Search

Pb toxicity is linked to cardiovascular and nephrotoxicity issues. Exposure to this heavy metal can occur through food and drinking water. Therefore, this study aimed to evaluate Pb exposure and assess health risks in Korean adults using a physiologically based toxicokinetic (PBTK) model. Human blood Pb concentrations were monitored using the Korean National Environmental Health Survey (KoNEHS) Cycle 4. The average Pb exposure in Korean adults was 0.520 μg/kg bw/day. The PBTK results were compared with scenario-based results from the 2021 risk assessment report of five heavy metals, including Pb, conducted by the MFDS. Exposure determined through reverse dosimetry was approximately two times higher than scenario-based exposure (0.264 μg/kg bw/day). The higher exposure levels obtained during PBTK analysis may be attributed to sustained exposure within historically more contaminated living environments and the long half-life of Pb. These findings suggest that the PBTK-based method can quantify aggregated exposure levels in the body over time, potentially serving as a complementary tool to address the constraints of scenario-based assessment methods for integrated risk assessment. Moreover, this model is convenient and cost-effective compared with scenario-based exposure estimation. These findings can facilitate the application of model for tracking continuous national changes in hazardous substance levels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The extent of heavy-metal-induced cardiotoxicity is proportional to the levels of metal bioaccumulation, and it was previously assumed that heavy metals accumulate uniformly in the myocardium. Therefore, the aim of this study was to investigate concentrations of metals and metalloids in two distant regions of the left ventricle (LV), the base of the LV, and apex of the LV using inductively coupled plasma mass spectrometry (ICP-MS). We also examined the potential correlation between metal levels and the thickness of the interventricular septum in twenty LV specimens (ten from the base of LV and ten from the apex of LV) from 10 individuals (mean age 75 ± 6 years). We found significantly higher concentrations of arsenic and lead in the LV apex compared to the base of the LV. We also found a positive correlation between the concentrations of arsenic in the myocardium of LV and the thickness of the interventricular septum. Our results indicate that arsenic and lead accumulate to a higher extent in the apex of the LV compared to the base of the LV. Therefore, future studies designed to measure levels of metals in heart muscle should consider non-uniform accumulation of metals in the myocardium.

Toxic heavy metals pollution in urban soil has become a major global issue due to its adverse effects on the environment and human health. In this paper, 26 soil samples were analyzed to assess the speciation, bioavailability and human health risk of Arsenic (As), Mercury (Hg), Lead (Pb) and Cadmium (Cd) in urban soils of a heavy industrial city in NE China by using a Monte Carlo simulation approach. The results showed that As, Hg, Pb and Cd concentrations in the soil all exceed the corresponding background value of study area. Mercury displays the highest value of geo-accumulation index (Igeo), followed by Cd, Pb and As. The pollution load index (PLI) value (>2) indicates a moderate pollution level in the study area. The chemical speciation of HMs mainly exists in residual fraction except Cd. The probabilistic health risk assessment demonstrated that the mean values of Total Carcinogenic Risk (TCR) and Hazard Index (HI) calculated with total concentration are at the unacceptable level, with a higher risk to children than adults. However, the mean values calculated with bioavailable fraction are all within the acceptable level. The mean value of TCR and HI obtained by bioavailable fraction is about 96% and 95% lower than that obtained by total concentration, respectively. Thus, this study suggested that the bioavailable fraction of HMs is a more reliable parameter for health risk assessment, while the total concentration of HMs can overestimate the true risk. The results of this study provide some insight into the speciation, bioavailability and health risks of toxic heavy metals in urban soils in those heavy industrial cities., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Discrepancies are present in the findings from clinical trials evaluating a physiological role of iron status in the lead-exposed population., Objective: The purpose of this article was to summarize the current understanding of cellular mechanisms of lead toxicity and present a comprehensive review of existing clinical trials related to associations of lead poisoning and iron status. Although an association of iron metabolism pathways that are affected by lead intoxication has been studied, there are still aspects that remain to be elucidated. The existence of additional Pb uptake pathways besides DMT1 transporter-mediated is postulated to non-specifically regulate lead absorption., Methods: Authors performed a systematic search of PubMed, EMBASE® and Web of Science databases to identify studies that reported an association between health risks of non-organic lead that are associated with iron status markers as possible effect modifier., Results: There were 58 studies that met the pre-defined inclusion criteria for the systematic review. There is a strong body of evidence supporting the hypothesis that alleviated blood lead level can be correlated with a reduced body iron store and increasing the risk of anemia. This association is of a high significance in cases of a young adolescent, weaker in groups of older children and often without a statistical significance in adults., Discussion: Discrepancies in the observations may result from different specificities of lead absorption pathways in children and adults, as well as the power of the statistical tests in varying population sizes. It may be assumed that the extent of iron deficits coupled together with source, timing, and severity of lead exposure, significantly influence the correlation between these factors. Some of the intervention programs of counteracting lead poisoning by iron supplementation proved to be effective and may be a promising prevention strategy for the exposed population., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Lead exposure can cause substantial organ damage. Enteral lead absorption may be reduced by concomitant intake of clinoptilolite tuff, a zeolite from natural sources. This study aimed to assess the effect of purified clinoptilolite tuff (G-PUR) on enteral lead uptake in adults using stable lead isotope 204 Pb as a tracer. In this randomized, placebo-controlled, double-blind, parallel-group study, 42 healthy participants were randomized to receive oral G-PUR 2.0 g, 2 * 2.0 g, or placebo, together with 2.5 µg of 204 Pb in water. The enrichment of 204 Pb caused by the tracer in blood and urine was measured by mass spectrometry. G-PUR was well tolerated. The mean maximum 204 Pb enrichment of 0.505% of total blood lead was significantly higher (p < 0.0001) in the placebo group compared to G-PUR 2.0 g (0.073%) or G-PUR 2 * 2.0 g (0.057%) group. Normalized 204 Pb AUC 0-192 was 86.5, 11.9, and 8.5% * h without and with G-PUR 2.0 g, and G-PUR 2 * 2.0 g, respectively (p < 0.0001 vs. placebo). This smaller 204 Pb exposure was paralleled by a reduced urinary excretion in subjects receiving G-PUR. Concomitant oral intake of purified clinoptilolite tuff reduced enteral uptake of 204 Pb in healthy humans by approximately 90%. The reduced bioavailability is demonstrable by a decrease of 204 Pb tracer enrichment in blood and urine.Trial registration: clinicaltrials.gov identifier: NCT04138693, registered 24/10/2019., (© 2021. The Author(s).)

In this study, the intestinal permeability of metal(loid)s (MLs) such as arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) was examined, as influenced by gut microbes and chelating agents using an in vitro gastrointestinal/Caco-2 cell intestinal epithelium model. The results showed that in the presence of gut microbes or chelating agents, there was a significant decrease in the permeability of MLs (As-7.5%, Cd-6.3%, Pb-7.9% and Hg-8.2%) as measured by apparent permeability coefficient value (P app ), with differences in ML retention and complexation amongst the chelants and the gut microbes. The decrease in ML permeability varied amongst the MLs. Chelating agents reduce intestinal absorption of MLs by forming complexes thereby making them less permeable. In the case of gut bacteria, the decrease in the intestinal permeability of MLs may be associated to a direct protection of the intestinal barrier against the MLs or indirect intestinal ML sequestration by the gut bacteria through adsorption on bacterial surface. Thus, both gut microbes and chelating agents can be used to decrease the intestinal permeability of MLs, thereby mitigating their toxicity., (© 2021. The Author(s).)

Animal bioassays have been developed to estimate oral relative bioavailability (RBA) of metals in soil, dust, or food for accurate health risk assessment. However, the comparability in RBA estimates from different labs remains largely unclear. Using 12 soil and soil-like standard reference materials (SRMs), this study investigated variability in lead (Pb) and arsenic (As) RBA estimates employing a mouse bioassay in 3 labs at Nanjing University, University of Jinan, and Shandong Normal University. Two performances of the bioassay at Nanjing University in 2019 and 2020 showed reproducible Pb and As RBA estimates, but increasing the number of mouse replicates in 2020 produced more precise RBA measurements. Although there were inter-lab variations in diet consumption rate and metal accumulation in mouse liver and kidneys following SRM ingestion due to differences in diet composition, bioassays at 3 labs in 2019 yielded overall similar Pb and As RBA estimates for the 12 SRMs with strong linear correlations between each 2 of the 3 labs for Pb (R 2  = 0.95-0.98 and slope = 0.85-1.02) and As RBA outcomes (R 2  = 0.46-0.86 and slope = 0.56-0.79). The consistency in RBA estimates was attributed to the relative nature of the final bioavailability outcome, which might overcome the inter-lab variation in diet consumption and metal uptake in mice. These results increased the confidence of use of mouse bioassays in bioavailability studies.

