Pb Binding Capacity Research Articles

TOXIC EFFECTS OF LEAD ON FISH AND HUMAN

Bioaccumulation is a characteristic aspect in toxicity caused by Pb exposure. Toxic effects are induced in fish due to Pb exposure effecting its biochemical and physiological functions. Exposure pathway (dietary and waterborne), environmental factors (salt-water or fresh water) and Pb binding capacity with protein, SH and sulfur group decide accumulation pattern of Pb exposure. Activation of antioxidant responses like TBARS, GSH, GST, CAT and SOD occurs in fish for its protection in response to the oxidative stresses induced in fish due to Pb accumulation. Disruption of neurotransmitter function also occurs due to Pb accumulation which causes neurotoxicity in fish. Pb interaction also disturbs immune system responses. In fish, various systems are affected due to Pb toxic exposure which can be used as an indicator of toxicity in aquatic environment.

Lactobacillus plantarum LP33 attenuates Pb-induced hepatic injury in rats by reducing oxidative stress and inflammation and promoting Pb excretion

Lead (Pb) is one of the most common heavy metals and is harmful to human health. The liver is considered as a major target organ for Pb poisoning. Although probiotics have been shown to alleviate liver injury, the protective effect of Lactobacillus plantarum LP33 (LP33) against Pb-induced hepatotoxicity remains unclear. In order to explore the hepatoprotective effect of LP33, LP33 was administered to Pb-intoxicated Sprague-Dawley rats once daily by oral gavage for 8 weeks. The present results showed that LP33 supplementation alleviated liver injury, and inhibited oxidative stress and inflammation in Pb-exposed rats. Treatment with LP33 also promoted the phosphorylation of adenosine monophosphate-activated protein kinase and protein kinase B, activated nuclear factor erythroid 2-related factor 2 signaling and inhibited the activation of nuclear factor-κB signaling in liver tissues of rats exposed to Pb. Additionally, LP33 exhibited adequate Pb-binding capacity and satisfactory survival under simulated gastrointestinal conditions in vitro, and promoted Pb excretion via enterohepatic circulation of bile acids. This study demonstrated that LP33 reduced Pb-induced oxidative stress and inflammation and promoted Pb excretion, thereby attenuating the Pb-induced hepatic injury. Our findings suggest that LP33 supplementation may be a potential strategy for the treatment of Pb-induced hepatic toxicity.

Comparative Assessment of the Bioremedial Potentials of Potato Resistant Starch-Based Microencapsulated and Non-encapsulated Lactobacillus plantarum to Alleviate the Effects of Chronic Lead Toxicity.

Lead (Pb) is a well-recognized and potent heavy metal with non-biodegradable nature and can induce the oxidative stress, degenerative damages in tissues, and neural disorders. Certain lactic acid bacterial strains retain the potential to mitigate the lethal effects of Pb. The present work was carried out to assess the Pb bio-sorption and tolerance capabilities of Lactobacillus plantarum spp. Furthermore, potato resistant starch (PRS)-based microencapsulated and non-encapsulated L. plantarum KLDS 1.0344 was utilized for bioremediation against induced chronic Pb toxicity in mice. The experimental mice were divided into two main groups (Pb exposed and non-Pb exposed) and, each group was subsequently divided into three sub groups. The Pb exposed group was exposed to 100 mg/L Pb(NO3)2 via drinking water, and non-Pb exposed group was supplied with plain drinking water during 7 weeks prolonged in vivo study. The accumulation of Pb in blood, feces, renal, and hepatic tissues and its pathological damages were analyzed. The effect of Pb toxicity on the antioxidant enzyme capabilities in blood, serum, as well as, on levels of essential elements in tissues was also calculated. Moreover, KLDS 1.0344 displayed remarkable Pb binding capacity 72.34% and Pb tolerance (680 mg/L). Oral administration of both non- and PRS- encapsulated KLDS 1.0344 significantly provided protection against induced chronic Pb toxicity by increasing fecal Pb levels (445.65 ± 22.28 μg/g) and decreasing Pb in the blood up to 137.63 ± 2.43 μg/L, respectively. KLDS 1.0344 microencapsulated with PRS also relieved the renal and hepatic pathological damages and improved the antioxidant index by inhibiting changes in concentrations of glutathione peroxidase, glutathione, superoxide dismutase, malondialdehyde, and activated oxygen species, which were affected by the Pb exposure. Overall, our results suggested that L. plantarum KLDS 1.0344 either in free or encapsulated forms hold the potentiality to deliver a dietetic stratagem against Pb lethality.

