The Effects of Cadmium Toxicity

Adsorption of Cd to TiO2-NPs Forms Low Genotoxic AGGREGATES in Zebrafish Cells

The aquatic environment is involved in the pollutants spreading mechanisms, including nanomaterials and heavy metals. The aims of this study were to assess the in vivo genotoxicity of Cd (1 mg/L) and to investigate the genomic effects generated by its co-exposure with TiO₂-NPs (10 µg/L). The study was performed using zebrafish as a model for 5, 7, 14, 21, and 28 days of exposure. The genotoxic potential was assessed by three experimental approaches: DNA integrity, degree of apoptosis, and molecular alterations at the genomic level by genomic template stability (% GTS) calculation. Results showed an increased in DNA damage after Cd exposure with a decrease in % GTS. The co-exposure (TiO₂-NPs + Cd) induced a no statistically significant loss of DNA integrity, a reduction of the apoptotic cell percentage and the recovery of genome stability for prolonged exposure days. Characterization and analytical determinations data showed Cd adsorption to TiO₂-NPs, which reduced free TiO₂-NPs levels. The results of our study suggest that TiO₂-NPs could be used for the development of controlled heavy metal bioremediation systems.

Cadmium exposure induces mitochondrial pathway apoptosis in swine myocardium through xenobiotic receptors-mediated CYP450s activation

Cadmium (Cd) pollution has become an important public and environmental health issue. Xenobiotic receptors (XRs, aryl hydrocarbon receptor, AHR; constitutive androstane receptor, CAR; pregnane X receptor, PXR) modulate downstream cytochrome P450 enzymes (CYP450s) expression to metabolize xenobiotics and environmental contaminants. However, the underlying mechanisms of cardiotoxicity induced by Cd(II) in swine and the roles of XRs and CYP450s remain poorly understood. In this study, the cardiotoxicity of Cd(II) was investigated by establishing a Cd(II)-exposed swine model (CdCl₂, 20 mg Cd/Kg diet). Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay and transmission electron microscope were used to observe the apoptosis. Antioxidant capacity was evaluated by free radicals contents and antioxidant enzymes activities. RT-PCR and western blot were used to measure the expression of XRs, CYP450s and apoptosis-related genes. Our results revealed that Cd(II) exposure activated the XRs and increased the CYP450s expression, contributing to the production of reactive oxygen species (ROS). Cd(II) exposure restrained the antioxidant capacity, causing oxidative stress. Moreover, mitogen-activated protein kinase (MAPK) pathway including c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (P38) was activated, triggering the mitochondrial apoptotic pathway. In brief, we concluded that Cd(II) caused mitochondrial pathway apoptosis in swine myocardium via the oxidative stress-MAPK pathway, and XRs-mediated CYP450s expression might participate in this process through promoting the ROS.

Heavy metals modulate DNA compaction and methylation at CpG sites in the metal hyperaccumulator Arabidopsis halleri

Excess heavy metals affect plant physiology by inducing stress symptoms, however several species have evolved the ability to hyperaccumulate metals in above-ground tissues without phytotoxic effects. In this study we assume that at subcellular level, different strategies were adopted by hyperaccumulator versus the non-accumulator plant species to face the excess of heavy metals. At this purpose the comet assay was used to investigate the nucleoid structure modifications occurring in response to Zn and Cd treatments in the I16 and PL22 populations of the hyperaccumulator Arabidopsis halleri versus the nonaccumulator species Arabidopsis thaliana. Methy-sens comet assay and RT-qPCR were also performed to associate metal induced variations in nucleoids with possible epigenetic modifications. The comet assay showed that Zn induced a mild but non significant reduction in the tail moment in A. thaliana and in both I16 and PL22. Cd treatment induced an increase in DNA migration in nuclei of A. thaliana, whereas no differences in DNA migration was observed for I16, and a significant increase in nucleoid condensation was found in PL22 Cd treated samples. This last population showed higher CpG DNA methylation upon Cd treatment than in control conditions, and an up-regulation of genes involved in symmetric methylation and histone deacetylation. Our data support the hypothesis of a possible role of epigenetic modifications in the hyperaccumulation trait to cope with the high Cd shoot concentrations. In addition, the differences observed between PL22 and I16 could reinforce previous suggestions of divergent strategies for metals detoxification developing in the two metallicolous populations.

