Toxic Effects Of Pb Research Articles

Behavior and toxic effects of Pb in a waterfowl model with oral exposure to Pb shots: Investigating Pb exposure in wild birds

Among wild birds, lead (Pb) exposure caused by ingestion of ammunition is a worldwide problem. We aimed to reveal the behavior and toxic effect of Pb caused by ingesting Pb shots in waterfowl. Four male, eight-week old Muscovy ducks (Cairina moschata) were given three Pb shots (approximately 240 mg in total) orally and then fed for 29 days after exposure, simulating a low-dose Pb exposure in wild waterfowl. During the breeding period, blood samples were collected 10 times, and fecal samples every day. Additionally, 22 fresh tissue and 6 bone samples were obtained from each duck through the dissection. Although there were no gross abnormalities, the maximum blood Pb concentration of each duck ranged from 0.6 to 3.7 mg/L, reaching a threshold concentration indicative of clinical symptoms (>0.5 mg/L). δ-aminolevulinic acid dehydratase declined one day after exposure and remained low throughout the feeding period. Hematocrit also tended to decrease, indicating signs of anemia. The highest Pb accumulation was observed in the bones, followed by the kidneys, intestinal tracts, and liver. High Pb accumulation in the bones, which are known to have a long Pb half-life, suggested that Pb would remain in the body and possibly affect bird health beyond 28 days after exposure. Gene expression analysis showed a significant increase in the expression of the toll-like receptor-3 gene, which is involved in virus discrimination in the liver, suggesting a disruption of the immune system. Microbiota analyses showed a correlation between the blood Pb concentration and the abundances of Lachnospiraceae and Ruminococcaceae, suggesting that Pb affects lipid metabolism. These results provide fundamental data on Pb exposure in wild birds and a new perspective on the damage such exposure causes.

Remediation mechanism of \u201cdouble-resistant\u201d bacteria\u2014Sedum alfredii Hance on Pb- and Cd-contaminated soil

BackgroundConcentrations of heavy metals continue to increase in soil environments as a result of both anthropogenic activities and natural processes. Cadmium (Cd) and lead (Pb) is one of the most toxic heavy metals and pose health risks to both humans and the ecosystem. Therefore, effectively solving the problem of heavy metal pollution is the concern of soil workers. Among the existing remediation techniques, only the combined use of microorganisms and plants for remediation of heavy metal-contaminated soil is the greenest and most developed one. Consequently, based on this background, this study investigates the remediation mechanism of Pb and Cd heavy metals using the combined action of bacteria and Sedum alfredii Hance.MethodsIn order to enrich the research theory of combined plant and microorganism remediation of heavy metal-contaminated soil, we constructed a heavy metal composite pollution remediation system by combining Pb and Cd-tolerant bacteria with the Pb and Cd hyperaccumulator plant—Sedum alfredii Hance to investigate its combined remediation effect on Pb and Cd composite contaminated soil.ResultsThe results showed that resistant bacteria were able to promote enrichment of Pb and Cd in Sedum alfredii Hance and J2 (200 ml of bacterial solution) was significantly (P < 0.05) more effective than J1 (100 ml of bacterial solution). The resistant bacteria were able to alleviate the toxic effects of Pb and Cd heavy metals on Sedum alfredii Hance and promote growth while reducing rhizosphere soil pH. The resistant bacteria were able to significantly reduce the effective state of Pb and Cd in the rhizosphere soil (P < 0.05), with the greatest reduction in the effective state of Pb in treatment A (Cd7Pb100 mg/kg), where J2 was reduced by 9.98% compared to J0, and the greatest reduction in the effective state of Cd in treatment C (Cd28Pb400 mg/kg), where J2 was 43.53% lower than J0. In addition, the resistant bacteria were able to increase the exchangeable state Cd content by 0.97 to 9.85%. The resistant bacteria had a weakly promoting effect and a highly inhibitory effect on the absorption of Pb by Sedum alfredii Hance.ConclusionsThe resistant bacteria can change the rhizosphere environment and significantly improve the remediation effect of Sedum alfredii Hance on heavy metal cadmium. The role of “double-resistant” bacteria in promoting the accumulation of Cd was greater than that of Pb.