In Vitro and In Vivo Evaluation of Lactobacillus delbrueckii subsp. bulgaricus KLDS1.0207 for the Alleviative Effect on Lead Toxicity.

Lead (Pb) is a toxic contaminating heavy metal that can cause a variety of hazardous effects to both humans and animals. In the present study, Lactobacillus delbrueckii subsp. bulgaricus KLDS1.0207 (L. bulgaricus KLDS1.0207), which has a remarkable Pb binding capacity and Pb tolerance, was selected for further study. It was observed that the thermodynamic and kinetic model of L. bulgaricus KLDS1.0207 Pb binding respectively fit with the Langmuir–Freundlich model and the pseudo second-order kinetic model. Scanning electron microscopy and energy dispersive spectroscopy analysis disclosed that the cell surfaces were covered with Pb and that carbon and oxygen elements were chiefly involved in Pb binding. Combined with Fourier transform infrared spectroscopy analysis, it was revealed that the carboxyl, phosphoryl, hydroxyl, amino and amide groups were the main functional groups involved in the Pb adsorption. The protective effects of L. bulgaricus KLDS1.0207 against acute Pb toxicity in mice was evaluated by prevention and therapy groups, the results in vivo showed that L. bulgaricus KLDS1.0207 treatment could reduce mortality rates, effectively increase Pb levels in the feces, alleviate tissue Pb enrichment, improve the antioxidant index in the liver and kidney, and relieve renal pathological damage. Our findings show that L. bulgaricus KLDS1.0207 can be used as a potential probiotic against acute Pb toxicity.

Dietary Lactobacillus plantarum supplementation decreases tissue lead accumulation and alleviates lead toxicity in Nile tilapia (Oreochromis niloticus )

Pollution by the heavy metal lead (Pb) has become a threat to both aquaculture and food safety. In this study, the protective effects of a selected probiotic with good Pb binding capacity (Lactobacillus plantarumCCFM8661) against waterborne Pb exposure were evaluated in Nile tilapia (Oreochromis niloticus). One hundred and eighty fish were divided into four groups as control, Pb-only, Pb-plus-CCFM8661 and CCFM8661-only. Fish were exposed to a dose of waterborne Pb level at 1 mg L−1 for 4 weeks, and the probiotic was administered at 108 CFU g−1 in fish diet twice daily. The results showed that dietary supplementation of CCFM8661 ameliorated the growth performance and prevented the death of Pb-exposed fish. Cotreatment with Pb and CCFM8661 also effectively decreased Pb accumulation in kidney, liver, gonad, brain, gills and muscle. Moreover, the administration of this probiotic alleviated Pb-induced oxidative stress, recovered digestive enzyme activities and blood δ-aminolevulinic acid dehydratase activity, reversed alterations in innate immune status and decreased the frequencies of the nuclear abnormalities in peripheral blood erythrocytes of fish. These results suggested that CCFM8661 may be a novel dietary supplement against Pb toxicity at least in tilapia.

Toxicity of lead and zinc to developing mussel and sea urchin embryos: Critical tissue residues and effects of dissolved organic matter and salinity