Cellular alterations and damage to the renal tissue of marine catfish Arius arius following Cd exposure and the possible sequestrant role of Metallothionein

Cd is a non-degradable heavy metal pollutant with no known biological role. When taken up by living organisms from the environment, it causes extensive tissue damage. Here, we studied the effects of exposure to 20 mg/L^-1CdCl₂for 0, 24, 48, and 72 h on the renal tissue of marine catfish Arius arius. Cd uptake, metallothionein (MT) induction, microarchitectural alterations, DNA fragmentation, and caspase-3 activity were studied. Cd and MT levels were time-dependent and positively correlated. The diameter of the Bowman's capsule and tubules was significantly increased. Meanwhile, the density, diameter, and volume of the glomerulus as well as the density and volume of tubules decreased. Cd induced apoptosis though elevatedcaspase-3 activity. These results support the notion that exposure to sublethal Cd levels induces oxidative stress, leading to structural and functional impairment of the kidneys. Cd uptake and MT induction can serve as useful environmental biomarkers.

Gene Expression Changes after Parental Exposure to Metals in the Sea Urchin Affect Timing of Genetic Programme of Embryo Development

It is widely accepted that phenotypic traits can be modulated at the epigenetic level so that some conditions can affect the progeny of exposed individuals. To assess if the exposure of adult animals could result in effects on the offspring, the Mediterranean sea urchin and its well-characterized gene regulatory networks (GRNs) was chosen as a model. Adult animals were exposed to known concentrations of zinc and cadmium (both individually and in combination) for 10 days, and the resulting embryos were followed during the development. The oxidative stress occurring in parental gonads, embryo phenotypes and mortality, and the expression level of a set of selected genes, including members of the skeletogenic and endodermal GRNs, were evaluated. Increased oxidative stress at F₀, high rates of developmental aberration with impaired gastrulation, in association to deregulation of genes involved in skeletogenesis (dri, hex, sm50, p16, p19, msp130), endodermal specification (foxa, hox11/13b, wnt8) and epigenetic regulation (kat2A, hdac1, ehmt2, phf8 and UBE2a) occurred either at 24 or 48 hpf. Results strongly indicate that exposure to environmental pollutants can affect not only directly challenged animals but also their progeny (at least F₁), influencing optimal timing of genetic programme of embryo development, resulting in an overall impairment of developmental success.

Ecotoxicity assessment of a molybdenum mining effluent using acute lethal, oxidative stress, and osmoregulatory endpoints in zebrafish (Danio rerio)

The present study investigated the ecotoxicity of raw mining effluent from the largest molybdenum (Mo) open-pit mine in the Qinling mountains, China, and the treated effluent with neutralization and coagulation/adsorption processes, using zebrafish (Danio rerio). The results showed the following: (1) the mining effluent is acid mine drainage (AMD) and is highly toxic to zebrafish with a 96-h median lethal concentration (LC₅₀) of 3.80% (volume percentage) of the raw effluent; (2) sublethal concentrations of the raw effluent (1/50, 1/10, and 1/2 96-h LC₅₀) induced oxidative stress and osmoregulatory impairment, as reflected by the alterations in activities of superoxide dismutase and catalase and contents of malondialdehyde, and inhibition of Na⁺, K⁺-ATPase activity in gills and muscle after 28 days of sub-chronic exposure when compared with the unexposed group; and (3) the treatment of the raw effluent with neutralizer (NaOH) and adsorbent activated carbon reduced the acute lethal effect of raw effluent. The used endpoints including acute lethal and biochemical parameters related to oxidative stress and osmoregulatory impairment in zebrafish are cost-effective for toxicity assessment of AMD like the studied Mo mining effluent. Mining effluent management strategies extended by these results, i.e., the restriction of discharging raw and diluted effluent to adjacent waterways and the introduction of bio-monitoring system across all mining drainages in this area, were also proposed and discussed.

Immunotoxicology of cadmium: Cells of the immune system as targets and effectors of cadmium toxicity

Cadmium (Cd) has been listed as one of the most toxic substances affecting numerous tissues/organs, including the immune system. Due to variations in studies examining Cd effects on the immune system (exposure regime, experimental systems, immune endpoint measured), data on Cd immunotoxicity in humans and experimental animals are inconsistent. However, it is clear that Cd can affect cells of the immune system and can modulate some immune responses. Due to the complex nature of the immune system and its activities which are determined by multiple interactions, the underlying mechanisms involved in the immunotoxicity of this metal are still vague. Here, the current knowledge regarding the interaction of Cd with cells of the immune system, which may affect immune responses as well as potential mechanisms of consequent biological effects of such activities, is reviewed. Tissue injury caused by Cd-induced effects on innate cell activities depicts components of the immune system as mediators/effectors of Cd tissue toxicity. Cd-induced immune alterations, which may compromise host defense against pathogenic microorganisms and homeostatic reparative activities, stress this metal as an important health hazard.