The Department of Defense (DOD) commissioned the National Research Council (NRC) to assess the potential health effects associated with exposure of DOD personnel to lead (Pb) at firing ranges. In that report, NRC concluded that the current Occupational Safety and Health Administration permissible exposure limit and the blood lead levels (BLLs) on which it was based were not sufficiently protective of worker populations covered under the general industry standard. In support of future selection of an occupational exposure limit, the relationship of airborne Pb levels to BLLs is of interest to the DOD. A subset of the BLLs identified as relevant to the management of health risks of exposed workers was selected as targets for extrapolation to equivalent airborne Pb values. The existing O'Flaherty physiologically based pharmacokinetic model for Pb in humans was modified to facilitate probabilistic predictions of DOD worker population BLLs, including 95th percentile values, based on current worker characteristics. Workplace airborne Pb 8-h time-weighted average concentrations of 1.1, 4.0, 6.8, or 9.8 μg/m 3 are anticipated to maintain BLLs below 5, 10, 15, or 20 μg/dl, respectively, in the vast majority of DOD workers exposed to Pb under full-time working lifetime occupational exposure., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The dispersion of mine tailings affects ecosystems due to their high content of potentially toxic elements. Environmental risk increases when the soil impacted by tailings is used for agriculture; this use may result in health impacts. This study analyzes the feasibility of remediating a calcareous soil (used for maize cultivation) polluted with lead in the semiarid zone of Zimapán, México, by using EDTA as an extractant. Total geoavailable and bioaccessible concentrations in the gastric and intestinal phases were determined to evaluate lead availability and health risk. The soil was then washed with EDTA, and the geochemical fractionation (interchangeable, carbonates, Fe/Mn oxy-hydroxides, organic matter-sulfides, and residual) and impact on the mesophile bacteria and fungi/yeast populations were analyzed. The results showed total Pb concentrations up to 647 ± 3.50 mg/kg, a 46% bioaccessible fraction (297 ± 9.90 mg/kg) in the gastric phase and a 12.2% (80 ± 5 mg/kg) bioaccessible fraction in the intestinal phase, indicating a health and environmental risk. Meanwhile, the geochemical fractionation before washing showed a Pb fraction mainly consisting of Fe/Mn oxy-hydroxides (69.6%); this reducible fraction may progressively increase its bioaccessibility. Geochemical fractionation performed in the washed soil showed differences from that determined before the treatment; however, the iron and manganese fraction, at 42.4%, accounted for most of the Pb. The soil microbiology was also modified by EDTA, with an increase in aerobic bacteria and a decrease in fungi/yeast populations. Although 44% total lead removal was achieved, corresponding to a final concentration of 363.50 ± 43.50 mg/kg (below national and USEPA standards), washing with EDTA increased the soluble and interchangeable lead concentrations. Statistical analysis indicated a significant effect (p < 0.05) of EDTA on the soil's geochemical fractionation of lead.

Background: Seafood present important advantages for human nutrition, but it can also accumulate high levels of toxic and potentially toxic elements. Culinary treatments could influence seafood chemical element content and element bioavailability. In this study, the influence of culinary treatments on the total concentration and on the bioavailability of Cd, Cr, Cu and Pb in shark, shrimp, squid, oyster, and scallop was assessed., Methods: Boiling, frying, and sautéing with or without seasonings (salt, lemon juice and garlic) were evaluated. Total concentration and bioavailability of Cd, Cr, Cu and Pb in seafood after all these culinary treatments were compared with those in uncooked samples. Analytes were determined by triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). An alternative to express the results avoiding underestimated or overestimated values was proposed., Results: The analytes concentration in seafood without culinary treatment varied from 0.0030 μg g -1 (shrimp) to 0.338 μg g -1 (oyster) for Cd; 0.010 μg g -1 (squid) to 0.036 μg g -1 (oyster) for Cr; 0.088 μg g -1 (scallop) to 8.63 μg g -1 (oyster) for Cu, and < 0.005 μg g -1 (shrimp, squid and oyster) to 0.020 μg g -1 (shark) for Pb. Only Cd (in scallop) was influenced by culinary treatments (reduction from 37 to 53 % after boiling, frying, and sautéing). Bioavailability percentage varied from 11% (oyster) for Cd; 18% (oyster) to 41% (shark) for Cr; 6% (shark) for Cu, and 8% (oyster) for Pb. Bioavailability percentage was not influenced by culinary treatments., Conclusion: Cadmium concentration was reduced in scallop after some culinary treatments (reduction o 37-53% after boiling, frying, and sautéing), but bioavailability percentage was not influenced. The employed analytical method was adequate for the purpose, presenting import results for food safety assessment about the influence of culinary treatments on metals concentration and bioavailability in seafood., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

Metal(loid) contamination of soil, resulting from the mining activities, is a major issue worldwide, due to its negative effects on the environment and health. Therefore, these contaminated soils need to be remediated. One realistic method is the assisted phytostabilization, which aims at establishing a vegetation cover on the soil that will reduce metal(loid) bioavailability and spreading through the prevention of wind erosion and water leaching. In addition, amendments are applied to improve soil conditions and ameliorate plant growth. In this goal, biochar and compost showed good results in terms of amelioration of soil fertility and reduction in lead bioavailability. However, they usually have a negative effect on arsenic. On the contrary, iron sulfate showed capacity to reduce arsenic mobility through interaction with its iron hydroxides. Finally, the choice of the appropriate plant species is crucial for the success of assisted phytostabilization. One good option is to use endemic species, adapted to the metal(loid) stress, with a fast growth and large shoot and root systems. The aims of this study were to (1) evaluate the effects of applying biochar, compost and iron sulfate, alone or combined, to a former mine soil on the soil properties and Agrostis capillaris growth, and (2) assess the difference between two Agrostis capillaris ecotypes, an endemic metallicolous ecotype and a non-metallicolous ecotype. Results of the mesocosm experiment showed that amendment application improved soil properties, i.e., reduced soil acidity, increased nutrient availability and lower metal(loid) stress, the best being the combination biochar-compost-iron sulfate. These ameliorations allowed a better plant growth. Finally, the metallicolous ecotype performed better in terms of growth than the non-metallicolous one and could thus be used in an assisted phytostabilization process on the former mine site.

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., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Combining biochar (BR) with other immobilizing amendments has additive effects on Pb immobilization and been recognized to be effective for the restoration of Pb polluted soils. However, the impacts of different proportions between BR and a highly efficient Pb immobilizing agent called "magnesium potassium phosphate cement (MC)" have never been earlier investigated. This work aimed to investigate the consequences of BR and MC alone and their mixtures of 25:75, 50:50, and 75:25 ratios on Pb bioavailability, Pb immobilization index (Pb-IMMi), and enzymatic activities in Pb polluted soil. Furthermore, amendments effects on Pb distribution in spinach, growth, antioxidant capacity, biochemical, and nutritional spectrum were also investigated. We found that MC alone performed well to immobilize Pb in soil and reducing its distribution in shoots, but was less efficient to improve soil enzymatic activities and plant attributes. Conversely, the application of BR alone stimulated soil enzymatic activities, plant growth, and quality but was less effective to immobilize Pb in soil and reducing shoot Pb concentrations. The combinations of BR and MC of various ratios showed variable results. Interestingly, the most promising outcomes were obtained with BR50%+MC50% treatment which resulted in enhanced Pb-IMMi (73%), activities of soil enzymes, plant growth and quality, and antioxidant capacity, compared to control. Likewise, significant reductions in Pb concentrations in shoots (85%), roots (78%), extractable Pb (73%) were also obtained with BR50%+MC50% treatment, compared to control. Such outcomes point towards a cost-effective approach for reducing Pb uptake by the plants via using MC and BR at a 50:50 ratio., (Copyright © 2020. Published by Elsevier Inc.)