Lead (Pb) EC50 values in the very sensitive early development phases (48–72h post-fertilization) of the mussels Mytilus galloprovincialis and Mytilus trossolus and sea urchin Strongylocentrotus purpuratus in 100% sea water were: M. trossolus — 45 (95% C.I.=22–72) μgL−1; M. galloprovincialis — 63 (36–94) μgL−1; S. purpuratus — 74 (50–101) μgL−1. Salinity thresholds for normal development varied: M. trossolus>21ppt; M. galloprovincialis>28ppt; S. purpuratus≥30ppt. Addition of two spectroscopically distinct dissolved organic matters (DOM) from fresh water (Nordic Reservoir) and sea water (Inshore) moderately decreased the toxicity of Pb to both mussels, but not in a concentration-dependent fashion, with only an approximate doubling of EC50 over the range of 1.4–11.2mgCL−1. Independent Pb binding capacity determinations for DOC explained the lack of a relationship between DOM concentration and toxicity. Salinity had no effect on Pb toxicity down to 21ppt in M. trossolus, and low salinity (21ppt) did not enhance the protective effect of DOC. Both DOMs increased the toxicity of Pb in developing sea urchin embryos, in contrast to mussels. Relative to Pb, the organisms were 6–9 fold less sensitive to Zn on a molar basis in 100% seawater with the following Zn EC50s: M. trossolus — 135 (103–170) μgL−1; M. galloprovincialis — 172 (126–227) μgL−1, S. purpuratus — 151 (129–177) μgL−1. Nordic Reservoir and Inshore DOM (2–12mgCL−1) had no significant effect on Zn toxicity to mussels, in accord with voltammetry data showing an absence of any strong ligand binding for Zn by DOMs. As with Pb, DOMs increased Zn toxicity to urchin larvae. Critical Tissue Residues (CTR) based on whole body concentrations of Pb and Zn were determined for M. galloprovincialis at 48h and S. purpuratus at 72h. The median lethal CTR values (LA50s), useful parameters for development of saltwater Biotic Ligand Models (BLMs), were approximately 4-fold higher on a molar basis for Zn than for Pb. The latter were not altered by DOM exposure, despite increased EC50 values, in accord with the tenets of the BLM.

Mechanism of lead immobilization by oxalic acid-activated phosphate rocks

Lead (Pb) chemical fixation is an important environmental aspect for human health. Phosphate rocks (PRs) were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs (APRs) were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate (CO2−3 in raw PRs and phosphate (PO3−4) groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs.

Assessment of lead speciation by organic ligands using speciation models

The biogeochemical behaviour of lead (Pb) in ecosystems greatly depends on its chemical species. Organic ligands strongly influence Pb species and mobility in soil solution. In the present study, two metal speciation models, Windermere Humic Aqueous Model (WHAM) and Visual Minteq are used to compute Pb speciation in nutrient solution in the presence and absence of organic ligands. The three organic ligands used include ethylenediamine tetraacetic acid (EDTA), citric acid (CA) and fulvic acid (FA). The results show that in the absence of organic ligands, Pb2+ is the dominant form under acidic conditions and Pb–OH under alkaline conditions. The presence of organic ligands strongly influences Pb speciation. EDTA is more effective than are CA and FA concerning its influence on Pb speciation due to high Pb binding capacity. The results also indicate that Pb binding capacity of organic ligands varies with solution pH.

Physicochemical study of amino-functionalized organosilicon cubes intercalated in montmorillonite clay: H-binding and metal uptake

Two organic-modified montmorillonite clays were prepared by embedding organosilanes bearing different chelating amino-functional groups [Apteos] (3-amino-propyltriethoxysilane), and [Edaptmos] (3-(2-aminoethylamino)propyltrimethoxysilane), in the interlayer space of a Zenith montmorillonite. XRD and FTIR spectroscopic data show that the amino organosilanes are intercalated into the interlamelar space forming cube-like structures bearing one polymanino tail at each cube apex. The intercalated cubes cause an increase of the interlayer spacing of the clay sheets by 6.6 Å in [Zenith–Apteos] and by 7.1 Å in [Zenith–Edaptmos]. The H-binding properties of the intercalated polyamino organosilanes were studied by potentiometric titration. The Cu-, Cd-, and Pb-binding capacity of [Zenith–Apteos] and [Zenith–Edaptmos] were evaluated in aqueous solution as a function of the pH. Both [Zenith–Apteos] and [Zenith–Edaptmos] showed improvement vs Zenith for metal binding in the order Cu > Pb > Cd. [Zenith–Edaptmos] showed the most important results vs Zenith. Theoretical analysis of the pH edge, achieved by a surface complexation model, shows that (a) the amino-functionalized cube-like structures constitute high affinity metal-binding sites; and (b) the metal ions are bound in a monodendate mode with the amino group of the cube, thus resulting in a maximization of metal-binding efficiency.

