Effects of subchronic exposure via drinking water to a mixture of eight water-contaminating metals: a biochemical and histopathological study in male rats

Extraction and preconcentration of lead (II) in various water and food samples by orbital shaker-assisted magnetic solid phase extraction method using a new magnetic poly linoleic acid-polystyrene-PDMS block copolymer

The aim of this study was to develop a practical orbital shaker-assisted magnetic solid phase extraction (OSA-MSPE) method for the determination of lead by FAAS. A new magnetic poly linoleic acid-polystyrene-polydimethylsiloxane (PSt-PLina-PDMS) hydrophobic graft copolymer was synthesized and characterized by NMR, FT-IR, SEM-EDX, DSC, TGA, BET and used as adsorbent for the extraction of Pb (II). This adsorbent can be used at least 50 times without any decrease of its adsorption properties for the adsorption and elution of analyte ions. Several analytical parameters including pH, adsorbent amount, sample volume, shaking time, etc. were optimized. Multivariate optimization was used for the investigation of different parameters. The linear range at optimum operating condition was 1.7-84 μg L-1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L-1, 1.7 μg L-1, respectively. Intraday and interday relative standard deviation (RSD %), enhancement factor (EF) and adsorbent capacity were found as 1.9%, 3.3%, 166.7, 50 mg g-1, respectively. OSA-MSPE method was tested with certified reference materials including LGC-6010 (Hard Drinking Water), NCS ZC73032 Celery and CS-M-3 Control Sample Microelements in Mushroom Powder for the accuracy. Experimental results for lead were confirmed with certified values. Present method was successfully applied to various liquid and solid food samples. The OSA-MSPE method has some important features such as selective, sensitive, low LOD, LOQ and RSD, pre-concentration factor (PF) and high enhancement factor (EF). High tolerance limits against matrix ions were achieved.

Prenatal arsenic exposure alters EZH2-H3K27me3 occupancy at TNF-α promoter leading to insulin resistance and metabolic syndrome in a mouse model

The global prevalence of Metabolic Syndrome (MetS) is continuously rising and exposure to environmental toxicants such as arsenic could be contributing to this rapid surge. In this study, we have assessed the effects of prenatal arsenic exposure on insulin resistance and MetS parameters in a mouse model, and an underlying mechanism was identified. We found that prenatal arsenic exposure promotes insulin resistance and adipocyte dysfunction which leads to the early onset of MetS in male offspring. Primary adipocytes isolated from 20-week-old arsenic-exposed offspring showed hypertrophy, elevated basal lipolysis, and impaired insulin response along with enhanced expression of Tumor necrosis factor-alpha (TNF-α). TNF-α levels were consistently high at gestational day 15.5 (GD15.5) as well as primary adipocytes of 6-week-old arsenic-exposed male offspring. Along with TNF-α, downstream p-JNK1/2 levels were also increased, which led to inhibitory phosphorylation of IRS1and reduced GLUT4 translocation upon insulin stimulation in adipocytes. Insulin response and downstream signaling were restored upon TNF-α inhibition, confirming its central role. The persistent overexpression of TNF-α in adipocytes of arsenic-exposed mice resulted from diminished EZH2 occupancy and reduced H3K27me3 (gene silencing histone marks) at the TNF-α promoter. This further led to chromatin relaxation, recruitment of c-Jun and CBP/p300, formation of an enhanceosome complex, and TNF-α expression. Our findings show how prenatal arsenic exposure can epigenetically modulate TNF-α expression to promote adipocyte dysfunction and insulin resistance which contributes to the early onset of MetS in offspring.

Emodin nanocapsules inhibit acute pancreatitis by regulating lipid metabolic reprogramming in macrophage polarization

BACKGROUND

Emodin is a chemical compound found in traditional Chinese herbs. It possesses anti-inflammatory and many other pharmacological effects. Our previous study showed that emodin significantly alleviates the inflammation effect of severe acute pancreatitis (SAP). However, its poor solubility, high toxicity and limited pancreas retention time hinder its clinical application.

PURPOSE

We aimed to prepare emodin nanocapsules with improved bioavailability to achieve the controlled release of emodin by targeting macrophages. Further, the mechanism of mannose-conjugated chitosan-coated lipid nanocapsules loaded with emodin (M-CS-E-LNC) in the treatment of SAP was explored.

METHODS

M-CS-E-LNC were prepared by the phase inversion method with slight modification. The expression of inflammation mediators and the anti-inflammation efficacy of M-CS-E-LNC were examined by ELISA, IHC and IF in macrophage cells and LPS-induced SAP mice. IVIS spectrum imaging and HPLC were applied to explore the controlled release of M-CS-E-LNC in the pancreas. LC-MS/MS was performed for lipidomics analysis of macrophages. Moreover, a vector-based short hairpin RNA (shRNA) method was used to silence CTP1 gene expression in macrophage cells.

RESULTS

The levels of inflammatory mediators in macrophages were markedly decreased after treatment with M-CS-E-LNC. The same anti-inflammation effects were detected in SAP mouse through the analysis of serum levels of amylase, TNF-α and IL-6. Importantly, M-CS-E-LNC allowed the emodin to selectively accumulate at pancreas and gastrointestinal tissues, thus exhibiting a targeted release. Mechanistically, the M-CS-E-LNC treatment group showed up-regulated expression of the carnitine palmitoyltransferase 1 (CPT1) protein which promoted intracellular long-chain fatty acid transport, thereby promoting the M2 phenotype polarization of macrophages.

CONCLUSION

M-CS-E-LNC exhibited significantly improved bioavailability and water solubility, which translated to greater therapeutic effects on macrophage polarization. Our findings also demonstrate, for the first time, that CPT1 may be a new therapeutic target for SAP treatment.

Neurotoxic effects of low dose ranges of environmental metal mixture in a rat model: The benchmark approach

Metals exert detrimental effects on various systems within the body, including the nervous system. Nevertheless, the dose-response relationship concerning the administration of low doses of metal mixtures remains inadequately explored. The assessment of neurotoxic effects of lead, cadmium, mercury, and arsenic mixture (MIX) administered at low dose ranges, was conducted using an in vivo approach. A subacute study was conducted on a rat model consisting of a control and five treatment groups subjected to oral exposure with gradually increasing doses (from MIX 1 to MIX 5). The results indicated that behavioural patterns in an already developed nervous system displayed a reduced susceptibility to the metal mixture exposure with tendency of higher doses to alter short term memory. However, the vulnerability of the mature brain to even minimal amounts of the investigated metal mixture was evident, particularly in the context of oxidative stress. Moreover, the study highlights superoxide dismutase's sensitivity as an early-stage neurotoxicity marker, as indicated by dose-dependent induction of oxidative stress in the brain revealed through Benchmark analysis. The narrowest Benchmark Dose Interval (BMDI) for superoxide dismutase (SOD) activity (1e-06 - 3.18e-05 mg As/kg b.w./day) indicates that arsenic may dictate the alterations in SOD activity when co-exposed with the other examined metals. The predicted Benchmark doses for oxidative stress parameters were very low, supporting "no-threshold" concept. Histopathological alterations were most severe in the groups treated with higher doses of metal mixture. Similarly, the brain acetylcholinesterase (AChE) activity demonstrated a dose-dependent decrease significant in higher doses, while BMDI suggested Cd as the main contributor in the examined metal mixture. These findings imply varying susceptibility of neurotoxic endpoints to different doses of environmentally relevant metal mixtures, advocating for risk assessment and regulatory measures to address metal pollution and enhance remediation strategies.

Protective effect of Lactiplantibacillus plantarum CCFM8661 against heavy metal mixture-induced liver and kidney injury in mice

Human health and the ecological balance are both gravely threatened by heavy metal pollution brought on by global industrialization. Probiotics are thought to represent a novel class of medicinal products for reducing heavy metal toxicity. Though simultaneous poisoning of numerous heavy metals is more prevalent, the majority of current studies on probiotics in the treatment of heavy metal poisoning concentrate on a single heavy metal. Thus, a mouse damage model was created in this investigation using five heavy metals (Pb, Cd, Hg, Cr, and As), and Lactiplantibacillus plantarum CCFM8661 was utilized as an intervention therapy. The oxidative stress markers, including superoxide dismutase (SOD), catalase (CAT), antioxidant capacity (T-AOC), and malondialdehyde (MDA), were evaluated in the blood, liver, and kidney tissues of mice throughout the experiment by tracking changes in body weight. Additionally, the amounts of five heavy metals were measured in the liver and kidney tissues. The alleviation of tissue damage and the detoxifying activity of L. plantarum CCFM8661 in mice with combined heavy metal intoxication were assessed by histopathological examination of liver and kidney tissues. Results revealed that during the test period, L. plantarum CCFM8661 significantly reduced the content of MDA and the contents of Pb, Cd, Hg, Cr, and As in liver and kidney tissues, while also significantly increasing weight gain and the activities of SOD, CAT, and T-AOC in mouse blood, liver, and kidney tissues compared to the model group. Mouse liver and kidney tissue damage from combined heavy metal exposure was considerably lessened by L. plantarum CCFM8661 when compared to the model group, according to H&E staining. This study demonstrates that L. plantarum CCFM8661 may be utilized as a useful intervention for the treatment of combined heavy metal poisoning by efficiently reducing the harm that heavy metals do to the body and maintaining bodily health.

