Cd Chloride Research Articles

Evaluation of hepatorenal impairments in Wistar rats coexposed to low-dose lead, cadmium and manganese: insights into oxidative stress mechanism

The study aims to evaluate effects of chronic low-dose coexposure to lead (Pb), cadmium (Cd) and manganese (Mn) on hepatorenal toxicity and oxidative stress. Young male Wistar rats were treated with Pb acetate (1.4 mg/kg BW), Cd chloride (0.01 mg/kg BW), Mn chloride (0.14 mg/kg BW) and their combination (Pb + Cd + Mn) by oral gavage, for 15 weeks. Liver enzymes, albumin (Alb), globulin (Glb), total protein, creatinine, urea and electrolyte concentrations were measured in the serum. Hepatic and renal malondialdehyde (MDA), glutathione peroxidase-1 (GPx1) and metallothionein-1 (MT1) concentrations were measured by enzyme immunoassay technique. Chronic exposure to the metals significantly (p < .05) increased serum Glb concentration and decreased Alb/Glb ratio, compared to the controls. Serum creatinine concentration significantly (p < .05) decreased in the Pb, Cd and Pb + Cd + Mn groups, but elevated in the Mn group. Hepatic MDAs rose significantly (p < .05) in the Pb group, while hepatic GPx1 activities increased significantly (p < .05) in the Cd, Mn and Pb + Cd + Mn groups. Hepatic and renal MT1 concentration decreased (p < .05) in the Mn group only. Biochemical alterations were confirmed by light microscopy of the liver and kidneys, which showed degenerative changes. It is concluded that prolonged coexposure to environmentally relevant levels of Pb, Cd and Mn impairs liver and kidney functions via the induction of oxidative stress, and it underlines the importance of studying toxicants in combination.

Protective Effects of Long Term Administration of Zinc on Bone Metabolism Parameters in Male Wistar Rats Treated with Cadmium

Background: Acute cadmium (Cd) intoxication can be caused by eating foods or drinks that are packed in metal containers coated with Cd. The exposure to Cd enhanced resorption and inhibited formation of the bone tissue resulting in its decreased mineralization and thus may lead to various complications. Zinc supplement can reduce Cd absorption as well as neutralize the Cd-induced toxicity. This study aimed to investigate the protective effect of zinc on bone metabolism parameters in male rats treated with Cd. Materials and Methods: In this experimental study, a total of 48 male Wistar rats were randomly allocated into eight groups: group 1 received 0.5 mL of normal saline, group 2 received 0.5 mg/kg zinc, three Cd groups that received three different Cd concentrations (0.5, 1 and 2 mg/kg) and the other three groups received three Cd concentrations and zinc simultaneously. Blood samples were taken over a 30-day period and factors related to bone metabolism were measured. Results: The results showed that administration of three different doses of Cd chloride (0.5, 1 and 2 mg/kg) increased the activity of alkaline phosphatase, calcium, phosphorus and magnesium and decreased the albumin concentration compared to the control group. Moreover, the simultaneous use of three concentrations of Cd chloride with zinc reduced the activity of alkaline phosphatase, calcium, phosphorus, magnesium and increased the albumin concentration (P<0.05). Conclusion: Zinc supplementation can have protective effects against the toxicity caused by Cd on parameters of bone metabolism.

The Protective Role of Curcumin and Melatonin in Amelioration of Cadmium- Induced Cardiac Toxicity in Adult Albino Rats