A soil microcosm experiment was carried out to quantify the transfer of cadmium (Cd) and lead (Pb) in a multi-species soil system (MS·3). Red earth from Jiangxi (S1), fluvo-aquic soil from Henan (S2), fluvo-aquic soil from Beijing (S3), and black soil from Heilongjiang (S4) were used for soil column packing with S1, S3, or S4 as the 20-50 cm layer and S2, which was Cd- and Pb-contaminated, as the top 0-20 cm layer. For each soil combination, four treatments were set up: CK (no wheat and no earthworm), W (only wheat), E (only earthworm), and E + W (earthworm and wheat). The results showed that the coexistence of earthworm with wheat reduced Cd and Pb contents in wheat plants and earthworms, and increased plant biomass, but had no significant effect on the survival rate and mean weight change rate of earthworms. Total Cd and Pb decreased remarkably in the 0-20 cm layer while increased in the 20-50 cm layer, and approximately 32.8%-51.1% of Cd and 0.35%-7.0% of Pb migrated down into the 20-50 cm soil layers from the 0-20 cm soil layers. The migration varied between the treatments from S2 to S1, S2, and S3. In S2-S1 and S2-S4 columns, the amount of Cd migration decreased when the earthworms coexisted with wheat, while in S2-S3 column, there was no significant difference on such amount regardless of the coexistence of earthworms with wheat. Taken together, the results indicated that the migration of Cd and Pb was not only associated with wheat and earthworm, but also depended on soil types., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The inhalation of metal (including lead) nanoparticles poses a real health issue to people and animals living in polluted and/or industrial areas. In this study, we exposed mice to lead(II) nitrate nanoparticles [Pb(NO 3 ) 2 NPs], which represent a highly soluble form of lead, by inhalation. We aimed to uncover the effects of their exposure on individual target organs and to reveal potential variability in the lead clearance. We examined (i) lead biodistribution in target organs using laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS) and atomic absorption spectrometry (AAS), (ii) lead effect on histopathological changes and immune cells response in secondary target organs and (iii) the clearance ability of target organs. In the lungs and liver, Pb(NO 3 ) 2 NP inhalation induced serious structural changes and their damage was present even after a 5-week clearance period despite the lead having been almost completely eliminated from the tissues. The numbers of macrophages significantly decreased after 11-week Pb(NO 3 ) 2 NP inhalation; conversely, abundance of alpha-smooth muscle actin (α-SMA)-positive cells, which are responsible for augmented collagen production, increased in both tissues. Moreover, the expression of nuclear factor κB ( NF-κB ) and selected cytokines, such as tumor necrosis factor alpha ( TNFα ), transforming growth factor beta 1 ( TGFβ1 ), interleukin 6( IL-6 ), IL-1α and IL-1β , displayed a tissue-specific response to lead exposure. In summary, diminished inflammatory response in tissues after Pb(NO 3 ) 2 NPs inhalation was associated with prolonged negative effect of lead on tissues, as demonstrated by sustained pathological changes in target organs, even after long clearance period.

Organisms employ various enzymatic and non-enzymatic detoxification mechanisms to minimize the harmful effects of metal pollution in the terrestrial environment. We examined the effects of copper (Cu), lead (Pb) and their mixture (Cu + Pb) on glutathione (GSH), metallothionein (MTs), cytochrome P450 (CYP 450), carboxylesterase (CarbE), acetylcholinesterase (AchE) and glutathione S-transferase (GST) in Lycosa terrestris and Pardosa birmanica via two exposure routes, i.e., soil and food for 10, 20 and 40 days. The present results revealed that the accumulation of Cu and Pb in both spiders' species increase with exposure duration and depend on the route of exposure and type of metal. The activities of CarbE, GST, and MTs significantly increased with increasing metal body burden for all experimental treatments. The CYP 450 activity exhibited a significant time-dependent decrease with increasing Cu concentration in both species. The AchE activity was significantly inhibited on Pb exposure via soil and Cu + Pb exposure via both routes. The decrease in the level of GSH was measured on Cu + Pb exposure via both routes. Thus, all these enzymatic and non-enzymatic responses are sensitive to the metals tested and could serve as early warning indicators for assessing the effects of metal pollution in these species., (Copyright © 2020. Published by Elsevier B.V.)

Lead (Pb) is the second most toxic metal on Earth and is toxic to humans and other living things. In plants, Pb commonly inhibits growth when it is at a concentration in the soil of 30 mg/kg or more but several Pb tolerant plants have been reported. However, few studies have focused on plant response to Pb exposure, particularly at concentrations higher than 30 mg/kg. The assessment and evaluation of metal dose-dependent plant responses will assist in future phytoremediation studies. Therefore, this work documents the Pb concentration-dependent antioxidative response in Tetraena qataranse. Young seedlings were irrigated with 0, 25, 50, and 100 mg/L Pb every 48 h for seven weeks under greenhouse conditions. A phytotoxicity test showed that at the lowest treatment concentration, Pb stimulates growth. However, at 100 mg/L (1600 mg/kg Pb in the growth medium at harvest), the metal disrupted healthy growth in T. qataranse, particularly root development. Metal accumulation in the root was higher (up to 2784 mg/kg) than that of the shoot (1141.6 mg/kg). Activity assays of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR) showed a progressive increase in enzymatic activities due to Pb treatment. Together, the results of this study suggest that T. qataranse is a Pb hyperaccumulator. Increased antioxidant enzyme activity was essential to maintaining cellular homeostasis and assisted in the arid plant's tolerance to Pb stress.

The aim of this study was to summarise the available information regarding the partition of toxic metal (Cd, Hg, Mn, Pb) levels in the maternal/foetal unit from large epidemiological studies. We performed a systematic search of PubMed/MedLine, EMBASE, and ISI Web of Science for papers on Cd, total Hg, Mn or Pb levels in the maternal/cord blood that were published in English (n > = 200; 2010-2017). Data on year of publication, sample size, location, year of survey, and main results were extracted. We found a total of 35 papers. Most studies included large convenience samples of healthy pregnant women. The maternal/cord blood was properly used as a biomarker of prenatal exposure to toxic metals. The partition of these toxic metal levels in the maternal/foetal unit was metal-specific. Cd median levels (IQR) in cord blood reported worldwide were much lower [∼ 70 % < LOD = ± 0.11 μg/L] than those found in maternal blood [0.23 μg/L (0.15-0.35), ∼ 65 % > LOD]. Considering that Cd was under LOD in 70 % of the cord blood, Cd cord:maternal ratio as well as Cd cord proportion were not provided. Total Hg median levels (IQR) in cord blood [0.75 μg/L (0.40-1.19), ∼30 % < LOD = ±0.35 μg/L] were usually higher than in maternal blood [0.55 μg/L (0.40-0.85), ∼ 10 % < LOD = ±0.15 μg/L]. Hg cord:maternal ratio was 1.34 (1.00-1.91), and infants born would have Hg cord:(cord + maternal) proportion ranged from 0.50 to 0.63. Mn was the only metal that was detected in 100 % in both maternal (LOD : ±0.50 μg/L) and cord (LOD = ±0.2 μg/L) blood. Mn median levels (IQR) in cord blood [32.96 μg/L (26.90-40.10)] were 2 times higher than in maternal blood [14.01 μg/L (11.50-17.58)]. Mn cord:maternal ratio was 2.35 (1.09-3.80), and infants born would have Mn proportion ranged from 0.52 to 0.79. Pb median levels (IQR) in cord blood [5.79 μg/L (4.34-8.38), ∼ 5% < LOD : ±2.07 μg/L] were usually equal to or lower than those reported in maternal blood [8.07 μg/L (5.79-10.76), ∼ 1% < LOD = ±1.03 μg/L]. Pb cord:maternal ratio was 0.71 (0.59-0.96), and infants born would have Pb proportion ranged from 0.37 to 0.49. Globally, the results indicate that total Hg and Mn levels were lower in maternal blood but higher in cord blood. However, much greater variability was seen with Cd and Pb. At delivery, total Hg and Pb levels in maternal blood were strong predictors of cord blood levels. Our findings empty that understanding the partition, levels and correlations of toxic metals in the maternal/cord blood may help to elucidate the adverse effects of these metals on foetuses and neonates., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Tomato is the most widespread vegetable crop in the world. In Italy, tomatoes are mainly cultivated in the South and in the Campania region, precisely in the area called Agro Nocerino-Sarnese. This flatland is affected by an extreme level of environmental degradation, especially related to the Sarno River, where concentrations of Potential Toxic Elements (PTEs) have been found to be higher than the maximum permitted level. The aim of this study was to determine the PTEs uptake by roots and their translocation to the aerial parts of the plants of two cultivars of tomatoes (Pomodoro Giallo and San Marzano Cirio 3). To the purpose, samples of the two cultivars were grown both in pots with experimentally contaminated soil containing: Cr or Cd or Pb at extremely high concentrations and in pots with uncontaminated soils (control). Additionally, the antioxidant properties of the cultivars selected grown on uncontaminated/contaminated soils were assessed. The results showed that Cd was the contaminant that most significantly interfered with the growth of both cultivars of tomato plants, whereas Pb caused lower phenotypical damage. Cd translocation from root to the organs of tomato plants was observed in both cultivars. Specifically, the total amount of Cd found in stems and leaves was higher in the Pomodoro Giallo (254.4 mg/kg dry weight) than in the San Marzano Cirio 3 (165.8 mg/kg dry weight). Cd was the only PTE found in the fruits of both cultivars, with values of 6.1 and 3.9 mg/kg dry weight of Pomodoro Giallo and San Marzano Cirio 3, respectively. The fruits of tomato plants grown in PTEs-contaminated soil showed inhibition or stimulations of the radical scavenging activity compared to the fruits grown in uncontaminated soil. This study highlighted that, despite the relatively high experimental concentrations of PTEs, their translocation to the edible part was comparatively low or absent., Competing Interests: The authors have declared that no competing interests exist.