Assessment of the effect of sodium tetraborate on oxidative stress, inflammation, and apoptosis in lead-induced nephrotoxicity

Exposure to Pb, a toxic heavy metal, is a risk factor for renal damage. Borax, an essential trace element in cellular metabolism, is a naturally occurring compound found in many foods. This study investigated the effects of sodium tetraborate (ST), a source of borax, on renal oxidative stress and inflammation in rats exposed to Pb. Wistar Albino rats (n = 24) were divided into four groups: Control (0.5 mL, i.p. isotonic), Pb (50 mg/kg/day/i.p.), ST (4.0 mg/kg/day/oral), and Pb + ST groups. At the end of the five-day experimental period, kidney tissue samples were obtained and analyzed. Histopathologically, the Pb-induced damage observed in the Pb group improved in the Pb + ST group. Immunohistochemically, Pb administration increased the expression of inducible nitric oxide synthase, cyclooxygenase-2, and caspase-3. When evaluated biochemically, Pb application inhibited catalase and glutathione peroxidase (GSH-Px) enzyme activities and activated superoxide dismutase enzyme activity. An increase in malondialdehyde levels was considered an indicator of damage. ST application increases glutathione peroxidase enzyme activity and decreased malondialdehyde levels. These results indicate that ST might play a protective role against Pb-induced renal damage via the upregulation of renal tissue antioxidants and cyclooxygenase-2, inducible nitric oxide synthase, and caspase-3 immunoexpression.

Prenatal arsenic exposure alters keratinocyte stem cell fate through persistent activation of IGF2R-MAPK cascade leading to aggravated skin carcinogenesis in mice offspring

Chronic exposure to arsenic (As) promotes skin carcinogenesis in humans and potentially disturbs resident stem cell dynamics, particularly during maternal and early life exposure. In the present study, we demonstrate how only prenatal arsenic exposure disturbs keratinocyte stem cell (KSC) conditioning using a BALB/c mice model. Prenatal As exposure alters the normal stemness (CD34, KRT5), differentiation (Involucrin), and proliferation (PCNA) program in skin of offspring with progression of age as observed at 2, 10, and 18 weeks. Primary KSCs isolated from exposed animal at Day-2 showed increased survival (Bax:Bcl-xL, TUNEL assay), proliferation (BrdU), and differentiation (KRT5, Involucrin) potential through the activation of pro-carcinogenic IGF2R-MAPK cascade (IGF2R-G(α)q-MEK1-ERK1/2). This was associated with reduced enrichment of histone H3K27me3 and its methylase, EZH2 along with increased binding of demethylase, KDM6A at Igf2r promoter. Altered KSCs conditioning through disturbed Igf2r imprint contributed to impaired proliferation and differentiation and an aggravated tumor response in offspring.

Biochemical, morphological and molecular assessments of n butanol fraction of Phoenix dactylifera L. following exposure to inorganic mercury on the liver of Wistar rats

BACKGROUND

Mercury chloride (HgCl2) damages tissues it comes in contact with in sufficient concentration. This study evaluated the protective effects of n-butanol fraction of Phoenix dactylifera (BFPD) on mercury-triggered liver toxicity in Wistar rats. 25 male rats were divided into 5 groups of 5 rats each. Group I was administered 2 ml/kg of distilled water; group II was administered 5 mg/kg of HgCl2; group III was administered 500 mg/kg of BFPD + 5 mg/kg of HgCl2; group IV was administered 1000 mg/kg of BFPD + 5 mg/kg of HgCl2, while group V was administered 100 mg/kg of silymarin + 5 mg/kg of HgCl2. orally for 2 weeks. The rats were euthanized and liver tissue blood samples were collected for histological, histochemical, stereological, immunohistochemical, molecular, and biochemical studies.

RESULTS

The results revealed that HgCl2 induced oxidative stress in the rats evident by histoarchitectural distortions and altered levels of liver enzymes, proteins, and oxidative stress biomarkers when compared to the control. However, BFPD treatment restored these changes. Glutathione peroxidase levels decreased (p < 0.05) in the HgCl2-treated group when compared to the control and BFPD-treated groups. HgCl2 group revealed reduced reactivity with histochemical and immunohistochemical stains (Masson's Trichrome and B cell Lymphoma 2) when compared to the control, with a significant decrease in quantified liver Bcl-2 stain intensity when compared to the silymarin-treated group. BFPD administration revealed normal staining intensity comparable to the control. HgCl2 administration revealed a remarked decrease in the number of hepatocytes when compared to the control, BFPD, and silymarin groups. BFPD preserved (p < 0.05) the stereological features when compared to the HgCl2-treated group. GPx activity in the liver decreased (p < 0.05) with HgCl2 administration when compared to the control and silymarin-treated groups. BFPD attenuated GPx gene activity to levels similar to the control indicating some level of amelioration against HgCl2-induced toxicity.

CONCLUSIONS

The ability of BFPD to mitigate HgCl2 triggered liver alterations could be attributed to the antioxidant property of its flavonoid content. Therefore, BFPD may be a potential candidate for treating and managing liver-induced mercury intoxication.

Neurotoxicity of Combined Exposure to the Heavy Metals (Pb and As) in Zebrafish (Danio rerio)

Lead (Pb) and arsenic (As) are commonly occurring heavy metals in the environment and produce detrimental impacts on the central nervous system. Although they have both been indicated to exhibit neurotoxic properties, it is not known if they have joint effects, and their mechanisms of action are likewise unknown. In this study, zebrafish were exposed to different concentrations of Pb (40 μg/L, 4 mg/L), As (32 μg/L, 3.2 mg/L) and their combinations (40 μg/L + 32 μg/L, 4 mg/L + 3.2 mg/L) for 30 days. The histopathological analyses showed significant brain damage characterized by glial scar formation and ventricular enlargement in all exposed groups. In addition, either Pb or As staining inhibited the swimming speed of zebrafish, which was enhanced by their high concentrations in a mixture. To elucidate the underlying mechanisms, we examined changes in acetylcholinesterase (AChE) activity, neurotransmitter (dopamine, 5-hydroxytryptamine) levels, HPI axis-related hormone (cortisol and epinephrine) contents and neurodevelopment-related gene expression in zebrafish brain. The observations suggest that combined exposure to Pb and As can cause abnormalities in swimming behavior and ultimately exacerbate neurotoxicity in zebrafish by interfering with the cholinergic system, dopamine and 5-hydroxytryptamine signaling, HPI axis function as well as neuronal development. This study provides an important theoretical basis for the mixed exposure of heavy metals and their toxicity to aquatic organisms.

Toxicity and bioremediation of the lead: a critical review

Lead is a naturally occurring, bluish-gray metal that is found in small quantities in the earth's crust. The existing literature demonstrates that non-biodegradable character and continuous use results in accumulation of lead concentration in the environment and causes various ill effects such as neurotoxicity, change in psychological and behavioral development of different organisms. Nowadays the most effective technique in the revival of the environment is bioremediation and it is environmentally friendly and cost-effective. Bacterial strains such as Oceanobacillus profundus and Lactobacillus acidophilus ATCC4356 have the ability to reduce lead 97% and 73.9%, respectively. Similarly some species of algae and fungal strains also showed lead removal efficiency as 74% (spirulina), 97.1% (Chlorella kessleri), 95.5% (Penicillium janthinillum) and 86% (Aspergillus flavus). Biodegradation of lead by various microbes would be the most efficient and sustainable approach. This review focuses on toxicity, fate of lead in the environment and its microbial degradation.