Cadmium (Cd), a common toxic environmental and occupational pollutant which cause many organ toxicities probably due to its ability to induce oxidative stress. Curcumin and melatonin have many beneficial effects. THE AIM of this study is to investigate the possible role of curcumin and melatonin in amelioration of cadmium-induced cardiac toxicity in rats. METHODS: This study was conducted on 140 adult male albino rats divided into 7 equal groups. Group I served as negative control. Group II received curcumin in an oral dose of 200mg/kg/day. Group III received melatonin in an oral dose of 10mg/kg/day .Group IV received cadmium chloride an oral dose of 5.2mg/kg/day for 15 days. By using the same doses and period Group V received cadmium chloride and curcumin, Group VI received cadmium chloride and melatonin, Group VII received cadmium chloride, curcumin and melatonin. At the end of the experiment, rats were sacrificed and samples were collected. Serum markers of myocardial damage were measured includingcreatine kinase –MB isoform (CK-MB) , lactate dehydrogenase (LDH) ,cardiac Troponin I (cTn-I). Oxidative status was evaluated by estimation of superoxide dismutase (SOD), catalase (CAT) and glutathione -S transferase (GST) activity Total antioxidant capacity (TAC) in serum in addition to tissue malondialdehyde (MDA) in heart. RESULTS: Compared to negative control group, there was insignificant difference in the mean values of all the tested parameters in groups II and III, while significant difference was found in group IV. Group V showed significant difference from cadmium chloride group regarding all studied parameters but in comparison with control group, there was insignificant difference regarding cardiac parameters only. On the other hand, Group VI showed significant difference from Cd chloride group regarding all studied parameters and in comparison with control group, there was insignificant difference regarding cardiac parameters and SOD. As for Group VII, it showed significant difference from Cd chloride group, and insignificant difference from control group regarding all studied parameters. CONCLUSION: Cadmium chloride caused significant oxidative cardiac toxicity. Co- administration of melatonin could improve such toxicity more significantly than curcumin did, while co-administration of both melatonin and curcumin provided superior protection against Cd chloride toxicities compared to either of them alone. RECOMMENDATIONS: Further research is needed to investigate the beneficial effects of curcumin and melatonin and its applicability in humans vulnerable to Cd toxicity.

Polydeoxyribonucleotide, an adenosine-A2A receptor agonist, preserves blood testis barrier from cadmium-induced injury

Cadmium (Cd) impairs the blood-testis barrier (BTB) with changes of its junctional complexes [1]. Polydeoxyribonucleotide (PDRN), an adenosine A2A agonist, has positive effects on male reproductive system [2]. We investigated the effects of PDRN on the morphological and functional Cd-induced changes in mice testes. Swiss mice were divided into four groups: control animals treated with 0.9% NaCl (1 ml/kg, i.p., daily); control animals treated with PDRN (8 mg/kg, i.p. daily), animals challenged with Cd chloride (CdCl2) (2 mg/kg i.p, daily) and animals challenged with CdCl2 and treated with PDRN. The experiments lasted 14 days. At the end of experiment, the testes were processed for biochemical, structural and ultrastructural evaluation. CdCl2 increased pERK 1/2 expression and Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) levels, decreased testosterone (TE) and inhibin-B levels and induced structural damages in the extratubular compartment and in the seminiferous epithelium, with ultrastructural features of BTB disruption. Many TUNEL-positive germ cells were present in the peripheral parts of the tubules. CdCl2 increased also tubular TGF-β3 immunoreactivity and reduced claudin-11, occludin and N-cadherin immunoreactivity. PDRN administration reduced pERK 1/2 expression, FSH and LH levels, increased TE and inhibin-B levels, ameliorated germinal epithelium changes and protected BTB ultrastructure. Only few TUNEL-positive germ cells were present and the extratubular compartment was preserved, showing only a mild edema. Furthermore PDRN decreased TGF-β3 immunoreactivity and enhanced claudin-11, occludin and N-cadherin immunoreactivity. We demonstrate, for the first time, a protective effect of PDRN on Cd-induced BTB damages in mice testes. We suggest that the A2A agonist may play an important role against environmental Cd, and in particular against its harmful effects on gametogenesis.

Synthesis and characterization of Hg(II) and Cd(II) complexes derived from the novel acenaphthaquinone-4-phenyl thiosemicarbazone and its CPE application

The new acenaphthaquinone-4-phenyl thiosemicarbazone (APTH) was synthesized. The reaction of Hg(II) and Cd(II) chloride with APTH yields bimetallic complexes, which are characterized by elemental, IR, UV-Vis., 1H-NMR and Mass spectroscopy. The APTH employed as a chelating agent for CPE procedure of trace amounts of mercury and cadmium from aqueous medium. The Hg(II) and Cd(II) is preconcentrated using 0.1% w/v Triton X-114 and 2 × 10−5 M APTH at pH 7. The calibration curve is linear in the ranges 0.25–3 and 0.25–7.5 ng/ml for Cd(II) and Hg(II), respectively. The proposed method was applied successfully in the determination of Hg(II) and Cd(II) in different water samples.