The Role of Electrospun Nanomaterials in the Future of Energy and Environment

Electrospinning is one of the most successful and efficient techniques for the fabrication of one-dimensional nanofibrous materials as they have widely been utilized in multiple application fields due to their intrinsic properties like high porosity, large surface area, good connectivity, wettability, and ease of fabrication from various materials. Together with current trends on energy conservation and environment remediation, a number of researchers have focused on the applications of nanofibers and their composites in this field as they have achieved some key results along the way with multiple materials and designs. In this review, recent advances on the application of nanofibers in the areas-including energy conversion, energy storage, and environmental aspects-are summarized with an outlook on their materials and structural designs. Also, this will provide a detailed overview on the future directions of demanding energy and environment fields.

Chronic Exposure to Cadmium Induces Differential Methylation in Mice Spermatozoa

Cadmium exposure is ubiquitous and has been linked to diseases including cancers and reproductive defects. Since cadmium is nonmutagenic, it is thought to exert its gene dysregulatory effects through epigenetic reprogramming. Several studies have implicated germline exposure to cadmium in developmental reprogramming. However, most of these studies have focused on maternal exposure, while the impact on sperm fertility and disease susceptibility has received less attention. In this study, we used reduced representation bisulfite sequencing to comprehensively investigate the impact of chronic cadmium exposure on mouse spermatozoa DNA methylation. Adult male C57BL/J6 mice were provided water with or without cadmium chloride for 9 weeks. Sperm, testes, liver, and kidney tissues were collected at the end of the treatment period. Cadmium exposure was confirmed through gene expression analysis of metallothionein-1 and 2, 2 well-known cadmium-induced genes. Analysis of sperm DNA methylation changes revealed 1788 differentially methylated sites present at regulatory regions in sperm of mice exposed to cadmium compared with vehicle (control) mice. Furthermore, most of these differential methylation changes positively correlated with changes in gene expression at both the transcription initiation stage as well as the splicing levels. Interestingly, the genes targeted by cadmium exposure are involved in several critical developmental processes. Our results present a comprehensive analysis of the sperm methylome in response to chronic cadmium exposure. These data, therefore, highlight a foundational framework to study gene expression patterns that may affect fertility in the exposed individual as well as their offspring, through paternal inheritance.

Analysis of Cadmium, Mercury, and Lead Concentrations in Erythrocytes of Renal Transplant Recipients from Northwestern Poland

Simple Summary

The aim of this study is to determine the blood erythrocyte concentrations of toxic metals (Cd, Pb, and Hg) in renal transplant recipients. Additionally, we analyzed the effect of selected biological and environmental factors, including the intake of various immunosuppressive drug regimens and smoking, on these xenobiotic concentrations. In summary, our data suggest that, smoking is associated with Pb and Cd concentrations, and gender, age change depending on Pb concentration in erythrocytes of renal transplant recipients. Additionally, this is the first research that suggests that immunosuppressive regimen, depending on type of immunosuppressive drugs combination affects Pb concentration in erythrocytes of the mentioned group of patients. It seems to be crucial information for patients who use immunosuppressive drugs.

Abstract

Cadmium (Cd), mercury (Hg), and lead (Pb) exhibit highly nephrotoxic properties, and their high concentrations can lead to renal failure. Much research has been conducted on the concentrations of heavy metals, microelements, and macroelements in the blood, but little is known about the concentration of Cd, Pb, and Hg in erythrocytes of renal recipients. The aim of this study is to determine the blood erythrocyte concentrations of toxic metals (Cd, Pb, and Hg) in renal transplant recipients (RTRs). Additionally, we analyzed the effect of selected biological and environmental factors, including the intake of various immunosuppressive drug regimens and smoking, on these xenobiotic concentrations. The material consisted of erythrocyte samples from 115 patients of the Department of Nephrology, Transplantology, and Internal Medicine at Independent Public Clinical Hospital No. 2, Pomeranian Medical University, Szczecin, in northwestern Poland. Cd, Hg, and Pb levels in the erythrocytes were quantified by inductively coupled mass spectroscopy (ICP-MS). Equal concentrations of Cd were found in erythrocytes of both female and male transplant recipients. The highest level of Hg was seen in women, and women overall had statistically higher concentrations of Pb than men. Comparison of metal concentrations between those over 50 years and those under it showed that Pb concentration was also significantly higher in renal transplant recipients over 50. Pb concentration was almost twice as high in RTRs who used tacrolimus with mycophenolate mofetil than in RTRs who used cyclosporine A with mycophenolate mofetil. The highest level of Cd was seen in smokers, who had 3.25 µg/L. This value was significantly higher than in ex-smokers (p = 0.001) and with RTRs who had never smoked. There were significantly higher levels of Pb in the erythrocytes of RTRs who were ex-smokers than in those who had never smoked. A statistically significant correlation was found between Cd and Pb concentrations. Additionally, we have noticed significant positive correlation between Pb and age (R = 0.37), gender (R = 0.24) and significant negative correlation of Pb with GFR (R = −0.33). We have also found significant positive correlation between Hg and age (R = 0.21). In summary, our data suggest that, smoking is associated with Pb and Cd concentrations, and gender, age change depending on Pb concentration in erythrocytes of RTRs. Additionally, this is the first research that suggests that immunosuppressive regimen, depending on type of immunosuppressive drugs combination affects Pb concentration in erythrocytes of RTRs. It seems to be crucial information for patients who use immunosuppressive drugs.

