Toxicity of lead: A review with recent updates

The influence of chronic and subacute exposure to lead on the levels of prolactin, leptin, osteopontin, and follistatin in humans

This study was designed to determine the levels of prolactin, leptin, osteopontin, and follistatin in workers chronically and subacutely exposed to lead compounds. The examined population consisted of three groups. The first group was composed of 56 male workers who were chronically exposed to lead for 13.38 ± 10.38 years. The second group served as a control group and consisted of 24 male administrative workers, while the third group included 32 male workers exposed to lead for 40 ± 3 days. The levels of leptin, osteopontin, and prolactin were significantly lower in the group of workers chronically exposed to lead than in the control group by 42%, 26%, and 41%, respectively. The levels of follistatin did not differ between those groups. The levels of all measured hormones did not change after a short-term exposure to lead compared to baseline. Chronic lead exposure is associated with significantly decreased level of prolactin, leptin, and osteopontin. Lead-induced changes in the levels of these hormones may disturb many functions of the human body, including the immune response, metabolism, reproduction, and bone turnover.

The protective effects of zinc in lead-induced testicular and epididymal toxicity in Wistar rats

The aim of this study was to investigate the beneficial effects of zinc (Zn) in preventing lead (Pb)-induced reproductive toxicity in Wistar rats. The rats were divided into four groups, namely, control group, Pb group, Zn group, and Pb + Zn group. Animals were exposed to Pb (819 mg of Pb/L) or Zn (71 mg of Zn/L) or both through drinking water for 65 days. Rats exposed to Pb showed decreased weights of testes and accessory sex organs. Significant decrease in the testicular daily sperm production, epididymal sperm count, motility, viability, and number of hypoosmotic tail coiled sperm was observed in Pb-exposed rats. Testicular 3β- and 17β-hydroxysteroid dehydrogenase activity levels and circulatory testosterone levels were also decreased significantly in Pb-exposed rats. A significant increase in the lipid peroxidation products with a significant decrease in the activities of catalase and superoxide dismutase were observed in the testes and epididymis of Pb-exposed rats. Moreover, the testicular architecture showed lumens devoid of sperm in Pb-exposed rats. Supplementation of Zn mitigated Pb-induced oxidative stress and restored the spermatogenesis and steroidogenesis in Pb-exposed rats. In conclusion, cotreatment of Zn is effective for recovering suppressed spermatogenesis, steroidogenesis, elevated oxidative status, and histological damage in the testis of rats treated with Pb.

Indigofera oblongifolia Prevents Lead Acetate-Induced Hepatotoxicity, Oxidative Stress, Fibrosis and Apoptosis in Rats

The current study was aimed to evaluate the preventive effects of Indigofera oblongifolia leaf extract (IOLE) on lead acetate (PbAc)-induced hepatotoxicity in adult male Wistar rats. PbAc was intraperitoneally injected at a dose of 20 mg/kg body weight for 5 days alone or in combination with the IOLE (100 mg/kg). Liver lead concentration and oxidative stress markers such as lipid peroxidation, hydrogen peroxide, nitric oxide, and glutathione content were investigated in addition to the enzymatic antioxidant activities. PbAc injection caused a significant elevation in the liver function parameters, lead level, lipid peroxidation, hydrogen peroxide, and nitric oxide, with a concomitant decline in the glutathione content compared with the control, accompanied by a significant inhibition of antioxidant enzyme activities. The induction of oxidative stress, lead accumulation, and histological alterations in the liver were successfully minimized by pre-administration of IOLE. In addition, the PbAc group showed increase in the levels of Bax, caspase-3, and matrix metalloproteinase-9 proteins, while the expression of Bcl-2 protein was decreased. Prior administration of IOLE significantly mitigated apoptosis and fibrosis in the liver. Finally, the major components in I. oblongifolia extract were identified as polyphenols, flavonoids, and organic acids using liquid chromatography coupled mass spectroscopy. Thus, the findings of the current study revealed that I. oblongifolia had protective, anti-fibrotic, antioxidant, and anti-apoptotic activities on PbAc-induced hepatotoxicity. The beneficial effects of I. oblongifolia were in part mediated by Nrf2/HO-1 pathway.

Inequitable Chronic Lead Exposure: A Dual Legacy of Social and Environmental Injustice

Both historic and contemporary factors contribute to the current unequal distribution of lead in urban environments and the disproportionate impact lead exposure has on the health and well-being of low-income minority communities. We consider the enduring impact of lead through the lens of environmental justice, taking into account well-documented geographic concentrations of lead, legacy sources that produce chronic exposures, and intergenerational transfers of risk. We discuss the most promising type of public health action to address inequitable lead exposure and uptake: primordial prevention efforts that address the most fundamental causes of diseases by intervening in structural and systemic inequalities.

Glutathione, glutathione-related enzymes, and oxidative stress in individuals with subacute occupational exposure to lead

The aim of the study was to investigate the influence of subacute exposure to lead on the glutathione-related antioxidant defense and oxidative stress parameters in 36 males occupationally exposed to lead for 40±3.2days. Blood lead level in the examined population increased significantly by 359% due to lead exposure. Simultaneously, erythrocyte glutathione level decreased by 16%, whereas the activity of glutathione-6-phosphate dehydrogenase in erythrocytes and leukocytes decreased by 28% and 10%, respectively. Similarly, the activity of glutathione-S-transferase in erythrocytes decreased by 45%. However, the activity of glutathione reductase in erythrocytes and leukocytes increased by 26% and 6%, respectively, whereas the total oxidant status value in leukocytes increased by 37%. Subacute exposure to lead results in glutathione pool depletion and accumulation of lipid peroxidation products; however, it does not cause DNA damage. Besides, subacute exposure to lead modifies the activity of glutathione-related enzymes.

