A global perspective on cadmium pollution and toxicity in non-occupationally exposed population

Enhanced Cd accumulation by Graphene oxide (GO) under Cd stress in duckweed

Effective phytoremediation by aquatic plant such as duckweed could be applied to solve Cd pollution. In the present study, the impact of Graphene oxide (GO) on the accumulation of Cd in duckweed has been studied. The response of duckweed was also investigated, concluding growth, Cd²⁺ flux, and gene expression response. Results showed that GO promoted the accumulation of Cd in duckweed. After 6 h of Cd enrichment in duckweed, Cd content was about 1.4 times that of the control group at fronds and 1.25 times that of the control group at roots, meanwhile, Cd content in the water system was 0.67 times that of the control group. The Cd²⁺ influx increased significantly. 4471 genes were up-regulated and 3230 genes were down-regulated significantly as duckweed treated with GO under Cd treatment. Moreover, phagosome pathway was downregulated, some key proteins: Stx7, Rab7 and Tubastatin B (TUBB) were significantly downregulated with GO addition under Cd stress. Scanning electron microscope (SEM) observation showed that GO and Cd were attached on the cell surface of duckweed as white crystal. GO could be applied in phytoremediation by duckweed of Cd in aquatic system.

Analysis of the effect of cadmium stress on root exudates of Sedum plumbizincicola based on metabolomics

Root exudates are the most direct manifestation of the response of plants changes in the external environment. Therefore, based on non-targeted gas chromatography-time-of-flight mass spectrometry and metabolomics, the response of Sedum plumbizincicola root exudates to Cd stress was used to reveal the possible mechanism of resistance to or accumulation of Cd. The results showed that Cd significantly changed the composition and contents of S. plumbizincicola root exudates. A total of 155 metabolites were identified in S. plumbizincicola root exudates, among which 33 showed significant differences under Cd stress, including organic acids, amino acids, lipids, and polyols. Cd stress suppressed organic acid metabolism and lipid metabolism in S. plumbizincicola and significantly affected amino acid metabolism. There were 16 metabolic pathways related to Cd stress, among which arginine and proline metabolism, valine, leucine, and isoleucine biosynthesis, glycine, serine, and threonine metabolism, glutathione metabolism, and purine metabolism were the key pathways with the highest correlation, and were closely related to the stress resistance of S. plumbizincicola.

Effect of Heavy Metal Contamination in the Environment on Antioxidant Function in Wumeng Semi-fine Wool Sheep in Southwest China

Many environmental accidents have led to worldwide heavy metal pollution, raising concern about heavy metal toxicity in Southwest China. To study the effects of Cd and Pb in the environment on antioxidant function in Wumeng semi-fine wool sheep, contents of Cu, Zn, Mn, Mo, Fe, Se, Cd, and Pb were measured in irrigation water, soil, herbage, and animal tissues. Hematological and biochemical parameters were also determined. The concentrations of Cu, Zn, Cd, and Pb in affected samples of irrigation water, soil, herbage, and tissues were significantly higher than those in the control (P < 0.01). There was no significant difference in other element contents between affected pastures and control areas. The occurrence of anemia affected Wumeng semi-fine wool sheep. The activities of SOD, CAT, and GSH-Px in affected animals were significantly decreased than those in the control (P < 0.01). Content of MDA in serum in affected animals was significantly increased than that in control (P < 0.01). Serum T-AOC in affected animal was significantly lower than that in control (P < 0.01). Consequently, it is suggested that heavy metal contamination in natural habitat caused serious harm to antioxidant function in Wumeng semi-fine wool sheep.

Comprehensive assessment of heavy metals pollution of farmland soil and crops in Jilin Province

As a major agricultural province in China, it is necessary to study the content of heavy metals in farmland soil and crop in Jilin Province and to evaluate the risks to ecology and human health. This study presented the work completed on 79 soil samples, 10 rice samples, 66 maize samples and 15 soybean samples collected from Jilin Province farmland and evaluated six heavy metals (Zn, Cu, Pb, Cd, Hg and As) concentrations. The results showed that the concentrations of the six heavy metals in farmland soil and crop samples from Jilin Province basically met the soil standards and food health standards of China. The agricultural soil pollution spatial distribution was the most serious in the south of Jilin Province and the lightest in the west. The non-carcinogenic risks faced by children eating crops were higher than those of adults, but the carcinogenic risks were lower than those of adults. Both of the two health risks to adults and children from eating crops were very limited. The results would help determine the heavy metals pollution in farmland soil in Jilin Province efficiently and accurately and helped decision makers to achieve a balance between production and environmental regulation.

Cadmium exacerbates dextran sulfate sodium-induced chronic colitis and impairs intestinal barrier

The potential health risk of environmental pollutant, cadmium, has become a public concern due to its widespread existence and long biological half-life. High-dose cadmium can induce various adverse outcomes, however, the chronic biological influences of cadmium at an environmental dosage and its mechanism remain largely unclear. Here, we investigated the effect of long-term exposure of cadmium at the environmental-relevant concentration on intestinal function. A chronic colitis mouse model was established through multiple cycles of dextran sulfate sodium (DSS) challenge and recovery. 200 nM cadmium in drinking water intensified colonic inflammation induced by DSS (histological score, DSS vs. DSS + Cd: 7.4 ± 1.21 vs. 10.67 ± 0.67, P < 0.05), including fecal occult bleeding and fecal consistency loss. Multiple inflammatory cytokines were significantly up-regulated by cadmium both in colon and plasma (P < 0.05). In addition, intestinal integrity was compromised by cadmium. Goblet cells were markedly reduced (ctrl vs. Cd: 48.33 ± 3.07 vs. 37.5 ± 2.14, P < 0.05) and plasma D-lactate (ctrl vs. Cd: 1.88 ± 0.20 vs. 2.80 ± 0.15, P < 0.01) and diamine oxidase (ctrl vs. Cd: 5.00 ± 0.87 vs. 11.21 ± 2.17, P < 0.05) were increased in cadmium-treated mice, indicating an elevated intestinal permeability. In vitro results showed that long-term exposure of cadmium down-regulated the expression and membrane localization of adherent and tight junction proteins in a time-dependent manner. In conclusion, long-term exposure of environmental dose of cadmium aggravated DSS-induced chronic colitis and disrupted intestinal barrier and impaired the adherent and tight junction proteins. These findings provide a better understanding about the health risk of cadmium in the environment.

Improved Mapping of Potentially Toxic Elements in Soil via Integration of Multiple Data Sources and Various Geostatistical Methods

Soil pollution by potentially toxic elements (PTEs) has become a core issue around the world. Knowledge of the spatial distribution of PTEs in soil is crucial for soil remediation. Portable X-ray fluorescence spectroscopy (p-XRF) provides a cost-saving alternative to the traditional laboratory analysis of soil PTEs. In this study, we collected 293 soil samples from Fuyang County in Southeast China. Subsequently, we used several geostatistical methods, such as inverse distance weighting (IDW), ordinary kriging (OK), and empirical Bayesian kriging (EBK), to estimate the spatial variability of soil PTEs measured by the laboratory and p-XRF methods. The final maps of soil PTEs were outputted by the model averaging method, which combines multiple maps previously created by IDW, OK, and EBK, using both lab and p-XRF data. The study results revealed that the mean PTE content measured by the laboratory methods was as follows: Zn (127.43 mg kg−1) > Cu (31.34 mg kg−1) > Ni (20.79 mg kg−1) > As (10.65 mg kg−1) > Cd (0.33 mg kg−1). p-XRF measurements showed a spatial prediction accuracy of soil PTEs similar to that of laboratory analysis measurements. The spatial prediction accuracy of different PTEs outputted by the model averaging method was as follows: Zn (R2 = 0.71) > Cd (R2 = 0.68) > Ni (R2 = 0.67) > Cu (R2 = 0.62) > As (R2 = 0.50). The prediction accuracy of the model averaging method for five PTEs studied herein was improved compared with that of the laboratory and p-XRF methods, which utilized individual geostatistical methods (e.g., IDW, OK, EBK). Our results proved that p-XRF was a reliable alternative to the traditional laboratory analysis methods for mapping soil PTEs. The model averaging approach improved the prediction accuracy of the soil PTE spatial distribution and reduced the time and cost of monitoring and mapping PTE soil contamination.