Influences of mycorrhizal inoculum on Cd and Pb uptake by wheat plant

Influences of mycorrhizal inoculum on Cd and Pb uptake by wheat plant

Ways of optimization of lead-polluted black earth soils in the soil-plant system

the most urgent problems of today. Ensuring the environmental safety of food raw materials and food products is one of the main tasks that determine the health of the human population and the preservation of its gene pool. Analysis of recent research and publications. Toxic effects of Pb on human bodies have been confirmed by numerous clinical studies that have shown the negative effects of heavy metals on the nervous, cardiovascular, immune systems and oncology. The works is devoted to the development of detoxification techniques, in which scientists proposed to reduce the content of heavy metals in chernozems by detoxifying soils by growing battery plants on them, which will «extract» heavy metals from soils disinfecting them. The disadvantage of the proposed technologies is the economic costs borne by farmers, producers and consumers. Farmers will suffer financial losses due to idle sown areas and the cost of seed. Producers will be forced to raise prices for the final food product as a result of reduced consumer purchasing power. Formulation of the purpose of the article. The aim of the article is to determine ways to optimize lead-contaminated chernozem soils in the system «soil – plant» (on the example of chernozem soils within the test sites on the territory of the collection nursery «Agrotek» in Kyiv region). Presentation of the main research material. The article presents the results of a study of ways to optimize lead-contaminated chernozem soils in the system «soil – plant». The objects of the study were soybean and chickpea varieties of different vegetation varieties, namely: ultra-early varieties, maturation period 95… 105 days. Мedium, maturation period 100…115 days. Мedium-ripe varieties maturation period115…125 days. Early ripening varieties of chickpeas growing period 95…115 days, and medium-ripe sotu chickpeas, growing period 115…125 days. Experimental studies were conducted during 2019 – 2021 within the test sites on the territory of the collection nursery «Agrotek» in Kyiv region. The method of ion exchange and liquid chromatography on the liquid chromatograph Shimadzu LC-20 (Japan). Studied the variability of nutrients (protein, fat, carbohydrates) in soybeans and chickpeas of different vegetation varieties. With the help of the MATLAB program, mathematical optimization was carried out and the five-year dynamics of protein, fat, and carbohydrate content in legumes grown on chernozem soils of the «Agrotek» collection nursery in the Kyiv region was determined. By the method of inversion-voltammetry with the help of voltammetric analyzer «ABA-3» (Russia) which is equipped with an indicator electrode for the determination of lead, the concentration of Pb in chernozems and soybeans and chickpeas with different protein content was studied. Concentrations of Pb in soybean and chickpea grains depending on the chemical composition of soils for cultivation were grown and studied at the test sites of the «Agrotek» collection nursery. Conclusions. As a result of experimental studies, it was found that the contamination of chernozem soils Pb and subsequent processes of its translocation in the system «soil – plant» have negative consequences and are manifested in the accumulation of toxicants in plants. It is significant that the largest metal-accumulating properties have cultivated early-ripening legumes, and the smallest – medium-ripe. It was determined that the indicators of Pb concentration in the storage organs of legume assimilants are influenced to a greater extent by the protein content in them than by mobile forms of Pb, which come due to translocation from soils contaminated with Pb. It is established that with the increase of protein in the organs of plant assimilators, the indicators of accumulation of toxic concentrations of Pb increase. Given that the genetic characteristics of chernozems allow us to consider them the most environmentally friendly soils in terms of anthropogenesis, however, they deposit contaminants and, accordingly, require optimization and development of detoxification methods. It has been experimentally established that when growing legumes of different vegetation varieties on chernozems contaminated with Pb, the intensity of their detoxification to obtain environmentally friendly plant products can be distributed as follows: N180P180K180 + Pb + lime + manure &gt; N360P360K360+ Pb &gt; N180P180K180 + Pb + lime &gt; N180P180K180 + Pb + manure. The obtained laws provide an opportunity to develop recommendations and propose ways to detoxify contaminated Pb soils. Which will provide an opportunity to significantly reduce budget expenditures, which is socially necessary and cost-effective.