Selenium and zinc alleviate hepatotoxicity induced by heavy metal mixture (cadmium, mercury, lead and arsenic) via attenuation of inflammo-oxidant pathways

Heavy metals (HM) are believed to be injurious to humans. Man is exposed to them on daily basis unknowingly, with no acceptable protocol to manage its deleterious effects. These metals occur as mixture of chemicals with varying concentrations in our atmosphere. There are growing calls for the use of essential metals in mitigating the injurious effects induced by heavy metals exposure to man; therefore, the aim of this study was to evaluate the protective effects of essential metals (Zinc and Selenium) in a mixture of heavy metal toxicity. In this study, except for negative controls, all other groups were treated with lead (PbCl2 , 20 mg kg-1 ); cadmium (CdCl2 , 1.61 mg kg-1 ); mercury (HgCl2 , 0.40 mg kg-1 ), and arsenic (NaAsO3, 10 mg kg-1 ) that were formed in distilled water. Pb, Cd, As, and Hg were administered as mixtures to 35, 6 weeks old rats weighing between 80 to 100 g for 60 days. Group I served as normal control without treatment, group II positive control received HM mixture, while groups III to V received HMM with Zn, Se, and Zn + Se respectively. Animal and liver weights, HM accumulation in the liver, food intake (FI), water intake (WI), liver function test, malondialdehyde (MDA), and inflammatory/transcription factor/apoptosis markers were checked. Also, antioxidant enzymes, and histological studies were carried out. Metal mixture accumulated in the liver and caused toxicities which were ameliorated by Zn and Se administration. HM caused significant decrease in FI, WI and distorted the level of liver enzymes, lipid peroxidation, inflammatory markers, antioxidants and architecture of the liver. Co administration with Zn or Se or both reversed the distortions. This study lays credence to the evolving research on the public health implications of low dose metal mixtures and the possible ameliorative properties of Zn and Se.

Impact of Cadmium and Lead Exposure on Camel Testicular Function: Environmental Contamination and Reproductive Health

The free grazing habits of camels from various sources may cause heavy metals to bioaccumulate in their tissues and organs, possibly resulting in higher amounts of these toxic substances in their bodies over time. The aim of this study was to assess the exposure impact of lead (Pb) and cadmium (Cd) on bull camels of the Lassi breed, aged 7 to 8 years, at a site near the industrial area and another two non-industrial sites, to analyze the presence of heavy metals. Samples from three sites were collected from thirty camels (n = 10/each), soil and water (n = 30), and five different plants (n = 15/each) for analysis. Testes were collected for atomic absorption spectrometry (AAS), and hematoxylin-eosin (HE) staining. Serum samples were obtained to measure testosterone levels by radioimmunoassay (RIA). Samples were obtained from plants, soil, water, blood, serum and urine for AAS. According to the results, the testes' weight, length, width, and volume significantly decreased at the industrial site compared with the other two sites as a result of exposure to Cd and Pb. Additionally, blood testosterone concentrations were considerably lower at the industrial site, indicating a detrimental impact on testicular steroidogenesis. The histological investigation of the industrial site indicated structural disturbances, including seminiferous tubule degeneration and shedding, cellular debris in seminiferous tubules, lining epithelium depletion, and vacuolation. Elevated amounts of Cd and Pb were found at the industrial site when analyzed using water, soil, plants, testes, serum, and urine. These findings demonstrate the adverse effects of Pb and Cd exposure on camel testicular function, including decreased weight and altered steroidogenesis. These findings are essential for understanding the impact of exposure to Pb and Cd on camel reproductive function and for developing successful prevention and management plans for these exposures in this species.

Elevated serum lead and cadmium levels associated with increased risk of dyslipidemia in children aged 6 to 9 years in Shenzhen, China

Exposure to heavy metals can influence on metabolism, but studies have not fully evaluated young children. We investigated the association between levels of serum lead (Pb), cadmium (Cd), chromium (Cr), and arsenic (As) and risk of dyslipidemia in children. A total of 4513 children aged 6 to 9 years at 19 primary schools in Shenzhen were enrolled. Overall, 663 children with dyslipidemia were matched 1:1 with control by sex and age, and levels of serum Pb, Cd, Cr, and As were detected by inductively coupled plasma-mass spectrometry. Demographic characteristics and lifestyle were covariates in the logistic regression to determine the association of heavy metal levels with risk of dyslipidemia. Serum Pb and Cd levels were significantly higher in children with dyslipidemia than controls (133.08 vs. 84.19 μg/L; 0.45 vs. 0.29 μg/L; all P < 0.05), but this association was not found in Cr and As. We found significant upward trends for the odds ratios (ORs) of dyslipidemia associated with increasing quartiles of Pb and Cd levels (highest quartile of serum Pb OR 1.86, 95% confidence interval (CI) 1.46-2.38; Cd OR 2.51, 95% CI 1.94-3.24). Elevated serum Pb and Cd levels were associated with increased risk of dyslipidemia among children.

Evaluation of Cadmium or Lead Exposure with Nannochloropsis oculata Mitigation on Productive Performance, Biochemical, and Oxidative Stress Biomarkers in Barki Rams

This study was designed to determine the lead or cadmium exposure of Barki rams and the beneficial role of Nannochlorposis oculata (N. oculata) 4% as a feed supplement, as well as its mitigating role against these elements' impacts concerning performance, biochemical markers of liver enzymes and kidney function, thyroid hormone activity, and oxidative stress markers. Six groups of 36 Barki rams (33.63 ± 1.29 kg) were divided into G1: which served as control; G2: was given 4% dietary N. oculata; G3: was given oral 1 mg/kg cadmium chloride; G4: was given 5 mg/kg/day lead acetate; G5: was given oral 1 mg/kg cadmium chloride and 4% dietary N. oculata, and G6: was given oral 5 mg/kg/day lead acetate and 4% dietary N. oculata; and treatments were continued for 60 days. Cadmium and lead-exposed groups exhibited lower and weaker weight gain as well as feed conversion ratio, respectively, than the control and other groups. Additionally, levels of T3, T4, total proteins, albumin, and glutathione (GSH) were significantly reduced in both G3 and G4 compared to control. However, urea, creatinine, ALT, AST, total cholesterol, triglycerides, protein carbonyl content (PCC), and malondialdehyde (MDA) were significantly increased (P ≤ 0.05) in cadmium and lead-exposed groups. Dietary N. oculata (4%) improves serum proteins, creatinine, urea, T4, and oxidative stress indicators as compared to the control group. Finally, 4% dietary N. oculata greatly enhances the investigated parameters in terms of performance, thyroid hormones, serum biochemical, and antioxidant activity and may assist in reducing the endocrine disrupting effects of Pb and Cd.

Impact of Heavy Metal Toxicity on the Gut Microbiota and Its Relationship with Metabolites and Future Probiotics Strategy: a Review

The gut microbiota has a vital role in the maintenance of intestinal homeostasis. Several studies have revealed that environmental exposure to pollutants such as heavy metals may contribute to the progression of extensive list of diseases which may further lead to perturbations in the gut leading to dysbiosis. This manuscript critically reviews the alterations in the gut microbiota composition and function upon exposure to various toxic heavy metals prevalent in the environment. The disturbance in gut microbial ecology also affects the microbial metabolic profile which may alter the speciation state and bioavailability heavy metals thus affecting metal uptake-absorption/detoxification mechanisms associated to heavy metal metabolism. The toxic effects of various heavy metals either in single or in multimetallic combination and the gut microbiota associated host health and disease condition need a comprehensive assessment with important consideration for therapeutic and protective strategies against the damage to gut microbiota.

Assessment of the toxicity of a mixture of five rare earth elements found in aquatic ecosystems in Hydra vulgaris

Rare earth elements (REEs) are considered critical elements for technology and their extraction through mining activities is expected to increase in the future. Due to their chemical similarities, they often co-occur in minerals and thus their ecotoxicity should be assessed as a group/family. However, the available ecotoxicological studies focused mainly on the evaluation of the potential toxicological impacts of individual REEs rather than their mixtures. The aim of this study was therefore to evaluate the toxicity of a representative mixture of five REEs (La, Ce, Pr, Nd and Sm) spanning environmentally relevant concentrations ranging from 0.05X (29 µg REEs L^-1) to 5X (2926 µg REEs L^-1) to the test organism, Hydra vulgaris, at the morphological, reproductive and regenerative levels. The data showed that lethality occurred at concentrations near (2.5 fold) to those inducing sublethal effects after chronic exposure of 7 days. The mixture affected reproduction and head regeneration and even lethality at concentrations even below those reported at environmental concentration (0.5X = 293 µg REEs L^-1) in lakes. This suggests that REEs concentrations found in lakes near mining activities could disrupt regeneration and impair embryonic development. Our data also revealed that combining the 5 REEs results in an antagonistic effect, suggesting that those elements share the same receptor and that low molecular weight and high radius elements (approaching iron) were less toxic. Taken together, hydra could be used as a sensitive model organism for the assessment of aquatic ecotoxicological risks of REE mixtures but further analyses of biochemical and gene expressions should improve our understanding of the long-term effects of REEs mixtures.