Synthesized chrysin-loaded nanoliposomes improves cadmium-induced toxicity in mice

In this study, chrysin as a natural flavonoid was encapsulated in nanoliposomal structures, and the synthesized nanoliposome-loaded chrysin (NLC) was further characterized for its physical properties and cytoprotective effects in mice that received cadmium-containing water. The results showed that the synthesized NLC is possessed spherical structure with the size of 185.1 nm and negative surface charge of - 26 mV with a poly dispersity index of 0.26. The mice received cadmium (2 mg/kg body weight/day) through drinking water showed weight loss and decease in the feed intake significantly (p ≤ 0.05). The cadmium notably (p ≤ 0.05) increased the liver enzymes including aspartate aminotransferase, alanine transaminase, and alkaline phosphatase; altered the liver metal deposition (cadmium, copper, manganese, selenium, and zinc); and induced hepatic oxidative stress (inducible nitric oxide synthase, catalase, superoxide dismutase, and glutathione peroxidase genes) with no remarkable histopathological changes. Furthermore, the cadmium impaired the morphology of jejunum through reducing villus height and villus width and increasing the crypt depth. Providing NLC as a dietary supplement at the concentrations of 2.5 and 5 mg/kg mice body weight significantly (p ≤ 0.05) improved the feed intake and body weight gain, modulated the liver enzymes, and alleviated the hepatic oxidative stress. The NLC also improved the antioxidant mineral deposition in the liver and morphohistological structure of jejunum. Consequently, the NLC is suggested as a potential dietary supplement to alleviate the symptoms of cadmium-induced toxicity in mice.

Cadmium and Lead Exposure, Nephrotoxicity, and Mortality

The present review aims to provide an update on health risks associated with the low-to-moderate levels of environmental cadmium (Cd) and lead (Pb) to which most populations are exposed. Epidemiological studies examining the adverse effects of coexposure to Cd and Pb have shown that Pb may enhance the nephrotoxicity of Cd and vice versa. Herein, the existing tolerable intake levels of Cd and Pb are discussed together with the conventional urinary Cd threshold limit of 5.24 μg/g creatinine. Dietary sources of Cd and Pb and the intake levels reported for average consumers in the U.S., Spain, Korea, Germany and China are summarized. The utility of urine, whole blood, plasma/serum, and erythrocytes to quantify exposure levels of Cd and Pb are discussed. Epidemiological studies that linked one of these measurements to risks of chronic kidney disease (CKD) and mortality from common ailments are reviewed. A Cd intake level of 23.2 μg/day, which is less than half the safe intake stated by the guidelines, may increase the risk of CKD by 73%, and urinary Cd levels one-tenth of the threshold limit, defined by excessive ß₂-microglobulin excretion, were associated with increased risk of CKD, mortality from heart disease, cancer of any site and Alzheimer's disease. These findings indicate that the current tolerable intake of Cd and the conventional urinary Cd threshold limit do not provide adequate health protection. Any excessive Cd excretion is probably indicative of tubular injury. In light of the evolving realization of the interaction between Cd and Pb, actions to minimize environmental exposure to these toxic metals are imperative.

Effects of ecologically relevant concentrations of cadmium on locomotor activity and microbiota in zebrafish

Cadmium (Cd) is widely spread in the aquatic environment, and its impact on humans and the ecosystem is an important issue in public health. However, its effects on zebrafish microbiota are still poorly understood. In this study, the potential developmental neurotoxicity and microbiota dysbiosis of ecologically relevant concentrations of Cd (0, 1.25, 2.5 and 5 μg/L) was evaluated by waterborne exposure for 7 days. The data showed that exposure to 5 μg/L of Cd significantly decreased survival rates and impaired locomotor activities. Uptake of Cd was enhanced with the increase of the concentration and duration of exposure. High-throughput sequencing analysis revealed a significant change in the richness and diversity of the microbiota of Cd-treated zebrafish. At the phylum level, the abundance of Proteobacteria increased, while that Firmicutes was significantly decreased after exposure to 5 μg/L Cd. At the genus level, there were significant changes in the abundances of several bacteria involved in the regulation of neurodegenerative diseases (Pseudomonas, Ruminococcaceae, Blautia, Bacteroides, Lactobacillus, Lachnospiraceae, and Phascolarctobacterium) in the Cd-treatment groups, as compared to the control group. In addition, the mRNA expression profiles of bdnf and genes involved in serotonin signaling and metabolism were changed in the Cd exposure groups. Together, these data suggest that Cd could be harmful to zebrafish health by inducing the microbiota changes, and the microbiota could serve as a potential target to protect against the adverse effects of Cd toxicity.

Selenium and L-Carnitine Ameliorate Reproductive Toxicity Induced by Cadmium in Male Mice

Cadmium (Cd) has been reported to reduce male fertility, impair reproductive capacity, and play a major role in the pathogenesis of infertility. This study was conducted to investigate the possible protective role of Selenium (Se) and L-carnitine (LC) against the adverse effects induced by Cd on the male reproductive system in mice. Animals were randomly divided into seven groups (n = 10); control group and six treated groups, as follows: Cd (0.35 mg/kg), Se (0.87 mg/kg), LC (10 mg/kg), and a combination of either Se or LC and then a combination of both with Cd, and all animals were injected for a period of 30 days. Exposure of Cd showed a significant decrease in enzymatic antioxidant activities, deficiency in reproductive performance, decrease serum testosterone level, severe changes in the histopathological architecture, and higher degree of damages and appearance of unblemished DNA strands. Treatment with Se and LC has the highly synergistic and ameliorates the damaging effect of Cd on the testis through the elevation of the enzymatic antioxidant and diminish histopathological abnormalities and DNA damage.

Selenium mitigates cadmium-induced crosstalk between autophagy and endoplasmic reticulum stress via regulating calcium homeostasis in avian leghorn male hepatoma (LMH) cells

Cadmium (Cd) is a toxic heavy metal and widespread in environment and food, which is adverse to human and animal health. Food intervention is a hot topic because it has no side effects. Selenium (Se) is an essential trace element, found in various fruits and vegetables. Many previous papers have described that Se showed ameliorative effects against Cd. However, the underlying mechanism of antagonistic effect of Se against Cd-induced cytotoxicity in avian leghorn male hepatoma (LMH) cells is unknown, the molecular mechanism of Se antagonistic effect on Cd-induced and calcium (Ca²⁺) homeostasis disorder and crosstalk of ER stress and autophagy remain to be explored. In order to confirm the antagonistic effect of Se on Cd-induced LMH cell toxicity, LMH cells were treated with CdCl₂ (2.5 μM) and Na₂SeO₃ (1.25 and 2.5 μM) for 24 h. In this study, Cd exposure induced cell death, disrupted intracellular Ca²⁺ homeostasis and Ca²⁺ homeostasis related regulatory factors, interfered with the cycle of cadherin (CNX)/calreticulin (CRT), and triggered ER stress and autophagy. Se intervention inhibited Cd-induced LDH release and crosstalk of ER stress and autophagy via regulating intracellular Ca²⁺ homeostasis. Moreover, Se mitigated Cd-induced Intracellular Ca²⁺ overload by Ca²⁺/calmodulin (CaM)/calmodulin kinase IV (CaMK-IV) signaling pathway. Herein, CNX/CRT cycle played a critical role for the protective effect of Se on Cd-induced hepatotoxicity. Based on these findings, we demonstrated that the application of Se is beneficial for prevention and alleviation of Cd toxicity.

The Role of Antioxidants in the Prevention of Cadmium-Induced Endothelial Dysfunction

Background:

Cadmium is a worldwide spread toxicant that accumulates in tissues and affects many organs, mainly through oxidative damage. Oxidative stress is often associated with cardiovascular diseases and, when it affects vessels, it induces endothelial dysfunction, which, in turn, could precipitate atherosclerosis and hypertension. Therefore, it is reasonable to suggest antioxidant supplementation as a therapy against cadmiuminduced endothelial dysfunction.