Differential cadmium translocation and accumulation between Nicotiana tabacum L. and Nicotiana rustica L. by transcriptome combined with chemical form analyses

Cadmium (Cd) is a severely toxic and carcinogenic heavy metal. Cigarette smoking is one of the major source of Cd exposure in humans. Nicotiana tabacum is primarily a leaf Cd accumulator, while Nicotiana rustica is a root Cd accumulator among Nicotiana species. However, little is known about the mechanisms of differential Cd translocation and accumulation in Nicotiana. To find the key factors, Cd concentration, Cd chemical forms, and transcriptome analysis were comparatively studied between N. tabacum and N. rustica under control or 10 μM Cd stress. The leaf/root Cd concentration ratio of N. tabacum was 2.26 and that of N. rustica was 0.14. The Cd concentration in xylem sap of N. tabacum was significantly higher than that of N. rustica. The root of N. tabacum had obviously higher proportion of ethanol extractable Cd (40%) and water extractable Cd (16%) than those of N. rustica (16% and 6%). Meanwhile the proportion of sodium chloride extracted Cd in N. rustica (71%) was significantly higher than that in N. tabacum (30%). A total of 30710 genes expressed differentially between the two species at control, while this value was 30,294 under Cd stress, among which 27,018 were collective genes, manifesting the two species existed enormous genetic differences. KEGG pathway analysis showed the phenylpropanoid biosynthesis pathway was overrepresented between the two species under Cd stress. Several genes associated with pectin methylesterase, suberin and lignin synthesis, and heavy metal transport were discovered to be differential expressed genes between two species. The results suggested that the higher accumulation of Cd in the leaf of N. tabacum depends on a comprehensive coordination of Cd transport, including less cell wall binding, weaker impediment by the Casparian strip, and efficient xylem loading.

Subacute cadmium exposure disrupts the hypothalamic-pituitary-gonadal axis, leading to polycystic ovarian syndrome and premature ovarian failure features in female rats

Cadmium (Cd), a toxic heavy metal, is a known endocrine disruptor that is associated with reproductive complications. However, few studies have explored the effects of Cd exposure on features of polycystic ovary syndrome (PCOS) and premature ovary failure (POF). In this study, we assessed whether doses found in workers occupationally exposed to Cd and subacute exposure result in hypothalamic-pituitary-gonadal (HPG) axis and other irregularities. We administered CdCl₂ to female rats (100 ppm in drinking water for 30 days) and then assessed Cd levels in the blood, HPG axis and uterus. Metabolic features, HPG axis function, reproductive tract (RT) morphophysiology, inflammation, oxidative stress (OS), and fibrosis were evaluated. Cd exposure increased Cd levels in the serum, HPG axis, and uterus. Cd rats displayed metabolic impairments, such as a reduction in adiposity, dyslipidemia, and insulin resistance (IR). Cd exposure also caused improper functioning in the HPG. Specifically, Cd exposure caused irregular estrous cyclicity, abnormal hypothalamic gene expression (upregulated - Kiss1, AR and mTOR; downregulated - Kiss1R, LepR and TNF-α), high LH levels, low AMH levels and abnormal ovarian follicular development, coupled with a reduction in ovarian reserve and antral follicle number was observed, suggesting ovarian depletion. Further, Cd exposure caused a reduction in corpora lutea (CL) and granulosa layer thickness together with an increase in cystic/atretic follicles. In addition, Cd exposure caused RT inflammation, OS and fibrosis. Finally, strong positive correlations were observed between serum, RT Cd levels, IR, dyslipidemia and estrous cycle length, cystic, atretic follicles, LH levels, and RT inflammation. Thus, these data suggest that subacute Cd exposure using doses found in workers occupationally exposed to Cd disrupt the HPG axis function, leading to PCOS and POF features and other abnormalities in female rats.