Environmental damage caused by coal combustion residue disposal: A critical review of risk assessment methodologies

Coal combustion generates almost 40% of world's electricity. However, it also produces 1.1 billion tons of coal combustion residues (CCR) annually, half of which end up in landfills. Although current regulations require proper lining and monitoring programs, the ubiquitous old, abandoned landfills are often not lined nor included in these programs. In addition, the total number of coal ash disposal sites and their status in the world is unknown. Therefore, this article reviews the environmental damage caused by CCR and three commonly used risk assessment methodologies: leaching assessment, groundwater assessment, and toxicity testing. Leaching methods are usually the first step in coal ash risk assessment, however, a large number of methods with different parameters make a comparison of data difficult. Groundwater pollution is commonly detected near coal ash disposal sites, but other anthropogenic activities may also exist nearby. Therefore, multivariate statistical methods and isotope traces should be used to differentiate between different sources of pollution. So far, both stable (δ¹⁸O, δD, δ¹¹B, δ³⁴S, δ⁷Li) and radiogenic (⁸⁷Sr/⁸⁶Sr, ²⁰⁶Pb/²⁰⁷Pb) isotopes have been successfully used as coal ash pollution tracers. Coal ash also negatively affects biota, reduces the diversity of organisms, affects children's health, and increases the risk for developing various diseases. Toxicity studies are great for early screening of coal ash safety; however, they provide no insights into mechanisms causing the adverse effects. Future directions are also proposed, such as the development of new 'low-level' detection methods for coal ash pollution and sustainable and selective method for recovery of critical elements.

Minocycline reverses developmental arsenic exposure-induced microglia activation and functional alteration in BALB/c mice

Arsenic activates microglia and exerts bystander effects on neuron. The present study is focused to test whether minocycline, a second generation antibiotic, can reverse the effect of developmental arsenic exposure on microglial activation and function. Pregnant Balb/c dams were gavaged with sodium arsenite (0.38 mg/kg bd wt) from gestational day 5 (GD5) till post natal day 21 (PND21) and then one group of pups continued till PND59 with arsenic gavage. Minocycline (33 mg/kg bd wt) was administered intraperitoneally two weeks till sacrifice, every alternate day. Mice were sacrificed on PND22 and PND60 and used for various assays. Primary microglial were isolated (ex vivo microglia) from experimental animals and used to measure reactive oxygen species (ROS), nitric oxide (NO), cytokine production and phagocytosis. The whole brain lysate was used for western blot analysis of microglial marker CD68 and synaptic marker, post synaptic density protein 95 (PSD95). For real-time PCR analysis of triggering receptor expressed on myeloid cells 2 (TREM2) and PSD95, RNA isolated from whole brain was used. The study reveals that minocycline administration reversed arsenic-induced increased expression of CD68, ROS, NO, cytokine production, phagocytosis and TREM2 expression. Arsenic-induced reduced expression of PSD95 protein was reversed by minocycline, although the mRNA of PSD95 was unaltered among different groups. Finally, we have checked the learning and memory response of the experimental animals using Y-maze test to correlate the arsenic-induced altered level of synaptic protein. Taken together, the present study finds minocycline to reduce arsenic-induced microglial activation and function which in turn reverses the arsenic-induced impaired learning and memory response.

Developmental Toxicology of Metal Mixtures in Drosophila: Unique Properties of Potency and Interactions of Mercury Isoforms

Mercury ranks third on the U.S. Agency of Toxic Substances and Disease Registry priority list of hazardous substances, behind only arsenic and lead. We have undertaken uncovering the mechanisms underlying the developmental toxicity of methylmercury (MeHg), inorganic mercury (HgCl2), lead acetate (Pb), and sodium arsenite (As). To probe these differences, we used the Drosophila model, taking advantage of three developmental transitions-pupariation, metamorphosis, and eclosion-to differentiate potentially unique windows of toxicity. We elaborated dose response profiles for each individual metal administered in food and accounted for internal body burden, also extending analyses to evaluate combinatorial metal mixture effects. We observed all four metals producing larval lethality and delayed pupariation, with MeHg being most potent. Compared to other metals, MeHg's potency is caused by a higher body burden with respect to dose. MeHg uniquely caused dose-dependent failure in eclosion that was unexpectedly rescued by titrating in HgCl2. Our results highlight a unique developmental window and toxicokinetic properties where MeHg acts with specificity relative to HgCl2, Pb, and As. These findings will serve to refine future studies aimed at revealing tissue morphogenesis events and cell signaling pathways, potentially conserved in higher organisms, that selectively mediate MeHg toxicity and its antagonism by HgCl2.

Effects of heavy metals on hypertension during menopause: a Korean community-based cross-sectional study

OBJECTIVE

To examine the associations between serum cadmium, lead, and mercury and hypertension in pre- and postmenopausal women.

METHODS

Serum heavy metal (cadmium, lead, and mercury) levels were analyzed in 7,226 randomly selected women who participated in Korean National Health and Nutrition Examination Surveys from 2009 to 2017. Odds ratios (ORs) for hypertension were calculated for log2-transformed serum heavy metal levels, median tertile levels of serum cadmium, mercury, and lead, and for interactions between heavy metal levels and tertiles, after covariate adjustment.

RESULTS

A doubling of serum cadmium was associated with hypertension in premenopausal (OR 2.47; 95% CI, 1.01-6.10, P = 0.049) and postmenopausal women (OR 1.70; 95% CI, 1.02-2.84, P = 0.043), and significant trends were observed for cadmium tertiles (P < 0.01). In premenopausal women, a two-fold increase in serum mercury increased the OR of hypertension by 3.08 (95% CI, 1.12-8.43, P = 0.029), and significant trends were also observed for serum mercury tertiles (P < 0.01). Interactions between serum cadmium, lead, and mercury levels in pre- and postmenopausal women were found to impact the prevalence of hypertension.

CONCLUSION

Given increasing exposure to heavy metals in Korea, further prospective study is needed to identify associations between heavy metal exposures, both separately and in combination, with the prevalence of cardiovascular disease risk factors in well-characterized cohorts of different populations and to determine means of preventing heavy metal exposure.

Health Risk Assessment of Heavy Metal Accumulation in Broiler Chickens and Heavy Metal Removal in Drinking Water using Moringa Oleifera Seeds in Lomé, Togo

BACKGROUND

Heavy metals are persistent in the environment and can cause bioaccumulation in the food chain. Drinking water contamination by heavy metals can pose a risk to poultry and to human health. The need for affordable, reliable and effective methods of water treatment has led to the use of plants materials, including coagulants such as Moringa oleifera seeds, to ensure poultry products are safe for consumers.

OBJECTIVES

The aim of the present study was to investigate the effects of drinking water treatment by Moringa oleifera seed on the concentration and distribution of metals such as arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) in different parts of broilers chickens and theirs effects on consumer health.

METHODS

A total number of 264 one-day old chickens (Cobb-500) were assigned to three treatments, with 22 birds in each treatment and replicated four times: untreated well water (UW), well water treated with Moringa oleifera seeds and filtered (MOF) and well water treated with Moringa oleifera seeds but unfiltered (MOU). Thirty birds were randomly chosen from different treatments and slaughtered at day 45 of the experiment and samples of livers, kidneys, gizzards and breasts were obtained and analyzed for toxic metals concentrations using atomic absorption spectrophotometry.

RESULTS

The results indicated that the bioaccumulation of heavy metals was lower in MOF than those in UW and MOU. The target hazard quotient (THQ) for individual metals was below acceptable limits except for As and Pb in UW and MOU. The carcinogenic risk (TR) was estimated for each metal due to consumption of different types of chicken.

CONCLUSIONS

Moringa oleifera seeds are an environmentally friendly natural coagulant and able to treat water containing undesirable heavy metal concentrations and ensure that poultry meat is safe for consumers.

COMPETING INTERESTS

The authors declare no competing financial interests.

ETHICS APPROVAL

This study was approved by the ethics Committee of the University of Lomé-Togo.

Erythrocytes as a Model for Heavy Metal-Related Vascular Dysfunction: The Protective Effect of Dietary Components

Heavy metals are toxic environmental pollutants associated with severe ecological and human health risks. Among them is mercury (Hg), widespread in air, soil, and water, due to its peculiar geo-biochemical cycle. The clinical consequences of Hg exposure include neurotoxicity and nephrotoxicity. Furthermore, increased risk for cardiovascular diseases is also reported due to a direct effect on cardiovascular tissues, including endothelial cells, recently identified as important targets for the harmful action of heavy metals. In this review, we will discuss the rationale for the potential use of erythrocytes as a surrogate model to study Hg-related toxicity on the cardiovascular system. The toxic effects of Hg on erythrocytes have been amply investigated in the last few years. Among the observed alterations, phosphatidylserine exposure has been proposed as an underlying mechanism responsible for Hg-induced increased proatherogenic and prothrombotic activity of these cells. Furthermore, following Hg-exposure, a decrease in NOS activity has also been reported, with consequent lowering of NO bioavailability, thus impairing endothelial function. An additional mechanism that may induce a decrease in NO availability is the generation of an oxidative microenvironment. Finally, considering that chronic Hg exposure mainly occurs through contaminated foods, the protective effect of dietary components is also discussed.

Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic

The industrial activities of the last century have caused massive increases in human exposure to heavy metals. Mercury, lead, chromium, cadmium, and arsenic have been the most common heavy metals that induced human poisonings. Here, we reviewed the mechanistic action of these heavy metals according to the available animal and human studies. Acute or chronic poisonings may occur following exposure through water, air, and food. Bioaccumulation of these heavy metals leads to a diversity of toxic effects on a variety of body tissues and organs. Heavy metals disrupt cellular events including growth, proliferation, differentiation, damage-repairing processes, and apoptosis. Comparison of the mechanisms of action reveals similar pathways for these metals to induce toxicity including ROS generation, weakening of the antioxidant defense, enzyme inactivation, and oxidative stress. On the other hand, some of them have selective binding to specific macromolecules. The interaction of lead with aminolevulinic acid dehydratase and ferrochelatase is within this context. Reactions of other heavy metals with certain proteins were discussed as well. Some toxic metals including chromium, cadmium, and arsenic cause genomic instability. Defects in DNA repair following the induction of oxidative stress and DNA damage by the three metals have been considered as the cause of their carcinogenicity. Even with the current knowledge of hazards of heavy metals, the incidence of poisoning remains considerable and requires preventive and effective treatment. The application of chelation therapy for the management of metal poisoning could be another aspect of heavy metals to be reviewed in the future.

Modulation of Cardiopulmonary Toxicity and Oxidative Stress by Phenolic-Rich Fraction of Croton zambiscus Leaves in Rat Exposed to Chronic Mixture of Environmental Toxicants

Chronic mixed toxicant exposure has been implicated in the aetiology of lung and heart failure through prolonged free radical generations. This study was carried out to assess the protective effect of naturally occurring phenolic components from Croton zambesicus (400 mg/kg C-ZAMB) leaves against cardiopulmonary toxicity induced by chronic mixed toxicant (0.5 mL EOMABRSL) in rats. Chronic cardiopulmonary injury via oral administration of 0.5 ml EOMABRSL for 98 days (non-withdrawal) and 70 days (withdrawal) caused unhealthy alteration in the levels of oxidative stress biomarkers [malondialdehyde (MDA), reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase]. Similarly, both withdrawal and non-withdrawal approaches of EOMABRSL-exposed animals exhibited increase in the activity of eco-51-nucleotidase (51ENT) with corresponding diminution in the activity of lactate dehydrogenase (LDH), i.e. the metabolic fuel for cardiopulmonary wellness. Ultimately, histology examination confirmed hyperplastic, bronchopneumonia and cloudy swelling of cardiovascular cells followed by the accumulation of cellular exudates and haemorrhage in the alveoli and bronchioles. The active antioxidants of 400 mg/kg C-ZAMB leaves were responsible for the biological protection of cardiopulmonary toxicity by modulating the activities of 51ENT and LDH. The oxidative stress was also reversed by 400 mg/kg phenolic C-ZAMB leaves in the heart and lungs. Hence, 400 mg/kg phenolic C-ZAMB leaves may be a natural therapy for the treatment of cardiovascular disorder associated with pulmonary dysfunction in rats.

The partial replacement of sodium chloride with sodium bicarbonate or sodium sulfate in laying hen diets improved laying performance, and eggshell quality and ultrastructure

This study investigated the effects of dietary chloride (Cl) reduction on laying performance and eggshell quality by substitution of sodium bicarbonate (NaHCO₃) or sodium sulfate (Na₂SO₄) for part of dietary sodium chloride (NaCl), and further explored its mechanism for improving eggshell quality. A total of 360 29-wk-old Hy-line Brown laying hens were randomly allocated to 5 dietary treatments, including a basal diet contained 0.33% NaCl (control group, 0.27% dietary Cl), and 4 experimental diets that contained 0.21% and 0.15% dietary Cl by substituting Na₂SO₄ or NaHCO₃ for part of NaCl in the basal diet. No significant differences were observed in blood Na⁺, Cl⁻, K⁺ and Ca²⁺ levels and pH value as well as serum creatinine and uric acid contents among 5 treatments (P > 0.05). Dietary Cl reduction increased egg production and ADFI during wk 33 to 36, 37 to 40 and 29 to 40 of age and decreased feed conversion ratio during wk 37 to 40 of age (P < 0.05). The hens fed with diets containing 0.15% Cl increased eggshell breaking strength, thickness and weight ratio in wk 40 of age (P < 0.05). Birds fed with dietary 0.21% and 0.15% Cl exhibited higher effective layer thickness and lower mammillary layer thickness of eggshell than those fed with dietary 0.27% Cl (P < 0.05). Apparent Ca metabolizability of hens was increased with dietary Cl reduction (P < 0.05). Total Ca of eggshell of dietary 0.15% Cl group was higher than that of dietary 0.27% Cl group (P < 0.05). No significant differences in laying performance, eggshell quality and Ca metabolism of layers were observed between Na₂SO₄ and NaHCO₃ replacement groups (P > 0.05). Overall, dietary Cl reductions could improve laying performance and eggshell quality by substitution of NaHCO₃ or Na₂SO₄ for part of NaCl, and there were no differences in the improvements between these two substitutes. The improved eggshell quality may be attributed to improved eggshell ultrastructure and increased supply of eggshell Ca₂CO₃.

Safety of livestock products of bulls on various diets during fattening in the conditions of radioactive contamination

Production of high-quality and safe food products in the conditions of technogenic environmental pollution is a problem worldwide, especially in Ukraine. As a result of the disaster at the Chornobyl Atomic Power Plant, radioactive substances, including caesium-137, contaminated the soil not only in Ukraine, but in many other countries. Zhytomyr Oblast is the fifth largest oblast in Ukraine and one of the regions that were the most damaged by the accident. Furthermore, this territory is contaminated by the most toxic heavy metals – lead (Pb) and cadmium (Cd) that actively migrate in the biological system: soil→ plant → animal → production → human, intensely accumulating in the products of plant and animal origin. The complex ecological situation and broad spectrum of biological and toxic actions of 137Cs, Pb, Cd require a number of measures that would prevent transformation of radioactive elements and heavy metals in the organism of animals, increase animals` productivity and safety of the food products made in the conditions of the Ukrainian Polisia. Therefore, we aimed at substantiating the practicability of using silage-concentrate, silage-concentrate-root vegetable and silage-concentrate-hay types of diet for young cattle during fattening and determining the impact of accumulation of 137Сs, Pb and Cd in livestock products. To perform the studies, we formed three groups of young bulls of Ukrainian Black Pied cattle using the method of analogues with creating comfortable maintenance condition and organization of in-detail planned feeding. The diet was composed of fodders prepared in the conditions of radioactive contamination. The laboratory surveys indicated that the main sources of 137Cs ingress in the organism of the animals were roughages and various types of silages, and the sources of heavy metals Pb and Cd were hay of red clover and concentrated fodders. In the experimental studies, we determined absolute and average daily weight gains, expenditures of metabolic energy per 1 kg of weight increment, specific activity of 137Сs and concentrations of the heavy metals (Pb and Cd) in the biological system “fodder-animal-production” during feeding of bulls with various-type diets in the conditions of the III zone of radioactive pollution. It was confirmed that substituting maize silage and carbohydrate fodders increased the average daily gains in the live weight by 2.3–4.6%, decreased specific activity of 137Cs by 8.7–20.1%, the content of Pb by 36.2%, Cd by 34.1–66.7% in the longissimus at silage-concentrate-root vegetable and silage-concentrate-hay types of diet for bulls. Thus, use of silage-concentrate-root vegetable and silage-concentrate-hay types of diets compared with silage-concentrate feeding had a positive effect on their productivity and safety of the food production.

Association of multiple metals with lipid markers against different exposure profiles: A population-based cross-sectional study in China

We sought to evaluate whether essential and toxic metals are cross-sectionally related to blood lipid levels using data among adults from Shimen (n = 564) and Huayuan (n = 637), two counties with different exposure profiles in Hunan province of China. Traditional and grouped weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were performed to assess association between exposure to a mixture of 22 metals measured in urine or plasma, and lipid markers. Most of the exposure levels of metals were significantly higher in Shimen area than those in Huayuan area (all P-values < 0.001). Traditional WQS regression analyses revealed that the WQS index were both significantly associated with lipid markers in two areas, except for the HDL-C. Grouped WQS revealed that essential metals group showed significantly positive associations with lipid markers except for HDL-C in Huayuan area, while toxic metals group showed significantly negative associations except for HDL-C and LDL-C in Huayuan area. There were no significant joint effects, but potential non-linear relationships between metals mixture and TC or LDL-C levels were observed in BKMR analyses. Although consistent significantly associations of zinc and titanium with TG levels were found in both areas, the metals closely related to other lipid markers were varied by sites. Additionally, the BKMR analyses revealed an inverse U shaped association of iron with LDL-C levels and interaction effects of zinc and cadmium on LDL-C in Huayuan area. The relationship between metal exposure and blood lipid were not identical against different exposure profiles.