Objective:

This literature review aims to present the mechanisms involving oxidative stress in which cadmium induces endothelial dysfunction and the benefits of antioxidant supplementation as a therapeutic strategy against its harmful effects.

Methods:

On PubMed Central, articles that contemplated studies on cadmium intoxication and associated oxidative stress with endothelial dysfunction as well as articles that reported the use of antioxidant supplementation in an attempt to prevent or avoid endothelial dysfunction induced by cadmium exposure were selected.

Results:

Most of the studies that associated cadmium intoxication with endothelial dysfunction suggested oxidative stress as the major mechanism for this damage. Furthermore, experimental studies also revealed that the administration of substances with antioxidant properties, such as ascorbic acid and curcumin, has beneficial effects on the prevention of such dysfunction, reducing reactive oxygen species within the vessels, preventing a reduction in the amount of glutathione and the increase in blood pressure observed in animals exposed to cadmium.

Conclusion:

Antioxidant therapy demonstrated to be a potential treatment to reduce cardiovascular injuries provoked by cadmium, but more studies are needed to determine the best antioxidant substance and dose to treat or avoid this complication.

Seafood consumption is associated with higher follicular fluid arsenic (As) and mercury (Hg) concentrations in women undergoing in vitro fertilization (IVF)

Human exposure to non-essential toxic metals such as cadmium (Cd), mercury (Hg), and lead (Pb), and metalloids such as arsenic (As) commonly occurs through diet. Toxic trace element exposures have been reported in association with fertility and fecundity in epidemiologic studies even at low to moderate levels. While most previous studies employed blood and urine biomarkers of exposure, few have assessed toxic trace elements in ovarian follicular fluid (FF), which surrounds the developing oocyte and hence may better reflect concentrations potentially affecting reproductive outcomes. Our objective was to identify dietary predictors of FF toxic trace elements in n = 56 women (mean age: 38.3 years) undergoing in vitro fertilization (IVF) at the University of California at San Francisco. We determined As, Hg, Cd, and Pb in 197 FF specimens, collected on the day of oocyte retrieval, using inductively coupled plasma tandem mass spectrometry. A comprehensive food frequency questionnaire was used to assess the weekly and annual dietary "patterns" of participants. Consumption of specific seafood items and turkey were correlated with individual FF toxic trace elements. We also found that each unit higher seafood consumption in the past week dominated by mollusks, shrimp, and bass was associated with 60% higher FF As (95% confidence interval (CI): 25%, 105%) and FF Hg (95%CI: 7%, 136%) concentrations. Higher annual seafood consumption dominated by urchin, crab, and trout was associated with 16% higher FF As (95%CI: -2%, 38%) and 31% higher FF Hg (95%CI: 7%, 60%) concentrations per unit intake. No associations were noted between diet and Cd and Pb levels in FF. Overall, our results suggest that higher seafood consumption contributes to elevated levels of As and Hg in FF. These findings are consistent with previous IVF studies that assessed toxic trace element exposures in blood and urine. To our knowledge, this is the first study to report that diet might be a source of As, Hg, Cd, and Pb in FF.

Aza- and Mixed Thia/Aza-Macrocyclic Receptors with Quinoline-Bearing Pendant Arms for Optical Discrimination of Zinc(II) or Cadmium(II) Ions

The synthesis and coordination properties of two fluorescent chemosensors, featuring [9]aneN₃ (1,4,7-triazacyclononane; L1) and [12]aneNS₃ (1-aza-4,7,10-trithiacyclododecane; L2) as receptor units, and a quinoline pendant arm with an amide group as a functional group spacer are described. The optical responses of L1 and L2 in the presence of several metal ions were analysed in MeCN/H₂ O (1 : 4 v/v) solutions. A selective chelation enhancement of fluorescence (CHEF) effect was observed in the presence of Zn²⁺ in the case of L1, and in the presence of Cd²⁺ in the case of L2, following the formation of a 1 : 1 and a 1 : 2 metal/ligand complex, respectively, which was also confirmed by potentiometric measurements. ¹ H and ¹³ C NMR measurements in CD₃ CN/CDCl₃ in combination with molecular mechanics calculations show that for both complexes of L1 and L2 with Zn²⁺ and Cd²⁺ , respectively, the coordination of the carbonyl group from the pendant arm could be the origin of the observed optical selectivity.

Boron inhibits cadmium uptake in wheat (Triticum aestivum) by regulating gene expression

Various nutrients (Mg, Zn, Fe, Mn, Si, etc.) can supress cadmium (Cd) uptake and alleviate Cd toxicity, but the mechanisms are not the same. In this study, the molecular mechanism governing the effects of boron (B) on uptake of Cd in hydroponically grown wheat was characterized. As compared to control (0 μM Cd), B concentration per plant decreased by 22% and 29% under 5 μM Cd and 50 μM Cd treatment respectively. In addition, B application decreased Cd concentration and accumulation in whole wheat. Correlation analysis of different elements show that there was a highly negative correlation between concentrations of B and Cd (r = -0.854 with significant correlation) in wheat. Additionally, 16,543 differentially expressed genes (DEGs) (7666 up- and 8877 down-regulated) were detected between 0 and 5 μM Cd treatments in wheat roots by transcriptome sequencing. Gene ontology functional category and Kyoto encyclopedia of genes and genomes pathway analyses indicated that the DEGs were involved in biological process, cellular component, and molecular function. Five highly homologous genes to Cd transporters were identified; these genes were involved in metal ion binding, transmembrane ion transport, and protein transport. According to the qRT-PCR results, expression of all these genes was down-regulated in the 462 μM of B treatment compared with the 46.2 μM of B treatment regardless of the Cd treatments (0.5 or 5 μM Cd). These results suggest that B is an inhibitor of Cd uptake, and the down-regulation of five highly homologous genes could be associated with decreased uptake of Cd after B application.

QTL mapping and candidate gene analysis of cadmium accumulation in polished rice by genome-wide association study

Cadmium (Cd) accumulation in rice is a serious threat to food safety and human health. Breeding rice varieties with low Cd accumulation is one of the most effective approaches to reducing health risks from Cd-polluted rice. However, the genetic basis of Cd accumulation in grains, especially in indica rice varieties, has not been fully elucidated. The evaluation of Cd-accumulation capacity was conducted among 338 diverse rice accessions grown in Cd-contaminated soils with different Cd contents. Thirteen rice lines with relatively low Cd accumulation, including six indica rice lines, were identified. Then, 35 QTLs significantly associated with Cd accumulation were identified through sequencing-based SNP discovery and a genome-wide association study (GWAS) in the two experimental years, and only qCd8-1 was detected in both years. Among of them, nine QTLs were co-localized with identified genes or QTLs. A novel QTL, qCd1-3, with the lowest P value was selected for further LD decay analysis and candidate gene prediction. We found differential expression of OsABCB24 between high-Cd-accumulative and low-Cd-accumulative accessions, suggesting it may be a candidate gene for qCd1-3 associated with low Cd accumulation. These results may be helpful for further exploiting novel functional genes related to Cd accumulation and developing rice variety with low Cd accumulation through marker-assisted breeding.