A national level assessment of metal contamination in bats

Many populations of bat species across the globe are declining, with chemical contamination one of many potential stressors implicated in these demographic changes. Metals still contaminate a wide range of habitats, but the risks to bats remain poorly understood. This study is the first to present a national scale assessment of toxic metal (Cd, Pb) and essential trace metal (Cu, Zn) concentrations in bats. Metal concentrations in tissues (kidneys, liver, stomach -stomach content, bones and fur) were measured in 193 Pipistrellus sp. in England and Wales using ICP-MS, and compared to critical toxic concentrations for small mammals. The concentrations of metals determined in bat tissues were generally lower than those reported elsewhere. Strong positive associations were found between concentrations in tissues for a given metal (liver and kidneys for Cd, Cu and Pb; stomach and fur and fur and bones for Pb), suggesting recent as well as long term exposure to these contaminants. In addition, positive correlations between concentrations of different metals in the same tissues (Cd and Zn, Cu and Zn, Cd and Pb, Pb and Zn) suggest a co-exposure of metals to bats. Approximately 21% of the bats sampled contained residues of at least one metal at concentrations high enough to elicit toxic effects (associated with kidney damage), or to be above the upper level measured in other mammal species. Pb was found to pose the greatest risk (with 7-11% of the bats containing concentrations of toxicological concern), followed by Cu (4-9%), Zn (0.5-5.2%) and Cd (0%). Our data suggest that leaching of metals into our storage matrix, formaldehyde, may have occurred, especially for Cu. The overall findings suggest that metal contamination is an environmental stressor affecting bat populations, and that further research is needed into the direct links between metal contamination and bat population declines worldwide.

Effects of Dietary Selenium Against Lead Toxicity on mRNA Levels of 25 Selenoprotein Genes in the Cartilage Tissue of Broiler Chicken

The interactions between the essential element selenium (Se) and the toxic element lead (Pb) have been reported extensively; however, little is known about the effect of Se on Pb toxicity and the expression pattern of selenoproteins in the cartilage of chicken. To investigate the effects of Se on Pb toxicity and the messenger RNA (mRNA) expressions of selenoproteins in cartilage tissue, an in vitro study was performed on 1-day-old broiler chickens (randomly allocated into four groups) with diet of different concentration of Se and Pb. After 90 days, the meniscus cartilage and sword cartilage tissue were examined for the mRNA levels of 25 selenoprotein genes. The results showed that Se and Pb influenced the expression of selenoprotein genes in the chicken cartilage tissue. In detail, Se could alleviate the downtrend of the expression of Gpx1, Gpx2, Gpx4, Txnrd2, Txnrd3, Dio1, Dio2, Seli, Selu, Sepx1, Selk, Selw, Selo, Selm, Sep15, Sepnn1, Sels, and Selt induced by Pb exposure in the meniscus cartilage. In the sword cartilage, Se alleviated the downtrend of the expression of Gpx2, Gpx3, Gpx4, Txnrd1, Txnrd2, Dio2, Dio3, Seli, Selh, SPS2, Sepx1, Selk, Selw, Selo, Selm, Sep15, Selpb, Sepn1, and Selt induced by Pb exposure. The present study provided some compensated data about the roles of Se against Pb toxicity in the regulation of selenoprotein expression.

Ginger extract modulates Pb-induced hepatic oxidative stress and expression of antioxidant gene transcripts in rat liver

CONTEXT

Spices and herbs are recognized sources of natural antioxidants that can protect from oxidative stress, thus play an important role in chemoprevention of liver diseases. Ginger is used worldwide primarily as a spicy condiment.

OBJECTIVE

This study evaluated the ability of ginger extract (GE) to ameliorate oxidative-hepatic toxicity induced by lead acetate (PbAc) in rats.

MATERIALS AND METHODS

Five groups of animals were used: group I kept as control; groups II, IV, and V received PbAc (1 ppm in drinking water daily for 6 weeks, and kept for an additional 2 weeks without PbAc exposure); group III treated orally with GE (350 mg/kg body weight, 4 d per week) for 6 weeks; group IV (protective) received GE for 2 weeks before and simultaneously with PbAc; and group V (treatment) received GE for 2 weeks after PbAc exposure.

RESULTS

GC-MS analysis of GE revealed its content of gingerol (7.09%), quercetin (3.20%), dl-limonene (0.96%), and zingiberene (0.18%). Treatment of PbAc-treated rats with GE has no effect on hepatic Pb concentrations. However, it maintained serum aspartate aminotransferase level, increased hepatic glutathione (157%), glutathione S-transferase (GST) (228%), glutathione peroxidase (GPx) (138%) and catalase (CAT) (112%) levels, and reduced hepatic malondialdehyde (80%). Co-treatment of PbAc group with GE upregulated mRNA expression of antioxidant genes: GST-α1 (1.4-fold), GPx1 (1.8-fold), and CAT (8-fold), while post-treatment with GE upregulated only mRNA expression of GPx1 (1.5-fold).

CONCLUSION

GE has an antioxidant protective efficacy against PbAc-induced hepatotoxicity, which appears more effective than its therapeutic application. However, the changes in antioxidant gene expression were not reflected at the protein level.

The detrimental effects of lead on human and animal health

Lead, a chemical element in the carbon group with symbol Pb (from Latin: Plumbum, meaning “the liquid silver”) and has an atomic number 82 in the periodic table. It was the first element that was characterized by its kind of toxicity. In animal systems, lead (Pb) has been incriminated in a wide spectrum of toxic effects and it is considered one of the persistent ubiquitous heavy metals. Being exposed to this metal could lead to the change of testicular functions in human beings as well as in the wildlife. The lead poising is a real threat to the public health, especially in the developing countries. Accordingly, great efforts on the part of the occupational and public health have been taken to curb the dangers of this metal. Hematopoietic, renal, reproductive, and central nervous system are among the parts of the human body and systems that are vulnerable toward the dangers following exposure to high level of Pb. In this review, we discussed the massive harmful impact that leads acetate toxicity has on the animals and the worrying fact that this harmful toxicant can be found quite easily in the environment and abundance. Highlighting its (Pb) effects on various organs in the biological systems, its economic, as well as scientific importance, with the view to educate the public/professionals who work in this area. In this study, we focus on the current studies and research related to lead toxicity in animals and also to a certain extent toward human as well.

Heavy metal exposure, in combination with physical activity and aging, is related with oxidative stress in Japanese women from a rural agricultural community

This study aimed to evaluate the relationships between oxidative stress and heavy metal exposure (lead [Pb] and cadmium [Cd]), as well as co-factors such as physical activity and age, in Japanese women. This study was conducted with female subjects from a rural agricultural community in Japan. Subjects were asked to complete lifestyle-related questionnaires and undergo a group health examination. Physical activity, alcohol consumption, body mass index, and other demographic information were collected. Blood and urine samples were collected to measure urinary 8-hydroxydeoxyguanosine (8-OHdG) levels and blood and urinary Cd and Pb concentrations. Urine samples were analyzed using high performance liquid chromatography and flameless atomic absorption spectrometry; blood samples were analyzed using inductively coupled plasma-mass spectrometry. Age, physical activity, and blood and urinary Cd and Pb concentrations were included in structural equation modeling analysis. Two latent factors for heavy metal exposure and physical activity were produced to predict the total influence of the variables. The final model was good: CMIN/DF = 0.775, CFI = 1.000, GFI = 0.975, AGFI = 0.954, RMSEA = 0.000. 8-OHdG levels were positively associated with heavy metal exposure, physical activity, and age (standard β of path analysis: 0.33, 0.38, and 0.20, respectively). Therefore, oxidative stress is associated with both, environmental and lifestyle factors, in combination with aging.

