewers independently assessed the risk of bias and certainty of the evidence. A narrative synthesis of results was conducted using the Synthesis Without Meta-analysis (SWiM) method. Pooled mean differences with 95% confidence intervals were calculated in a random-effects meta-analysis for the outcomes of interest in the review. From 450 studies identified through the search strategy, 14 observational epidemiological studies were included in the review. Most studies reported significantly higher welding fumes levels in welders than in controls. The narrative synthesis results of SOD showed a significant difference between welders and controls, while the meta-analysis results of MDA did not show a significant difference between the studied groups (MD = 0.26; 95% CI, -0.03, 0.55). The meta-analysis results of 8-OHdG (MD = 9.38; 95% CI, 0.55-18.21) and DPC (MD = 1.07; 95% CI, 0.14-2) revealed significantly differences between the studied groups. The included studies were at high risk of exclusion and confounding bias. The certainty of the evidence for oxidative stress and DNA damage results were very low and moderate, respectively. Exposure to welding fumes and metal particles is associated with DNA damage in professional welders, and 8-OHdG and DPC might be considered reliable markers to assess DNA damage resulting from exposure to welding fumes. We recommend, however, that the evaluation of oxidative stress resulting from welding fumes exposure not be solely based on MDA and SOD.

Association of α-klotho and lead and cadmium: A cross-sectional study

Epigenetic aging is associated with harmful health effects such as oxidative stress from heavy metal exposure. We considered the relationship between genes and heavy metals in association with oxidative stress and then investigated the association between serum α- klotho and lead and cadmium exposure among adults in the United States from 2007 to 2016 participating in the National Health and Nutrition Examination Survey (NHANES). Samples included 9800 adults aged 40 to 79 years with measurements of serum α-klotho, lead and cadmium, and complete covariate data. Lead and cadmium levels were measured by inductively coupled plasma mass spectrometry and serum α-klotho levels were measured using enzyme-linked immunosorbent assay (ELISA). Multivariate linear regression analysis was used to estimate the association between serum α-klotho and blood lead, blood cadmium, and urinary cadmium. A percent increase in blood lead, blood cadmium, and urinary cadmium was associated with a statistically significant 4.0 % (p < 0.001), 2.0 %, (p = 0.003) and 1.0 % (p = 0.020) decrease in serum klotho. After adjustment, a percent increase in blood lead was associated with a statistically significant 4.0 % (p < 0.001) decrease in serum klotho; blood and urinary cadmium did not show any statistically significant associations after adjustment (β (95 % CI), p-value for blood cadmium: 0.00 (-0.02-0.01), p = 0.573; urinary cadmium: -0.01 (-0.03-0.01), p = 0.210). Mean serum klotho levels showed a statistically significant decreasing trend with increasing blood lead quartiles (unadjusted and all-adjusted geometric means and 95 % confidence intervals of serum klotho (in pg/mL) for Q1, Q2, Q3, and Q4: unadjusted: 827.49 (814.20-840.92), 811.92 (794.73-829.48), 791.48 (775.11-808.19), and 772.01 (754.23-790.29); adjusted: 830.64 (805.53-856.45), 816.07 (789.18-843.87), 800.71 (773.71-828.57), and 784.31 (757.94-811.59)). Blood lead and levels were negatively associated with serum α-klotho levels in a representative population of US adults. These results suggest that blood lead levels may be associated with the serum levels of a protein associated with cognition and aging. Further research is recommended to investigate the causality behind such relationship.

Association between lead exposure and DNA damage (genotoxicity): systematic review and meta-analysis

Studies suggest that chronic lead (Pb) exposure may induce deoxyribonucleic acid (DNA) damage. However, there is no synthesised evidence in this regard. We systematically reviewed existing literature and synthesised evidence on the association between chronic Pb exposure and markers of genotoxicity. Observational studies reporting biomarkers of DNA damage among occupationally Pb-exposed and unexposed controls were systematically searched from PubMed, Scopus and Embase databases from inception to January 2022. The markers included were micronucleus frequency (MN), chromosomal aberrations, comet assay, and 8-hydroxy-deoxyguanosine. During the execution of this review, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Mean differences in the biological markers of DNA damage between Pb-exposed and control groups were pooled using the random-effects model. The heterogeneity was assessed using the Cochran-Q test and I² statistic. The review included forty-five studies comparing markers of DNA damage between Pb-exposed and unexposed. The primary studies utilised buccal and/or peripheral leukocytes for evaluating the DNA damage. The pooled quantitative results revealed significantly higher DNA damage characterised by increased levels of MN and SCE frequency, chromosomal aberrations, and oxidative DNA damage (comet assay and 8-OHdG) among Pb-exposed than the unexposed. However, studies included in the review exhibited high levels of heterogeneity among the studies. Chronic Pb exposure is associated with DNA damage. However, high-quality, multicentred studies are required to strengthen present observations and further understand the Pb's role in inducing DNA damage. CRD42022286810.