Effects of short- and long-term exposure to cadmium on salivary glands and fat body of soil centipede Lithobius forficatus (Myriapoda, Chilopoda): Histology and ultrastructure

Cadmium (Cd) is the most widely studied heavy metal in terms of food-chain accumulation and contamination because it can strongly affect all environments (e.g., soil, water, air). It can accumulate in different tissues and organs and can affect the organism at different levels of organization: from organs, tissues and cells though cell organelles and structures to activation of mechanisms of survival and cell death. In soil-dwelling organisms heavy metals gather in all tissues with accumulation properties: midgut, salivary glands, fat body. The aim of this study was to describe the effects of cadmium on the soil species Lithobius forficatus, mainly on two organs responsible for gathering different substances, the fat body and salivary glands, at the ultrastructural level. Changes caused by cadmium short- and long-term intoxication, connected with cell death (autophagy, apoptosis, necrosis), and the crosstalk between them, were analyzed. Adult specimens of L. forficatus were collected in a natural environment and divided into three experimental groups: C (the control group), Cd1 (cultured in soil with 80 mg/kg of CdCl₂ for 12 days) and Cd2 (cultured in soil with 80 mg/kg of CdCl₂ for 45 days). Transmission electron microscopy revealed ultrastructural alterations in both of the organs analyzed (reduction in the amount of reserve material, the appearance of vacuoles, etc.). Qualitative analysis using TUNEL assay revealed distinct crosstalk between autophagy and necrosis in the fat body adipocytes, while crosstalk between autophagy, apoptosis and necrosis in the salivary glands was detected in salivary glands of the centipedes examined here. We conclude that different organs in the body can react differently to the same stressor, as well as to the same concentration and time of exposure. Different mechanisms at the ultrastructural level activate different types of cell death and with different dynamics.

Cadmium induces iron deficiency anemia through the suppression of iron transport in the duodenum

Cadmium (Cd) is an environmental contaminant that triggers toxic effects in various tissues such as the kidney, liver, and lung. Cd can also cause abnormal iron metabolism, leading to anemia. Iron homeostasis is regulated by intestinal absorption. However, whether Cd affects the iron absorption pathway is unclear. We aimed to elucidate the relationship between the intestinal iron transporter system and Cd-induced iron deficiency anemia. C57BL/6J female and male mice, 129/Sv female mice, and DBA/2 female mice were given a single oral dose of CdCl₂ by gavage. After 3 or 24 h, Cd decreased serum iron concentrations and inhibited the expression of iron transport-related genes in the duodenum. In particular, Cd decreased the levels of divalent metal transporter 1 and ferroportin 1 in the duodenum. In addition, human colon carcinoma Caco-2 cells were treated with CdCl₂. After 72 h, Cd decreased the expression of iron transport-related factors in Caco-2 cells with a pattern similar to that seen in the murine duodenum. These findings suggest that Cd inhibits iron absorption through direct suppression of iron transport in duodenal enterocytes and contributes to abnormal iron metabolism.

Distribution of Trace Metals in Street Dusts and Tree Leaves and Their Source Identification in a Mid-Populated Anatolian City

Sivas is a central Anatolian city in Turkey with mid-population. Due to its geographical structure high air pollution episodes can be observed in the atmosphere of Sivas. A study with city wide sampling campaign can help to identify the possible sources. Therefore, we aimed to investigate the multi-elemental and multi-point analysis of trace metals in street dusts and tree leaves in Sivas. In the street dusts, Ca concentration was > 10%. Fe, Cl, and K contribution was 2.5%, 1.75%, and 1.1%, respectively. The average S and Ti concentrations were between 1 and 10 mg/g, I, Mn, Sr, Cr, V, Ba, Zn, Ni, Zr, and Cu were between 1 and 0.1 mg/g, and W, Pb, Sn, Th, Rb, Sb, Co, Bi, As, U were between 0.1 and 0.01 mg/g, in the ascending order. The same elements were investigated for vegetation. Ca, K, S, and Cl were the elements with highest contribution.

Morphine-element interactions - The influence of selected chemical elements on neural pathways associated with addiction

Addiction is a pressing social problem worldwide and opioid dependence can be considered the strongest and most difficult addiction to treat. Mesolimbic and mesocortical dopaminergic pathways play an important role in modulation of cognitive processes and decision making and, therefore, changes in dopamine metabolism are considered the central basis for the development of dependence. Disturbances caused by excesses or deficiency of certain elements have a significant impact on the functioning of the central nervous system (CNS) both in physiological conditions and in pathology and can affect the cerebral reward system and therefore, may modulate processes associated with the development of addiction. In this paper we review the mechanisms of interactions between morphine and zinc, manganese, chromium, cadmium, lead, fluoride, their impact on neural pathways associated with addiction, and on antinociception and morphine tolerance and dependence.

Imbalance in zinc homeostasis enhances lung Tissue Loss following cigarette smoke exposure

Cigarette smoke exposure is a major cause of chronic obstructive pulmonary disease. Cadmium is a leading toxic component of cigarette smoke. Cadmium and zinc are highly related metals. Whereas, zinc is an essential metal required for normal health, cadmium is highly toxic. Zrt- and Irt-like protein 8 (ZIP8) is an avid transporter of both zinc and cadmium into cells and is abundantly expressed in the lung of smokers compared to nonsmokers. Our objective was to determine whether disturbed zinc homeostasis through diet or the zinc transporter ZIP8 increase susceptibility to lung damage following prolonged cigarette smoke exposure.

METHODS

Cigarette smoke exposure was evaluated in the lungs of mice subject to insufficient and sufficient zinc intakes, in transgenic ZIP8 overexpressing mice, and a novel myeloid-specific ZIP8 knockout strain.

RESULTS

Moderate depletion of zinc intakes in adult mice resulted in a significant increase in lung cadmium burden and permanent lung tissue loss following prolonged smoke exposure. Overexpression of ZIP8 resulted in increased lung cadmium burden and more extensive lung damage, whereas cigarette smoke exposure in ZIP8 knockout mice resulted in increased lung tissue loss without a change in lung cadmium content, but a decrease in zinc.

CONCLUSIONS

Overall, findings were consistent with past human studies. Imbalance in Zn homeostasis increases susceptibility to permanent lung injury following prolonged cigarette smoke exposure. Based on animal studies, both increased and decreased ZIP8 expression enhanced irreversible tissue damage in response to prolonged tobacco smoke exposure. We believe these findings represent an important advancement in our understanding of how imbalance in zinc homeostasis and cadmium exposure via tobacco smoke may increase susceptibility to smoking-induced lung disease.

Selective detection of cadmium ions using plasmonic optical fiber gratings functionalized with bacteria

Environmental monitoring and potable water control are key applications where optical fiber sensing solutions can outperform other technologies. In this work, we report a highly sensitive plasmonic fiber-optic probe that has been developed to determine the concentration of cadmium ions (Cd²⁺) in solution. This original sensor was fabricated by immobilizing the Acinetobacter sp. around gold-coated tilted fiber Bragg gratings (TFBGs). To this aim, the immobilization conditions of bacteria on the gold-coated optical fiber surface were first experimentally determined. Then, the coated sensors were tested in vitro. The relative intensity of the sensor response experienced a change of 1.1 dB for a Cd²⁺ concentration increase from 0.1 to 1000 ppb. According to our test procedure, we estimate the experimental limit of detection to be close to 1 ppb. Cadmium ions strongly bind to the sensing surface, so the sensor exhibits a much higher sensitivity to Cd²⁺ than to other heavy metal ions such as Pb²⁺, Zn²⁺ and CrO₄^2- found in contaminated water, which ensures a good selectivity.

Colorimetric cadmium ion detection in aqueous solutions by newly synthesized Schiff bases

Two newly synthesized Schiff bases DMCA and DMBA were used for selective detection of Cd²⁺ over a wide range of other metal ions in acetonitrile (ACN)/ Tris-HCl buffer (10 mM, pH 7.32, v/v 2:1). The sensors can detect Cd²⁺ ions by colour changes from colourless to orange for DMBA and yellow to reddish for DMCA. Response of the probes towards metal ions was investigated by using UV-vis spectroscopy. The complex stoichiometry between the sensors, DMBA and DMCA, and Cd²⁺ was found to be 2:1 and the binding constants were calculated to be 2.65 ×10¹² M^-2 and 4.95 ×10¹² M^-2, respectively. The absorbance-based detection limits of DMBA and DMCA were calculated as 0.438 μM and 0.102 μM, respectively. The sensors were also successfully applied to real samples.