Selective Solid-Phase Extraction of Lead Ions in Water Samples Using Three-Dimensional Ion-Imprinted Polymers

Ion-imprinted polymers (IIPs) have drawn much attention in the selective determination of heavy metals. In this study, 8-hydroxyquinoline-grafted gelatin with different types of functional groups was first introduced as a biomolecular monomer to enhance the selectivity of imprinted cavities. Based on its swelling and film-forming properties, a simple strategy containing formation of the hydrogel film, swelling/folding followed by cross-linking, was proposed to prepare three-dimensional IIPs with high adsorption capacity (235.7 mg g(-1)), strong selectivity (imprinted factor was 2.9), and rapid kinetics. Based on the different swelling container, different morphologies of IIPs could be prepared to satisfy the requirements of practical application. Consequently, the IIPs extraction coupled with a spectrophotometric method was applied for determination of lead ions, and the limit of detection was 0.2 ng mL(-1), which could be used for monitoring of Pb(II) in drinking water and surface water.

Aqueous Extract of Allium sativum (Linn.) Bulbs Ameliorated Pituitary-Testicular Injury and Dysfunction in Wistar Rats with Pb-Induced Reproductive Disturbances

AIM

To determine the effects of aqueous extract of Allium sativum bulbs (AEASAB) on pituitary-testicular injury and dysfunction in Wistar rats with lead-induced reproductive disturbances.

MATERIALS AND METHODS

Male Wistar rats were divided into 7 groups such that the control group received propylene glycol at 0.2 ml/100 g intraperitoneally for 10 consecutive days, the toxic group received lead (Pb) alone at 15 mg/kg/day via intraperitoneal route for 10 days while the treatment groups were pretreated with lead as the toxic group after which they received graded doses of the extract at 50, 100 and 200 mg/kg/day via oral route for 28 days.

RESULTS

Pb administration induced significant deleterious alterations in the antioxidant status of the brain and testis, sperm characterization (counts, motility and viability) as well as reproductive hormones (FSH, LH and testosterone) of exposed rats (p < 0.05). These were significantly reversed in the AEASAB-treated groups (p < 0.05). Also, there was marked improvement in the Pb-induced vascular congestion and cellular loss in the pituitary while the observed Pb-induced severe testicular vacuolation was significantly reversed in the representative photomicrographs, following administration of the extract.

CONCLUSION

AEASAB treatment ameliorated the pituitary-testicular injury and dysfunction in Wistar rats with Pb-Induced reproductive disturbances.

Indigofera oblongifolia mitigates lead-acetate-induced kidney damage and apoptosis in a rat model

This study was conducted to appraise the protective effect of Indigofera oblongifolia leaf extract on lead acetate (PbAc)-induced nephrotoxicity in rats. PbAc was intraperitoneally injected at a dose of 20 mg/kg body weight for 5 days, either alone or together with the methanol extract of I. oblongifolia (100 mg/kg). Kidney lead (Pb) concentration; oxidative stress markers including lipid peroxidation, nitrite/nitrate, and glutathione (GSH); and antioxidant enzyme activities, namely superoxide dismutase, catalase, GSH peroxidase, and GSH reductase were all determined. The PbAc injection elicited a marked elevation in Pb concentration, lipid peroxidation, and nitrite/nitrate, with a concomitant depletion in GSH content compared with the control and a remarkable decrease in antioxidant enzymes. Oxidant/antioxidant imbalance, Pb accumulation, and histological changes in the kidneys were successfully prevented by the pre-administration of I. oblongifolia extract. In addition, the elevated expression of proapoptotic protein, Bax, in the kidneys of the PbAc-injected rats was reduced as a result of I. oblongifolia pre-administration, while the hitherto reduced expression of the anti-apoptotic protein Bcl-2 was elevated. Based on the current findings, it can be concluded that I. oblongifolia successfully minimizes the deleterious effects in kidney function and histological coherence associated with nephrotoxicity by strengthening the antioxidant defense system, suppressing oxidative stress, and mitigating apoptosis.

Lead exposure reduces carotenoid-based coloration and constitutive immunity in wild mallards

The ingestion of spent lead (Pb) from ammunition is a known cause of mortality in waterfowl, but little is known about sublethal effects produced by Pb poisoning on birds, especially in wild populations. The authors studied potential sublethal effects associated with Pb exposure in mallards (Anas platyrhynchos) from the Ebro delta (northeastern Spain) after a ban on Pb ammunition. They analyzed the relationships between blood Pb levels and oxidative stress, immune response, and carotenoid-based coloration, which are known to be influenced by oxidative stress. Levels of Pb were reduced by half from 6 yr to 9 yr after the ban. Lipid peroxidation was positively related to Pb levels in females. The δ-aminolevulinic acid dehydratase activity was suppressed by Pb exposure and negatively associated with the activity of antioxidant enzymes. Carotenoid levels were positively associated with blood Pb concentration in both sexes, and males with higher Pb levels presented a less intense coloration in legs and beak. Levels of Pb were positively related to hemolytic activity of circulating immune system components and negatively related to lysozyme levels. In summary, Pb exposure was associated in a gender-specific way with increased oxidative stress, consequences on color expression, and impaired constitutive immunity. In females, antioxidants seemed to be allocated mostly in reproduction rather than in self-maintenance, whereas males seemed to better maintain oxidative balance to the detriment of coloration. Environ Toxicol Chem 2016;35:1516-1525. © 2015 SETAC.

Physical Activity and Blood Lead Concentration in Korea: Study Using the Korea National Health and Nutrition Examination Survey (2008-2013)

Physical activity normally has a positive influence on health, however it can be detrimental in the presence of air pollution. Lead, a heavy metal with established adverse health effects, is a major air pollutant. We evaluated the correlation between blood lead concentration and physical activity using data collected from the Korea National Health and Nutrition Examination Survey. Multivariate logistic regression analysis was performed after dividing participants according to whether they were in the top 25% in the distribution of blood lead concentration (i.e., ≥ 2.76 µg/dL), with physical activity level as an independent variable and adjusting for factors such as age, sex, drinking, smoking, body mass index, region, and occupation. The high physical activity group had greater odds of having a blood lead concentration higher than 2.76 µg/dL (odds ratio 1.29, 95% CI 1.11-1.51) compared to the low physical activity group. Furthermore, blood lead concentration is correlated with increasing physical activity.