Trace metals are found naturally in soil. However, the increase in industrial and agricultural polluting activities has increased trace metal contamination and raised high concerns in the public health sector. The study was conducted on Origanum syriacum, one of the most consumed herbs in the Middle East, and was divided into three parts. (1) Pot experiment: to study the effect of Cd, Pb, or Ni levels in soil on their uptake by O. syriacum. (2) Field samples: collected from major agricultural regions in Lebanon to analyze Cd, Pb, and Ni concentrations in soil and leaves. (3) Sale outlets samples: to measure the levels of Cd, Pb, and Ni in O. syriacum tissues in the market. Results showed that there was a positive correlation between levels of Cd, Pb, and Ni in soil and those in O. syriacum tissues. None of the field samples contained Pb or Ni that exceeded the maximum allowable limits (MAL). Three samples collected from heavily poultry-manured soil contained Cd higher than the MAL. Samples collected from sale outlets did not exceed the MAL for Ni but two exceeded the MAL for Cd and one for Pb. Trace metal contamination is not a major concern in O. syriacum produced in Lebanon. Only one mixture sample from a sale outlet was higher in Pb than the MAL and three samples from heavily manured fields exceeded the MAL for Cd.

The lead was one of the main elements in the glazes used to colour ceramic tiles. Due to its presence, ceramic sludge has been a source of environmental pollution since this dangerous waste has been often spread into the soil without any measures of pollution control. These contaminated sites are often located close to industrial sites in the peri-urban areas, thus representing a considerable hazard to the human and ecosystem health. In this study, we investigated the lead transfer into the vegetation layer (Phragmites australis, Salix alba and Sambucus nigra) growing naturally along a Pb-contaminated ditch bank. The analysis showed a different lead accumulation among the species and their plant tissues. Salix trees were not affected by the Pb contamination, possibly because their roots mainly develop below the contaminated deposit. Differently, Sambucus accumulated high concentrations of lead in all plant tissues and fruits, representing a potential source of biomagnification. Phragmites accumulated large amounts of lead in the rhizomes and, considering its homogeneous distribution on the site, was used to map the contamination. Analysing the Pb concentration within plant tissues, we got at the same time information about the spread, the history of the contamination and the relative risks. Finally, we discussed the role of natural recolonizing plants for the soil pollution mitigation and their capacity on decreasing soil erosion and water run-off.

Sodium sulfide (Na 2 S) is usually used as an amendment in industrial sewage treatment. To evaluate the effects of Na 2 S on the growth of Robinia pseudoacacia (black locust), heavy metal immobilization, and soil microbial activity, the R. pseudoacacia biomass and nutrient content and the soil heavy metal bioavailability, enzyme activity, and arbuscular mycorrhizal (AM) fungal community were measured by a single-factor pot experiment. The Pb-Zn-contaminated soil was collected from a Pb-Zn mine that had been remediated by R. pseudoacacia for five years. Three pollution levels (unpolluted, mildly polluted, and severely polluted) were evaluated by the pollution load index. Na 2 S application increased the shoot biomass under severe and mild contamination. In soil, Na 2 S application decreased the bioavailable Pb and Zn contents under severe and mild contamination, which resulted in a decrease in the Pb and Zn content in R. pseudoacacia. However, Na 2 S application did not affect the total Pb content per plant and enhanced the total Zn content per plant because of the higher biomass of the plants under Na 2 S application. Increased phosphatase activity and increased available phosphorous content may promote the uptake of phosphorus in R. pseudoacacia. Moreover, Na 2 S application is beneficial to the diversity of AM fungi under mild and severe pollution. Overall, Na 2 S application has great potential for enhancing soil heavy metal immobilization, enhancing soil microbial activity, and improving the growth of R. pseudoacacia in polluted soils. Therefore, Na 2 S is suitable for use in Pb-Zn remediation to ameliorate environmental heavy metal pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Contamination of arable land with trace metals is a global environmental issue which has serious consequences on human health and food security. Present study evaluates the adsorption of cadmium (Cd) and lead (Pb) by using different quantities of composite of sepiolite, organic manure and lime (SOL) at field and laboratory scale (batch experiments). Characterization of SOL by SEM, EDS and FTIR spectroscopy revealed the presence of elemental and functional groups (hydroxyl, C⋯H and -COOH groups) on its surface. The field experiment was performed in a paddy field of gleysol having moderate contamination of Cd and Pb (0.64 mg kg -1 and 53.44 mg kg -1 ). Here, different rates of SOL (0.25, 0.5, 1, 1.5 and 2% w/w) were applied by growing low and high Cd accumulator rice cultivars. Application of SOL at 2% w/w showed considerable efficiency to increase soil pH (up to 19%) and to reduce available Cd (42-66%) and Pb (22-55%) as compared to the control. Moreover, its application reduced metal contents in roots, shoots and grains of rice by 31%, 36% and 72% (for Cd) and 41%, 81% and 84% (for Pb), respectively in low accumulator cultivar. Further, the batch sorption experiment was performed to evaluate the adsorption capacity of SOL in a wide range of contamination. Obtained sorption data was better fitted to the Langmuir equation. Our results highlight the strong efficiency of composite treatment for an enhanced in-situ metal immobilization under field and lab conditions. Further, applied treatments greatly reduced the metal contents in rice grains. In a nut shell, application of SOL in a contaminated gleysol should be considered for soil remediation and safe food production., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

California's Division of Occupational Safety and Health has initiated a process to update its standards for exposure to lead in workplaces. In support of this effort, the state's Office of Environmental Health Hazard Assessment evaluated the age-specific, bio-kinetic model of lead metabolism in humans, originally published by R.W. Leggett in 1993. This model was ultimately chosen for its physiologic realism and practicality in characterizing the relationship between air lead concentrations and blood lead levels in chronically exposed worker and its practicality in making necessary adjustments. Leggett's original model systematically under-predicts bone and blood levels in workers such that several adjustments to the parameters are needed to improve predictions for occupational exposure scenarios. The aim of this work is to incorporate new information about the bio-kinetics of lead in workers and to adjust the Leggett model to improve its predictions.The Leggett model was evaluated by comparing its predictions with information on lead concentrations in bone, blood, and urine from workers and other chronically exposed adults. Key model parameters were identified based upon a review of the relevant exposure assessment and modeling literature. Adjustments to the model parameters were made based on empirical evidence. They included reducing the level of lead in blood (BLL) where the rate of decrease in red blood cell binding begins and ends, lead accumulation rate in cortical bone, the rate of lead elimination in trabecular bone, and rate of lead transferred from diffusible plasma to urine. Regression methods and visual inspection of plotted data were used to assess the effect of adjustments on model predictions. When compared with the original, the adjusted Leggett model more accurately predicted lead concentrations observed in active and retired workers. Also, the adjusted Leggett model required less lead uptake to reach the same BLLs for BLLs less than 25 µg/dL and more time for BLLs to decline than the original Leggett model. These findings are important for defining an adequately protective occupational standard for lead exposure.

