Lead toxicity: a review

Calixresorcin[4]arene-Mediated Transport of Pb(II) Ions through Polymer Inclusion Membrane

A facilitated transport of Pb(II) through polymer inclusion membrane (PIM) containing 1,8,15,22-tetra(1-heptyl)-calixresorcin[4]arene and its tetra- and octasubstituted derivatives containing phosphoryl, thiophosphoryl or ester groups as an ion carrier was investigated. The efficiency of Pb(II) removal from aqueous nitrate solutions was considered as a function of the composition of membrane (effect of polymer, plasticizer, and carrier), feed (effect of initial metal concentration and presence of other metal ions) and stripping phases, and temperature of the process conducting. Two kinetic models were applied for the transport description. The highest Pb(II) ions removal efficiency was obtained for the membrane with tetrathiophosphorylated heptyl-calixresorcin[4]arene as an ion carrier. The activation energy value, found from Eyring plot to be equal 38.7 ± 1.3 kJ/mol, suggests that the transport process is controllable both by diffusion and chemical reaction. The competitive transport of Pb(II) over Zn(II), Cd(II), and Cr(III) ions across PIMs under the optimal conditions was also performed. It was found that the Cr(III) ions’ presence in the feed phase disturb effective re-extraction of Pb(II) ions from membrane to stripping phase. Better stability of PIM-type than SLM-type membrane was found.

Evaluation of Analytes Characterized with Potential Protective Action after Rat Exposure to Lead

Lead (Pb) was revealed for its role as a neurodevelopmental toxin. The determination of neurotransmitters (NTs) in particular brain regions could ameliorate the precise description and optimization of therapeutic protocols able to restore the harmony of signaling pathways in nervous and immune systems. The determination of selected analytes from the group of NTs based on the liquid chromatography (LC)-based method was carried out to illustrate the changes of amino acid (AA) and biogenic amine (BA) profiles observed in chosen immune and nervous systems rat tissues after Pb intoxication. Also, a protective combination of AA was proposed to correct the changes caused by Pb intoxication. After the administration of Pb, changes were observed in all organs studied and were characterized by a fluctuation of NT concentrations in immune and nervous systems (hypothalamus samples). Using a protective mixture of bioactive compounds prevented numerous changes in the balance of NT. The combined analysis of the immune and nervous system while the normalizing effect of curative agents on the level of differentially secreted NTs and AA is studied could present a new approach to the harmonization of those two essential systems after Pb intoxication.

Nanomaterial-based fluorescent sensors for the detection of lead ions

Lead (Pb) poisoning has been a scourge to the human to pose sighnificant health risks (e.g., organ disorders, carcinogenicity, and genotoxicity) as observed from many different parts of the world, especially in developing countries. The demand for accurate sensors for its detection, especially in environmental media (soil, water, food, etc.) has hence been growing steadily over the years. The potential utility of fluorescent nanosensors as an important analytical tool is recognized due to their astonishing characteristics (e.g., high sensitivity/selectivity, enhanced detection performance, low cost, portability, and rapid on-site detection ability). This review is organized to offer insight into the recent developments in fluorescent nanosensing technology for the detection of lead ions (Pb²⁺). To this end, different types of nanomaterials explored for such applications have been classified and evaluated with respect to performance, especially in terms of sensitivity. This review will help researchers gain a better knowledge on the status and importance of optical nanosensors so as to remediate the contamination of lead and associated problems. The technical challenges and prospects in the development of nanosensing systems for Pb²⁺ are also discussed.

Environmentally Benign Synthesis and Color Tuning of Strontium-Tantalum Perovskite Oxynitride and Its Solid Solutions

A facile method was successfully developed to prepare strontium-tantalum perovskite oxynitride, SrTaO₂N, and its solid solutions. Urea was employed as a solid nitriding agent to eliminate the use of toxic NH₃ gas. In addition, utilization of sol-gel-derived Ta₂O₅ gel as a Ta precursor allowed for completion of nitridation within a shorter period and at a lower calcination temperature compared with the conventional ammonolysis process. Optimization of the reaction conditions, such as the urea content, allowed for the production of solid solutions of SrTaO₂N and Sr_1.4Ta_0.6O_2.9. The products exhibited optical absorption and chromatic colors because of the narrower band gaps of oxynitrides compared with those of oxides. The O/N ratios of the solid solutions were easily adjusted by varying the amount of urea in the mixture of precursors. As a result, the colors of the products ranged from yellow to brown. The nitridation process and products developed in this study are interesting environmentally benign alternatives to conventional inorganic pigments.