Effect of Cadmium on Trophoblast Cell Proliferation and Apoptosis in Different Gestation Periods of Rat Placenta.

In this study, we aimed to show how cadmium (Cd) affects the trophoblast proliferation and differentiation in the placenta and the apoptotic activity in different gestational days and, hence, its effects of placental development with immunohistochemical and TUNEL techniques. Experimental model of our study consisted of placental development of control and Cd groups on 15, 17, 19, and 21th days of the gestation. Female rats in Cd groups were subcutaneously administered a single dose of 0.5mg Cd/kg/day dissolved in sodium chloride as 2mL/kg Cd chloride until the day they sacrificed. Embryo and placenta of female rats were separately removed on 15, 17, 19, and 21th days of the gestation in which the placental development takes place and placentas were processed for microscopic examinations. In the placentas of the control group, all layers were observed to be formed on the 15th gestational day and thereafter a continuous growth was monitored. In the Cd group also all layers existed from the 15th gestational day. However, they were smaller in size than control groups. Frequency of proliferating cell nuclear antigen (PCNA)-positive cells was decreased and the number of apoptotic cells was increased in all the gestational days related to Cd. In conclusion, Cd administered during the pregnancy was observed to cause abnormal placental development by disrupting the normal structure of the placenta, inhibiting the proliferation of trophoblast and increasing the number of apoptotic trophoblast cells.

Dermatopontin is a novel regulator of the CdCl2-induced decrease in claudin-11 expression

Cadmium (Cd) is a ubiquitous environmental heavy metal, which may be harmful to the reproductive functions through injury to the blood-testis barrier (BTB). However, the underlying mechanism of this adverse effect on the BTB remains uncharacterized. A preliminary study revealed that dermatopontin (DPT) expression was significantly increased in Cd chloride (CdCl2)-treated Sertoli cells in vitro, which suggested that an increase in DPT expression is crucial for CdCl2-induced BTB damage. To explore this further, in the present study we initially determined that DPT is expressed in testis Sertoli cells. The treatment of cells with CdCl2 resulted in a significant increase in DPT expression and a parallel decrease in claudin-11 expression, both in vivo and in vitro. To confirm the relationship between DPT and claudin-11, a DPT-silenced 15P-1 Sertoli cell model was established. We determined that DPT silencing could partly reduce the CdCl2-induced decrease in claudin-11 expression. Additionally, western blot analyses demonstrated that the p38 signaling pathway is involved in the effect of CdCl2 on DPT expression. In conclusion, the present study provides the first evidence that DPT may be a novel effector of CdCl2, highlighting the significant role of DPT in the regulation of claudin-11 expression.

Continuous cadmium exposure from weaning to maturity induces downregulation of ovarian follicle development-related SCF/c-kit gene expression and the corresponding changes of DNA methylation/microRNA pattern

Cadmium (Cd) impairs ovary structure and function in mature animals. However, the influence of Cd on follicle development from weaning to maturity is obscure. In the current study, 21-day-old Wistar rats were administered Cd chloride at doses of 0, 0.5, 2.0 and 8.0mg/kg body weight once a day for eight weeks by gavage. After administration, a significant decrease in ovarian wet weight, ovarian/body weight ratios, and primordial follicles, in addition to an increase in atresic follicles, were observed. Transmission electron microscopy and TUNEL assay confirmed the increase of follicle apoptosis as Cd concentration increased. Real-time quantitative PCR and Western blotting showed a significantly decreased expression of follicle development-related factors, stem cell factor (SCF) and c-kit. Bisulfite sequencing suggested that the total methylation percentages of SCF/c-kit promoter region were not obvious change after Cd exposure. Real-time quantitative PCR revealed a significantly increased expression of miR-193, miR-221 and miR-222, which regulate c-kit, in the 2.0mg/kg and 8.0mg/kg treatment groups. Overall, this study proved that Cd administration from weaning to maturity could damage follicle development, suggesting that SCF/c-kit might play an important role in this effect. In addition, microRNAs might play a role in c-kit protein downregulation.