Role of Ape1 in Impaired DNA Repair Capacity in Battery Recycling Plant Workers Exposed to Lead

Exposure to lead in environmental and occupational settings continues to be a serious public health problem. At environmentally relevant doses, two mechanisms may underlie lead exposition-induced genotoxicity, disruption of the redox balance and an interference with DNA repair systems. The aim of the study was to evaluate the ability of lead exposition to induce impaired function of Ape1 and its impact on DNA repair capacity of workers chronically exposed to lead in a battery recycling plant. Our study included 53 participants, 37 lead exposed workers and 16 non-lead exposed workers. Lead intoxication was characterized by high blood lead concentration, high lipid peroxidation and low activity of delta-aminolevulinic acid dehydratase (δ-ALAD). Relevantly, we found a loss of DNA repair capacity related with down-regulation of a set of specific DNA repair genes, showing specifically, for the first time, the role of Ape1 down regulation at transcriptional and protein levels in workers exposed to lead. Additionally, using a functional assay we found an impaired function of Ape1 that correlates with high blood lead concentration and lipid peroxidation. Taken together, these data suggest that occupational exposure to lead could decrease DNA repair capacity, inhibiting the function of Ape1, as well other repair genes through the regulation of the ZF-transcription factor, promoting the genomic instability.

Genotoxic Effects of Lead and Their Impact on the Expression of DNA Repair Genes

Exposure to lead (Pb) continues to be a significant worldwide problem. Pb is a highly poisonous heavy metal affecting several organ systems in the body. Although Pb has been shown to be genotoxic to experimental animals and humans, the underlying mechanisms are still not understood. An indirect mechanism related to the inhibition of DNA repair systems by Pb has been suggested. Heavy metals can interfere with the activities of several proteins and gene expressions. Recent studies gathered in this review article demonstrated an altered expression of DNA repair genes due to Pb toxicity. However, their findings are conflicting. Furthermore, the interaction of Pb and epigenetic mechanisms regulating gene expression may have a crucial role in the inhibition of DNA repair systems. Therefore, additional studies are needed to evaluate these findings and to obtain a complete picture of the genotoxic properties of Pb and the underlying mechanisms that may have a crucial role in carcinogenesis.

Novelkaraya gum micro-particles loaded Ganoderma lucidum polysaccharide regulate sex hormones, oxidative stress and inflammatory cytokine levels in cadmium induced testicular toxicity in experimental animals

Presented research aimed to develop a spray drying process without the use of organic solvents for the preparation of novel Karaya gum polymer microparticles (MPs) of Ganoderma lucidum polysaccharide (GLP). The prepared microparticles were characterized and evaluated. Prepared novel karaya gum micro-particles loaded Ganoderma lucidum polysaccharide (GLP MPs) were observed an effect on cadmium (CAD) induced testicular toxicity. A total of 40 rats (male) was divided into 4 groups viz. 1. Control group, 2. GLP MPs (250 mg/kg, 60 days of b.w per day), 3. CAD (60 days of 30 mg/l/day), 4. GLP MPs + CAD. CAD was responsible for altering the sex hormones, oxidative stress and inflammatory cytokines. Furthermore, elevated levels of indicator of oxidative stress, malondialdehyde, and a reduced action of SOD, GSH, and CAT (antioxidant enzymes), were observed in the tissues of the testicles of CAD- treated group. Such harmful occurrences were followed by an up-regulation in proinflammatory cytokines (TNF-α, IL-1β) levels, protein expression of Nrf2, and HO-1 expression was decreased. GLP MPs pre-treatment significantly abrogated these toxic effects which were confirmed histologically. This study concluded that pre-treatment with GLP MPs exerts a protective effect against CAD-induced male reproductive testicular toxicity.

N-Acetylcysteine Reduces miR-146a and NF-κB p65 Inflammatory Signaling Following Cadmium Hepatotoxicity in Rats

We performed a thorough screening and analysis of the impact of cadmium chloride (CdCl₂) and N-acetylcysteine (NAC) on the miR146a/NF-κB p65 inflammatory pathway and mitochondrial biogenesis dysfunction in male albino rats. A total of 24 male albino rats were divided into three groups: a control group, a CdCl₂-treated group (3 mg/kg, orally), and a CdCl₂ + NAC-treated group (200 mg/kg of NAC, 1 h after CdCl₂ treatment), for 60 consecutive days. Real-time quantitative PCR was used to analyze the expression of miR146a, Irak1, Traf6, Nrf1, Nfe2l2, Pparg, Prkaa, Stat3, Tfam, Tnfa, and Il1b, whereas tumor necrosis factor-α, interleukin-1β, and cyclooxygenase-2 protein levels were assessed using ELISA, and NF-κB p65 was detected using western blotting. A significant restoration of homeostatic inflammatory processes as well as mitochondrial biogenesis was observed after NAC and CdCl₂ treatment. Decreased miR146a and NF-κB p65 were also found after treatment with NAC and CdCl₂ compared with CdCl₂ treatment alone. Collectively, our findings demonstrate that CdCl₂ caused mtDNA release because of Tfam loss, leading to NF-κB p65 activation. Co-treatment with NAC could alleviate Cd-induced genotoxicity in liver tissue. We concluded that adding NAC to CdCl₂ resulted in a decreased signaling of the NF-κB p65 signaling pathway.