Alterations in gene expression due to chronic lead exposure induce behavioral changes

Lead (Pb) is a pollutant commonly found in the environment, despite the implementation of public health policies intended to remove it. Due to its chemical characteristics as a divalent ion, Pb interacts with cells, enzymes, and tissues, causing pathological, physical, and behavioral alterations. Recent biotechnological advances have helped us to understand the mechanisms underlying the damage caused by Pb in human populations and in experimental models, and new evidence on the epigenetic alterations caused by exposition to environmental Pb is available. It is known that Pb exposure impacts on behavior (causing aggressiveness, anxiety, and depression), leading to learning deficit and locomotor activity alterations, and its presence has been linked with the abnormal release of neurotransmitters and other biochemical changes involved in these disorders. Still, further reductionist studies are required to determine the effects of Pb exposure on DNA and protein expression and understand the processes underlying the diseases caused by Pb. This will also indicate possible therapeutic targets to offset the negative effects of the heavy metal. By elucidating the epigenetic changes involved, it would be possible to manipulate them and propose novel therapeutic approaches in this area. This review is aimed to provide an overview of studies that link Pb exposure to behavioral changes, as well as biochemical and epigenetic alterations at a neurotransmitter level, considering the importance of this metal in behavior abnormalities.

Subacute exposure to lead promotes disruption in the thyroid gland function in male and female rats

Exposure to heavy metals, such as lead, is a global public health problem. Lead has a long historic relation to several adverse health conditions and was recently classified as an endocrine disruptor. The aim of this study was to investigate the effects of subacute exposure to lead on the thyroid gland function. Adult male and female Wistar rats received a lead acetate solution containing 10 or 25 mg/kg, by gavage, three times a week, for 14 days. One week later, behavioral testing showed no alterations in anxiety and motor-exploratory parameters, as evaluated by Open-Field and Plus-Maze Tests, but impairment in learning and memory was found in the male 25 mg/kg lead-treated group and in both female lead-treated groups, as evaluated by the Inhibitory Avoidance Test. After one week, serum levels of tT3 were reduced in the 25 mg/kg female group and in the 10 mg∕ kg male group. However, tT4 levels were increased in the 25 mg/kg male group and in both female treated groups. TSH levels did not change and lead serum levels were undetectable. Morphologic alterations were observed in the thyroid gland, including abnormal thyroid parenchyma follicles of different sizes, epithelial stratification and vacuolization of follicular cells, decrease in colloid eosinophilia and vascular congestion, accompanied by morphometric alterations. An increase in collagen deposition was also observed. No differences were observed in TPO activity or protein expression, H₂O₂ generation by NADPH oxidases or hepatic D1 mRNA expression. However, thyroid NIS protein expression was considerably decreased in the male and female lead-treated groups, while TSHr expression was decreased in the 25 mg/kg female lead-treated group. These findings demonstrated that subacute exposure to lead acetate disrupts thyroid gland function in both sexes, leading to morphophysiological impairment and to changes in learning and memory abilities.

Adaptive epigenetic response of glutathione (GSH)-related genes against lead (Pb)-induced toxicity, in individuals chronically exposed to the metal

It is well known that one of the most outstanding adverse effects related to lead (Pb) exposure is oxidative stress; moreover, recent findings suggest that disturbances of the redox status of cells are associated with epigenetic responses, and metabolism of glutathione (GSH) plays an important role in this process. This study aimed to assess Pb exposure on % methylation of GSH-related genes' promoter regions (%CH₃-CpG) and their influence on biomarkers of oxidative stress, in workers exposed to the metal. One hundred nine male workers participated in the study; ICP-MS determined blood lead levels (BLL); biochemical parameters related to redox status, named GSH, glutathione peroxidase (GPX) and glutathione-S-transferase (GST) were quantified by UV/Vis spectrophotometry. Determination of %CH₃-CpG of genes GCLC, GPX1, GSR, and GSTP1 were done by pyrosequencing. Inverse associations were seen between BLL and %CH₃-CpG-GCLC, and %CH₃-CpG-GSTP1. Moreover, metal exposure did not impact GSH, GPX, and GST; however, negative associations were observed between %CH₃-CpG-GPX1 and %CH₃-CpG-GSTP1, and the activities of GPX and GST, respectively. Taken together, our results give further evidence about adaptive epigenetic response to avoid oxidative damage induced by Pb exposure, allowing a better understanding of the molecular mechanisms related to the metal toxicity.

[Lead in drinking water-an old problem, a new EU directive]

BACKGROUND

Lead pipes have been used in drinking water installations for a long time. Only since 1973 have their use in new buildings been strongly discouraged; nevertheless, they are still found in old buildings. Furthermore, lead-containing alloys are still used today in components such as fittings. This results in an avoidable pollution of drinking water. The health significance of this pollution is acknowledged by a reduction of the currently valid limit value from 10 µg/l to 5 µg/l by the new EU drinking water directive passed in 2020. This directive provides for a transition period of 15 years.