Landfill leachate treatment using bacto-algal co-culture: An integrated approach using chemical analyses and toxicological assessment

The present study aims to evaluate the feasibility of leachate treatment using a synergistic approach by microalgae and bacteria. Leachate from one of the landfill of Northern India showed the presence of various toxic organic contaminants like naphthalene, benzene, phenol and their derivatives, napthols, pesticides, epoxides, phthalates and halogenated organic compounds. ICP-AES analysis revealed high concentrations of Zn, Cr, Fe, Ni, and Pb beyond the maximum permissible limit of discharge. Bacto-algal co-culture was found to be the most efficient in removal of toxic organic contaminants and heavy metals. Further, detoxification efficiency of bacto-algal treatment was evaluated by Methyl tetrazolium (MTT) assay for cytotoxicity and alkaline comet assay for genotoxicity using hepatoma HepG2 cells. Reduction in toxicity was confirmed by an increase in LC50 by 1.9 fold and reduction in Olive Tail Moment by 40.6 fold after 10 days of treatment. Results of the study indicate bioremediation and detoxification potency of bacto-algal co-culture for leachate treatment.

Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates

In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

Environmental monitoring of the area surrounding oil wells in Val d'Agri (Italy): element accumulation in bovine and ovine organs

In this work, environmental heavy metal contamination in the Val d'Agri area of Southern Italy was monitored, measuring the accumulation of 18 heavy metals (U, Hg, Pb, Cd, As, Sr, Sn, V, Ni, Cr, Mo, Co, Cu, Zn, Ca, Mn, Fe, and Al) in the organs of animals raised in the surrounding area (kidney, lung, and liver of bovine and ovine species). Val d'Agri features various oil processing centers which are potentially a significant source of environmental pollution, making it essential to perform studies that will outline the state of the art on which any recovery plans and interventions may be developed. The analysis was carried out using official and accredited analytical methods based on inductively coupled plasma mass spectrometry, and the measurements were statistically processed in order to give a contribution to risk assessment. Even though five samples showed Pb and Cd concentrations above the limits defined in the European Commission Regulation (EC) No 1881/2006, the mean concentrations of most elements suggest that contamination in this area is low. Consequently, these results also suggest that there is no particular risk for human exposure to toxic trace elements. Nevertheless, the findings of this work confirm that element accumulation in ovine species is correlated with geographical livestock area. Therefore, ovine-specific organs might be used as bioindicators for monitoring contamination by specific toxic elements in exposed areas.

The microscopic and ultramicroscopic changes in the skeletal muscles, caused by heavy metal salts

PURPOSE

The article is devoted to study the structural changes in the skeletal muscles caused by heavy metal salts.

MATERIALS AND METHODS

The study was conducted on 72 mature male rats. The experimental groups were given to drink water with combinations of heavy metal salts for one, two and three months. This type of water is typical for the water basins in the northern districts of the Sumy region. The study of morphological changes in the striated muscles was concluded using light and scanning electron microscopy.

RESULTS

The data analysis revealed that a prolonged duration of negative factor could intensify sclerotic and edematous processes. The structure of muscle fibers was destroyed, nuclei were deformed and placed irregularly, and many petechial hemorrhages occurred. Besides, cross-striation was irregular, I and A bands were deformed and destroyed, H band was hardly visualized. The inner mitochondrial membrane and cristae become deformed. The symplastic nuclei were placed irregularly within sarcoplasm. Besides, they were swollen. Against swollen and enlarged symplastic nuclei, pyknotic nuclei were also found. The structures of sarcoplasmic reticulum were mainly dilated with deformed and ruptured areas.

CONCLUSION

Our study approves that high concentrations of heavy metal salts have a destructive influence on the skeletal striated muscles.

Protective effect of thymoquinone against lead-induced hepatic toxicity in rats

Lead (Pb) intoxication is a worldwide health problem which frequently affects the liver. This study was carried out to investigate the potential protective effect of thymoquinone (TQ), the major active ingredient of volatile oil of Nigella sativa seeds, against Pb-induced liver damage. Adult male rats were randomized into four groups: Control group received no treatment, Pb group was exposed to 2000 ppm Pb acetate in drinking water, Pb-TQ group was cotreated with Pb plus TQ (5 mg/kg/day, per orally), and TQ group receiving only TQ. All treatments were applied for 5 weeks. Results indicated that Pb exposure increased hepatic Pb content, damaged hepatic histological structure (necrotic foci, hepatic strands disorganization, hypertrophied hepatocytes, cytoplasmic vacuolization, cytoplasmic loss, chromatin condensation, mononuclear cell infiltration, congestion, centrilobular swelling), and changed liver function investigated by plasma biochemical parameters (AST, ALT, ALP, γ-GT, LDH). Pb treatment also decreased total antioxidant status level and increased lipid peroxidation in the liver. Supplementation with TQ remarkably improved the Pb-induced adverse effects without significantly reducing the metal accumulation in the liver. In conclusion, our results indicate, for the first time, a protective effect of TQ against Pb-induced hepatotoxicity and suggest that this component might be clinically useful in Pb intoxication.

Influence of Electromagnetic Fields on Lead Toxicity: A Study of Conformational Changes in Human Blood Proteins

Background

Electromagnetic fields (EMF) are associated with oxidative stress, which is in turn associated with reactive oxygen species (ROS), anemia, and hypoxia.

Objectives

This study focused on the synergistic effects of lead ions and EMF on oxidative modifications in hemoglobin (Hb) and plasma proteins.

Patients and Methods

In this experimental study, the blood samples were obtained from age- and sex-matched healthy subjects at Arak University of Medical Sciences, Arak, Iran. The collected bloods were prepared as 55 samples and then divided into different groups for incubating with 0 to 100 uM of lead ions in 2 mT and 50 Hz of EMF for 120 minutes. The carbonyl group was determined to be an oxidative biomarker in plasma proteins. The ferric reducing ability of plasma (FRAP) was considered to be an antioxidant power of human plasma. The conformational changes in hemoglobin, met-Hb, and hemichrome were considered to be oxidative markers in red blood cells. To predict the factors affecting the oxyHb, the artificial neural network (MLP: 11,2,2,1) in SPSS software was applied.