Effect of Cd with or without se Supplementation on Spermatogenesis and Semen Quality in the Rooster (Gallus gallus)

In human and animals, it has been reported that Cd was linked with a number of health problems including marked damage of testes and fertility reduction. As for the sensitivity of fowl testes to Cd the results published so far differ from those reported in mammalian species. In this experiment, the effect of Cd with and without Se on spermatogenesis and semen quality in the rooster was studied after dietary Cd uptake. Cadmium (Cd) as Cd chloride (CdCl2) and Se (Se) as sodium selenite (Na2SeO3) were added to the feed at dosages: group 0 – control, group 1 – 20 mg kg−1 Cd, group 2 – 30 mg kg−1 Cd + 4 mg kg−1 Se. The cocks were exposed to Cd for 8 weeks. The structure of seminiferous tubules and boundary tissue, volume of semen, motility, concentration of spermatozoa and total sperm count were evaluated. In groups with 20 mg kg−1 Cd, the disarrangement of germinal epithelium, diminution of spermiocytes, detachment and presence of developing cells in the lumen of seminiferous tubules was observed. Analysis of the semen showed a significant decrease of volume of semen, the total sperm count and motility of spermatozoa ( P &lt; 0.05). In the group with 30 mg kg−1 Cd and Se supplementation, seminiferous tubules displayed all the developing spermatogenic cells. Local disarrangement and accumulation of germ cells in the luminal space was observed. In semen, a significant increase of volume of semen, motility and total sperm count ( P &lt; 0.05) was observed. A beneficial effect of Se on the development of spermatogenic cells and on semen quality was observed.

Coordination behavior and binding properties of (3,5-dimethyl-1H-pyrazol-1-yl)ethanol with Cu(II), Zn(II), Cd(II), and Pb(II) metals

The coordination chemistry and binding properties of (3,5-dimethyl-1H-pyrazol-1-yl)ethanol (L1) with Cu(II), Zn(II), Cd(II), and Pb(II) have been investigated. Reactions of L1 with Zn(II) and Cd(II) nitrate or chloride salts produced the corresponding monometallic and bimetallic complexes [Zn(NO3)2(L1)] (1), [ZnCl2(L1)] (2), [Cd(NO3)2(L1)2] (3) and [Cd2Cl2(μ-Cl2)(L1)2] (4). Solid-state structures of 3 and 4 confirmed the bidentate coordination mode of L1. The extraction efficiency of the metals by L1 is dependent upon the size and electronic properties of the metal. Binding affinities of 92% for Cu(II), 90% for Zn(II), 70% for Pb(II), and 61% for Cd(II) were observed.

Modelling the speciation pattern of metals in Ondo coastal water with geochemical model – PHREEQCI

The speciation pattern of ten metals was studied in the coastal water of Ondo State, Nigeria using geochemical modelling software (PHREEQCI). The metals classified as macronutrients – Na, Ca, K, Mg; micronutrients – Fe, Cu, Mn, Zn; toxic metals – Cd, Pb were evaluated along with other general water quality parameters from ten sampling sites. The results served as input data for the modelling. The outcomes of the water speciation modelling revealed that the macronutrient metals exist as free ions which aid the reduction of free ion species of toxic metals. The micronutrients exist as neutral or complex salts which are less toxic according to free ion activity model theory. The self purification capacity of the coastal water was aided by the abundant formation of Fe-hydroxide precipitates; high alkalinity; pH; salinity of the coastal water which are responsible for the reduction of free ion specie of Pb and its ecotoxicity but increased the concentration of toxic Cd chloride species. Therefore, the prevailing biogeochemistry of the coast enhances demobilization of the metal contaminants and favours the reduction of their toxicity except Cd.

The Effect of Cadmium, with and without Supplemental Selenium, on Reproductive Performance in Chickens

The objective of our work was to study the effect of Cd alone and in combination with Se on the reproductive performance of hens, cocks and chicks. Cadmium as Cd chloride (CdCl2) and Se as sodium selenite (Na2SeO3) were added to feed at the following dosages: group 0, control; group 1, 20 mg kg−1 Cd; group 2, 30 mg kg−1 Cd + 4 mg kg−1 Se. The birds were exposed to Cd for 2 months. The following parameters were then evaluated: egg production, fertility, hatchability, and mortality of embryos and chicks of the F1 generation. Cadmium administration at 20 mg kg−1 significantly affected production of eggs after 56 days of the experiment. Significant improvements in egg production in the group receiving 30 mg kg−1 Cd+ 4 mg kg−1 Se in comparison with group receiving 20 mg kg−1 Cd alone and the control group was observed. Fertility and embryo mortality in the 20 mg kg−1 Cd group was not significantly different from controls, whereas both these factors decreased in the group receiving 30 mg kg−1 Cd + 4 mg kg−1 Se. Hatchability in the 20 mg kg−1 Cd group decreased, while this was significantly higher in the group receiving 30 mg kg−1 Cd plus Se than in the group without Se supplementation and the control group. The negative effects of Cd ingestion on egg production can therefore be at least partially ameliorated by supplementation with dietary selenium.