Agricultural production of Ligusticum chuanxiong Hort. is often affected by heavy metal pollution in soil, especially mixtures of cadmium (Cd) and lead (Pb). We assessed metal-induced phytotoxicity in L. chuanxiong by exposing the plants to soil treated with Cd, Pb, or Cd/Pb mixtures. A combined Cd/Pb treatment alleviated the inhibition in plant growth, photosynthesis, and secondary metabolite generation seen in single-metal exposures in three of the four combinations. Most combined Cd/Pb treatments resulted in preferential uptake of magnesium, copper, and nitrogen in underground plant parts and accumulation of phosphorus and calcium in aboveground plant parts, thereby leading to improvements in photosynthetic potential. Compared with single-metal exposures, combined Cd/Pb treatment significantly decreased the contents of Cd by 16.67%-40.12% and Pb by 10.68%-21.70% in the plant, respectively. At the subcellular level, the Pb presence increased the Cd percentage associated with cell wall from 64.79% to 67.93% in rhizomes and from 32.76% to 45.32% in leaves, while Cd reduced Pb contents by 9.36%-46.39% in the subcellular fractions. A combined Cd/Pb treatment decreased the contents of water- and ethanol-extractable metal forms and increased the contents of acetic acid- and hydrochloric acid-extractable forms. The lower toxic effects of the Cd/Pb mixture in L. chuanxiong were associated with photosynthetic potential, subcellular distribution, the chemical forms of Cd and Pb, and synthesis of secondary metabolites. These findings are useful for plant production strategies in soils contaminated by heavy metals., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Trace metal elements are significant stressors in urban areas. Their harmful effects on physiological parameters are demonstrated, but current laboratory studies are not representative of wild chronic exposure to a trace metal cocktail. Calcium can reduce the accumulation and toxicity of several metals, but soil acidification in cities leads to a decrease in bioavailability of this element. The objective of this study was to investigate the accumulation and toxicity of a trace metal cocktail representative of urban exposure on passerine birds, and test the importance of calcium availability on these toxic effects. We exposed zebra finches (Taeniopygia guttata) to a cocktail of seven metals and one metalloid in drinking water, with or without calcium supplementation. We monitored the concentration of metals in the blood and feathers, and their effects on oxidative status and telomere length. The metal cocktail led to higher concentration of all elements in the feathers, and of arsenic and lead in the blood. Birds with a higher concentration of cadmium, arsenic and lead in the feathers had shorter telomeres, but no impact of the cocktail was detected on oxidative status. Birds of the 'calcium' group and the 'calcium and metal' group accumulated higher concentrations of zinc, chromium and nickel in feathers. The 'calcium and metal' group also accumulated lower concentrations of arsenic and lead in feathers compared to the 'metal' group. Our results suggest that chronic exposure to a cocktail of metals at low concentrations has deleterious effects on birds, which can be limited through calcium intake., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Dwarf bamboo Sasa argenteostriata (Regel) E.G. Camus is considered as potential plants for metal phytoremediation in previous filed observations. However, the mechanisms of lead (Pb) detoxification has not been described. The objective of this study was to explore the difference strategies or mechanisms of Pb detoxification in plant tissues. In this regard, four Pb treatments with hydroponics including 0 (control), 300, 600, and 900 mg L -1 were conducted to examine subcellular compartmentalization, Pb accumulation/species and antioxidant-assisted chelation. Our findings showed the retention of Pb by the whip-root system is one of its detoxification mechanisms to avoid damage the shoots. In addition, the cell wall retention is the dominant detoxification strategy of whips, new roots, old roots and new/old stems, while vacuolar compartmentalization is for new/old leaves. Interestingly, four low-mobility/-toxicity Pb species (i.e., FNaCl, FHAc, FHCl and FR) are distributed in roots, whips and stems, while two high-mobility/-toxicity Pb species (FE and FW) in leaves. The conversion of Pb to low-toxicity/-migration is a Pb-detoxification strategy in roots, whips and stems but not in leaves. Besides, the new/old roots and leaves can alleviate Pb damage through the synthesis of non-protein thiol, glutathione and phytochelatins. Among these, phytochelatins play a leading role in the detoxification in new/old roots, while glutathione is in new/old leaves. This study provides the first comprehensive evidence regarding the different strategies for Pb detoxification in dwarf bamboo tissues from physiological to cellular level, supporting that this plant could be rehabilitated for phytoremediation in Pb-contaminated media., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

In this study, the predominant Pb minerals prior to and after Pb relative bioavailability (Pb-RBA) and Pb bioaccessibility (Pb-BAc) tests were identified using SEM (scanning electron microscopy), XANES (X-ray absorption near edge structure) and XRD (X-ray diffraction). The correlations between in vitro Pb-BAc (using the UBM (Unified BARGE Method) and RBALP (Relative BioAccessibility Leaching Procedure) models) and in vivo Pb-RBA (using endpoints of kidney and liver in an mice model) were determined. The results demonstrated that both RBALP and UBM (gastric phase) reliably indicate Pb-RBA (Pb-RBA). However, raising the solid:liquid ratio of the gastric phase of UBM is necessary to determine Pb-BAc if the soils contain total Pb >10,000 mg/kg. The comparison of Pb minerals prior to and after in vitro extractions demonstrated that the relatively soluble forms of Pb (PbSO 4 , PbO 2 and MgO Pb) start to dissolve than other forms of Pb minerals, suggesting there was no difference in Pb 2+ release between chemical-based (RBALP) and physiologically-based (UBM) models. The identification of the Pb minerals of Pb 5 (PO 4 ) 3 Cl and organically-complexed Pb in mice excreta demonstrated that a portion of Pb 2+ combined with food and humic acid to generate organically-complexed Pb in mice excreta, and that Pb 5 (PO 4 ) 3 Cl is not bioavailable., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aquatic environments contaminated by lead (Pb) are a problem in many regions of world. Since Pb has high toxicity, the identification of species for phytoremediation is important for the recovery of these areas. Thus, the phytoremediation potential of Panicum aquaticum Poir. (Poaceae) was evaluated. The anatomical and physiological responses of P. aquaticum were assessed under different concentrations of Pb [0.0, 0.5, 1.0, 2.0, 4.0, and 8.0 mM of Pb(NO 3 ) 2 ]. Plant growth, anatomy of roots and leaves, root uptake, root to shoot translocation, and the concentration and accumulation of Pb in organs were analyzed. Regarding leaf anatomy, Pb treatment led to changes in epidermis thickness, stomatal density, stomatal diameter, and sclerenchymal area. Endoderm thickness was increased at the highest concentrations of Pb, which may be related to reduced translocation and shoot accumulation. The roots of P. aquaticum presented increased absorption (2279 μg g -1 DW -1 of Pb). In conclusion, P. aquaticum was found to have potential for the phytoremediation of areas contaminated with Pb., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The effects of lead as a dietary pollutant remain a global public health concern that needs urgent resolution. Children are highly susceptible to the adverse outcomes of lead pollution, as even low levels of lead may cause irreversible damage to intellectual development. Since several sources of lead exposure are present in the environment, it is necessary to identify the attributable burden of lead-related diseases arising from different exposure sources. In the present study, we used epidemiological data from studies around the nation to estimate the burden of mild intellectual disability (MID) attributed to lead exposure sources by using disability-adjusted life years (DALYs). To this end, a dose-response approach was used and a model comprising three components was established: exposure, dose-response, and DALYs module. In Chinese children aged 0-6 years, blood lead levels (BLLs) of 5.34 ± 3.09 μg/dL resulted in a MID incidence rate of 12.84 cases per 1000 children, with an estimated burden of disease (BoD) of 42.23 DALYs per 1000 children. Owing to dietary lead exposure, 36.64 healthy life years per 1000 children were lost, which was notably higher than the outcomes associated with exposure from other sources. This was consistent with the result that dietary exposure was the main contributor to children's lead exposure, accounting for 86.76%. According to the regional distribution based on the existing literature, the areas in China with higher BLLs were Heilongjiang, Shanxi, and Jiangxi. Our findings provided the information for lead risk management decisions and policies making., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier Ltd.)