Usage of atomic force microscopy for detection of the damaging effect of CdCl2 on red blood cells membrane

The possibility of detecting the damaging effect of cadmium salts on red blood cells (RBC) membrane by atomic force microscopy and light microscopy was studied. White wistar rats RBC were incubated with cadmium chloride in concentrations of 1 μg/l, 10 μg/l, 100 μg/l, and 1000 μg/l for the research. A comparison of sample preparation methods proposed by other authors in previous studies is made. The optimal method that does not significantly affect the change in the morphological features of the cell is selected. The quantitative assessment of damaged and destroyed RBC depending on the concentration of cadmium was performed by optical microscopy. The study showed that CdCl₂ has a damaging effect on the RBC membrane, which leads to the formation of non-specific cell forms. A comparative assessment was made between the methods of optical microscopy and atomic force microscopy for the suitability of studying the morphological characteristics of abnormal forms of the RBC. It is shown that the method of atomic force microscopy allows registering morphological changes in the RBC that cannot be registered by optical microscopy. It is pointed that CdCl₂ has effect on destruction of the RBC and the formation of specific bulges on the RBC membrane. Influence of CdCl₂ on the RBC mechanical properties was studied using atomic force microscopy. The possibility of using atomic force microscopy in studies of morphology and mechanical properties of the RBC under toxicity effect of cadmium is shown.

The association of cadmium and lead exposures with red cell distribution width

Elevated red blood cell distribution width (RDW), traditionally an indicator of anemia, has now been recognized as a risk marker for cardiovascular disease incidence and mortality. Experimental and acute exposure studies suggest that cadmium and lead individually affect red blood cell production; however, associations between environmental exposures and RDW have not been explored. We evaluated relationships of environmental cadmium and lead exposures to RDW. We used data from 24,607 participants aged ≥20 years in the National Health and Nutrition Examination Survey (2003-2016) with information on blood concentrations of cadmium and lead, RDW and socio-demographic factors. In models adjusted for age, sex, race/ethnicity, education, poverty income ratio, BMI, alcohol consumption, smoking status and serum cotinine, RDW was increasingly elevated across progressively higher quartiles of blood cadmium concentration. A doubling of cadmium concentration was associated with 0.16 higher RDW (95% CI: 0.14, 0.18) and a doubling of lead concentration with 0.04 higher RDW (95% CI: 0.01, 0.06). Also, higher cadmium and lead concentrations were associated with increased odds of high RDW (RDW>14.8%). The associations were more pronounced in women and those with low-to-normal mean corpuscular volume (MCV) and held even after controlling for iron, folate or vitamin B12 deficiencies. In analysis including both metals, cadmium remained associated with RDW, whereas the corresponding association for lead was substantially attenuated. In this general population sample, blood cadmium and lead exposures were positively associated with RDW. The associations may indicate hemolytic or erythropoietic mechanisms by which exposure increases mortality risk.

The Double Face of Metals: The Intriguing Case of Chromium

Chromium (Cr) is a common element in the Earth’s crust. It may exist in different oxidation states, Cr(0), Cr(III) and Cr(VI), with Cr(III) and Cr(VI) being relatively stable and largely predominant. Chromium’s peculiarity is that its behavior relies on its valence state. Cr(III) is a trace element in humans and plays a major role in glucose and fat metabolism. The beneficial effects of Cr(III) in obesity and types 2 diabetes are known. It has been long considered an essential element, but now it has been reclassified as a nutritional supplement. On the other hand, Cr(VI) is a human carcinogen and exposure to it occurs both in occupational and environmental contexts. It induces also epigenetic effects on DNA, histone tails and microRNA; its toxicity seems to be related to its higher mobility in soil and swifter penetration through cell membranes than Cr(III). The microorganisms Acinetobacter sp. Cr1 and Pseudomonas sp. Cr13 have been suggested as a promising agent for bioremediation of Cr(VI). This review intends to underline the important role of Cr(III) for human health and the dangerousness of Cr(VI) as a toxic element. The dual and opposing roles of this metal make it particularly interesting. An overview of the recent literature is reported in support.