Biological Markers of Fetal Lead Exposure at Each Stage of Pregnancy

It has been suggested that plasma lead (Pb) represents the fraction of circulating Pb that crosses the placenta. Whole-blood Pb levels, the conventional method for measuring circulating Pb, may not adequately reflect plasma Pb levels. The objective of this study was to assess the relationship between whole-blood and plasma Pb in a cohort of pregnant women. A group of 237 pregnant women, recruited in Mexico City from 1997 to 1999, was studied. whole-blood and plasma lead concentrations were evaluated at 12, 24, and 34 wk of gestation by inductively coupled plasma–mass spectrometry. Data were analyzed using a mixed-effects regression model. An exponential relationship was found between plasma and whole-blood Pb levels and significant modification of the association by stage of pregnancy. The association was stronger in the second trimester relative to the first, and it further increased in the third trimester. The model predicts increased plasma Pb levels for a given whole-blood Pb value as pregnancy advances for whole-blood Pb levels greater than ∼110 µg/L, but not for blood Pb levels less than 100 µg/L. These findings could be due to physiologic changes during pregnancy, such as decreasing hematocrit, saturation of red cell Pb binding capacity, and increased bone resorption or intestinal absorption. Collectively, these data suggest that at elevated maternal blood Pb levels the developing fetus may be at greater risk of Pb exposure from increased maternal plasma Pb than otherwise predicted from whole-blood Pb levels.

Lead adsorption by silica-immobilized humin under flow and batch conditions: Assessment of flow rate and calcium and magnesium interference

Batch and column experiments were performed to determine the Pb(II) binding ability of silica-immobilized humin biomass under different conditions. Batch experiments were performed to determine the interference of Ca(II) and Mg(II) and column experiments were used to determine the effect of flow rate and the presence of Ca(II) and Mg(II) on the Pb(II) adsorption by the humin biopolymer. The results from the batch experiments showed that Pb binding decreased as the concentrations of Ca and Mg increased. At a concentration of 100 mM, the interference of Ca alone was 36%, while for Mg it was 26%; however, when both cations were present, the interference increased up to 42%. Column experiments were performed at flow rates of 1, 1.5, 2, and 3 mL min −1 using a 0.1 mM Pb(II) solution. The results showed that the highest Pb adsorption was obtained at the flow rates of 1 and 1.5 mL min −1. The average Pb binding capacity at these two flow rates was 182.3 ± 0.7 μM Pb g −1. In addition, a recovery of 99.5 ±0.3% was obtained. Immobilized humin exposed under flow conditions to Pb–Ca, Pb–Mg or Pb–[Ca + Mg] solutions (Pb used at 0.1 mM and Ca and Mg at 1 mM) showed a Pb binding capacity of 161 ± 5, 175 ± 5, and 171 ± 1 μM g −1, respectively. In mixtures containing Pb–Ca, Pb–Mg and Pb–Ca–Mg, the Pb recovery was 89.8% ± 0.35, 90.3% ± 0.43, and 88.1% ± 0.5, respectively. Pb recovery was performed using 30 bed volumes of 0.1 M HCl as stripping agent. The results of these experiments demonstrated that silica-immobilized humin biomass has the potential for Pb removal from aqueous solution even in the presence of 20 mM of calcium and magnesium.

BIOLOGICAL MARKERS OF FETAL LEAD EXPOSURE AT EACH STAGE OF PREGNANCY

ISEE-348 Introduction: It has been suggested that plasma lead (Pb) represents the fraction of circulating Pb that crosses the placental barrier with consequent exposure to the fetus. Evidence indicates that whole blood Pb levels, the conventional method for measuring circulating Pb, may not adequately reflect plasma Pb levels. The objective of this study was to longitudinally assess the relationship between whole blood and plasma Pb in a cohort of environmentally exposed pregnant women in Mexico City. Methods: We studied 237 pregnant women. Whole blood and plasma lead concentrations were evaluated at 12th, 24th and 34th weeks of gestation by inductively coupled plasma mass spectrometry. Data were analyzed in a longitudinal fashion using a mixed-effects regression model. Results: We found an exponential relationship between plasma and whole blood Pb levels and sign ificant modification of the association by the stage of pregnancy. The association was stronger in the 2nd trimester relative to the 1st, and it further increased in the 3rd trimester. The fitted model, which accounts for 60% of the variability in plasma Pb levels, predicts increased plasma Pb levels for a given whole blood Pb value as pregnancy advances for whole blood Pb levels greater than ∼110 μg/L, but not for blood Pb levels less than 100 μg/L. Discussion: These findings could be due to a combination of physiologic changes that occur as pregnancy progresses such as decreasing hematocrit, saturation of red cell Pb binding capacity at higher Pb levels, and increased input of Pb to plasma from increased bone resorption and/or intestinal absorption. Collectively, these data suggest that at elevated maternal blood Pb levels the developing fetus may be at greater risk of Pb exposure and toxicity from increased maternal plasma Pb than otherwise predicted from whole blood Pb levels.