Risk Assessment of Trace Element Contamination in Drinking Water and Agricultural Soil: A Study in Selected Chronic Kidney Disease of Unknown Etiology (CKDu) Endemic Areas in Sri Lanka

Unexplained or unclear etiology of chronic kidney disease (CKDu) has been reported in Sri Lanka’s North Central Province (NCP) for more than two decades. Meanwhile, high exposure to heavy metals/metalloids and their accumulation are recognized as the origin of many acute and chronic diseases in certain vulnerable human tissues including kidneys. This study evaluates the contamination status of heavy metals/metalloids of the drinking water and agricultural soil in two CKDu endemic areas compared with a reference area in Sri Lanka based on common indexes and attribute of the commonly used fertilizers evaluated to identify the basic sources of toxic metals in the agricultural soil. Mean concentrations of heavy metals/metalloids such as Mn, Co, As, Cd, Pb, Cu, Zn, and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissible limits). In addition, all sampling locations dropped below the medium range of the heavy metal pollution index of water (HPI 15–40). Geoaccumulation indexes (Igeo) of soil reveal that paddy soil in CKDu endemic areas is being moderately polluted with toxic metals/metalloids such as As, Pb, Cu, Ni, Cr, Zn, and Cd. On the other hand, the application of fertilizers, which contained a high dose of toxic metals, could be the driving force for agricultural soil pollution, and limitless application of low-quality fertilizer would lead to more soil contamination with heavy metals. Hence, hazardous metals can be incorporated into the food chains via contaminated paddy soil.

Multimarker approach to assess the exposure of the wild rodent Calomys laucha to a simulated crude oil spill

A mysterious oil spill occurred in the ocean near Brazil in 2019, which affected coastal areas in northeastern Brazil. When oil pollution occurs in coastal zones, organisms such as small mammals can suffer deleterious effects to their health. This study aimed to evaluate the effects of exposure to contaminated sandy soil with different crude oil concentrations in males of the species Calomys laucha. The exposure to crude oil resulted in multiple health issues for the subjects in the very first days of exposure. Furthermore, the exposure resulted in mutagenic damage to bone marrow blood cells and behavioral and morphological alterations, which were almost always in a dose-dependent form. The present study demonstrates the sensibility of the biomarkers used and highlights that small wild mammals such as C. laucha are useful for predicting environmental damage caused by the exposure to crude oil.

Redox and essential metal status in the brain of Wistar rats acutely exposed to a cadmium and lead mixture

Most Pb and Cd neurotoxicity studies investigate exposure to either of the toxic metals alone, while data on co-exposure are scarce. The aim of our study was to fill that gap by investigating acute combined effects of Pb and Cd on redox and essential metal status in the brain of Wistar rats. Animals were randomised in four groups of six to eight rats, which received 15 or 30 mg/kg of Cd, 150 mg/kg of Pb, or 150 mg/kg of Pb + 15 mg/kg of Cd by gavage. The fifth, control, group received distilled water only. Co-treatment with Pb and Cd induced significant increase in malondialdehyde (MDA) and thiobarbituric acid-reactive substances (TBARS) compared to control and groups receiving either metal alone. This is of special importance, as MDA presence in the brain has been implicated in many neurodegenerative disorders. The groups did not significantly differ in Zn, Cu, Mn, and Fe brain levels. Our findings highlight the importance of metal mixture studies. Neurotoxicity assessments of single chemicals do not provide a real insight into exposure to mixtures in real life. Further research should look into interactions between these metals to reveal complex molecular mechanisms of their neurotoxicity.

Micro-RNAs: Crossroads between the Exposure to Environmental Particulate Pollution and the Obstructive Pulmonary Disease

Environmental pollution has reached a global echo and represents a serious problem for human health. Air pollution encompasses a set of hazardous substances, such as particulate matter and heavy metals (e.g., cadmium, lead, and arsenic), and has a strong impact on the environment by affecting groundwater, soil, and air. An adaptive response to environmental cues is essential for human survival, which is associated with the induction of adaptive phenotypes. The epigenetic mechanisms regulating the expression patterns of several genes are promising candidates to provide mechanistic and prognostic insights into this. Micro-RNAs (miRNAs) fulfil these features given their ability to respond to environmental factors and their critical role in determining phenotypes. These molecules are present in extracellular fluids, and their expression patterns are organ-, tissue-, or cell-specific. Moreover, the experimental settings for their quantitative and qualitative analysis are robust, standardized, and inexpensive. In this review, we provide an update on the role of miRNAs as suitable tools for understanding the mechanisms behind the physiopathological response to toxicants and the prognostic value of their expression pattern associable with specific exposures. We look at the mechanistic evidence associable to the role of miRNAs in the processes leading to environmental-induced pulmonary disease (i.e., chronic obstructive pulmonary disease).

The genotoxic effects of mixture of aluminum, arsenic, cadmium, cobalt, and chromium on the gill tissue of adult zebrafish (Danio rerio, Hamilton 1822)

The aim of this study is to investigate the genotoxic effects of mixtures of five metals on zebrafish at two different concentrations; at the permissible maximum contamination levels in drinking water and irrigation waters. The drinking water limits are as follows: 300 µg/L for Aluminum (Al⁺³), 10 µg/L for Arsenic (As⁺³), 5 µg/L for Cadmium (Cd⁺²), 10 µg/L for Cobalt (Co⁺²), and 50 µg/L for Chromium (Cr⁺²). The irrigation water limits: 5000 µg/L for Al⁺³, 100 µg/L for As⁺³, 10 µg/L for Cd⁺², 50 µg/L for Co⁺², and 100 µg/L for Cr⁺². The zebrafish underwent chronic exposure for periods of 5, 10, and 20 days. The gene expressions for mitochondrial superoxide dismutase (SOD2), stress-specific receptor protein NCCRP1, the heat shock proteins: Hsp9, Hsp14, Hsp60, Hsp70, DNA repair (XRCC1 and EXO1), and apoptosis (BOK and BAX) were evaluated. It was found that exposure to the low- and high-concentrations of the heavy metal mixtures caused cell stress, an increased expression of the antioxidant genes, and repair proteins. As the duration of exposure was increased, the cells progressed through the apoptotic pathway. This was more evident in the high-concentration exposure groups. The results demonstrated the necessity for a reevaluation of the maximum values of heavy metal and toxic element concentrations as prescribed by the Local Standing Rules of Water Pollution Control Regulation, as well as a reevaluation of the limitations of heavy metal mixture interactions with respect to ecological balance and environmental health.HighlightsThe purpose of this study was to investigate the genotoxic effects of a mixture of Aluminum, Arsenic, Cadmium, Cobalt, Chromium on zebrafish, within drinking water, and irrigation water limits determining the concentration.The zebrafish were exposed to two different concentrations of each metal mixture for 5-, 10-, and 20-day periods. Following exposure, gene expressions of the zebrafish's gill tissues were examined.As a result of the exposure to the metal mixtures, the following occurred: cell stress, increased antioxidant gene activity, and attempts to protect cell viability. However, the cells progressed through the apoptotic pathway after prolonged exposure.The results demonstrated the necessity for a reevaluation of the maximum limits of metal and toxic element concentrations as stated in the Standing Rules of Water Pollution Control Regulation.

The protective effect of rutin against busulfan-induced testicular damage in adult rats

Here, we studied the protective effect of rutin (RUT) against testicular damage caused by busulfan (BUS) in rats. Adult male Wistar rats were intraperitoneally injected with BUS (4 mg/kg body weight at day 7 and 14), and then treated with RUT (30 mg/kg body weight) by gavage thrice weekly for 60 days. The results showed that BUS-induced increase in 3β-hydroxysteroid dehydrogenase (3β-HSD) was significantly decreased by RUT, whereas 17β-HSD activity and plasma testosterone concentration remained unaffected (p > 0.05). It was also observed that RUT inhibited BUS-induced increase in nitrite concentrations and myeloperoxidase enzyme activities in the plasma and testes (p < 0.05). Similarly, BUS-induced decrease in glutathione and increase in malondialdehyde concentrations in the testes were significantly normalized to control values by RUT. Finally, RUT administration showed some tendency to improve the architecture of the seminiferous epithelium of the rat's testes after BUS treatment. Overall, RUT inhibited BUS-induced oxidative damage and inflammation in the testis of an experimental rat model.