Objective: This study aims to observe the effect on urine and sweat excretion levels of cadmium (Cd) and lead (Pb) in healthy men in a maximum incremental test until exhaustion and repeated exposure to heat., Methods: twenty-nine adult men divided into control group (CG; n = 14) and experimental group (EG; n = 15) performing two maximum tests until exhaustion in normothermia (22 °C) and hyperthermia (42 °C). EG experienced 9 sessions of heat exposure at high temperatures (100 °C) (HEHT). After the nine sessions, the initial tests were repeated in both groups. Urine samples were collected before and after each test. After the hyperthermia tests, sweat samples were gathered., Results: Urinary Cd increased after initial tests in GC and in hyperthermia in EG (p < 0.05). Urinary excretion of Pb rose after HEHT (p < 0.05). Pb in sweat was higher in EG than in CG after HEHT (p < 0.05)., Conclusion: Heat exercise and constant exposure to heat can be a valid method to increase the excretion of toxic metals., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Environmental metal exposure during pregnancy can affect intrauterine growth and disrupt child development. Metal exposure in urban areas can occur through the air, water and food routes. The city of Rio de Janeiro is the second more populous of Brazil and the sixth most populous in the American continent and is characterized by a significant social-economic inequality and a large range of urban organization problems., Objectives: To evaluate environmental heavy metal (arsenic, cadmium, lead and mercury) exposure in mother-newborns pairs in an urban area in Rio de Janeiro, Brazil., Methods: All pregnant women, over 16 years of age, who came to the University Maternity School for newborn delivery orientation, between October and November 2017, were invited to participate in the project. Socioeconomic, cultural, leisure, and living conditions data of from the parents were collected via questionnaire; whole maternal blood and umbilical cord blood samples were also collected., Results: Of the 209 eligible pregnant women 142 (68%) accepted the invitation to participate in the study. A total of 131 (92.3%) mothers delivered live born children, and maternal blood and umbilical cord blood were collected from 117 mother-newborn pairs. Metal concentrations above the detection limit were detected in all maternal and cord blood samples. Strong correlations of arsenic, cadmium, lead and mercury concentrations between maternal and umbilical cord blood were observed. Median lead and arsenic concentrations in maternal and umbilical cord blood were higher than values reported in other studies conducted in Brazil and worldwide. Lead concentrations in 25% of the umbilical cord blood samples were near of 5 μg/dL (P75 = 4.92 μg/dL)., Conclusion: The results reported herein indicate the need for the establishment of health surveillance programs in Brazil, in order to investigate and monitor the health effects of environmental heavy metal exposure in children since the gestation period., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Despite extensive research progress in the recent past, the data regarding foliar uptake of heavy metals, associated biophysiochemical changes inside plants and possible health hazards are limited. This study determined the effect of foliar application of lead oxide nanoparticles (PbO-NPs) on lead (Pb) accumulation, physiological and biochemical changes inside spinach plants and associated health risks. A green method was used to prepare PbO-NPs using coconut water. Scanning electron microscopy (SEM) showed the preparation of smooth, unwrinkled, granular and spherical PbO-NPs. Spinach leaves were exposed via foliar application to three concentrations of PbO-NPs (0, 10 and 50 mg/plant). Foliar PbO-NPs application resulted in a significant accumulation of Pb in leaves (42.25 μg g -1 ), with limited translocation towards root tissues (4.46 μg g -1 ). This revealed that spinach can accumulate considerable amount of Pb via foliar uptake. Lead accumulation inside spinach caused a significant decrease in pigment contents (38%) and dry weight (67%). After foliar uptake, Pb caused several-fold increase in the activities of catalase and peroxidase. However, foliar PbO-NPs did not induce significant changes in H 2 O 2 production, lipid peroxidation and superoxide dismutase activity. Application of PbO-NPs (50 mg/plant) showed possible health risks (non-carcinogenic) due to ingesting Pb-contaminated leaves of spinach. It is proposed that atmospheric contamination and foliar deposition of metal-PM can seriously affect vegetable growth and can provoke health issues due to ingestion of metal-enriched vegetables. Therefore, atmospheric levels of heavy metals need to be monitored on a regular basis to avoid their food chain contamination and possible human exposure., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this article., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Hen eggs contaminated with lead can be harmful to the health of children and adults. The objective of this pilot study was to investigate if sub-chronic treatment with ascorbic acid can reduce lead levels in the different parts of hen eggs after intentionally exposing the laying hens to a concentrated source of lead., Methods: Clinically normal mixed-breed egg laying hens (n = 18) were used in this pilot study. Hens were exposed to a concentrated source of lead (200 mg/kg body weight /day lead acetate) for 1 week. Subsequently, egg laying hens were either treated with sub-chronic doses of ascorbic acid (500 mg/kg body weight /day) or left untreated for 4 weeks. Lead levels were assessed in egg-shell, egg-albumen, and egg-yolk samples using a graphite furnace atomic absorption spectrophotometer., Results: Lead levels increased significantly (p-value < 0.01) from baseline in egg-yolk, egg-albumen, and egg-shell samples following 1 week exposure to lead acetate. Sub-chronic treatment of egg laying hens with high doses of ascorbic acid could bring statistically significant reduction (p-value < 0.01) in lead levels in egg-yolk, egg-albumen, and egg-shell samples after intentional exposure to a concentrated source of lead., Conclusions: Findings of this pilot study showed that sub-chronic treatment of egg laying hens with ascorbic acid can reduce lead levels in different egg parts after intentional exposure to a concentrated source of lead. Supplementing feedstuffs and water with sources of ascorbic acid could be beneficial in reducing lead levels in hen egg tissues following environmental exposure. Further studies are still required to investigate if ascorbic acid can reduce lead levels in other chicken tissues.

Evaluation of the transportation of heavy metals in food chain has received a great deal of attention. In this study, the mobility of cadmium (Cd) and lead (Pb) in soil-mulberry-silkworm system was assessed. The results showed that bioconcentration factors for Cd and Pb were lower than 1 for all the three mulberry cultivars. Higher translocation factors (TFs) were observed in the levels from branch to leaf, larvae to excrement. The BCFs of Pb in root and silkworm excrement were higher than those in the other parts. Meanwhile, most of Cd accumulated from soils located in the root (48.00-54.40%) and only about 10% was in the leaf. But the Cd and Pb had significant effects on the ratios of cocoon shell with Yuesang 11 under different planting densities. For Yuesang 11 and Qiangsang 1, the Pb percentages were roots > branches > leaves > stems. The rates of ingestion (IR) and digestion (DR) were a little higher than those in the control at first and then decreased gradually with time. The IR reached the lowest values on 8th day while the DR arrived at the highest. Planting mulberry and raising silkworm could be a reasonable method for the utilization of heavy metal contaminated paddy soils., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Ulcerative dermatitis in laboratory mice remains an ongoing clinical problem and animal welfare issue. Many products have been used to treat dermatitis in mice, with varying success. Recently, the topical administration of healing clays, such as bentonite and green clays, has been explored as a viable, natural treatment. We found high concentrations of arsenic and lead in experimental samples of therapeutic clay. Given the known toxic effects of these environmental heavy metals, we sought to determine whether the topical administration of a clay product containing bioavailable arsenic and lead exerted a biologic effect in mice that potentially could introduce unwanted research variability. Two cohorts of 20 singly housed, shaved, dermatitis free, adult male CD1 mice were dosed daily for 2 wk by topical application of saline or green clay paste. Samples of liver, kidney and whole blood were collected and analyzed for total arsenic and lead concentrations. Hepatic and renal concentrations of arsenic were not different between treated and control mice in either cohort; however, hepatic and renal concentrations of lead were elevated in clay treated mice compared to controls in both cohorts. In addition, in both cohorts, the activity of δ-aminolevulinate acid dehydratase, an enzyme involved with heme biosynthesis and a marker of lead toxicity, did not differ significantly between the clay-treated mice and controls. We have demonstrated that these clay products contain high concentrations of arsenic and lead and that topical application can result in the accumulation of lead in the liver and kidneys; however, these concentrations did not result in measurable biologic effects. These products should be used with caution, especially in studies of lead toxicity, heme biosynthesis, and renal α2 microglobulin function.