Selective and sensitive electrochemical sensors based on an ion imprinting polymer and graphene oxide for the detection of ultra-trace Cd(ii) in biological samples

New selective and sensitive electrochemical sensors were designed based on the deposition of a promising ion imprinted polymer (IIP) on the surface of glassy carbon electrode (GCE) for the detection and monitoring of Cd(ii) in different real samples. Herein, a highly selective Cd-imprinted polymer was successfully synthesized using a novel heterocyclic compound based on the benzo[f]chromene scaffold that acted as a complexing agent and a functional monomer in the presence of azobisisobutyronitrile (initiator) and ethylene glycol dimethacrylate (cross-linker). The characterization of the synthesized chelating agent and IIP was performed using FT-IR, SEM, ¹H-NMR, EIMS, and EDX analyses. After that, the voltammetric sensor was manufactured by introducing graphene oxide (GO) on the surface of GCE; then, the IIP was grown by a drop coating technique. The electrochemical characterization of the voltammetric sensor (IIP/GO@GCE) was performed by CV and EIS. For comparison, the potentiometric sensor was also prepared by embedding IIP in plasticized polyvinyl chloride and depositing it as one layer on the GCE surface. Anodic stripping voltammetry was used to construct the calibration graph; the IIP/GO@GCE exhibited a wider detection range (4.2 × 10⁻¹²–5.6 × 10⁻³ mol L⁻¹) and extremely low detection limit (7 × 10⁻¹⁴ mol L⁻¹) for Cd(ii). Meanwhile, the potentiometric sensor showed a linear calibration curve for Cd(ii) over a concentration range from 7.3 × 10⁻⁸ mol L⁻¹ to 2.4 × 10⁻³ mol L⁻¹ with a detection limit of 6.3 × 10⁻¹⁰ mol L⁻¹. Furthermore, both sensors offered outstanding selectivity for Cd(ii) over a wide assortment of other common ions, high reproducibility, and excellent stability.

New selective and sensitive electrochemical sensors were designed based on the deposition of a promising ion imprinted polymer (IIP) on the surface of glassy carbon electrode (GCE) for the detection and monitoring of Cd(ii) in different real samples.

Signaling Proteins That Regulate Spermatogenesis Are the Emerging Target of Toxicant-Induced Male Reproductive Dysfunction

There is emerging evidence that environmental toxicants, in particular endocrine disrupting chemicals (EDCs) such as cadmium and perfluorooctanesulfonate (PFOS), induce Sertoli cell and testis injury, thereby perturbing spermatogenesis in humans, rodents and also widelife. Recent studies have shown that cadmium (e.g., cadmium chloride, CdCl₂) and PFOS exert their disruptive effects through putative signaling proteins and signaling cascade similar to other pharmaceuticals, such as the non-hormonal male contraceptive drug adjudin. More important, these signaling proteins were also shown to be involved in modulating testis function based on studies in rodents. Collectively, these findings suggest that toxicants are using similar mechanisms that used to support spermatogenesis under physiological conditions to perturb Sertoli and testis function. These observations are physiologically significant, since a manipulation on the expression of these signaling proteins can possibly be used to manage the toxicant-induced male reproductive dysfunction. In this review, we highlight some of these findings and critically evaluate the possibility of using this approach to manage toxicant-induced defects in spermatrogenesis based on recent studies in animal models.

Protective Effect of Combined Long Time Administration of Selenium and Vitamin C on Liver and Kidney Toxicity of Cadmium in Rats

Background & Objective:

Increased industrial activities leads to prolonged human exposure to industrial pollutant such as cadmium (Cd). ‍Chronic exposure to Cd in Mammals and also human being, can cause damages to various organs and particularly kidneys and liver. The goal of this study was to investigate the prophylactic effects of combined selenium (Se) and ascorbic acid supplement in rat cadmium toxicity.

Methods:

Sixty adult male Wistar rats were divided to 10 groups: one control, one sham and two clusters of 4 intervention groups which were fed with 1 or 5 mg Cd /kg water, for 28 days. Ascorbic acid supplement was added to drinking water of four groups (10 mg/L). Four groups received intraperitoneal Se (1 mg/kg) at day 1, 5, 10, 15, 20 and 25. Finally, Cd concentration was measured by atomic absorption spectrophotometry in liver and kidney sections. Furthermore, pathological changes were investigated in these sections.

Results:

The results showed weight gain in Cd groups which received ascorbic acid and Se, in contrast to weight loss in parallel groups without vitamin C and Se. The stronger necrosis and inflammation have been observed in group received 5 mg/kg Cd compared to group with 1 mg/kg Cd (P<0.05). In addition, cadmium level was higher in untreated groups without any supplements, significantly (P<0.05).

Conclusion:

Drinking water with ascorbic acid may have prophylactic effects across cadmium, and combination of Se and ascorbic acid are associated with higher prophylactic effects in both kidney and liver in rats to decrease the Cd toxicity.