Effect of a Prolonged Dietary Iron Intake on the Gene Expression and Activity of the Testicular Antioxidant Defense System in Rats

Despite the fact that iron represents a crucial element for the catalysis of many metabolic reactions, its accumulation in the cell leads to the production of reactive oxygen species (ROS), provoking pathological conditions such as cancer, cardiovascular diseases, diabetes, neurodegenerative diseases, and fertility. Thus, ROS are neutralized by the enzymatic antioxidant system for the purpose of protecting cells against any damage. Iron is a potential risk factor for male fertility. However, the mechanism of action of iron on the testicular antioxidant system at the gene and protein levels is not fully understood. Thus, the purpose of the current research was to ensure a better understanding of how the long-term iron treatment influences both gene expression and enzyme activities of the testicular antioxidant system in rat testis. The data of our study showed that a significant dose-dependent increase occurred in the iron level in rat testis. A reduction occurred in reduced glutathione (GSH) levels, which represent a marker of oxidative stress, along with long-term iron overload. The expression and activity of glucose 6-phosphate dehydrogenase (G6pd), glutathione reductase (Gr), glutathione peroxidase (Gpx), and glutathione S-transferases (Gst) were significantly affected by the presence of iron. The findings of the current research demonstrate that the long-term toxic dietary iron overload influences the gene expression and enzyme activity of the testicular antioxidant defense system, but the actual effect occurs at the protein level. This may modify the sperm function and dysfunction of the male reproductive system.

Dietary chloride levels affect performance and eggshell quality of laying hens by substitution of sodium sulfate for sodium chloride

The objective of this study was to evaluate the effect of dietary chloride (Cl) levels on performance, eggshell mechanical quality, and ultrastructure in layers based on the substitution of sodium chloride (NaCl) by sodium sulfate (Na₂SO₄). Three hundred sixty Jing Brown laying hens aged 43 wk were randomly divided into 5 groups and fed with corn–soybean meal diets containing 0.06, 0.10, 0.15, 0.20, and 0.25% total Cl inclusion. Every group had 8 replicates of 9 birds each. The feeding trial lasted for 12 wk. The results showed dietary 0.06% Cl due to complete substitution of NaCl by Na₂SO₄, depressed performance (P < 0.05) from 45 to 54 wk of age, increased serum creatinine level (P < 0.05), and caused visible renal tubular atrophy. Dietary Cl levels quadratically affected breaking strength, thickness, and weight of eggshell (P < 0.05). Better eggshell quality could be obtained when NaCl was partly replaced by Na₂SO₄ in laying hen diets maintaining Cl level at 0.10 or 0.15%. Moreover, the eggshell ash content was affected by Cl levels in a quadratic (P < 0.001) manner, with higher values observed in the 0.10 and 0.15% Cl groups (P < 0.05). Besides, the eggshell ultrastructural data showed that the total thickness and effective thickness significantly increased (P < 0.05) and mammillary thickness decreased (P < 0.05) in the group of dietary 0.15% Cl compared with the groups of 0.06 and 0.25% Cl. In conclusion, the complete substitution of dietary NaCl by Na₂SO₄ may induce Cl deficiency and depress laying performance and eggshell quality. Na₂SO₄ could partly replace NaCl in diets for laying hens (43–54 wk of age) without adverse effects on performance at the dietary Cl level from 0.10 to 0.25%. Better eggshell quality could be obtained when NaCl was partly replaced by Na₂SO₄ in laying hen diets maintaining Cl level at ∼0.15%.

Effects of secondary biological treatment plant effluent administration, as drinking water, to rats' urogenital system in relation to cadmium and lead accumulation

The aim of this study was to examine the effect of the secondary biological treatment plant effluent administration on the kidneys, urinary bladder, and testis of Wistar rats in relation to lead (Pb) and cadmium (Cd) accumulation, since such an effluent is used for irrigation of edible plants. Male Wistar rats, randomly assigned into 5 groups, were treated with domestic sewage effluent (DSE) for 24 months. Cadmium and lead concentrations in the DSE, rats' tissues, and urine were estimated by means of atomic spectroscopy. Lead was rapidly accumulated in high amounts in rats' kidney and to a lesser extent in the testis whereas Cd concentration was raised in all tissues examined. Deposition of Cd and Pd in the kidney of the rats resulted in profound damage over time. The results showed that long-term administration to DSE as drinking water exposes living organisms to urogenital stress related to heavy metal concentration and pH of the effluent.

Metal-induced nephrotoxicity to diabetic and non-diabetic Wistar rats

The present study was conducted to examine the nephrotoxic effects of heavy metals including lead (Pb), manganese (Mn), arsenic (As), and cadmium (Cd) in diabetic and non-diabetic Wistar rats. Animals were exposed to heavy metals for 30 days, Pb was injected as lead acetate (C₄H₆O₄Pb), Mn was injected as manganese chloride (MnCl₂), Cd was injected as cadmium chloride (CdCl₂), and As was administered orally to rats in the form of sodium arsenite (AsO₂Na). Results showed that metal deposition trends in tissues were Pb > As > Cd > Mn and the urinary metal levels were Pb > Cd > As > Mn. Diabetic metal alone, as well as metal mixture-treated groups, showed decreased urinary metal levels as compared with non-diabetic metal alone and metal mixture-treated groups. Both diabetic- and non-diabetic metal mixture-treated groups revealed an increasing trend of blood urea nitrogen (BUN) and serum creatinine. In addition, heavy metal treatments resulted in elevated malondialdehyde (MDA) levels in the kidney tissue while decreased levels of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GHS) were observed in the kidney tissue in comparison with the control group. The histological analysis of the kidney tissues showed tubular degeneration, fibrosis, and vacuolation as a result of heavy metal exposure. The present study revealed that co-exposure of heavy metals (Pb, Cd, Mn, As) induced more nephrotoxicity as compared with the metal alone treatment. Moreover, diabetic Wistar rats are more prone to kidney damage as a result of heavy metal exposure.

Ameliorative Effect Of Zinc Oxide Nanoparticles Against Dermal Toxicity Induced By Lead Oxide In Rats

Background

Recently, several studies demonstrate the possible role of zinc oxide (ZnO) in the protection of several skin diseases, but less is known about the role of ZnO nanoparticles in the inflammatory skin disease. So, this study was designed to confirm the pivotal role of the nano zinc oxide cream in the alleviation of lead oxide (PbO) induced-allergic dermatitis in rats.

Materials and methods

Two concentrations (1% and 6%) of ZnONPs creams were prepared and characterized prior to being used in the study. A total number of 30 male Wistar rats were randomly divided into six groups. Group 1 (negative control), groups 2&3 (either 1% or 6% ZnONPs control groups), group 4 (PbO), groups 5&6 (co-treatment of each ZnONPs concentration+PbO). All rats in different groups were observed daily to determine the severity of dermal gross lesions. Histopathological studies, mRNA analysis, and oxidative stress evaluations were performed on the affected skin tissue. Immunohistochemical studies were performed to evaluate the expression of cluster of differentiation CD4, CD8 and intercellular adhesion molecules ICAM-1 in different groups.

Results

PbO caused extensive skin oxidative damage manifested by a significant increase in MDA level with a decrease in GSH content and CAT activity. The results of histopathological and immunohistochemical examinations revealed that topical application of PbO for 14 days led to severe allergic dermatitis with remarkable elevations in the number of CD4+ T-helper, CD8+ T-cytotoxic lymphocytes, and ICAM-1 expression. On the other hand, noticeable improvements were recorded in all the previous toxicopathological parameters among the groups treated by either 1% or 6% ZnO-NPs cream. However, the best results were observed in the group treated with 1% ZnO-NPs cream.

Conclusion

Our findings suggest that 1% of ZnO-NPs cream is safe when applied topically on the inflamed skin. Moreover, it had anti-inflammatory and antioxidant effects so that, it is recommended to use the 1% ZnO-NPs cream to avert the dermal toxicity-induced by PbO.

Chronic exposure to Pb2+ perturbs ChREBP transactivation and coerces hepatic dyslipidemia

Dysregulated hepatic de novo lipogenesis contributes to the pathogenesis of nonalcoholic fatty liver disease in both humans and rodents. Clinical evidence suggests fatty liver to have a positive correlation with serum lead (Pb²⁺ ) levels. However, an exact mechanism of Pb²⁺ -induced fatty liver progression is still unknown. Here, we show that exposure to Pb²⁺ regulates ChREBP-dependent hepatic lipogenesis. Presence of Pb²⁺ ions within the hepatocytes reduces transcript and protein levels of sorcin, a cytosolic adaptor partner of ChREBP. Adenovirus-mediated overexpression of sorcin in Pb²⁺ exposed hepatocytes and an in vivo mouse model ameliorates liver steatosis and hepatotoxicity. Hereby, we present Pb²⁺ exposure to be a lethal disruptor of lipid metabolism in hepatocytes and highlight sorcin as a novel therapeutic target against Pb²⁺ -induced hepatic dyslipidemia.