Lead impaired immune function and tissue integrity in yellow catfish (Peltobargus fulvidraco) by mediating oxidative stress, inflammatory response and apoptosis

Lead (Pb) widely exists in the water environment and has severe toxic effects on aquatic organisms. The yellow catfish (Pelteobagrus fulvidraco) is one of the most important commercial species in China, and moreover, its natural populations are declining with the degradation of environmental water quality. However, little is known about the toxic effects of Pb on its immune organs. This study was performed to determine waterborne Pb exposure on bioaccumulation, histomorphology, antioxidant status, apoptotic and immune response in the head kidney and spleen of yellow catfish. Experimental fish were randomly allocated into twelve tanks (3 tanks per group), and the Pb concentrations of the four groups were 0, 5, 50, and 500 μg/L, respectively. The results reflected that the Pb bioaccumulation of the head kidney and spleen increased with increasing Pb exposure dose and time. Severe histological alterations in the head kidney and spleen were observed at concentration 500 ug/L. With increasing Pb exposure concentrations, the plasma activity of superoxide dismutase (SOD) and catalase (CAT) significantly increased after exposure 7 days and 14 days, and the levels significantly decreased after exposure 28 days. The change trend of glutathione (GSH) levels was opposite to that of SOD and CAT at corresponding exposure time. The plasma malondialdehyde (MDA) levels together with the activities of plasma alkaline phosphatase (AKP) and acid phosphatase (ACP) increased significantly with the increasing Pb concentrations. In contrast, the levels of lysozyme (LYZ), complement 3 (C3) and immunoglobulin M (IgM) decreased significantly with increasing Pb concentrations. Moreover, Pb exposure induced transcriptional upregulation of heat shock protein 70 (hsp70), metallothionein (mt), sod, cat, interleukin-10 (il-10), transforming growth factor-β (tgf-β), and tumor necrosis factor-α (tnf-α), bcl-2-associated X protein (bax), and cysteinyl aspartate specific proteinase -9 (caspase-9), genes in the head kidney and spleen tissues, while downregulating the levels of the lyz, c3, igm and B-cell lymphoma-2 (bcl-2) genes. Our data provide evidence that Pb impaired immune function and tissue integrity in yellow catfish through oxidative stress, inflammatory and apoptosis, and the results can serve as reference data to better protect water environments from Pb eco-toxicants.

Lead exposure affects cephalic morphogenesis and neural crest cells in Gallus gallus embryo

The morphogenesis of the head of vertebrates is a process that involves rapid growth and dynamic movements of various cell populations, including the neural crest cells (NCC). These pluripotent cells generated during neurulation have high proliferative and migratory capacity but xenobiotic agents can affect these migratory periods and cause congenital malformations. Lead (Pb) is the most common toxic metal in the environment and a potent teratogen that can affect growth and induce malformations. Despite the known toxic effects of Pb, there is a gap in knowledge about the impact of realistic concentrations of Pb at critical periods of early development. Here, we evaluated mortality, embryonic morphology, NCC migration, and the amount of Pb deposition in chicken embryos after 3 to 4 days of exposure. One of the most interesting observations in this study is that only about 34% of the injected Pb was present in the embryos after 4 days. We observed that exposure to Pb, even under low concentrations, increased mortality and the occurrence of malformations during embryonic development, especially in the cephalic region (CR). Although Pb was found widely distributed in the CR, no relation between its presence and the migration routes of cephalic NCC was observed. But the number of NCC and their migratory distance were reduced. These changes are consistent and explain the morphological anomalies described in this study, which also correlates with the morphofunctional abnormalities reported in the literature. Therefore, this study highlights the concern of exposure to low concentrations of this metal.

NLRP3 inflammasome is involved in the mechanism of mitigative effect of selenium on lead-induced inflammatory damage in chicken kidneys.

Lead (Pb) is a kind of widespread toxic environmental pollutant which can cause harm to organisms. Selenium (Se) has the property of mitigating Pb toxicity through decreasing oxidative stress and inflammation caused by Pb. Nucleotide-binding domain, leucine-rich-containing family, and pyrin-domain containing-3 (NLRP3) inflammasome involve in inflammation process. However, the effect of NLRP3 inflammasome in heavy metal-caused animal damage remains unknown. This research aimed to explore the mechanism of mitigative role of Se on Pb-caused renal inflammatory injury in chickens. One-week-old male chickens were provided a standard diet and drinking water, a standard diet added with 1 mg kg-1 of Se and drinking water, a standard diet and drinking water added with 350 mg L-1 Pb, and a standard diet added with 1 mg kg-1 Se and drinking water added with 350 mg L-1 Pb. On the 4th, 8th, and 12th weeks, serum was used to measure creatinine (CREA) and uric acid (UA) contents, and kidneys were used to measure Se and Pb concentrations, histological structure, oxidative stress indicators, relative expressions of cytokines, and inflammatory factors. The results showed that Pb accumulated, Se concentration decreased, CREA and UA contents increased, and renal injury occurred in Pb-treated chicken kidneys. Excess Pb increased MDA content and the expressions of IL-1β, IL-6, IL-17, NLRP3, caspase-1, NF-κB, COX-2, TNF-α, and PTGEs and decreased GSH content, GPx and SOD activities, and IFN-γ expression in the chicken kidneys. Se administration alleviated the aforementioned changes. In addition, toxic effect of Pb on the chicken kidneys was time-dependent. NLRP3 inflammasome, caspase-1, and IL-1β may be sensitive indicators in Pb-induced chicken kidney inflammatory damage. In conclusion, NLRP3 inflammasome took part in antagonistic role of Se against Pb-caused inflammation via changing oxidative stress indicators, cytokines, and inflammation-related genes in the chicken kidneys.