Results

The test subjects showed increased concentrations of metHb (1.8 ± 0.19 vs. 1.36 ± 0.25) and hemichrome (6.01 ± 0.57) in relation to the control subjects. The decreased absorbance at 340 nm (0.88 ± 0.09 vs. 1.07 ± 0.08) demonstrated the reduced interaction between the globin chain and the heme ring. The decreased absorbance at 420 nm (Soret band) (2.96 ± 0.13) and the increased absorbance at 630 nm (0.07 ± 0.002 vs. 0.064 ± 0.005) indicated the conversion of oxyHb to metHb, which confirmed the oxidative damage to the erythrocytes. The linear regression analysis showed significant positive correlations between lead concentration and the percentage of plasma carbonyl content (R2 = 0.96), the relation of plasma carbonyl content to Hb absorbance at 630 nm (R2 = 0.97), and the relation of plasma carbonyl content to metHb concentration (R2 = 0.95) after 120 minutes incubation with lead ions in 20 millitesla and 50 hertz EMF. The artificial neural network analysis showed the significant importance of hemichrome, PCO, metHb, and lead concentration to the oxyHb content of erythrocytes.

Conclusions

Lead contamination in the presence of an EMF exacerbates the oxidative damage to plasma proteins as well as the conformational changes in Hb. An artificial neural network can be used as a predictive tool for the oxidative danger posed to workers in industrial fields, battery manufacturing companies, and power plants.

The role of PGC-1α and MRP1 in lead-induced mitochondrial toxicity in testicular Sertoli cells

The lead-induced toxic effect on mitochondria in Sertoli cells is not well studied and the underlying mechanism is poorly understood. Here we reported the potential role of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and multidrug resistance protein 1 (MRP1) in lead acetate-induced mitochondrial toxicity in mouse testicular Sertoli cells TM4 line. We found that lead acetate treatment significantly reduced the expression level of PGC-1α, but increased the level of MRP1 in mitochondria of TM4 cells. To determine the role of PGC-1α and MRP1 in lead acetate-induced mitochondrial toxicity, we then generated PGC-1α stable overexpression and MRP1 stable knockdown TM4 cells, respectively. The lead acetate treatment caused TM4 cell mitochondrial ultrastructure damages, a decrease in ATP synthesis, an increase in ROS levels, and apoptotic cell death. In contrast, stably overexpressing PGC-1α significantly ameliorated the lead acetate treatment-caused mitochondrial toxicity and apoptosis. Moreover, it was also found that stably knocking down the level of MRP1 increased the TM4 cell mitochondrial lead-accumulation by 4-6 folds. Together, the findings from this study suggest that PGC-1α and MRP1 plays important roles in protecting TM4 cells against lead-induced mitochondrial toxicity, providing a better understanding of lead-induced mitochondrial toxicity.

Elevated Concentrations of Lead in Particulate Matter on the Neighborhood-Scale in Delhi, India As Determined by Single Particle Analysis

High mass concentrations of atmospheric lead particles are frequently observed in the Delhi, India metropolitan area, although the sources of lead particles are poorly understood. In this study, particles sampled across Delhi (August - December 2008) were analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) to improve our understanding of the spatial and physicochemical variability of lead-rich particles (>90% lead). The mean mass concentration of lead-rich particles smaller than 10 μm (PM10) was 0.7 μg/m(3) (1.5 μg/m(3) std. dev.) with high variability (range: 0-6.2 μg/m(3)). Four samples (16% of 25 samples) with PM10 lead-rich particle concentrations >1.4 μg/m(3) were defined as lead events and studied further. The temporal characteristics, heterogeneous spatial distribution, and wind patterns of events, excluded regional monsoon conditions or common anthropogenic sources from being the major causes of the lead events. Individual particle composition, size, and morphology analysis indicate informal recycling operations of used lead-acid batteries as the likely source of the lead events. This source is not typically included in emission inventories, and the observed isolated hotspots with high lead concentrations could represent an elevated exposure risk in certain neighborhoods of Delhi.

Possible protective role of elderberry fruit lyophilizate against selected effects of cadmium and lead intoxication in Wistar rats

The objective of this study was the investigation whether the administration of the elderberry fruit lyophilizate under exposure to cadmium(Cd) and (Pb) lead may protect against some effects of their toxic action in Wistar rats. Rats were fed with diets containing Cd (Cd 0.025 mg/kg b.m.) or Pb (Pb 0.025 mg /kg b.m.) with the addition of the freeze-dried elderberry fruits (BEF) in the amount of 5 %. BEF added to the diet with Cd significantly decreased the activity of AST and ALT compared to the rats fed with the control diet with Cd (C + Cd). Activity of glutathione peroxidase was significantly higher in the blood of rats fed with BEF diet compared with animals fed with BEF + Cd, BEF + Pb, and C + Pb diets. Addition of BEF to the diets with Cd or Pb significantly decreased the uric acid concentration compared to the level of this parameter in the serum of animals fed with control diets containing Cd or Pb. The level of the Cd significantly decreased in the livers of rodents fed with BEF + Cd diet as compared to the concentration of this metal in the livers of rats fed with C + Cd diet. Elderberry fruit lyophilizate did not protect against the increased concentration of Cd or Pb in kidneys and bones of experimental rats; however, it improved the function of livers and kidneys, especially of rats intoxicated with Cd.

Effects of experimental calcium availability and anthropogenic metal pollution on eggshell characteristics and yolk carotenoid and vitamin levels in two passerine birds

The maternal investment into egg quality depends on the condition of the female, the quality of the mate, and the quality of the environment. In that sense, availability of nutrients and exposure to pollutants are essential parameters to consider. The main aim of this study is to assess the effects of calcium (Ca) availability and anthropogenic metal pollution on early-stage reproduction in two passerine species, great tits (Parus major) and pied flycatchers (Ficedula hypoleuca), inhabiting a Ca-poor and metal-polluted area in SW Finland. Both species were able to obtain sufficient Ca for eggshell formation, and metal pollution was below the level of having negative effects in the egg size and eggshell characteristics. However, metal polluted environment negatively affected yolk lutein and vitamin D3 levels in both species, probably because of a lower access to carotenoid-rich diet and higher metal interference with vitamin D3 metabolism. The higher levels of vitamin D3 in yolks in the unpolluted zone could also be due to upregulated D3 levels as a response to the lower natural Ca availability. Yolk carotenoids and vitamin D3 were positively associated with nestling growth and size, supporting their importance for the appropriate chick development. The interspecific differences in yolk nutrient concentrations possibly reflect the different growth rate of these species. Pied flycatchers are likely adapted to low Ca availability through an efficient vitamin D3 metabolism, but their Ca intake could be close to a deficient level.