Heavy Metals Contamination in Shellfish: Benefit-Risk Evaluation in Central Italy

Seafood is a source of nutrients in human diet but also of environmental contaminants and its consumption could pose a risk to consumers' health. A survey regarding the exposure to cadmium, lead and mercury through the consumption of bivalve mollusks, gastropods and sea urchins collected on Italian coasts was carried out among central Italian population over a period of three years. A limited number of samples exceeds the threshold set by legislation (6 samples) and the average level of contamination was low in all the species considered. The contribution Acceptable Daily Intake (ADI) was higher for cadmium (9.17%) than lead (1.44%) and mercury (0.20%). The benefit-risk evaluation suggests that the bivalve mollusks and sea urchins consumption (Benefit Risk Quotient < 1) could be increased without health detrimental effects.

Synergistic Effect of Bacillus thuringiensis IAGS 199 and Putrescine on Alleviating Cadmium-Induced Phytotoxicity in Capsicum annum

Plant growth-promoting bacteria (PGPB) and putrescine (Put) have shown a promising role in the mitigation of abiotic stresses in plants. The present study was anticipated to elucidate the potential of Bacillus thuringiensis IAGS 199 and Put in mitigation of cadmium (Cd)-induced toxicity in Capsicum annum. Cadmium toxicity decreased growth, photosynthetic rate, gas exchange attributes and activity of antioxidant enzymes in C. annum seedlings. Moreover, higher levels of protein and non-protein bound thiols besides increased Cd contents were also observed in Cd-stressed plants. B. thuringiensis IAGS 199 and Put, alone or in combination, reduced electrolyte leakage (EL), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) level in treated plants. Synergistic effect of B. thuringiensis IAGS 199 and Put significantly enhanced the activity of stress-responsive enzymes including peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD). Furthermore, Put and microbial interaction enhanced the amount of proline, soluble sugars, and total soluble proteins in C. annum plants grown in Cd-contaminated soil. Data obtained during the current study advocates that application of B. thuringiensis IAGS 199 and Put establish a synergistic role in the mitigation of Cd-induced stress through modulating physiochemical features of C. annum plants.

Effects of Cadmium, Lead, and Mercury on the Structure and Function of Reproductive Organs

Reproductive organs are essential not only for the life of an individual but also for the survival and development of the species. The response of reproductive organs to toxic substances differs from that of other target organs, and they may serve as an ideal “barometer” for the deleterious effects of environmental pollution on animal and human health. The incidence of infertility, cancers, and associated maladies has increased in the last fifty years or more, while various anthropogenic activities have released into the environment numerous toxic substances, including cadmium, lead, and mercury. Data from epidemiological studies suggested that environmental exposure to cadmium, lead, and mercury may have produced reproductive and developmental toxicity. The present review focused on experimental studies using rats, mice, avian, and rabbits to demonstrate unambiguously effects of cadmium, lead, or mercury on the structure and function of reproductive organs. In addition, relevant human studies are discussed. The experimental studies reviewed have indicated that the testis and ovary are particularly sensitive to cadmium, lead, and mercury because these organs are distinguished by an intense cellular activity, where vital processes of spermatogenesis, oogenesis, and folliculogenesis occur. In ovaries, manifestation of toxicity induced by cadmium, lead, or mercury included decreased follicular growth, occurrence of follicular atresia, degeneration of the corpus luteum, and alterations in cycle. In testes, toxic effects following exposure to cadmium, lead, or mercury included alterations of seminiferous tubules, testicular stroma, and decrease of spermatozoa count, motility and viability, and aberrant spermatozoa morphology.

House J, L. Maguire R, G. Skinner H, Hoyo C. Associations between Maternal Cadmium Exposure with Risk of Preterm Birth and Low after Birth Weight Effect of Mediterranean Diet Adherence on Affected Prenatal Outcomes

Prenatal cadmium exposure at non-occupational levels has been associated with poor birth outcomes. The intake of essential metals, such as iron and selenium, may mitigate cadmium exposure effects. However, at high levels, these metals can be toxic. The role of dietary patterns rich in these metals is less studied. We used a linear and logistic regression in a cohort of 185 mother-infant pairs to assess if a Mediterranean diet pattern during pregnancy modified the associations between prenatal cadmium exposure and (1) birth weight and (2) preterm birth. We found that increased cadmium exposure during pregnancy was associated with lower birth weight (β = -210.4; 95% CI: -332.0, -88.8; p = 0.008) and preterm birth (OR = 0.11; 95% CI: 0.01, 0.72; p = 0.04); however, these associations were comparable in offspring born to women reporting high adherence to a Mediterranean diet (β = -274.95; 95% CI: -701.17, 151.26; p = 0.20) and those with low adherence (β = -64.76; 95% CI: -359.90, 230.37; p = 0.66). While the small sample size limits inference, our findings suggest that adherence to a Mediterranean dietary pattern may not mitigate cadmium exposure effects. Given the multiple organs targeted by cadmium and its slow excretion rate, larger studies are required to clarify these findings.