Characterisation of early responses in lead accumulation and localization of Salix babylonica L. roots

BackgroundLead (Pb) is a harmful pollutant that disrupts normal functions from the cell to organ levels. Salix babylonica is characterized by high biomass productivity, high transpiration rates, and species specific Pb. Better understanding the accumulating and transporting Pb capability in shoots and roots of S. babylonica, the toxic effects of Pb and the subcellular distribution of Pb is very important.ResultsPb exerted inhibitory effects on the roots and shoots growth at all Pb concentrations. According to the results utilizing inductively coupled plasma atomic emission spectrometry (ICP-AES), S. babylonica can be considered as a plant with great phytoextraction potentials as translocation factor (TF) value > 1 is observed in all treatment groups throughout the experiment. The Leadmium™ Green AM dye test results indicated that Pb ions initially entered elongation zone cells and accumulated in this area. Then, ions were gradually accumulated in the meristem zone. After 24 h of Pb exposure, Pb accumulated in the meristem zone. The scanning electron microscopy (SEM) and energy-dispersive X-ray analyses (EDXA) results confirmed the fluorescent probe observations and indicated that Pb was localized to the cell wall and cytoplasm. In transverse sections of the mature zone, Pb levels in the cell wall and cytoplasm of epidermal cells was the lowest compared to cortical and vessel cells, and an increasing trend in Pb content was detected in cortical cells from the epidermis to vascular cylinder. Similar results were shown in the Pb content in the cell wall and cytoplasm of the transverse sections of the meristem. Cell damage in the roots exposed to Pb was detected by propidium iodide (PI) staining, which was in agreement with the findings of Pb absorption in different zones of S. babylonica roots under Pb stress.ConclusionS. babylonica L. is observed as a plant with great potential of Pb-accumulation and Pb-tolerance. The information obtained here of Pb accumulation and localization in S. babylonica roots can furthers our understanding of Pb-induced toxicity and its tolerance mechanisms, which will provide valuable and scientific information to phytoremediation investigations of other woody plants under Pb stress.

AN EXPERIMENTAL TRIAL OF BIOPROPHYLACTIC FORMULA DESIGNED TO MINIMIZE COMBINED TOXICITY OF BOTH LEAD AND CADMIUM

Introduction. The increase in the body resistance to the combined effects of lead and cadmium (including systemic toxicity, cardiovascular effects, and genotoxicity) by using a specific bioprotective formula (based on theoretical knowledge and experimental research) remains a pressing challenge. However, a data search has not yielded any results on either an experimental trial or a theoretical justification of the means of biological protection against a variety of adverse effects caused by Pb and Cd combination. Material and methods. The experiment was conducted on the outbred male rats. The animals received repeated intraperitoneal injections of water solutions of lead acetate and cadmium chloride, 3 times per week for 6 weeks. After the exposition was completed, more than 50 indices of toxic exposure (including biochemical and histo-morphological ones) were estimated in all groups of the tested animals. To assess the genotoxic effect of “in vivo” there was used amplified fragment length polymorphism (AFLP) analysis. Statistical analysis was done using Student’s t-test. Results. We found the administration of the bioprotective formula to improve the indices of general toxicity. Genotoxicity studied using AFLP analysis of blood cells DNA was shown to be mitigated. Histo-morphological indices of Pb+Cd hepato- and nephrotoxicity improved under a bioprotective complex (BPC) administration. Blood Pb and Cd decreased during BPC administration. There was a statistically reliable decrease in the mean diameter of cardiomyocytes associated with Pb+Cd administration. These changes became less apparent with the BPC administration. Conclusion. We developed and tested a strategy to mitigate the toxic effects of Pb and Cd at organ and organ system levels, including general toxicity, target organ toxicity (with cardiotoxicity) and genоtoxicity.