Humic acids from oxidized coals: I. Elemental composition, titration curves, heavy metals in HA samples, nuclear magnetic resonance spectra of HAs and infrared spectroscopy

The formation of humic acids (HAs) from bituminous coal was verified by laboratory oxidation. In a relatively short time the oxidation by air at temperature above 150 °C led to the formation of HAs. These HAs were compared with those isolated from oxidized bituminous coal from the vicinity of red bed bodies, from weathered bituminous coal, oxihumolite and lignite. For this the organic and inorganic elemental composition of HAs, apparent dissociation constants, metal-binding capacities, nuclear magnetic resonance and infrared spectra were determined and evaluated. With increasing temperature of laboratory oxidation of bituminous coal the percentage of aromaticity of HAs increases. HAs prepared from coal oxidized at 150 °C are characterized by an aromaticity index 78% while for HAs prepared at 250 and 300 °C by 95% aromaticity. The same index for HAs isolated from naturally oxidized bituminous coals is of about 87% whereas it is of about 50% for oxihumolite and lignite. The apparent dissociation constants ( K app) are much higher in HAs isolated from oxihumolite and lignite (p K app from 3.35 to 3.80) than those from oxidized bituminous coal samples (p K app from 4.47 to 4.85). There is a good negative correlation between Pb-binding capacity and p K app of all samples suggesting that metallic ions are bonded to acidic groups of HAs. Also contents of inorganic elements like Fe, Al, Si are much higher in HAs isolated from lignite and oxihumolite than those in HAs from oxidized bituminous coal. Thus, it seems that the temperatures below 150 °C and the long oxidation time are necessary conditions for the formation of HAs in oxidative altered bituminous coal deposited deeply under the earth surface.

Cation exchange capacity and lead sorption in ectomycorrhizal fungi

Two ectomycorrhizal fungi, Paxillus involutus 533 and Laccaria bicolor S238, differing greatly in their mycelial characteristics, were investigated with regard to their cation exchange capacity and Pb-binding capacity in vitro after growth with either NO3- or NH4+ as N source. The CECs of 800–1200 μmol g-1 dry weight for Paxillus involutus 533 and 2000–3000 μmol g-1 dry weight for Laccaria bicolor S238, were high compared to plant roots. The fungal mycelium also had a high Pb sorption capacity. It was higher in Laccaria bicolor S238 than in Paxillus involutus 533 and higher after pregrowth in NO3- compared to NH4+. Both the higher CEC and the higher Pb sorption capacity of Laccaria bicolor S238 compared to Paxillus involutus 533 might have been the result of the hydrophilic nature of the of Laccaria bicolor S238 mycelium. It would have absorbed the solutions better than the hydrophobic mycelium of Paxillus involutus 533. X-ray microanalysis of the cell walls revealed that the Pb content of the cell walls was higher in Paxillus involutus 533 than in Laccaria bicolor S238. Nevertheless, electron dense deposits in the cell walls of Laccaria bicolor S238 contained large amounts of Pb, P and S. Thus, while Pb was evenly distributed in the cell walls of Paxillus involutus 533, Pb was accumulated in electron dense deposits in Laccaria bicolor S238. The results are discussed in view of their significance for the mycorrhizal symbiosis.

Metal binding capacity of northern European surface waters for Cd, Cu, and Pb

Total concentrations of and binding capacities for Cd, Cu, and Pb were measured in selected surface waters from northwestern Europe. Linear multiple regression predictive models explained 97, 93, and 96% of the observed variation in Cd, Cu and Pb binding capacities, respectively. The models constructed used (CO 2 3−) and (SO 2 2−) to predict Cd binding capacity, (OH −) and (SO 4 2−) to predict Cu binding capacity and (OH −), (CO 3 2−) and (SO 4 2−) to predict Pb binding capacity. Organic carbon was not significantly correlated with binding capacities for Cd, Cu, and Pb and was unimportant in explaining a significant amount of the variability in binding capacities for the metals of northern European surface waters. Thus, the effects of these organics on trace metal speciation can be ignored and predictive models of trace metal speciation constructed, using inorganic solubility equilibria only. Ratios of total Cd, Cu, and Pb concentrations to their respective binding capacities were much less than unity for all waters studied. Copper exhibited the greatest metal concentrations: binding capacity ratio in all waters investigated.