Sp1 participates in the cadmium-induced imbalance of the placental glucocorticoid barrier by suppressing 11β-HSD2 expression

Cadmium (Cd) is widely present in the environment as a heavy metal poison. Prenatal Cd exposure can damage the placental glucocorticoid barrier, leading to foetal growth restriction (FGR), but the molecular mechanism is unknown. We aimed to study the effects of prenatal Cd exposure on 11β-HSD2 and its possible involvement in Cd induced damage in the placental glucocorticoid barrier. Pregnant rats were treated with CdCl2 (1.0 mg/kg/day) by gavage from gestational day (GD) 9-19. Maternal exposure to Cd increased the FGR rate of the offspring, and the levels of corticosterone in the placenta, maternal and foetal serum. Further in vitro experiments with placenta or JEG3 cells indicated that Cd was able to decrease 11β-HSD2 and Sp1 expression in trophoblast cells but did not affect 11β-HSD1. Additionally, decreased p300 and Sp1 enrichment at the 11β-HSD2 promoter region was observed in the cells treated with Cd. Decreasing or increasing Sp1 expression accordingly inhibited or promoted the expression of 11β-HSD2 and further decreased or increased p300 and Sp1 enrichment at the 11β-HSD2 promoter region. In conclusion, Cd inhibits the expression of 11β-HSD2 by affecting the binding of p300 to 11β-HSD2 via a decrease in Sp1 expression, which damages the placental glucocorticoid barrier and exposes the foetus to excessive glucocorticoids, resulting in FGR. These findings reveal a possible underlying molecular mechanism by which Cd exposure leads to FGR.

Molybdenum and Cadmium co-induced the levels of autophagy-related genes via adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin signaling pathway in Shaoxing Duck (Anas platyrhyncha) kidney

To investigate Molybdenum (Mo) and Cadmium (Cd) co-induced the levels of autophagy-related genes via AMPK/mTOR signaling pathway in Shaoxing Duck (Anas platyrhyncha) kidney, 60 healthy 11-day-old ducks were randomly divided into 6 groups, which were treated with Mo or/and Cd at different doses on the basal diet for 120 d. Kidney samples were collected on day 120 to determine the mRNA expression levels of adenosine 5′-monophosphate (AMP)-activated protein kinase α1 (AMPKα1), mammalian target of rapamycin (mTOR), Beclin-1, autophagy-related gene-5 (Atg5), microtubule-associated protein light chain A (LC3A), microtubule-associated protein light chain B (LC3B), sequestosome-1, and Dynein by real-time quantitative polymerase chain reaction. Meanwhile, ultrastructural changes of the kidney were observed. The results indicated that the mTOR and P62 mRNA expression levels were significantly downregulated, but the Atg5 and Beclin-1 mRNA levels were remarkably upregulated in all treated groups compared to control group, and their changes were greater in joint groups. Additionally, compared to control group, the Dynein mRNA expression level was apparently downregulated in co-treated groups, the LC3B, LC3A, and AMPKα1 expression levels were dramatically upregulated in single treated groups and they were not obviously different in co-treated groups. Ultrastructural changes showed that Mo and Cd could markedly increase the number of autophagosomes. Taken together, it suggested that dietary Mo and Cd might induce autophagy via AMPK/mTOR signaling pathway in duck kidney, and it showed a possible synergistic relationship between the 2 elements.

Toxicomicrobiomics: The Human Microbiome vs. Pharmaceutical, Dietary, and Environmental Xenobiotics

The harmful impact of xenobiotics on the environment and human health is being more widely recognized; yet, inter- and intraindividual genetic variations among humans modulate the extent of harm, mostly through modulating the outcome of xenobiotic metabolism and detoxification. As the Human Genome Project revealed that host genetic, epigenetic, and regulatory variations could not sufficiently explain the complexity of interindividual variability in xenobiotics metabolism, its sequel, the Human Microbiome Project, is investigating how this variability may be influenced by human-associated microbial communities. Xenobiotic-microbiome relationships are mutual and dynamic. Not only does the human microbiome have a direct metabolizing potential on xenobiotics, but it can also influence the expression of the host metabolizing genes and the activity of host enzymes. On the other hand, xenobiotics may alter the microbiome composition, leading to a state of dysbiosis, which is linked to multiple diseases and adverse health outcomes, including increased toxicity of some xenobiotics. Toxicomicrobiomics studies these mutual influences between the ever-changing microbiome cloud and xenobiotics of various origins, with emphasis on their fate and toxicity, as well the various classes of microbial xenobiotic-modifying enzymes. This review article discusses classic and recent findings in toxicomicrobiomics, with examples of interactions between gut, skin, urogenital, and oral microbiomes with pharmaceutical, food-derived, and environmental xenobiotics. The current state and future prospects of toxicomicrobiomic research are discussed, and the tools and strategies for performing such studies are thoroughly and critically compared.

Metal Levels, Genetic Instability, and Renal Markers in Electronic Waste Workers in Thailand

Background:

Informal electronic waste (e-waste) recycling is an increasingly important industry worldwide. However, few studies have studied the health risks in this group of workers.

Objective:

To assess the associations between occupational exposures to metals and genetic instability and renal markers among e-waste recycling workers.

Methods:

We recruited informal e-waste recycling workers from a community in northeastern Thailand. Participants completed a questionnaire, several health measurements, and provided urine and blood samples, which we then analyzed for a number of metals including lead (Pb), cadmium (Cd), and manganese (Mn). Samples were analyzed for a marker of RNA and DNA damage (ie, oxidative stress), 8-hydroxy-2'-deoxyguanosine (8-OHdG). Glomerular filtration rate (GFR) and fractional excretion of calcium (FECa%) were measured as markers of renal function. Correlations and regression models were used to assess associations between these various factors.

Results:

We found significantly higher levels of Cd and Pb in blood of men compared with those in women. Men who worked >48 hours/week had significantly higher levels of 8-OHdG compared with men who worked ≤48 hours/week. Smoking was significantly associated with higher blood Pb and Cd concentrations among men.

Conclusion:

Our results suggest gender differences in both blood concentrations of metals associated with e-waste recycling and smoking and highlight potentially elevated oxidative stress associated with longer work hours. Health promotion efforts are needed among informal e-waste recyclers to reduce possible risks of renal damage and cancer.

Assessing the Cadmium Effects on the Benthic Foraminifer Ammonia cf. parkinsoniana: An Acute Toxicity Test

Heavy metals are one of the most hazardous pollutants in marine environments because of their bioaccumulation and biomagnification capabilities. Among them, cadmium (Cd) has been considered as one of the most dangerous for marine organisms. Here we incubated Ammonia cf. parkinsoniana specimens, a benthic foraminiferal taxon used in previous experiments, for up to 48 h in natural seawater with different concentrations of Cd to unravel the physiological change. We document a reduced pseudopodial activity of the Cd-treated specimens at concentrations >10–100 ppb in comparison with the control specimens. Moreover, confocal images of Cd-treated specimens using Nile Red as a fluorescent probe reveal an enhanced intracellular neutral lipid accumulation in the form of lipid droplets at 6 h and 12 h. This bioassay experiment allows for the direct evaluation of Cd-dose to A. cf. parkinsoniana-response relationships under laboratory controlled conditions and provides complementary information to field observations as well as to water quality guidelines and thresholds.