The role of NF-κB and AhR transcription factors in lead-induced lung toxicity in human lung cancer A549 cells

Lead (Pb) is recognized as the first heavy metal of the top six toxic air pollutants threatening human health and the second hazardous substance. Pb exposure is associated with lung impairment and high incidences of lung cancer. Nuclear factor kappa B (NF-κB) and aryl hydrocarbon receptor (AhR) signaling pathways are known to be expressed and play an important role in the lung. However, the link between Pb lung toxicity and NF-κB and/or AhR pathways remains unclear. This study was established to explore the role of NF-κB and AhR modulation in Pb-induced lung toxicity in human lung cancer A549 cells. In the current study, treatment of A549 cells with Pb significantly induced cell apoptosis as evidenced by increasing a) the percentage of cells underwent apoptosis determined by flow cytometry and b) p53 mRNA level. Pb treatment induced oxidative stress by a) increasing the formation of reactive oxygen species and b) decreasing GSTA1 mRNA levels. The toxic effects of Pb on the lung was associated with significant increases in NF-κB and AhR levels which was accompanied with increases in downstream targets genes, iNOS and CYP1A1, respectively. Inhibition of NF-κB or AhR either chemically using resveratrol or genetically using small interfering RNA (siRNA) significantly rescued A549 cells from Pb-mediated lung toxicity. The results clearly indicate that Pb-mediated lung toxicities are NF-κB and AhR-dependent mechanism.

24-Epibrassinolide modulates primary metabolites, antioxidants, and phytochelatins in Acutodesmus obliquus exposed to lead stress

Aquatic organisms are exposed to many stressors, e.g., heavy metals. Brassinosteroids, a plant hormone group, can effectively stimulate plants to defend against the negative impact of a heavy metal. The present study was conducted with an aim to find out the influence of 24-epibrassinolide (EBL) on Acutodesmus obliquus treated with 0.01 and 500 μM of lead (Pb) ions during 7 days of cultivation. Pb has a toxic effect on algal cultures because it limits both the growth and development and induces oxidative stress. Simultaneously, 1 μM EBL was involved in protecting algal cells against the toxic effect of Pb. Despite the presence of Pb, EBL significantly increased the number of algal cells and their metabolite content (e.g., proteins, monosaccharides, chlorophylls, carotenes, and xanthophylls). Cultures treated concurrently with EBL and Pb were characterized by a reduction in their content of endogenous Pb, H2O2, and malondialdehyde. Also, EBL increased the activity of catalase, ascorbate peroxidase, superoxide dismutase, glutathione reductase, and the content of ascorbate and glutathione. EBL increased the phytochelatin synthase activity, thereby enhancing the production of phytochelatins accountable for both binding and detoxification of Pb. These results indicate the influence of EBL on the inhibitory effect of Pb in A. obliquus. These findings help to clarify the role of BRs in the algal adaptation to the prevailing stressful conditions.

Toxic effects of Pb on Spirodela polyrhiza (L.): Subcellular distribution, chemical forms, morphological and physiological disorders

The impact of lead (Pb) on Spirodela polyrhiza was studied to determine the subcellular distribution, chemical forms, and resulting morphophysiological modifications after treatments with 20 or 80 μM Pb(NO3)2 for 10 days. At the subcellular level, the Pb uptake by S. polyrhiza was mainly compartmentalized in the cell walls (70%), and the majority of Pb (approximately 70%) was extracted using 1 M NaCl and 2% acetic acid (HAc). Visual symptoms of phytotoxcity, surface roughness and closure of stomata, were observed in Pb-treated fronds. Electron-dense precipitates were present in cell walls, and changes to the ultrastructure were most noticeably exhibited in organelle shape, internal organization, and size of the plastoglobules of chloroplasts. Toxic concentrations of Pb induced oxidative stress in fronds, characterized by an accumulation of malondialdehyde (MDA) and decreased chlorophyll and unsaturated fatty acid contents. Pb exposure increased ABS/RC, TRo/RC, DIo/RC, Vj, and φDo (Fv/Fm), indicating that reaction centers were transformed to dissipation sinks, leading to a decrease in the efficiency of photosystem II, which was evident from the decreased values of Fv/Fo, Fv/Fm, ψEo, φEo, RC/ABS, and PIabs. These results indicated that decreased photosynthesis in Pb-treated fronds was partially ascribed to the lower pigment content, inhibition of electron transport, inactivation of the reaction centers, damage to the chloroplast ultrastructure, and stomatal closure. The physiological implications of subcellular distribution and chemical forms are discussed in relation to Pb accumulation and detoxification. However, Pb accumulation significantly impaired photosynthesis and membrane integrity in the fronds of S. polyrhiza.