Effect of Magnesium Supplementation on the Distribution Patterns of Zinc, Copper, and Magnesium in Rabbits Exposed to Prolonged Cadmium Intoxication

The present study is designed to investigate whether magnesium (Mg) supplementation may prevent Cd-induced alterations in zinc (Zn), copper (Cu), and magnesium (Mg) status in rabbits. For this purpose, the concentrations of Zn, Cu, and Mg were estimated in blood, urine, and organs (brain, heart, lungs, liver, kidney, spleen, pancreas, skeletal muscle, and bone) of rabbits given Cd (10 mg/kg b.w.) and rabbits cotreated with Mg (40 mg/kg b.w.) orally, as aqueous solutions of Cd chloride and Mg acetate every day for 4 weeks. Samples were mineralized with conc. HNO3 and HClO4 (4:1) and metals concentrations were determined by atomic absorption spectrophotometry (AAS). Magnesium supplementation succeeded to overcome Cd-induced disbalance of investigated bioelements. Beneficial effects of Mg were observed on Zn levels in blood and urine, on Cu levels in urine, and on Mg levels in blood. Magnesium pretreatment also managed to counteract or reduce all Cd-induced changes in levels of Cu and Mg in organs, while it did not exert this effect on Zn levels. These findings suggest that enhanced dietary Mg intake during Cd exposure can have at least partly beneficial effect on Cd-induced alterations in homeostasis of zinc, copper, and magnesium.

Interrelationships between cadmium, zinc and antioxidants in the liver of the rat exposed orally to relatively high doses of cadmium and zinc

Zinc (Zn) reduces cadmium (Cd)-induced toxicity in the liver although it increases Cd tissue burden in some conditions; hence, the present study is designed to study the relationships between Cd, Zn and antioxidants in the liver of rats exposed to Cd. Livers of male rats which received orally relatively high doses of Cd (200 mg Cd/L as Cd chloride or Cd (200 mg/L)+Zn (500 mg Zn as Zn chloride) during five weeks, were investigated. Cd induced an accumulation of Cd and Zn in parallel to depletion in important variables (GSH, GSH/GSSG, CuZn-SOD and GPx activities) and to elevation in others (Cd/Zn and GSSG). Cd, did not affect CuZn SOD/GPx, nor Mn-SOD in the liver. Cd accumulation, Cd/Zn, CuZn SOD activity and CuZn SOD/GPx, was increased remarkably under Zn action. Zn supply ameliorated GSH level and partially reversed the decrease in GSH/GSSG, but it did not ameliorate GPx activity. Analysis showed high correlations between Cd and the majority of the variables, while Zn was positively correlated with only GSSG. We suggest from our results that Zn has indirect ameliorative effects on Cd-induced toxicity in the liver and that the increase in Cd retention is probably the key mechanism modulating, in the case of relatively high doses of Cd, the antioxidant response during exposure to Cd and Zn.

The Effects of a Vitamin D–deficient Diet on Chronic Cadmium Exposure in Rats

Itai-itai disease (IID) of humans is one of the most severe forms of chronic cadmium (Cd) intoxication. Itai-itai disease occurs mainly in post-menopausal women and is characterized by osteoporosis with osteomalacia, renal tubular disorder, and renal anemia. Some researchers insist the major cause of IID is not Cd, but rather malnutrition, especially hypovitaminosis D. We administrated a low concentration of Cd chloride intravenously to ovariectomized female rats that were fed a vitamin D-deficient diet or a normal diet for fifty weeks. The vitamin D-deficient diet decreased serum concentration of vitamin D, but it did not affect the metabolism of the kidney or bone. Cadmium treatment alone induced a decrease in serum concentration of vitamin D, as well as renal dysfunction, renal anemia, and abnormal bone metabolism. Osteoporosis with osteomalacia, tubular nephropathy, fibrous osteodystrophy, and bone marrow hyperplasia occurred following Cd treatment. In rats treated with Cd and administered a vitamin D-deficient diet, the toxic effects of Cd on kidney, bone, and hematopoiesis were enhanced in comparison to rats treated with Cd and a normal diet. The present experiment demonstrated that hypovitaminosis D did not evoke morphologic features of IID in humans but did enhance Cd-induced toxicity in the rat model of this disease.