Effect of Prepubertal Exposure to CdCl2 on the Liver, Hematological, and Biochemical Parameters in Female Rats; an Experimental Study

The examination chemical factors including industrial toxins and heavy metals seem to be crucial during the prepubertal period. In order to investigate the effects of prepubertal exposure to toxic doses of Cd on liver, hematological, and biochemical parameters in the serum, 16 female rats weaned on postnatal day (PND) 21 were randomly divided into four groups with four rats in each (n = 4). The treatments were as follows: control (0.5 mL distilled water), 25, 50, and 75 mg/kg/day received cadmium chloride (CdCl2). The CdCl2 were administered orally from PND 21 days until observed first vaginal opening (VO). The result showed that the treatment of 75 mg/kg CdCl2 dramatically increased the serum level of LDL (P < 0.0001) and LDL/HDL ratio (P = 0.0004). Conversely, treatment of 75 mg/kg CdCl2 considerably decreased the serum level of HDL in comparison with control group (P = 0.0002). Nevertheless, the rats that received different doses of CdCl2 showed no significant differences in Glu, TG, and TC compared to control group. Number of RBC and Hb of rats treated with 75 mg/kg CdCl2 were significantly less than the other groups (P < 0.0001), whereas a number of WBCs in rats treated with 75 mg/kg CdCl2 (5.27 ± 0.13 10³/μL) showed significant difference (P < 0.0001) compared to control group (4.23 ± 0.09 10³/μL). Histopathological exams showed nodular accumulation of lymphocytes in the liver (lymphocytic hepatitis) of rats, treated with 75 mg/kg CdCl2. These results showed that CdCl2 could cause change in serum lipidome and hematological parameters. What is more, exposure to Cd triggers liver injury and cardiovascular disease during the prepubertal period.

Association of urinary cadmium, circulating fatty acids, and risk of gestational diabetes mellitus: A nested case-control study in China

BACKGROUND

Previous studies have observed that cadmium (Cd) exposure of pregnant women was associated with increased risk of gestational diabetes mellitus (GDM). However, the potential mechanism still remains unclear. In addition, various animal studies have suggested that Cd exposure could affect fatty acids (FAs) metabolism, but data on humans are scant.

OBJECTIVES

We conducted a nested case-control study to investigate the associations of urinary Cd concentrations with levels of circulating FAs and risk of GDM in pregnant women, and further to examine the role of FAs in mediating the relationship between Cd exposure and risk of GDM.

METHODS

A total of 305 GDM cases were matched to 305 controls on pregnant women's age (±2 years) and infant's gender from a birth cohort study conducted in Wuhan, China. Urinary Cd concentrations and levels of plasma FAs between 10 and 16 gestational weeks were measured using inductively coupled plasma mass spectrometry and gas chromatography-mass spectrometry, respectively. Conditional logistic regressions models were used to estimate the associations of Cd concentrations and levels of FAs with the risk of GDM. Multiple linear regression models were applied to estimate the associations between Cd concentrations and levels of FAs. Mediation analysis was used to assess the mediating role of FAs in the association of Cd with the risk of GDM.

RESULTS

Urinary concentrations of Cd in cases (median: 0.69 μg/L) were significantly higher than controls (median: 0.59 μg/L, P < 0.05). Cd concentrations were positively associated with the risk of GDM (P_trend = 0.003). Compared to the first tertile of Cd, the adjusted odds ratios (95% confidence intervals) of GDM risk were 2.08 (1.29, 3.36) for the second tertile and 2.09 (1.32, 3.33) for the third tertile. Cd concentrations were positively correlated with levels of eicosadienoic acid and arachidonic acid/eicosapentaenoic acid ratio, but negatively correlated with levels of stearic acid, eicosapentaenoic acid, total odd-chain saturated fatty acids, total n-3 polyunsaturated fatty acids (PUFAs), and n-3 PUFAs/n-6 PUFAs ratio. We did not observe evidence that the association of Cd exposure and risk of GDM was mediated through FAs.

CONCLUSIONS

Our findings confirmed the association of higher Cd exposure with increased risk of GDM in pregnant women, and provided forceful epidemiological evidence for the relation of Cd concentrations and levels of FAs.

The influence of long-term cadmium exposure on the male advertisement call of Xenopus laevis

Cadmium (Cd) is a non-essential environmental endocrine-disrupting compound found in water and a potential threat to aquatic habitats. Cd has been shown to have various short-term effects on aquatic animals; however, evidence for long-term effects of Cd on vocal communications in amphibians is lacking. To better understand the long-term effects of low-dose Cd on acoustic communication in amphibians, male Xenopus laevis individuals were treated with low Cd concentrations (0.1, 1, and 10 μg/L) via aqueous exposure for 24 months. At the end of the exposure, the acoustic spectrum characteristics of male advertisement calls and male movement behaviors in response to female calls were recorded. The gene and protein expressions of the androgen receptor (AR) were determined using Western blot and RT-PCR. The results showed that long-term Cd treatment affected the spectrogram and formant of the advertisement call. Compared with the control group, 10 μg/L Cd significantly decreased the first and second formant frequency, and the fundamental and main frequency, and increased the third formant frequency. One and 10-μg/L Cd treatments significantly reduced the proportion of individuals responding to female calls and prolonged the time of first movement of the male. Long-term Cd treatment induced a downregulation in the AR protein. Treatments of 0.1, 1, and 10 μg/L Cd significantly decreased the expression of AR mRNA in the brain. These findings indicate that long-term exposure of Cd has negative effects on advertisement calls in male X. laevis.

Cadmium behavior in a karst environment hydrological cycle

Karst regions are important water providers, supplying approximately 25% of the world population. These areas present higher vulnerability to contamination due to hydrodynamics, which hampers the natural depuration of these waters until reaching the underground environment. High concentrations of cadmium (Cd) are observed in the São Miguel watershed, state of Minas Gerais, Brazil. This toxic element is generally and predominantly released into the atmosphere by burning materials that have Cd in their composition, potentially contaminating surface and groundwater. Therefore, the objective of the study is to map Cd concentrations in the hydrological cycle of the São Miguel karst watershed and, through natural background level values (NBL 90%) of rainwater, surface water and groundwater, to understand the seasonal behavior of this element, and to identify the most vulnerable areas to contamination. To achieve this goal, rainwater, surface, and groundwater seasonal monitoring were conducted in 87 sampling stations. A total of 335 samples were collected, distributed over a watershed area of 520 km². Concentrations of cadmium above 1 μg/L were found in 21.49% of samples during the rainy season. The origin and distribution of Cd were related to rainfall. For rainwater samples, 90% presented Cd concentration of 3.06 μg/L. When these waters precipitate, they contaminate surface waters (NBL 90% = 1.50 μg/L) and groundwater (NBL 90% = 2.81 μg/L). This study presented a hydrochemical cycle map and proposed NBL values of Cd for surface water and groundwater, helping to understand how the environment is contaminated by this element.

A highly sensitive fluorescent sensor for Cd2+ and Zn2+ based on diarylethene with a pyrene unit

A novel multifunctional diarylethene fluorescence sensor 1O containing pyrene unit was designed and synthesized. The photochromism and fluorescence photoswitching properties of this diarylethene were studied in detail by irradiation of UV/Vis lights and response of metal ions in acetonitrile solution. Diarylethene fluorescence sensor 1O has high selectivity and sensitivity for the detections of Cd²⁺ and Zn²⁺. The limit of detections (LODs) for Cd²⁺ and Zn²⁺ were determined to be 1.85 × 10^-9 mol L^-1 and 7.68 × 10^-9 mol L^-1, respectively. The binding constants (K_a) of 1O with Cd²⁺ and Zn²⁺ in acetonitrile solution were calculated to be 5.8 × 10⁴ mol^-1 L and 6.0 × 10⁴ mol^-1 L, respectively. The compound 1O responded to the metal ions (Cd²⁺/Zn²⁺) to form complexations with 1 : 1 stoichiometry which were verified by Job's plot and MS analysis, respectively. In addition, the fluorescence sensor 1O has been successfully applied to the detection of Cd²⁺ and Zn²⁺ in real water samples and processed into test strips for on-site analysis and testing.

Regional characteristics of cadmium intake in adult residents from the 4th and 5th Chinese Total Diet Study

Cadmium (Cd) is a heavy metal known to be harmful to human health. The aim of this study was to analyze the regional characteristics of dietary Cd intake of adult male residents in different regions of China. The value of this research is to guide regional consumers to minimize Cd intake by adjusting diets for different food categories in various regions. Dietary Cd intake data is used from the 4th and 5th Chinese Total Diet Studies (CTDS). The 4th CTDS collected data from 12 provinces, covering about 50% of the Chinese population. The 5th CTDS collected data from 20 provinces, covering about 67% of the Chinese population. Over 200 kinds of foods were sampled and divided into 13 categories and organized by geographic information system (GIS) mapping. The results showed that firstly, the dietary Cd intake of Chinese residents has increased; secondly, the food groups with the highest Cd intake were cereals and vegetables; and thirdly, the main food group of dietary Cd intake in different regions is presented such as cereals in Sichuan, Jiangxi, Zhejiang, Guangdong, Fujian, and Guangxi and vegetables in Shanghai, Ningxia, and Heilongjiang. Lastly, the food product with the highest dietary Cd intake concentration was found to be nori in 5 provinces. The other notable foods, with Cd intake, included peanuts, rice, squid, cuttlefish, and mushrooms.