Microbial induced carbonate precipitation for immobilizing Pb contaminants: Toxic effects on bacterial activity and immobilization efficiency

Microbial induced carbonate precipitation (MICP) is a natural bio-mediated process, which has been explored for soil stabilization and heavy metals immobilization in soil and groundwater. Previous studies have shown that MICP is capable of immobilizing various heavy metals including lead (Pb). However, most studies focus merely on the immobilization of heavy metals with relatively low concentration. This study: (1) presents results of an investigation into the toxic effects of Pb on bacterial activity and immobilization efficiency within a wide range of Pb concentrations; and (2) identifies controlling biotic and abiotic factors of Pb immobilization by MICP. In the first series of tests, bacterial strains (Sporosarcina pasteurii) are inoculated into nutrient solutions containing 0–50 mM Pb(NO3)2 and incubated at 30 °C. Biochemical parameters are measured over time, which include pH, electrical conductivity, urease activity, and viable cell number. In the second series of tests, grown bacterial strains are mixed with urea, calcium salts and Pb(NO3)2 in solution. Viable cell number, produced ammonium concentration, aqueous Pb concentration of the mixed solution, and total precipitation mass are measured. The results show that the presence of Pb has marginal effect on bacterial growth and associated urease activity at Pb concentration < 30 mM. The calcium source and initial bacteria concentration are found to remarkably influence Pb immobilization efficiency in terms of Pb removal percentage. Supplementary geochemical simulation results indicate that the Pb immobilization mechanisms includes abiotic precipitation, biotic precipitation and bio-sorption.

227 - Neuroprotective efficacy of curcumin in lead (Pb) induced inflammation and cholinergic dysfunction in mice

Curcumin from the rhizomes of Curcuma longa has many pharmacological activities including antioxidant, anti-inflammatory and cancer preventive properties. This study was designed to assess the protective effect of Curcumin against lead induced neurotoxicity. ICR mice were exposed to lead acetate (Pb) in drinking water (1%) with or without orally administrated Curcumin (100 and 200 mg/kgBW) and Vitamine E, the antioxidant positive control, once daily for 38 days. The results exhibited that Curcumin significantly protected against Pb induced learning deficit and memory loss in a concentration dependent manner, indicated by Water maze swimming test and Forced depression test. Pb induced a profound alteration of circulating Tumor necrosis factor-α (TNF-α), alteration inflammatory markers, TNF-α, COX-2 and iNOS, and elevation of oxidative damage, as evidenced by increasing lipid peroxide (malondialdehyde, MDA) levels in blood and brain tissues of mice as found in mice-treated with Vitamine E. The toxic effects of Pb may be mitigated by Curcumin and Vitamine E due to ameliorated inflammatory markers and increased expression of ChAT and AChE proteins lead to increased AChE activity in the brain compared to Pb alone, as shown by Western blot analysis. Taken together, these results suggested that Curcumin significantly alleviates Pb induced neurotoxicity, at least in part, by suppression inflammation, oxidative damage, alteration in neurotransmitter and enzyme expression (AChE and ChAT) with a reduction learning deficit and memory loss.

Concentration and exposure assessments of cadmium and lead in pumpkin, sunflower, watermelon, and jabooni seeds collected in Iran