Alteration of Heart Tissue Protein Profiles in Acute Cadmium-Treated Scallops Patinopecten yessoensis

Cadmium (Cd) is an extremely toxic metal that induces a wide spectrum of toxic responses in organisms in the environment. In the present study, scallops (Patinopecten yessoensis), after acclimation for 1 week in the laboratory, were subjected to acute Cd chloride (CdCl₂) toxicity, and ultramorphological and proteomic changes in their heart tissues were analyzed and compared with those of the nonexposed control group. Electron microscopy showed that ultrastructures of the cytoplasm and mitochondria in scallop hearts were badly damaged, and two-dimensional gel electrophoresis showed 32 protein spots that were differentially expressed after exposure to 10 mg/l CdCl₂ for 24 h. Of these spots, 8 were upregulated, 16 were downregulated, and 8 showed low expression. Proteins from these spots were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and database searching. The results indicated that these proteins are involved in the regulation of cell structure, transport, signal transduction, and metabolism. Among other things, four proteins-identified as amino acid adenosine triphosphate (ATP)-binding cassette transporter, glycerol-3-phosphate dehydrogenase (nicotinamide adenine dinucleotide phosphate), nicotinamide adenine dinucleotide oxidase, and ATPase-were demonstrated to be especially associated with Cd toxicity. Some of the other proteins observed in this work are of particular interest in terms of their responses to Cd, which have not been reported previously. These data may provide novel biomarkers for monitoring the Cd contamination level of flowing seawater as well as provide useful insights into the mechanisms of Cd toxicity.

Structure and stability of cadmium chloride complexes in hydrothermal fluids

The identity and stability of aqueous species formed by cadmium in H 2O–Na/LiCl–HCl–HNO 3 solutions were investigated using in situ X-ray absorption spectroscopy (XANES and EXAFS) at 20–450 °C and 1–600 bar, combined with solubility measurements of CdO and CdS solids at 350–400 °C and 300–600 bar. Results show that aqueous Cd speciation is dominated by the cation Cd(H 2O) 6 2+ in acidic Cl-free solutions, and by chloride species CdCl m (H 2O) n 2 − m over a wide range of temperatures (20 ≤ T ≤ 450 °C), acidities (1 ≤ pH ≤ 8), and chloride concentrations (0.04 ≤ m Cl ≤ 18 mol/kg H 2O). EXAFS spectra from chloride solutions show that with increasing T and m Cl the average number of Cl atoms increases from 1 to ∼ 3 (± 0.6), accompanied by a decrease of the number of O from 6 to ∼ 1 (± 0.7), in the nearest coordination sphere around Cd. Average Cd–Cl distances in Cd complexes vary in the range 2.41–2.52 (± 0.02) Å, increasing with increasing m Cl and decreasing with increasing T, while Cd–O distances remain constant within errors at 2.30 (± 0.05) Å in the whole T and m Cl range investigated. This evolution of the Cd atomic environment is accompanied by changes in geometry of the dominant Cd–O/Cl species from octahedral-like to tetrahedral-like with increasing T and m Cl, as shown by XANES spectra analyses. These structural data are consistent with the formation of octahedral Cd(H 2O) 6 2+ and CdCl(H 2O) 5 + and tetrahedral CdCl 2(H 2O) 2 0, CdCl 3(H 2O) − and CdCl 4 − species at T ≤ 200–300 °C and m Cl ≤ 18. At T > 300 °C, aqueous Cd speciation is dominated by two complexes, CdCl 2(H 2O) 2 0 and CdCl 3(H 2O) − in a wide m Cl range (0.04–5 m). The stability constants of these complexes, derived from solubility measurements at 400 °C and 600 bar are ∼ 6 orders of magnitude higher than available HKF-model predictions based on low- T data. The new data on aqueous Cd complexes may be used for interpretation of Cd/Zn ratios measured in natural hydrothermal saline fluids and volcanic vapors in which the greater stability of Cd chloride species as compared to their Zn analogs is likely to be responsible for the elevated Cd/Zn ratios in comparison to crustal rocks and Cl-poor waters.