Cadmium-binding proteins in human blood plasma

Blood is the transmission medium for metal contaminants to and from bodily organs; as such, it can provide useful and reliable information about their bio-kinetics as they're distributed throughout the body. Metals can interact with endogenous proteins present in the blood, and these metal-protein complexes often dictate the fates of the introduced metals. The aim of this study was to investigate cadmium-binding protein characteristics in normal human plasma. Cadmium-binding plasma proteins in two different groups: normal human plasma (n = 29), and normal paired maternal and fetal umbilical cord plasmas (n = 3), were analyzed. In order to detect cadmium-binding plasma proteins present in low concentrations, blood plasma samples were first depleted of their two most abundant proteins - albumin and immunoglobulin G. Both the crude and depleted plasma samples were analyzed using column gel electrophoresis in conjunction with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). One cadmium-binding protein was detected in 11 of 29 normal plasma samples and all three paired maternal and cord plasma samples. This protein was further identified as apolipoprotein A-I by high-resolution mass spectrometry. To the best of our knowledge, this is the first study to reveal cadmium-binding proteins in real human blood plasma, which is extremely critical to our understanding of cadmium transportation and accumulation in human blood.

An operon consisting of a P-type ATPase gene and a transcriptional regulator gene responsible for cadmium resistances in Bacillus vietamensis 151-6 and Bacillus marisflavi 151-25

BACKGROUND

Cadmium (Cd) is a severely toxic heavy metal to most microorganisms. Many bacteria have developed Cd²⁺ resistance.

RESULTS

In this study, we isolated two different Cd²⁺ resistance Bacillus sp. strains, Bacillus vietamensis 151-6 and Bacillus marisflavi 151-25, which could be grown in the presence of Cd²⁺ at concentration up to 0.3 mM and 0.8 mM, respectively. According to the genomic sequencing, transcriptome analysis under cadmium stress, and other related experiments, a gene cluster in plasmid p25 was found to be a major contributor to Cd²⁺ resistance in B. marisflavi 151-25. The cluster in p25 contained orf4802 and orf4803 which encodes an ATPase transporter and a transcriptional regulator protein, respectively. Although 151-6 has much lower Cd²⁺ resistance than 151-25, they contained similar gene cluster, but in different locations. A gene cluster on the chromosome containing orf4111, orf4112 and orf4113, which encodes an ATPase transporter, a cadmium efflux system accessory protein and a cadmium resistance protein, respectively, was found to play a major role on the Cd²⁺ resistance for B. vietamensis 151-6.

CONCLUSIONS

This work described cadmium resistance mechanisms in newly isolated Bacillus vietamensis 151-6 and Bacillus marisflavi 151-25. Based on homologies to the cad system (CadA-CadC) in Staphylococcus aureus and analysis of transcriptome under Cd²⁺ induction, we inferred that the mechanisms of cadmium resistance in B. marisflavi 151-25 was as same as the cad system in S. aureus. Although Bacillus vietamensis 151-6 also had the similar gene cluster to B. marisflavi 151-25 and S. aureus, its transcriptional regulatory mechanism of cadmium resistance was not same. This study explored the cadmium resistance mechanism for B. vietamensis 151-6 and B. marisflavi 151-25 and has expanded our understanding of the biological effects of cadmium.

Oleic acid protects against cadmium induced cardiac and hepatic tissue injury in male Wistar rats: A mechanistic study

AIMS

The aim of the present study was to evaluate the possible antioxidant role of oleic acid (OA) against Cd-induced injuries in the heart and liver tissues of male Wistar rats.

MAIN METHODS

Rats were treated with either vehicle (control), or OA (10 mg/kg b.w., fed orally), or Cd (0.44 mg/kg b.w., s.c.), or both (OA + Cd) for 15 days. Following completion of the treatment period, biomarkers of organ damage and oxidative stress including ROS, activities of antioxidant enzymes and their level, activities of Krebs cycle enzymes and respiratory chain enzymes were measured. Levels of interleukins (IL-1β, IL-6, IL-10), tumor necrosis factor (TNF-α) and nuclear factor kappa B (NFκB) were estimated to evaluate the state of inflammation. In addition, changes in mitochondrial membrane potential and status of cytochrome c (Cyt c) were also studied.

KEY FINDINGS

Pre-treatment of rats with OA significantly protected against Cd-induced detrimental changes possibly by decreasing endogenous ROS through regulation of antioxidant defense system, inflammatory responses and activities of metabolic enzymes. Moreover, OA was also found to restore mitochondrial membrane potential possibly by regulating Cyt c leakage thereby increasing mitochondrial viability.

SIGNIFICANCE

Our results for the first time demonstrated systematically that OA provided protection against Cd-induced oxidative stress mediated injuries in rat heart and liver tissues through its antioxidant mechanism. The results raise the possibility of using OA singly or in combination with other antioxidants or diet in the treatment of situations arising due to oxidative stress and may have future therapeutic relevance.

Cadmium-Induced Renal Cell Toxicity Is Associated With MicroRNA Deregulation

Cadmium is an environmental pollutant well known for its nephrotoxic effects. Nevertheless, mechanisms underlying nephrotoxicity continue to be elucidated. MicroRNAs (miRNAs) have emerged in recent years as modulators of xenobiotic-induced toxicity. In this context, our study aimed at elucidating whether miRNAs are involved in renal proximal tubular toxicity induced by cadmium exposure. We showed that cadmium exposure, in 2 distinct renal proximal tubular cell models (renal proximal tubular epithelial cell [RPTEC]/human telomerase reverse transcriptase [hTERT] and human kidney-2), resulted in cytotoxicity associated with morphological changes, overexpression of renal injury markers, and induction of apoptosis and inflammation processes. Cadmium exposure also resulted in miRNA modulation, including the significant upregulation of 38 miRNAs in RPTEC/hTERT cells. Most of these miRNAs are known to target genes whose coding proteins are involved in oxidative stress, inflammation, and apoptosis, leading to tissue remodeling. In conclusion, this study provides a list of dysregulated miRNAs which may play a role in the pathophysiology of cadmium-induced kidney damages and highlights promising cadmium molecular biomarkers that warrants to be further evaluated.

N2S2 pyridinophane-based fluorescent chemosensors for selective optical detection of Cd2+ in soils

A fluorescent sensor array for the quantitative determination of Cd²⁺ in soils based on two N₂S₂ pyridinophane chemosensors is presented.