Despite the global importance of atmospheric heavy metal input into agricultural soils, research has primarily focused on the amount of the depositions with limited attention given to the risk of the newly deposited heavy metals. To understand the remobilization of the newly deposited copper (Cu) and lead (Pb) from the atmosphere and explore the metals' mobility and bioavailability to rice (Oryza sativa L.), a soil transplant experiment was conducted in three areas along a gradient of atmospheric depositions. Approximately 61% of the Cu and 76% of the Pb depositions tended to be present in potentially mobile fractions. The soil retention of newly deposited Cu and Pb presented as higher mobile fractions than these in the original soil. The newly deposited Cu and Pb in soils only accounted for 0.34-8.7% and 0.07-0.29% of the total soil Cu and Pb pools, but they contributed 30-84% and 6-41% in rice tissues, respectively. A major implication of these findings is that once the heavy metal is deposited, it may be reactivated in soils and transported to aerial parts or foliar uptake into plant tissues, emphasizing the important role of the newly deposited Cu and Pb in contributing to the edible parts of crops., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Many studies have used grit (in the form of lead (Pb) pellets) presence in avian gizzards as an indicator of Pb shot exposure. However, due to nearly complete pellet absorption in gizzards or rapid passage of pellets, the absence of Pb shot presence in a gizzard does not confirm lack of Pb shot exposure. This study provides the basis for an additional technique to identify if elevated tissue Pb concentration is due to Pb shot exposure. Bioaccessibility of Pb and trace elements (Sb, As, and Sn) present in Pb shot were quantified to determine if any of these elements would be useful as a secondary marker of Pb shot exposure. An avian physiologically based extraction test (PBET) was used to determine pellet dissolution rate and bioaccessible concentrations of Pb, Sb, As, and Sn in a simulated gizzard environment. Of the three trace elements, only Sb concentrations (44-302 μg/mL) extracted into the gizzard solution were greater than environmental background levels (US soil average 0.48 μg/g); thus, no natural source likely provides this amount of Sb. Therefore, there is evidence that Sb can be extracted from Pb shot in bird gizzards at detectable concentrations (above natural background). While further studies are needed to delineate the mechanisms of absorption and distribution, this study lends credence to the hypothesis that Sb may be a useful marker of Pb shot exposure in biological tissues, particularly when Pb pellets are not present nor observed in avian tissues., Competing Interests: The authors have declared that no competing interests exist.

Along with non-biodegradability and accumulation in agricultural soil, lead (II) ions exert considerable harmful effects on plants even at trace amount, especially for the oxidative damages elicited by the lead ions-induced excessive reactive oxygen species (ROS). The glutathione peroxidases were reported to be correspondent with the oxidative stress induced by heavy metals. However, limited data are available about the potential hazardous mechanisms of the lead ions-induced oxidative damage to plants at molecular level. In this study, the harmful impacts of lead ions on Arabidopsis thaliana glutathione peroxidase 6 (AtGPX6) were assessed based on multi-spectroscopic measurements and molecular docking study. The characteristic fluorescence of AtGPX6 was quenched by lead ions with static mechanism at different temperatures. AtGPX6 exhibits a single binding site with lead ions, and then the complex formation was mainly driven by hydrogen bonding interaction and van der Waals forces on account of the negative ΔH and ΔS. The secondary structural changes were observed from the synchronous fluorescence, UV-visible absorption and Circular dichroism spectra, which led to loosen and unfold of the protein framework accompanied by the incremental hydrophobicity around the vicinity of the tryptophan residues. Therefore, this work illustrates the detailed binding mode between lead (II) ions and glutathione peroxidase 6 from Arabidopsis thaliana and the toxic effects on antioxidative defense system induced by lead ions at molecular level., (Copyright © 2019. Published by Elsevier B.V.)

Although there are a number of computational approaches available for the aqueous solubility prediction, a majority of those models rely on the existence of a training set of thermodynamic solubility measurements or/and fail to accurately account for the lattice packing contribution to the solubility. The main focus of this study is the validation of the application of a physics-based aqueous solubility approach, which does not rely on any prior knowledge and explicitly describes the solid-state contribution, in order to guide the improvement of poor solubility during the lead optimization. A superior performance of a quantum mechanical (QM)-based thermodynamic cycle approach relative to a molecular mechanical (MM)-based one in application to the optimization of two pharmaceutical series was demonstrated. The QM-based model also provided insights into the source of poor solubility of the lead compounds, allowing the selection of the optimal strategies for chemical modification and formulation. It is concluded that the application of that approach to guide solubility improvement at the late discovery and/or early development stages of the drug design proves to be highly attractive.

The present experiment was conducted to derive equations for predicting daily lead (Pb) intake and tissue Pb concentrations in broiler chickens using feather Pb concentrations. A total of 800 3-day-old broiler chickens were allotted to one of five dietary treatments with 16 replicates, each replicate consisting of 10 birds, in a completely randomized design. Dietary Pb concentrations were set to 0, 50, 100, 200, or 400 mg/kg by adding a lead acetate. The experimental diets were provided ad libitum for 32 days. Results indicated that growth performance and serum measurements were not affected by increasing concentrations of Pb in diets, which represented that the toxic level of dietary Pb may exceed over 400 mg/kg in broiler diets. Increasing concentrations of Pb in diets increased Pb concentrations in the liver (linear and quadratic, P < 0.05), breast (linear, P < 0.01), and feather (linear, P < 0.01). Feather Pb concentrations were greater than Pb concentrations in the liver and breast, indicating that the feather is highly responsive tissue of broiler chickens to various dietary Pb concentrations. Consequently, the equations for predicting daily Pb intake and Pb concentrations in the liver and breast were derived from Pb concentrations in the feather. Resulting equations indicated that feather Pb concentrations in broiler chickens can be used to predict both daily Pb intake and Pb concentrations in the liver and breast.

Microorganisms with the function of bio-mineralization were isolated from a soil. They were identified as urease-producing bacteria and phosphate-solubilizing bacteria. These two kinds of bacteria belong to the eosinophilic bacteria, which regulated the pH of solution and removed Pb 2+ the best at the initial solution pH of 4. The Pb 2+ removal mechanism was further explored using various techniques including zeta potential measurement, three-dimensional fluorescence, FTIR, XRD, and TEM-EDS. The results showed that extracellular adsorption, intracellular accumulation and bio-mineralization occurred at the same time and converted to each other. The extracellular adsorption of urease-producing bacteria was through electrostatic adsorption and gradually decomposed urea to produce PbCO 3 minerals. The extracellular adsorption of phosphate-solubilizing bacteria was controlled by extracellular polymeric substances (EPS) and rapidly formation of Pb 3 (PO 4 ) 2 stable minerals. In addition, the stabilities of Lead minerals of the two strains were compared. The results showed that the precipitates of phosphate-solubilizing bacteria were more stable. While phosphate-solubilizing bacteria have some advantages, both strains can play important roles in bio-mineralization of HMs in acidic wastewater., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In order to assess and optimize frequently used in vitro inhalation bioaccessibility procedures for heavy metals in the inhalation risk assessment, in vivo inhalation bioavailability of Pb in simulated atmosphere fine particles (PM 2.5 ) from aging soils spiked with lead compounds and field soils in lead-zinc mining areas was investigated via intranasally instilled experiments with these PM 2.5 suspensions to mice and Pb bioaccessibility was extracted by using four frequently used in vitro procedures (Gamble Solution, simulated lung fluid, simulated epithelial lung fluid and artificial lysosomal fluid). Mouse exposure experiments showed that Pb was mainly distributed in the liver, kidneys, blood and spleen. Based on the kidney model, in vitro inhalation bioaccessibility of Pb extracted with optimized Gamble Solution, in which solid to liquid ratio (S/L) was optimized to 1:1000 g ml -1 and DTPA was proved to be the key effective component, showed a strong linear relationship with its in vivo inhalation bioavailability (y = 1.07x - 3.86, R 2  = 0.73). Moreover, in vitro bioaccessible and bioavailable fractions of Pb were mainly from acid exchangeable and reducible fractions of Pb in PM 2.5 . Altogether, optimized Gamble Solution was suggested for the analysis of in vitro bioaccessibility for risk-based assessments., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A greenhouse pot experiment was conducted to evaluate the effect of biochar on the growth and uptake of Pb and Zn by tomato plants ( Solanum lycopersicum, L.) cultivated in two highly contaminated Kosovo soils, A and B. Plants were cultivated in the biochar amended and unamended soils. As expected, the biochar addition to the two polluted soils has contributed to significantly improve the crop yields, in terms of both fresh and dry weight. Further, results indicated that the effect of biochar on metal mobility is closely related, besides its properties, to soil's native characteristics. In fact, the addition of biochar to soil B had also beneficial effects on the uptake of both metals, halving in some cases the values of the biological accumulation and transfer coefficients, while it did not show the same efficacy on soil A.