Vitamin C Protects Porcine Oocytes From Microcystin-LR Toxicity During Maturation

Microcystin-leucine arginine (MC-LR) is the most toxic cyanotoxin found in water bodies. Microcystins are produced as secondary products of cyanobacteria metabolism. They have a stable structure, and can bioaccumulate in living organisms. Humans and livestock who drink fresh water containing MC-LR can be poisoned. However, few studies have reported the effects of MC-LR exposure on livestock or human reproduction. In this study, we used porcine oocytes as a model to explore the effects of MC-LR on oocyte maturation, and studied the impact of vitamin C (VC) administration on MC-LR-induced meiosis defects. Exposure to MC-LR significantly restricted cumulus cell expansion and decreased first polar body extrusion. Further studies showed that MC-LR exposure led to meiosis arrest by disturbing cytoskeleton dynamics with MC-LR exposed oocytes displaying aberrant spindle organization, low levels of acetylate α-tubulin, and disturbed actin polymerization. Additionally, MC-LR exposure impaired cytoplasmic maturation by inducing mitochondria dysfunction. Moreover, MC-LR also produced abnormal epigenetic modifications, and induced high levels of oxidative stress, caused DNA damage and early apoptosis. The administration of VC provided partial protection from all of the defects observed in oocytes exposed to MC-LR. These results demonstrate that MC-LR has a toxic effect on oocyte meiosis through mitochondrial dysfunction-induced ROS, DNA damage and early apoptosis. Supplementation of VC is able to protect against MC-LR-induced oocyte damage and represents a potential therapeutic strategy to improve the quality of MC-LR-exposed oocytes.

Preparation of biochar by mango peel and its adsorption characteristics of Cd(ii) in solution

Biochars were prepared by pyrolyzing mango peel waste at 300, 400, 500, 600 and 700 °C. Various characterizations were carried out to explore the effect of pyrolysis temperature on the biochars. The data indicated that the physical and chemical properties of biochar such as pH, element ratio, specific surface area and functional groups changed with the increase of pyrolysis temperature. The yield and contents of hydrogen, nitrogen and oxygen decreased, while contents of the ash and carbon, pH and specific surface area of the biochars increased. In addition, the molar ratios of H/C, O/C and (O + N)/C decreased. In this study, batch adsorption experiments for Cd(ii) adsorption were performed with initial Cd(ii) concentrations of 10-300 mg L-1, contact times of 0-2880 min, various pH (2-8) and biochar dose (1-20 g L-1). Langmuir isotherm and pseudo-second-order kinetics models were better fits than other models, suggesting the dominant adsorption of mango peel biochars is via monolayer adsorption. Biochar derived at 500 °C was found to have the highest adsorption capacity of 13.28 mg g-1 among all biochars and the adsorption efficiency was still 67.7% of the initial adsorption capacity after desorption for 4 times. Based on adsorption kinetics and isotherm analysis in combination with EDS, FTIR and XRD analysis, it was concluded that cation exchange, complexation with surface functional groups and precipitation with minerals were the dominant mechanisms responsible for Cd adsorption by mango peel biochar. The study suggested that mango peel can be recycled to biochars and can be used as a low-cost adsorbent for Cd(ii) removal from wastewater.

Phytoremediation of Cadmium: Physiological, Biochemical, and Molecular Mechanisms

Cadmium (Cd) is one of the most toxic metals in the environment, and has noxious effects on plant growth and production. Cd-accumulating plants showed reduced growth and productivity. Therefore, remediation of this non-essential and toxic pollutant is a prerequisite. Plant-based phytoremediation methodology is considered as one a secure, environmentally friendly, and cost-effective approach for toxic metal remediation. Phytoremediating plants transport and accumulate Cd inside their roots, shoots, leaves, and vacuoles. Phytoremediation of Cd-contaminated sites through hyperaccumulator plants proves a ground-breaking and profitable choice to combat the contaminants. Moreover, the efficiency of Cd phytoremediation and Cd bioavailability can be improved by using plant growth-promoting bacteria (PGPB). Emerging modern molecular technologies have augmented our insight into the metabolic processes involved in Cd tolerance in regular cultivated crops and hyperaccumulator plants. Plants’ development via genetic engineering tools, like enhanced metal uptake, metal transport, Cd accumulation, and the overall Cd tolerance, unlocks new directions for phytoremediation. In this review, we outline the physiological, biochemical, and molecular mechanisms involved in Cd phytoremediation. Further, a focus on the potential of omics and genetic engineering strategies has been documented for the efficient remediation of a Cd-contaminated environment.