Introduction â�� Heavy metals such as lead (Pb) and cadmium (Cd) are known to have high human toxicity. Their presence at various rates in oilseeds has gained more importance during the last few years in the absence of regulation in seeds. The consumption of seeds has been recently reported to increase in Iran, especially among adolescents and young people, so that heavy metal contamination in these seeds could become a great problem of public health. Materials and methods â�� This study investigated the Cd and Pb levels present in 168 seed samples (pumpkin, sunflower, watermelon and jabooni seeds) collected over the country, using graphite furnace atomic absorption spectrometry after microwave digestion. The data were used to estimate the weekly intake of Cd and Pb in Iranian consumers. Results and discussion â�� The highest concentrations of Pb and Cd were found in pumpkin shells and sunflower kernels, respectively. The concentrations of Pb and Cd detected in the seed samples averaged 77±28 I¼g kg-1 and 264±177 I¼g kg-1, respectively. The Pb content in 39 seed samples was exceeding the limit of 100 I¼g kg-1 established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The seeds with the highest Pb contamination were pumpkin seeds (67), followed by sunflower (30), watermelon (25), and jabooni seeds (15). None of the watermelon and jabooni seed samples were contaminated with Cd. The highest concentration (731 I¼g kg-1) and the highest number of samples (35) contaminated with Cd were recorded in the sunflower seeds. The differences in mean value of Pb and Cd among the seeds collected in various Iranian cities were not found statistically significant. Similarly, the mean intake of Pb and Cd estimated from the seed samples was much lower than the tolerable weekly intake (25.0 and 2.5 µg kg-1 week-1 for Pb and Cd, respectively) estimated by the JECFA. Conclusion â�� Although the mean dietary exposure of cadmium and lead was much lower than the reference doses, the high incidence of Pb and Cd in widely consumed oilseeds in Iran, and the toxic effects of Pb and Cd, indicate the necessity for regular surveillance to reduce intake of heavy metals by Iranian population. © ISHS 2018.

Al2O3 nanoparticle impact on the toxic effect of Pb on the marine microalga Isochrysis galbana

The rapid development and application of nanotechnology have led to increasing concern about the environmental implications of released nanomaterials and potential risks to public health and aquatic ecosystems. Information on the joint effect of nanomaterials and co-existing contaminants such as heavy metals is still inadequate. Our work investigated the effect of Al2O3 nanoparticles (NPs; nano-Al2O3) on the toxic effect of Pb in the unicellular marine phytoplankton Isochrysis galbana. Results showed that a dose–response effect of nano-Al2O3 was found. Significant enhancement of fluorescence in cell cytoplasm rather than cell membrane occurred in the presence of nano-Al2O3, indicating that nano-Al2O3 can penetrate cells and affect the fluorescence emitted from the chloropigments inside them. The presence of nano-Al2O3 has no impact on the toxic effect of Pb at an NP concentration of 1 mg/L but increased that at NP concentrations of 10 mg/L and 100 mg/L. A synergistic effect was also found for the toxic effect of Pb in the presence of 10 mg/L nano-Al2O3. The presence of 100 mg/L nano-Al2O3 significantly increased the bio-uptake of Pb in the range of 0.25 mg/L to 2.0 mg/L Pb, and the maximum accumulated Pb in algae can reach up to 18.22 ng/105 cells with 100 mg/L nano-Al2O3 compared with Pb alone at 2.0 mg/L(12.53 ng/105 cells). Inside cells, Pb loaded onto nano-Al2O3 can be more toxic than the same amount of free Pb species. The results of toxicity tests and accumulated Pb in algae imply that, in addition to the total Pb cell content, the bioavailability of Pb inside algae should be taken into consideration in evaluating the joint toxicity effect. Our work enhances understanding of the combined toxicity of NPs and co-existing heavy metals and is of practical significance in the natural environment.

Enhanced Lead Uptake by an Association of Plant and Earthworm Bioaugmented with Bacteria

Lead (Pb) is recorded as the second most hazardous pollutant of the environment. Previous cases of Pb bioremediation has been reported using single biosystem, but very few reports are available in biological approaches using multi-biosystems to achieve an enhanced bioremoval of Pb. The present study evaluated the capacity of a unique association of Pennisetum purpureum, a hyperaccumulator plant, and Lumbricus terrestris (earthworm) bioaugmented with a Pb-resistant bacterium, obtained from an industrially contaminated site and identified as isolate VITMVCJ1 Klebsiella variicola, to bioremediate Pb. The Pb-resistant gene was amplified in the bacterial isolate VITMVCJ1. The study was conducted for 60 d. Results verified that the bioaugmentation process enhanced 1) root and shoot length of the plants, 2) chlorophyll content of the plants, and 3) biofilm-producing ability of the microbes from the rhizosphere region of the plants. The total phenolic and flavonoid contents were found to be lower in the plants in the bioaugmented setup. The study also observed a reduction in the toxic effects of Pb on earthworm and plant. The earthworm was used to assess the Pb-induced stress syndrome after exposure to sublethal concentrations of Pb in the soil. A reduction in the content of malondialdehyde, a potential biomarker, on exposure to Pb demonstrated the role of the inoculum to alleviate heavy metal-induced stress in earthworms. All three symbionts accumulated Pb; Pb was accumulated mainly in the root of the plant, and poorly in the shoot of the plant and body mass of the earthworm. The bioaugmentation system exhibited stable and excellent uptake of Pb from the contaminated soils. The results of the present study suggest the positive effect of the synergistic association of the plant and earthworm with appropriate microbes for the bioremoval of Pb.