Metal Exposures, Noise Exposures, and Audiometry from E-Waste Workers in Agbogbloshie, Ghana

Metals, such as lead, may be ototoxic, but this property is not well understood, especially in conjunction with noise. This cross-sectional study investigated hearing, noise, and metal biomarkers in informal electronic waste (e-waste) recycling workers in Accra, Ghana. Workers (N = 58) participated in audiometric testing, a survey, blood collection, and personal noise dosimetry. Sixty percent of participants displayed audiometric notches indicative of noise-induced hearing loss (NIHL). Most workers (86%) reported high noise while working. Daily average noise levels were in the range 74.4-90.0 dBA. Linear regression models indicated participants who lived at Agbogbloshie Market for longer periods were significantly associated with worse hearing thresholds at 4 and 6 kHz. The models did not identify blood levels of lead, mercury, or cadmium as significant predictors of worse hearing thresholds or larger noise notches, but increased levels of selenium were significantly associated with better hearing at 6 kHz. Models of thresholds at 4 and 6 kHz were improved by including an interaction term between the maximum noise exposure and the level of zinc in whole blood, suggesting that zinc may protect hearing at lower noise levels, but not at higher levels. Further study of the relationships between elements, noise, and NIHL is needed.

Occupational exposure to metal-rich particulate matter modifies the expression of repair genes in foundry workers

Foundry workers are exposed to numerous occupational health hazards, which may result in increased risk of cancer, respiratory disease, and other diseases. Oxidative stress is known to be involved in the pathogenesis of such diseases. The present study aimed to investigate the association between multiple occupational exposures in foundry workers and expression of deoxyribonucleic acid (DNA) repair genes as a biomarker of oxidative DNA damage. The study sample comprised 17 foundry workers and 27 matched control subjects. Expression of 8-oxoguanine DNA glycosylase-1 (OGG1), inosine triphosphate pyrophosphate (ITPA), and MutT homolog 1 (MTH1) in peripheral blood was examined using the real-time polymerase chain reaction method. Air sampling to determine exposure to metal-rich particulate matter and measurement of extremely low-frequency electromagnetic fields (ELF-EMFs) were conducted according to the National Institute for Occupational Safety and Health standard methods. Personal air sampling revealed that occupational exposure to particulate matter exceeded the threshold limit values (TLVs) in 76% of the workstations, whereas ELF-EMF exposure appeared to be lower than the TLV. ITPA was significantly upregulated in foundry workers compared with control subjects, whereas no significant difference was observed for OGG1 and MTH1. Moreover, ITPA was strongly and positively correlated with the concentration of metal-rich particulate matter in foundry workers. No significant correlation was found between ELF-EMF exposure and expression of DNA repair genes. DNA repair gene expression may be a sensitive biomarker for occupational exposures, which suggests an involvement of oxidative stress in metal-induced toxicity. Further studies are needed to determine the role of DNA repair gene expression in response to occupational/environmental hazards.

Assessment of circulating miR-20b, miR-221, and miR-155 in occupationally lead-exposed workers of North-Western India

Lead (Pb), a toxic heavy metal, is capable of inducing several adverse health effects following its accumulation in the body. Lead is a potential carcinogen, capable of causing multisystem alterations. Recent reports identify small regulatory RNA molecules-miRNAs-which show differential expression in individuals exposed to similar levels of lead. These miRNAs can become potential molecular biomarkers of lead toxicity in the future and may unravel the possible molecular pathways through which this metal may exert its toxic manifestations. The present study aimed to assess the circulating levels of miRNA-20b, 221, and 155 in occupationally lead-exposed workers and correlate them with blood lead levels. One hundred ten participants working in various factories of Jodhpur and 97 participants not occupationally exposed to lead were recruited after obtaining due informed consent. Blood lead level (BLL) was estimated by graphite furnace atomic absorption spectrophotometry (GF-AAS). Circulating miRNAs were isolated from serum by Qiagen miRNA isolation kit and converted to cDNA by commercial kit. Expression profiles of miR-20b, miR-221, and miR-155 were performed in RT-PCR using Qiagen miRNA PCR assays. The blood lead level (mean ± SD) of occupationally lead-exposed subjects was 6.94 ± 11.96 μg/dL while that of non-exposed was 2.39 ± 4.66 μg/dL. Out of the three miRNAs, miR-155 and miR-221 were significantly upregulated, while miR-20b did not show significant difference among study groups. The fold change of miR-20b, miR-221 and miR-155 expression were 1.08, 2.71 and 2.07 respectively. Functional analysis revealed that these miRNAs have the potential to trigger various genes and cellular pathways. The findings of our study highlight the importance of miRNA dysregulation in lead-exposed individuals that may contribute to the systemic effects of lead toxicity.