Pot experiments were conducted under abiotic conditions to investigate the interactive influence of decabromodiphenyl ether (BDE-209) and lead (Pb) on the seed germination, germ length, root exudation and physiological characteristics of tall fescue (Festuca arundinaceae), and the uptake, accumulation of Pb and BDE-209 in the plant tissues. Results show that seed germination and germ length were impacted by Pb but less influenced by BDE-209. BDE-209 spiking (10 and 50 mg/L) could alleviate the toxicity of high Pb concentration on seed germination and growth. The chlorophyll content was significantly increased at 500 mg/kg Pb but declined at 2000 mg/kg Pb. Low-level Pb contamination (500 mg/kg) activated antioxidase activity; however, 2000 mg/kg Pb significantly reduced the antioxidase activity. Plant biomass slightly decreased at 500 mg/kg Pb but significantly declined at 2000 mg/kg Pb. The addition of a moderate dosage of BDE-209 (10-50 mg/kg) lessened Pb phytotoxicity, leading to improved plant growth relative to the case of Pb spiking alone. The exudate secretion was significantly enhanced by Pb addition, but BDE-209 spiking only caused slightly increased secretion. Pb could interfere with BDE-209 adsorption and translocation of tall fescue by affecting physiological behavior of the plant, but BDE-209 exhibited little influence on the Pb fate in the plant. Overall, BDE-209 had slight interference on the impact of Pb towards tall fescue. The results demonstrate the complex interactive effects of organic pollutants and heavy metals in the soil-plant system., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Lead can be immobilized in contaminated soils by phosphate rock (PR) amendment, but its efficiency is generally limited by low solubility of PR. Our study aimed to elucidate whether phosphate solubilizing bacteria (PSB) can promote Pb immobilization through PR solubilization. Results showed that P. ananatis HCR2 and B. thuringiensis GL-1 could effectively solubilize PR by producing citric, glucose, and α-Ketoglutaric acids. In broth assay, phosphate solubilized from PR by PSB rapidly reacted with Pb 2+ and formed insoluble lead compounds, as confirmed by scanning electron microscope, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Pot experiment using lettuce (Lactuca sativa L.) and diffusive gradients in thin films (DGT) verified the effectiveness of soil remediation using PR amendment and PSB inoculation, as plant shoot biomass and net photosynthetic rate as well as soil bioavailable phosphate concentration have significantly increased, while the phytoavailability of Pb, Cd, and Zn greatly reduced. This study suggested that PR amendment combined with PSB inoculation could be applied for remediation of agricultural fields contaminated with multiple heavy metals., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Better understanding of microbial activity in the rhizosphere soils associated with lead (Pb) uptake by plants may help with the phytoremediation of Pb-contaminated soils. In this work, the effects of Pb exposure (0, 200, 400, 600, 800 mg kg -1 ) on Pb accumulation and soil microbial activity in the rhizosphere of the mining ecotype (ME) and corresponding non-mining ecotype (NME) of Athyrium wardii (Hook.) Makino were investigated through a pot experiment. Although the plant growth of the two ecotypes was inhibited under Pb stress, the ME showed a less biomass decrease (12.6-44.0%) for aboveground than the NME, showing a greater tolerance to Pb stress. Pb concentrations as well as Pb accumulation in the two ecotypes showed an increasing trend with increasing soil Pb concentrations. The ME presented greater Pb accumulation ability than the NME, especially in underground parts. Pb availability in the rhizosphere soils of the two ecotypes after harvest decreased compared with those before transplantation. Available Pb in the rhizosphere of the ME was 1.4-4.8 times higher than that of the NME under exposure to 200-800 mg kg -1 Pb. The ME shows a greater ability to mobilize Pb in the rhizosphere soils. Pb exposure resulted in an inhibition of microbial activity in the rhizosphere of the two ecotypes. The ME demonstrated greater soil respiration and microbial biomass carbon (MBC) in the rhizosphere than the NME when treated with 200-800 mg kg -1 Pb. The ME showed a less decrease for MBC and a less increase for metabolic quotient in the rhizosphere soils than the NME when exposed to Pb generally. Microorganisms in the rhizosphere soils of the ME seem to be much more adapted to Pb stress, thus showing a great benefit for Pb accumulation and the phytostabilization of Pb-contaminated soils by the ME.

The present study was designed to evaluate in vivo the oral bioavailability of lead (Pb) present in the marine bivalve Dosinia exoleta. This infaunal clam, despite inhabiting in clean areas, presents Pb concentrations that are over the 1.5 mg kg -1 wet weight limit for human consumption set by the European Commission. However, Pb is accumulated in this clam in the form of metal rich granules, and it has been shown to be unavailable for trophic transfer to a marine decapod, so it was hypothesised that it might be unavailable for human consumers as well. Twelve Sprague Dawley rats were fed during 14 days with a diet including control mussels (Mytilus galloprovincialis), D. exoleta, or mussels enriched in Pb to the same levels as those found in D. exoleta. Pb accumulation in different rat tissues (blood, bone, kidneys and liver) was analysed. It was observed that Pb assimilation from D. exoleta was about half of Pb assimilation from M. galloprovincialis, and absolute bioavailabilities were around 2% for M. galloprovincialis and 1% for D. exoleta. These results suggest that it might be possible to increase the limit for human consumption for this bivalve to 3 mg kg -1 wet weight without representing an increase in the risk for consumers., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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(NO 3 ) 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 F v /F o , F v /F m , ψEo, φEo, RC/ABS, and PI abs . 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., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Lead is a naturally-occurring element. It has been known to man for a long time, and it is one of the longest established poisons. The current consensus is that no level of lead exposure should be deemed "safe". New evidence regarding the blood levels at which morbidities occur has prompted the CDC to reduce the screening guideline of 10 μg/dl to 2 μg/dl. Measurable cognitive decline (reduced IQ, academic deficits) have been found to occur at levels below 10 μg/dl, especially in children. Knowledge of lead pharmacology allows us to better understand its absorption and metabolization, mechanisms that produce its medical consequences. Based upon an original and very simplified compartmental model of Rabinowitz (1973) with only three major compartments (blood, bone and soft tissue), extensive biophysical models sprouted over the following two decades. However, none of these models have been specifically designed to use new knowledge of lead molecular dynamics to understand its deleterious effects on the brain. We build and analyze a compartmental model of lead pharmacokinetics, focused specifically on addressing neurotoxicity. We use traditional phase space methods, parameter sensitivity analysis and bifurcation theory to study the transitions in the system's behavior in response to various physiological parameters. We conclude that modeling the complex interaction of lead and calcium along their dynamic trajectory may successfully explain counter-intuitive effects on systemic function and neural behavior which could not be addressed by existing linear models. Our results encourage further efforts towards using nonlinear phenomenology in conjunction with empirically driven system parameters, to obtain a biophysical model able to provide clinical assessments and predictions.