Reusable fluorescent photocrosslinked polymeric sensor for determining lead ions in aqueous media

In this study, 1-vinylimidazole units bearing photocured films were prepared as fluorescent sensors towards Pb(2+) in aqueous solutions. The influence of experimental parameters such as pH, time and foreign ion concentrations were investigated. Sensor response was linear over a concentration range of 4.83×10(-8) to 4.83×10(-7) mol L(-1). The sensor was highly sensitive with a detection limit as low as 1.87×10(-8)molL(-1), and having a selectivity of over four thousand fold. The response time of the sensor was found to be 5 min. When stored in a desiccator at room temperature the sensor showed good stability after a 5 month period. The fluorescence sensors were successful in the determination of Pb(2+) in water samples as well as in the determination of the quantitative amount of lead and the results were satisfying. Compared with previously reported literature, the prepared new sensor is highly sensitive and selective.

Prevention of gastrointestinal lead poisoning using recombinant Lactococcus lactis expressing human metallothionein-I fusion protein

Low-level lead poisoning is an insidious disease that affects millions of children worldwide, leading to biochemical and neurological dysfunctions. Blocking lead uptake via the gastrointestinal tract is an important prevention strategy. With this in mind, we constructed the recombinant Lactococcus lactis strain pGSMT/MG1363, which constitutively expressed the fusion protein glutathione S-transferase (GST)–small molecule ubiquitin-like modifier protein (SUMO)–metallothionein-I (GST-SUMO-MT). The thermodynamic data indicated that the average number of lead bound to a GST-SUMO-MT molecule was 3.655 and this binding reaction was a spontaneous, exothermic and entropy-increasing process. The total lead-binding capacity of pGSMT/MG1363 was 4.11 ± 0.15 mg/g dry mass. Oral administration of pGSMT/MG1363 (1 × 10¹⁰ Colony-Forming Units) to pubertal male rats that were also treated with 5 mg/kg of lead acetate daily significantly inhibited the increase of blood lead levels, the impairment of hepatic function and the decrease of testosterone concentration in the serum, which were all impaired in rats treated by lead acetate alone. Moreover, the administration of pGSMT/MG1363 for 6 weeks did not affect the serum concentration of calcium, magnesium, potassium or sodium ions. This study provides a convenient and economical biomaterial for preventing lead poisoning via the digestive tract.

Occupational Lead Exposure from Indoor Firing Ranges in Korea

Military personnel often use ammunitions that contain lead. The present study aimed to identify the risks for lead exposure and lead poisoning among workers at indoor firing ranges. A special health examination, including blood lead level (BLL) testing, was performed for all 120 workers at the indoor firing ranges of the Republic of Korea's Air Force, Navy, and Armed Forces Athletic Corps. The overall mean BLL was 11.3 ± 9.4 µg/dL (range: 2.0-64.0 µg/dL). The arithmetic mean of the BLL for professional shooters belong to Armed Forces Athletic Corps was 14.0 ± 8.3 µg/dL, while those of shooting range managers and shooting range supervisors were 13.8 ± 11.1 µg/dL and 6.4 ± 3.1 µg/dL, respectively. One individual had a BLL of 64 µg/dL, and ultimately completed chelation treatment (with CaNa2-ethylenediaminetetraacetic acid) without any adverse effects. These findings indicate that indoor firing range workers are exposed to elevated levels of lead. Therefore, when constructing an indoor firing range, a specialist should be engaged to design and assess the ventilation system; and safety guidelines regarding ammunition and waste handling must be mandatory. Moreover, workplace environmental monitoring should be implemented for indoor firing ranges, and the workers should undergo regularly scheduled special health examinations.

The effects of α-tocopherol administration in chronically lead exposed workers

The aim of the study was to investigate whether α-tocopherol supplementation for workers who are chronically exposed to lead would normalize/improve the values of parameters that are associated with the lead-induced oxidative stress. Study population included chronically lead exposed males who were divided into two groups. Workers in the first group (reference group) were not given any antioxidants, while workers in the second group (αT group) received supplementation with α-tocopherol. After treatment, the blood lead and leukocyte malondialdehyde levels decreased significantly in the αT group compared to the baseline levels and reference group. However, the erythrocyte malondialdehyde, conjugated dienes, and lipofuscin levels significantly increased compared to the baseline levels. The glutathione level significantly increased compared with the baseline. Effects of supplementation with α-tocopherol on oxidative damage were not satisfactory. Therefore, there is no reason to administer α-tocopherol to workers chronically exposed to lead as a prophylaxis of lead poisoning.

Severe Abdominal Pain Caused by Lead Toxicity without Response to Oral Chelators: A Case Report

A 19-year-old woman was referred to the Emergency Surgery Department with severe abdominal pain, icterus, and anemia. The patient’s clinical and paraclinical findings in addition to her occupational and social history, convinced us to assay blood lead level (BLL), which was 41/5 μg/dL. Therefore toxicology consult was performed to treat lead toxicity.

Recheck of the BLL showed the level as 53/7 μg/dL. So oral chelator with succimer was started. Despite consumption of oral chelator, there was no response and the pain continued. Because our repeated evaluations were negative, we decided to re-treat lead poisoning by intravenous and intramuscular chelators. Dimercaprol (BAL) + calcium EDTA was started, and after 5 days, the pain relieved dramatically and the patient was discharged.

We recommend more liberal lead poisoning therapy in symptomatic patients, and also suggest parenteral chelator therapy, which is more potent, instead of oral chelators in patients with severe symptoms.

The Level of Selenium and Oxidative Stress in Workers Chronically Exposed to Lead

The possible beneficial role of selenium (Se) on the oxidative stress induced by lead (Pb) is still unclear in humans. Therefore, the aim of the present study was to explore the associations among the Se levels, chronic Pb exposure, oxidative stress parameters, and parameters characterizing the function of the antioxidant defense system in men who are occupationally exposed to Pb. Based on the median serum Se concentrations, the 324 study subjects were divided into two subgroups: a subgroup with a low Se level (L-Se) and a subgroup with a high Se level (H-Se). The levels of lead (PbB) and zinc protoporphyrin (ZPP) in the blood and the delta-aminolevulinic acid (ALA) level in the urine served as indices of Pb exposure. The PbB level was significantly lower in the H-Se group compared to that in the L-Se group by 6 %. The levels of 8-hydroxyguanosine and lipofuscin (LPS) and the activity of superoxide dismutase were significantly lower in the H-Se group compared to that in the L-Se group by 17, 19, and 11 %, respectively. However, the glutathione level (GSH) and the activities of glutathione peroxidase (GPx) and catalase were significantly higher by 9, 23, and 3 %. Spearman correlations showed positive associations between the Se level and GPx activity and GSH level. A lower serum Se level in chronically Pb-exposed subjects is associated with higher Pb blood levels and an elevated erythrocyte LPS level, which reflects the intensity of oxidative stress. Besides, in a group of Pb-exposed subjects with lower serum Se level, depleted GSH pool and decreased activity of GPx in erythrocytes were reported. However, the present results are inadequate to recommend Se supplementation for chronic lead exposure at higher doses than would be included in a normal diet except for selenium deficiency.