A survey of trace metal burdens in increment cores from eastern cottonwood (Populus deltoides) across a childhood cancer cluster, Sandusky County, OH, USA

A dendrochemical study of cottonwood trees (Populus deltoides) was conducted across a childhood cancer cluster in eastern Sandusky County (Ohio, USA). The justification for this study was that no satisfactory explanation has yet been put forward, despite extensive local surveys of aerosols, groundwater, and soil. Concentrations of eight trace metals were measured by ICP-MS in microwave-digested 5-year sections of increment cores, collected during 2012 and 2013. To determine whether the onset of the first cancer cases could be connected to an emergence of any of these contaminants, cores spanning the period 1970-2009 were taken from 51 trees of similar age, inside the cluster and in a control area to the west. The abundance of metals in cottonwood tree annual rings served as a proxy for their long-term, low-level accumulation from the same sources whereby exposure of the children may have occurred. A spatial analysis of cumulative metal burdens (lifetime accumulation in the tree) was performed to search for significant 'hotspots', employing a scan statistic with a mask of variable radius and center. For Cd, Cr, and Ni, circular hotspots were found that nearly coincide with the cancer cluster and are similar in size. No hotspots were found for Co, Cu, and Pb, while As and V were largely below method detection limits. Whereas our results do not implicate exposure to metals as a causative factor, we conclude that, after 1970, cottonwood trees have accumulated more Cd, Cr, and Ni, inside the childhood cancer cluster than elsewhere in Sandusky County.

di-Cysteine Residues of the Arabidopsis thaliana HMA4 C-Terminus Are Only Partially Required for Cadmium Transport

Cadmium (Cd) is highly toxic to the environment and humans. Plants are capable of absorbing Cd from the soil and of transporting part of this Cd to their shoot tissues. In Arabidopsis, the plasma membrane Heavy Metal ATPase 4 (HMA4) transporter mediates Cd xylem loading for export to shoots, in addition to zinc (Zn). A recent study showed that di-Cys motifs present in the HMA4 C-terminal extension (AtHMA4c) are essential for high-affinity Zn binding and transport in planta. In this study, we have characterized the role of the AtHMA4c di-Cys motifs in Cd transport in planta and in Cd-binding in vitro. In contrast to the case for Zn, the di-Cys motifs seem to be partly dispensable for Cd transport as evidenced by limited variation in Cd accumulation in shoot tissues of hma2hma4 double mutant plants expressing native or di-Cys mutated variants of AtHMA4. Expression analysis of metal homeostasis marker genes, such as AtIRT1, excluded that maintained Cd accumulation in shoot tissues was the result of increased Cd uptake by roots. In vitro Cd-binding assays further revealed that mutating di-Cys motifs in AtHMA4c had a more limited impact on Cd-binding than it has on Zn-binding. The contributions of the AtHMA4 C-terminal domain to metal transport and binding therefore differ for Zn and Cd. Our data suggest that it is possible to identify HMA4 variants that discriminate Zn and Cd for transport.

Cadmium Toxicity in Wheat: Impacts on Element Contents, Antioxidant Enzyme Activities, Oxidative Stress, and Genotoxicity

Cadmium (Cd) pollution is constantly increasing in agricultural systems due to anthropogenic activities and causes significant reductions in the yield of crop species. In this study, we aimed to determine the effect of Cd stress on growth, element contents, oxidative damage, antioxidant enzyme activities, and genotoxicity in wheat (Triticum aestivum L.). To achieve this goal, 7-day-old wheat seedlings were subjected to different concentrations of Cd(NO₃)₂·4H₂O (250, 500, and 1000 µM) for 4 days. The results show that Cd stress induces growth inhibition, oxidative injury, and genotoxicity in wheat seedlings. Moreover, the highest concentration of Cd treatment led to a significant increase in the activities of antioxidant enzymes, except for catalase. In addition, a dramatic decrease was observed in K and Ca contents in response to Cd treatments. Overall, our findings suggest that even short-term exposure to Cd can impair key physiological processes influencing growth, oxidative homeostasis, and genomic stability in wheat.

The cadmium-induced changes in the polar and neutral lipid compositions suggest the involvement of triacylglycerol in the defense response in maize

Cadmium (Cd) is a heavy metal ion leading to morphological and physiological disorders in plants; a specific toxicity target is the membrane lipids. The total lipids were separated by thin-layer chromatography, and the fatty acid composition of the total (TLs), polar lipids (PLs) and triacylglycerol (TAG)-a neutral lipid-was analyzed in maize seedlings in hydroponics and treated by various Cd concentrations (0-200 µM Cd). The TLs and PLs significantly decreased in roots after Cd treatment, suggesting the onset of lipid peroxidation mediated by oxygen free radicals, that induce alterations of the membrane structure and function. There were also increases in the TAG from 28.2 to 36.9% of TLs, and the TAG/PLs ratio varied from 0.59 to 0.84, in control and after exposure to 200 µM Cd, respectively. The TAG plays potent roles in membrane turnover serving as energy and carbon resources for the biosynthesis of membrane lipids, to preserve membrane structure and function, and therefore cell homeostasis in response to Cd. In shoots, a significant increase in the levels of C16:0, C18:1, and C18:2, while a decrease in that of C18:3 was observed, suggesting inhibition of desaturases enzymes. These lead to impairment of the chloroplast membrane. The total lipid content did not change under Cd stress. The PLs, however, decreased from 22.4 to 13.6 mg g^-1 DW; their percent to TLs varied from 86.6 to 52.5%, in control, and after Cd treatment, respectively. In conclusion, the accumulation of TAG may represent a defense strategy by which maize seedlings can withstand the effects of Cd toxicity, leading to reduced oxidative stress.

Efficient removal of Cd (II) from contaminated water and soils using nanoparticles from nitrogen fertilizer industry waste

BACKGROUND

Cadmium (Cd) is used extencively in many industries and can cause environmenal pollution and severe damage to human health. As millions of tons of lime-based solid by-product from nitrogen fertilizer industry (NFIB) are produced each year, the main purpose of this study was to develop a novel, efficient and cheap nanoscale sorbent from NFIB for remediation of Cd (II) contaminated soil and water to protect and preserve public and ecosystem health.

METHODS

A novel nanoscale adsorbent was developed from the nitrogen fertilizer industry byproduct (NFIB) and was characterized using X-ray diffraction(XRD) and scanning electron microscope (SEM). Batch sorption equilibrium and kinetic experiments were conducted to evaluate the efficiency of nano- NFIB (nNFIB) in sequestering Cd(II) in contaminated soil and water.

RESULTS

The results of adorption equilibrium and kinetics experiments revealed that Langmuir and power function models best described Cd adsorption on bulk NFIB and nNFIB as evidenced by high R²(determination coefficient) and low SE(standard error of estimates) values. The Langmuir maximum adsorption capacity (q푞_max) of nNFIB for Cd(II) was 100 mg g^-1 which is twenty times higher than that of Bulk NFIB. The distinguishing features of NIFB nanoparticles involve efficient removal of Cd(II) from contaminated water (>90%) and enhancement of Cd (II) immobilization (146%) in cotaminated soil.Fourier Transmission Infrared (FTIR) spectra of Cd(II) contaminated water and soil before and after nNFIB application revealed the important rule of calcite nanoparticles in Cd(II) sequestration.

CONCLUSIONS

The accessibility, low cost, and Cd sequestration efficiency of nNFIB nominate it to be an economic and a promised adsorbent for environmental remediation.

An environmental friendly enrichment method for microextraction of cadmium and lead in groundwater samples: Impact on biological sample of children

A novel ionic liquid-based vortex assisted dispersive liquid-liquid micro extraction procedure(IL-VADLLμE) was proposed for the enrichment of toxic metals, cadmium (Cd) and lead (Pb) in different types of water samples, domestic treated and groundwater (tube well and hand pump). Whereas, the concentration of both toxic metals was also determined in the scalp hair of children (age ranged 1-3 years), drinking contaminated groundwater termed as exposed group, whereas for comparative purposes scalp hair of age matched children consumed domestically treated water, named as non-exposed group. To preconcentrate the trace levels of Cd and Pb, a green chelating agent, l-cysteine (2-amino-3-sulfhydrylpropanoic acid) was used for complexation, an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM] [PF₆] utilized as extractant and hexafluorophosphate ion (PF₆^-) as anion pairing agent, which facilitate the enrichment of hydrophobic complexes of analytes into the acceptor phase. Various operative features for the IL-VADLLμE method like pH of standards/samples, volume of ionic liquid and sample solution, concentration of ligand, ion pair reagent and ionic liquid, vortex and electrical shaking time (for comparative purpose), were thoroughly optimized. The projected method was effectively applicable to assess the Cd and Pb in trace level in real water sample (surface and groundwater) and scalp hair samples of children belongs to exposed and non-exposed areas. The high contents of both toxic metals in scalp hair samples of children consuming groundwater indicate that the adverse impacts of both toxic metals especially Pb on the general health as well as neuron and skeletal problem, from child hood.