A study on the concentration of heavy metals and histopathological changes in Persian jirds (Mammals; Rodentia), affected by mining activities in an iron ore mine in Iran

Mining activity constitutes a potential source of heavy metal pollution in the environment. Long-term exposure to heavy metals (e.g., cadmium) has adverse health effects. Rodents frequently serve as bioindicators to monitor the levels of heavy metals in the environment. In the present study, concentrations of 10 heavy metals (Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Sb, and Zn) in kidney, liver, and muscle tissue of the Persian jird (Meriones persicus) were evaluated. This is the first study to examine the histopathological changes in Persian jird tissues caused by the bioaccumulation heavy metals. The samples were taken at location that surrounded by Sangan Iron Ore Mine (SIOM) mining activities, in northeastern Iran. The results show that the highest concentrations for the metals were observed in kidney and liver, whereas lowest concentrations were found in muscle of Persian jirds. The concentration of Pb was below the limit of detection. Sex and age were two factors that could explain the different levels of heavy metal bioaccumulation, which affects the concentration of some metals. Adults had significantly higher Cu and Cd levels compared to juveniles. Males bioaccumulated more Zn in their kidneys than females, whereas females bioaccumulated more Fe in their livers. As expected, heavy metals affected various organs of the studied specimens. Hyperemia, hemorrhage, necrosis, and degenerative damage to the epithelial cells of the tubules, the presence of hyaline casts, and in one case, mononuclear leukocyte infiltration, were observed in samples of renal tissue. Hemorrhage and hepatocyte vacuolization were the most common histopathological changes found in samples of hepatic tissue. These effects and the concentrations of heavy metals in the studied specimens indicate the need for monitoring and frequent sampling to evaluate long-term persistent pollutants.

Impact of in vitro heavy metal exposure on pancreatic β-cell function

Susceptibility to type-2 diabetes mellitus (DM) is determined, in part, by a variety of environmental factors, including exposure to metals. Heavy metals including inorganic arsenic (iAs), zinc (Zn), manganese (Mn), and cadmium (Cd) have been reported to affect glucose homeostasis or DM risk in population-based and/or laboratory studies. Previous evidence from our lab has shown that iAs can increase DM risk by impairing mitochondrial metabolism, one of the key steps in the regulation of glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells. The goal of the current study was to compare the effects of iAs on GSIS and mitochondrial function in INS-1 832/13 β-cells with those of Cd, Mn, and Zn, and to evaluate effects of binary mixtures of these metals. As expected, 24-hour exposure to iAs (arsenite, ≥1 μM) significantly inhibited GSIS as did Cd (5 μM) and Mn (12.5, 25, or 50 μM). Zn had no effects on GSIS at concentrations up to 50 μM. Mitochondrial function was assessed by measuring oxygen consumption rate (OCR) after glucose stimulation and during simulated mitochondrial stress. While both iAs and Mn impaired mitochondrial function (inhibiting OCR, maximal respiration, and/or spare respiratory capacity of mitochondria), no significant effects were found in cells exposed to Cd. Interestingly, no additive or synergistic effects on GSIS or OCR were observed in binary mixtures of iAs with either Mn or Cd. These data suggest that Mn, like iAs, may inhibit GSIS by impairing mitochondrial function, whereas Cd may target other mechanisms that regulate GSIS in β-cells.

In vitro and in vivo effects of iron on the expression and activity of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase in rat spleen

Iron is an indispensable element for vital activities in almost all living organisms. It is also a cofactor for many proteins, enzymes, and other essential complex biochemical processes. Therefore, iron trafficking is firmly regulated by Hepcidin (Hamp), which is regarded as the marker for iron accumulation. The disruption of iron homeostasis leads to oxidative stress that causes various human diseases, but this mechanism is still unclear. The aim of this study is to provide a better in vivo and in vitro understanding of how long-term iron overload affects the gene expression and activities of some antioxidant enzymes, such as glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and glutathione reductase (GR) in the spleen. The findings of this study show that iron overload reduces the gene expression of G6pd, 6pgd, and Gr, but its actual effect was on the protein level.

Heavy Metal Mixture Exposure and Effects in Developing Nations: An Update

The drive for development and modernization has come at great cost. Various human activities in developed and developing countries, particularly in sub-Saharan Africa (SSA) have given rise to environmental safety concerns. Increased artisanal mining activities, illegal refining, use of leaded petrol, airborne dust, arbitrary discarding and burning of toxic waste, absorption of production industries in inhabited areas, inadequate environmental legislation, and weak implementation of policies, have given rise to the incomparable contamination and pollution associated with heavy metals in recent decades. This review evaluates the public health effects of heavy metals and their mixtures in SSA. This shows the extent and size of the problem posed by exposure to heavy metal mixtures in regard to public health.

Activation of TRPV1 receptors affects memory function and hippocampal TRPV1 and CREB mRNA expression in a rat model of biliary cirrhosis

OBJECTIVE

Memory impairment induced by biliary cirrhosis is associated with abnormalities in the function of different neurotransmitter systems. However, the exact molecular mechanisms involved in the learning and memory dysfunctions following biliary cirrhosis is largely unknown. This study set out to determine whether activation of transient receptor potential vanilloid type 1 (TRPV1) in the CA1 area of the hippocampus in rats improve memory impairment induced by biliary cirrhosis.

METHODS

To assess learning and memory, passive avoidance task was carried out using a shuttle box. The mRNA expression of TRPV1 and cAMP response element binding (CREB) protein in the hippocampus were also evaluated by qT-PCR.

RESULTS

Our results indicated that activation of TRPV1 channels by capsaicin significantly decreased memory impairment and increased mRNA expression of the TRPV1 and CREB in the hippocampus of rats with biliary cirrhosis. Our findings also demonstrated that a positive correlation existed between mRNA expression of TRPV1 and CREB, and between memory function and TRPV1 expression.

DISCUSSION

Taken together, the results of this study support the view that TRPV1 receptor may play an important role in the regulation of learning and memory functions, and suggest that activation of TRPV1 channels seems to be a promising therapeutic target for learning and memory impairments following biliary cirrhosis.

Consolidating probiotic with dandelion, coriander and date palm seeds extracts against mercury neurotoxicity and for maintaining normal testosterone levels in male rats

Objective

Heavy metals are major elements polluting our universe. The inhalation, ingestion or even contacting human body with these elements results in huge health problems. The most common pollutant in our surrounding is mercury. Therefore, the present study aimed to elucidating the protective ability of hot water extracts of dandelion (DA), coriander (CO), date palm seeds (DS), probiotic supernatant (PS) and their combined mixture against mercury-induced neurotoxicity and altered testosterone levels in male rats.

Methods

Fifty six male rats were randomly allotted into seven groups (n = 8 rats/group). Group1 (negative control; NC) animals were fed on the basal diet only, group2 (positive controls; PC) animals were fed on the basal diet and given an aqueous solution of mercuric chloride (25 ppm mercuric) in drinking water. Animals of the antioxidant-treated groups (3–7) were fed on the basal diet and given an aqueous solution of mercuric chloride (25 ppm mercuric) in drinking water together with the herbal antioxidant extracts and probiotics (25 ml/rat/day) throughout the experimental period. Where, group3 (Hg/CO) given coriander extract, group4 (Hg/DA) given dandelion extract, group5 (Hg/DS) given date palm seeds extract, group6 (Hg/PS) given probiotic supernatant, and group7 (Hg/Mix) given mixture of equal quantities of probiotic supernatant together with the three herbal extracts. The treatment lasted for 6 weeks, animals were sacrificed and blood samples were collected. Blood testosterone, enzyme activity and histopathological sections were performed.

Results

The obtained data exhibited that mercury intoxication revealed increases of lactic dehydrogenase and decreases of glutathione-s-transferase and testosterone. Light microscopic investigations of the brain cortex and cerebellum were suggestive of multiple foci of inflammation, cellular infiltration, gliosis and degeneration. Moreover, decreased glial fibrillary acidic protein (GFAP)-immunoreactivity and potential astrocyte toxicity both reflected impaired neuro-protective function of astrocytes necessary for maintaining the brain structure and function.

Conclusion

Administration of the herbal extracts and their mixture with probiotics enhance the body defense and contain protective factor against mercury neurotoxicity and for maintaining normal testosterone levels in male rats. Also, treatment restored the normal control levels of biochemical attributes and histological architecture.