Characterization and distribution of metal and nonmetal elements in the Alberta oil sands region of Canada

This review covers the characterization and distribution of metals and nonmetals in the Alberta oil sands region (AOSR) of Canada. The development of the oil sands industry has resulted in the release of organic, metal and nonmetal contaminants via air and water to the AOSR. For air, studies have found that atmospheric deposition of metals in the AOSR decreased exponentially with distance from the industrial emission sources. For water, toxic metal concentrations often exceeded safe levels leading to the potential for negative impacts to the receiving aquatic environments. Interestingly, although atmospheric deposition, surface waters, fish tissues, and aquatic bird eggs exhibited increasing level of metals in the AOSR, reported results from river sediments showed no increases over time. This could be attributed to physical and/or chemical dynamics of the river system to transport metals to downstream. The monitoring of the airborne emissions of relevant nonmetals (nitrogen and sulphur species) was also considered over the AOSR. These species were found to be increasing along with the oil sands developments with the resultant depositions contributing to nitrogen and sulphur accumulations resulting in ecosystem acidification and eutrophication impacts. In addition to direct monitoring of metals/nonmetals, tracing of air emissions using isotopes was also discussed. Further investigation and characterization of metals/nonmetals emissions in the AOSR are needed to determine their impacts to the ecosystem and to assess the need for further treatment measures to limit their continued output into the receiving environments.

Cytoprotective and Antioxidant Effects of an Edible Herb, Enhydra fluctuans Lour. (Asteraceae), against Experimentally Induced Lead Acetate Intoxication

Background

Enhydra fluctuans Lour. (Asteraceae), an edible aquatic herb, is traditionally employed against toxic effects of heavy metals in India. The present study was planned to discover the protective effect of edible extract of E. fluctuans (AEEF) against Pb toxicity.

Methods

The cytoprotective role of AEEF was determined on murine hepatocytes employing MTT assay and Hoechst staining. The effects on lipid peroxidation, protein carbonylation, endogenous redox systems and the transcription levels of apoptotic proteins were studied after incubating the hepatocytes with AEEF (400 μg/ml) + Pb-acetate (6.8 μM). The defensive role of AEEF (100 mg/kg) against Pb-acetate (5 mg/kg) intoxication was measured in mice by in vivo assays. Biochemical, haematological and histological parameters, intracellular Pb burden and redox status were measured.

Results

AEEF exhibited a concentration dependent cytoprotective effect against Pb-induced cytotoxicity in vitro. Pb-acetate incubation significantly (p < 0.01) altered the extents of ROS production ↑, protein carbonylation ↑, lipid peroxidation ↑, endogenous antioxidant enzymes ↓ and GSH ↓ in vitro. Besides, Pb-acetate significantly (p < 0.01) induced apoptosis in the hepatocytes apparent from the altered expressions of apoptotic proteins viz. Apaf-1 ↑, Bad ↑, Bcl-2 ↓, Cyt C ↑, cleaved caspases↑, Bid ↑ and Fas ↑. However, AEEF (400 μg/ml) could significantly (p < 0.05–0.01) attenuate the Pb-acetate mediated toxic manifestation in vitro. In in vivo assay, Pb-acetate (5 mg/kg) treated mice exhibited significantly (p < 0.01) high intracellular Pb content. A high Pb-burden within the tissues caused significant (p < 0.05–0.01) patho-physiological alterations viz. ROS production ↑, protein carbonylation↑, lipid peroxidation ↑, DNA fragmentation ↑, ATP formation ↑, mitochondrial co-enzymes Q ↓, endogenous antioxidant enzymes ↓ and GSH ↓ within the selected tissues. The haematological and serum biochemical parameters were significantly (p < 0.05–0.01) different in the Pb-acetate treated mice. Finally, histological assessment imposed significant toxic occurrence within the organs of Pb-intoxicated animals. However, concurrent administration of AEEF (100 mg/kg) could significantly (p < 0.05–0.01) reinstate the Pb-acetate mediated toxicity.

Conclusion

Presence of metal chelators and phyto-antioxidants within AEEF would offer overall protection through promoting Pb clearance coupled with restoring redox balance.

The association between blood lead level and clinical mental disorders in fifty thousand lead-exposed male workers

BACKGROUND

While there has been research into the relationship between blood lead (BPb) level and mental disorders, there have been few investigations that use clinically diagnosed mental disorders in the adult population with a retrospective cohort study design. Hence, our study investigated the association between BPb level and risk of clinically diagnosed mental disorders.

METHODS

The data of male workers exposed to lead (Pb; n=54,788) were collected from annual Pb associated medical check-ups from 2000 to 2004 in Korea. The workers' hospital admission histories due to mental disorders (International Classification of Diseases, 10th revision, F00-F99) were used to identify clinically diagnosed mental disorders. After merging the data, the hazard ratio (HR) with a 95% confidence interval (95% CI) was calculated by survival analysis using the Cox proportional hazards model according to the quartile level of BPb (1st quartile<4.10 μg/dl, 2nd quartile<6.04 μg/dl, 3rd quartile<10.00 μg/dl, and 4th quartile≥10 μg/dl).

RESULTS

In a total of 54,788 workers, there were 223 admission cases of mental disorders (F00-F99) during the follow-up period. The HR (95% CI) of total mental and behavioral disorders (F00-F99) was 1.63 (1.12-2.39) in the 4th quartile group compared to the HR of the 1st quartile group after adjusting for age. The HR (95% CI) of the 4th quartile group was 2.59 (1.15-5.82) for mood (affective) disorders (F30-F39).

LIMITATION

The hospital admission data, not outpatient data, were used for current study while almost affective disorder treated at outpatient clinic level.

CONCLUSION

Our study highlighted that Pb exposure can cause clinical mental disorders that require hospital admission in adult male workers. Our relatively large sample size strengthens the evidence of the association between BPb level and risk of clinically diagnosed mental disorders.