Differential sensitivity and responsiveness of three human cell lines HepG2, 1321N1 and HEK 293 to cadmium

Cadmium (Cd) is a toxic heavy metal with no uniform mechanism of toxicity. In this the present study, the toxic effect of 5, 10 and 50 microM of Cd chloride was compared in three human cell lines; a human hepatoma cell line HepG2, a human astrocytoma cell line 1321N1, and a human embryonic kidney cell HEK 293. The results indicate a decrease in the viability of all three cell lines following exposure to Cd with HepG2 cells (IC50=13.96 microM) showing the most sensitivity when measured using the MTT assay. There was significant increase in lactate dehydrogenase leakage, DNA damage, malondialdeyde and antioxidant enzymes activities in all three cell lines especially at 50 microM Cd. Significant decreases in ATP production were also observed at all Cd concentrations in HepG2 and HEK 293 cell lines. ROS levels significantly increase and GSH/GSSG ratio significantly decrease in all the three cell lines after Cd exposure, but these effects were attenuated by the presence of N-acetylcysteine (NAC). The present study therefore shows that ROS production and glutathione (GSH) depletion may play a role in Cd-induced toxicity in all the three cell lines. The endogenous levels of protective enzymes as well as their responsiveness are likely to determine a cell's susceptibility to Cd.

Comparative sensitivity of a tropical mysid Metamysidopsis insularis and the temperate species Americamysis bahia to six toxicants

The sensitivity of the tropical mysid, Metamysidopsis insularis relative to that of the sub-tropical North American mysid, Americamysis bahia was determined by comparing their acute toxicity to six toxicants. The 96 h LC50 values for M. insularis ranged from 0.03 mg L−1 (cadmium (Cd) chloride) to 466 mg L−1 (potassium chloride (KCL) whereas those for A. bahia ranged from 0.1 mg L−1 for Cd chloride to 501 mg L−1 for KCl. The interspecies correlation indicated that the mean acute toxicities for M. insularis showed a high positive correlation with A. bahia (r 2 = 1.0). Data suggest there were no significant differences between acute toxic responses of the two species to these toxicants. The results suggest that though M. insularis and A. bahia occur in different climatic zones, the difference in relative sensitivities of the two species due to temperature preferenda may be negligible. Consequently, M. insularis may be considered suitable tropical test species for use in toxicity testing in Trinidad and Tobago.

Restoration of cadmium-contaminated paddy soils by washing with ferric chloride: Cd extraction mechanism and bench-scale verification

The ability of FeCl 3 to extract Cd from three paddy soils was compared with that of various irons, manganese, and zinc salts to elucidate the extraction mechanism. Manganese, zinc and iron salts (including FeCl 3) extracted 4–41%, 8–44% and 24–66% of total Cd, respectively. This difference reflected the pH of the extraction solution, indicating that the primary mechanism of Cd extraction by FeCl 3 is proton release coupled with hydroxide generation, as iron hydroxides are insoluble. Washing with FeCl 3 led to the formation of Cd–chloride complexes, enhancing Cd extraction from the soils. FeCl 3 effectively extracted Cd from all of the three soils compared to HCl that is a conventional washing chemical, when the concentrations of the two washing chemicals were between 15 and 60 mM c (at above extraction pH 2.4), while the corresponding extraction pH of FeCl 3 was slightly higher than HCl. As HCl is the strong acid of complete dissociation, if excess amount of HCl was added to soil, it is possible to give the dissolution of clay minerals in soils. In contrast, proton release from FeCl 3 is controlled by the chemical equilibrium of hydroxide formation. While soil fertility properties were affected by a bench-scale soil washing with 45 mM c FeCl 3, adverse effects were not crucial and could be corrected. The bench-scale test confirmed the effectiveness of FeCl 3 for removal of soil Cd. The washing had no negative effect on rice yield and lowered the Cd concentration of rice grain and rice straw in a pot experiment.