Early Life Pb Exposure and its Effect on Later Life Retinal Degeneration.

The study presents the longitudinal effect of early life lead exposure on retinal ischemia. Swiss albino mice were exposed to lead acetate at two different timepoints viz. postnatal day 1-20 and at 7th week of age. These mice were then followed till 10 week of age and subjected to retinal ischemia. Retinal ischemia was induced using pterygopalatine artery ligation. The effect of prior lead exposure on ischemic insult was determined using various histological and molecular parameters. Although toxic effects of Pb are well reported, but the results in this study showed not much significant effect of early life Pb exposure on later life retinal degeneration. While retinal thickness was decreased in surgery group and 7th week Pb exposed group, PND Pb exposed mice showed retinal thickness comparable to normal control. There was no difference in TUNEL positive cells in Pb exposed group when compared to surgery group. The molecular studies revealed overexpression of BDNF and GFAP in PND Pb exposed mice reflecting more injury and inflammation. The combined results revealed that Pb exposure have mild effect on overall susceptibility to retinal damage in later life. The Pb may exert its toxic effects at longer duration and thus the toxic effects may be mapped at longer timepoints. The study provides a new dimension to the already well known toxic effects of lead which needs to be further explored. J. Cell. Biochem. 118: 3213-3224, 2017. © 2017 Wiley Periodicals, Inc.

Accumulation, elimination, sequestration, and genetic variation of lead (Pb2+) loads within and between generations of Drosophila melanogaster

We examined accumulation, sequestration, elimination, and genetic variation for lead (Pb) loads within and between generations of Drosophila melanogaster. Flies were reared in control or leaded medium at various doses and tested for their Pb loads at different stages of development (larvae, eclosion, newly-eclosed adults, and mature adults). Pb loads were tested using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). We found that D. melanogaster readily accumulated Pb throughout their lifespan and the levels of accumulation increased with Pb exposure in the medium. Wandering third-instar larvae accumulated more Pb than mature adults; this phenomenon may be due to elimination of Pb in the pupal cases during eclosion and/or depuration in adults post-eclosion. The accumulated Pb in mature adults was not transferred to F1 mature adult offspring. Using a set of recombinant inbred strains, we identified a quantitative trait locus for adult Pb loads and found that genetic variation accounted for 34% of the variance in Pb load. We concluded that D. melanogaster is a useful model organism for evaluating changes in Pb loads during development, as well as between generations. Furthermore, we found that genetic factors can influence Pb loads; this provides an essential foundation for evaluating phenotypic variation induced by the toxic effects of Pb.

In situ remediation and phytotoxicity assessment of lead-contaminated soil by biochar-supported nHAP

In this study, a kind of biochar-supported nano-hydroxyapatite (nHAP@BC) material was used in in-situ remediation of lead-contaminated soil. Column experiments were performed to compare the mobility of nHAP@BC and Bare-nHAP. The immobilization, accumulation and toxic effects of Pb in the after-amended soil were assessed by the in vitro toxicity tests and pot experiments. The column experiments showed a significant improvement in the mobility of nHAP@BC. The immobilization rate of Pb in the soil was 74.8% after nHAP@BC remediation. Sequential extraction procedures revealed that the residual fraction of Pb increased by 66.6% after nHAP@BC remediation, which greatly reduced the bioavailability of Pb in the soil. In addition, pot experiments indicated that nHAP@BC could effectively reduce the upward translocation capacity of Pb in a soil-plant system. The concentration of Pb in the aerial part of the cabbage mustard was 0.1 mg/kg, which is lower than the tolerance limit (0.3 mg/kg). nHAP@BC can remediate Pb-contaminated soil effectively, which can restore soil quality for planting.