Hexagonal sheet-like mesoporous titanium phosphate for highly efficient removal of lead ion from water

Hexagonal sheet-like mesoporous titanium phosphate nanostructured materials synthesized via a simple hydrothermal method showed highly efficient removal of Pb(ii) ions from water.

Graphite pencil electrodes as electrochemical sensors for environmental analysis: a review of features, developments, and applications

Graphite pencil electrodes (GPEs) are carbon-based electrodes that are recognized by their low cost, simplicity, commercial availability, ease of modification and disposability.

Preparation and characterization of sodium polyacrylate-grafted bentonite and its performance removing Pb2+ from aqueous solutions

A new adsorbent, sodium polyacrylate (PAANa) grafted onto the surface of bentonite (Bent), was successfully synthesized by a facile and green Ce(iv)-redox process, to remove Pb²⁺ from aqueous solutions.

Lead neurotoxicity: exploring the potential impact of lead substitution in zinc-finger proteins on mental health

This critical review focuses on one possible link between the cellular biology of lead and its neurotoxic effects: the link between Pb²⁺substitution for Zn²⁺in zinc-finger proteins and mental illness in adulthood.

Maternal blood lead concentrations, DNA methylation of MEG3 DMR regulating the DLK1/MEG3 imprinted domain and early growth in a multiethnic cohort

Prenatal exposure to lead (Pb) is known to decrease fetal growth; but its effects on postnatal growth and mechanistic insights linking Pb to growth are not clearly defined. Genomically imprinted genes are powerful regulators of growth and energy utilization, and may be particularly vulnerable to environmental Pb exposure. Because imprinting is established early and maintained via DNA methylation, we hypothesized that prenatal Pb exposure alters DNA methylation of imprinted genes resulting in lower birth weight and rapid growth. Pb was measured by inductively coupled plasma mass spectrometry (ICP-MS) in peripheral blood of 321 women of the Newborn Epigenetic STudy (NEST) obtained at gestation ~12 weeks. Linear and logistic regression models were used to evaluate associations between maternal Pb levels, methylation of differentially methylated regions (DMRs) regulating H19, MEG3, PEG3, and PLAGL1, measured by pyrosequencing, birth weight, and weight-for-height z score gains between birth and age 1yr, ages 1-2yrs, and 2-3yrs. Children born to women with Pb levels in the upper tertile had higher methylation of the regulatory region of the MEG3 DMR imprinted domain (β= 1.57, se= 0.82, p= 0.06). Pb levels were also associated with lower birth weight (β= -0.41, se= 0.15, p= 0.01) and rapid gains in adiposity (OR= 12.32, 95%CI=1.25-121.30, p= 0.03) by age 2-3 years. These data provide early human evidence for Pb associations with hypermethylation at the MEG3 DMR regulatory region and rapid adiposity gain-a risk factor for childhood obesity and cardiometabolic diseases in adulthood.

Comparative assessment of the effects of salinomycin and monensin on the biodistribution of lead and some essential metal ions in mice, subjected to subacute lead intoxication

In this study, we present a comparative assessment of the effects of two polyether ionophorous antibiotics (monensin and salinomycin) on the concentrations of lead (Pb), cooper (Cu), zinc (Zn) and iron (Fe) in the kidneys, spleen, liver and brain of Pb-intoxicated animals. Our data demonstrated that the intoxication of ICR male mice with Pb salt resulted in a significant accumulation of Pb in all studied organs of the mice compared to the untreated control animals. The biodistribution of the toxic metal was in the order kidneys>spleen>liver>brain. The treatment of the Pb-intoxicated animals with tetraethylammonium salts of monensic and salinomycinic acids significantly decreased the concentration of the toxic metal ion compared to the toxic control. The effect varied in the interval 38% (for kidneys) to 52% (for brain) compared to the toxic control group (Pb). The tetraethylammonium salt of salinomycinic acid was more effective in reducing the Pb concentration in the brain of the Pb-treated mice compared to monensin. Pb-intoxication did not affect significantly the Zn endogenous concentration compared to the normal values. The treatment of ICR male mice with Pb-salt decreased the Cu concentration in the spleen and increased the Cu concentration in the liver compared to the untreated control animals. The detoxification of the Pb-intoxicated mice with tetraethylammonium salts of salinomycinic and monensic acids restored the Cu concentration in the spleen, but did not affect the Cu levels in the liver. The Pb-intoxication of the ICR mice resulted in a significant decrease of the Fe-concentration in the spleen and liver compared to the untreated control animals. The administration of the tetraethylammonium salts of salinomycinic and monensic acids to the Pb-treated animals restored the levels of Fe in both organs.

Lead Toxicity, Antioxidant Defense and Environment

Environmental and occupational exposure to a large number of chemicals occurs at various stages throughout human life. Many of these are devoid of toxicity, but some could pose a significant health risk, i.e. the exposure to environmental xenobiotic metals as lead, mercury (Sinicropi et al. 2010a; Carocci et al. 2014), cadmium, etc. In particular, lead has long been a widespread public concern (Basha and Reddy 2010). Lead is one of the earliest heavy metals discovered by men. Due to its unique properties, as low melting point, softness, malleability, ductility, and resistance to corrosion, men have used lead for the last 5000 years in a wide range of applications.

t-BHQ Provides Protection against Lead Neurotoxicity via Nrf2/HO-1 Pathway

The neurotoxicity of lead has been well established, and oxidative stress is strongly associated with lead-induced neurotoxicity. Nrf2 is important for protection against oxidative stress in many disease models. We applied t-BHQ, which is an Nrf2 activator, to investigate the possible role of Nrf2 in the protection against lead neurotoxicity. t-BHQ significantly attenuated the oxidative stress in developmental rats by decreasing MDA level, as well as by increasing SOD activity and GSH content, in the hippocampus and frontal cortex. Furthermore, neuronal apoptosis was detected by Nissl staining, and Bax expression was inhibited in the t-BHQ-treated group. Results showed that t-BHQ suppressed ROS production and caspase 3/7 activity but increased intracellular GSH content, in SH-SY5Y cells under lead exposure. Moreover, in vivo and in vitro, t-BHQ enhanced the nuclear translocation of Nrf2 and binding to ARE areas but did not induce Nrf2 transcription. These phenomena were confirmed using RT-PCR, EMSA, Western blot, and immunofluorescence analyses. Subsequent upregulation of the expression of HO-1, NQO1, and GCLC was observed. However, knockdown of Nrf2 or HO-1 adversely affected the protective effects of t-BHQ against lead toxicity in SH-SY5Y cells. Thus, t-BHQ can protect against lead neurotoxicity, depending on the Nrf2/HO-1 pathway.