OBJECTIVES

The relevance of a stricter limit value for lead in drinking water will be evaluated based by the results of routine analyses, and the necessary public health measures to prevent exposure of vulnerable groups will be formulated.

MATERIAL AND METHODS

A retrospective analysis of routine samples from the city of Bonn, which an accredited drinking water laboratory had examined in the years 1997-2019, was performed.

RESULTS

Of the 16,060 samples analyzed, 75.36% were below the quantitative limit of quantification. The median of the quantifiable samples was above the future limit for lead in drinking water in each year considered. No effect of the last transition period of 10 years (2003-2013) could be detected.

DISCUSSION

Even though no systematic studies on lead pollution in German municipalities are available, the subject is still highly topical. Lead exposure from drinking water installations is a completely avoidable health risk, but it can only be regulated by consistent enforcement of the applicable rules by the health authorities. The health authorities must be adequately equipped in terms of personnel, material, and financial resources.

The Effects of Calcium, Magnesium, Phosphorus, Fluoride, and Lead on Bone Tissue

Bones are metabolically active organs. Their reconstruction is crucial for the proper functioning of the skeletal system during bone growth and remodeling, fracture healing, and maintaining calcium-phosphorus homeostasis. The bone metabolism and tissue properties are influenced by trace elements that may act either indirectly through the regulation of macromineral metabolism, or directly by affecting osteoblast and osteoclast proliferation or activity, or through becoming part of the bone mineral matrix. This study analyzes the skeletal impact of macroelements (calcium, magnesium, phosphorus), microelements (fluorine), and heavy metals (lead), and discusses the concentration of each of these elements in the various bone tissues.

Study on the Evaluation of (Heavy) Metals in Water and Sediment of Skadar Lake (Montenegro), with BCF Assessment and Translocation Ability (TA) by Trapa natans and a Review of SDGs

Skadar Lake is a crypto-depression, a shallow lake, near to the Adriatic coast; the largest in the Balkan Peninsula and in southeastern Europe. The Lake is a very complex aquatic ecosystem in which anthropogenic activities have a long history in terms of the impact on wildlife and the overexploitation of natural resources. Such consequences related to heavy metals represent a global problem. Heavy metal pollution can cause severe ecological consequences in aquatic ecosystems. These pollutants accumulate in the aquatic biota from water, sediment and through the food chain, the impact can magnify. Aquatic macrophytes are good indicators of the health of a water body. This research was carried out to evaluate heavy metals concentration in water, sediment and in the aquatic macrophyte Trapa natans (water chestnut), with BCF (bio-concentration factor), BSAF (biota sediment accumulation factor) and TA (translocation ability), in order to determine the water quality of this specific part of the aquatic ecosystem of Skadar Lake near to the settlement of Vranjina, a fishing village. The determination of heavy metals was carried out by ICP-OES. (Inductively coupled plasma-optical emission spectrometry). Statistical analysis was established by R statistical computing software, version 3.5.3. The metal concentration in the water decreases in the following sequential order: As > Pb > Zn > Cu = Al = Cr > Cd = Hg. Meanwhile in the sediment, the descending sequence is as follows: Cr > Zn > Cu > Pb > As > Cd > Hg. The ability of plants to absorb and accumulate metals from the aqueous growth medium was assessed using a bio-concentration factor. The BCF in the stem, leaf and fruit has high values, mainly, of Al, Cr, Cu and Zn, while for the biota sediment accumulation factor, the highest values were recorded for the following elements: Hg, Cd, Cu and Zn. Analysis of the translocation ability of TA shows the dominance of four metals: Pb, Cd, Hg and As. A significant positive Kendall’s correlation coefficient between sediment and stem (R = 0.73, p < 0.05), stem and leaf (R = 0.87, p < 0.05) and leaf and fruit (R = 1, p < 0.05) was established.

Artisanal and Small Gold Mining and Petroleum Production as Potential Sources of Heavy Metal Contamination in Ecuador: A Call to Action

Mining and petroleum production are the source of many elements and base materials fundamental for our modern way of life. The flip side of these keystone industries is the environmental degradation they can cause if not properly managed. Metallic mining and petroleum production can contaminate the local ecosystem with sediments, chemicals used in the industrial processes and heavy metals, part of the metallic ore or oil reservoir. The objective of this project was to analyze the spatial distribution of the presence of different potentially hazardous elements that make up the metallic deposits and oil reservoirs in Ecuador, focused mainly on artisanal and small-scale gold mining (ASGM) districts. Additionally, we were interested in analyzing this information under the local political and administrative contexts which are key to determining how likely it is that mismanagement of the local mineral deposits and petroleum exploitation projects will end up causing environmental degradation. An extensive and intensive literature search was conducted for information on the presence and concentration of 19 potentially harmful elements. We analyzed data on 11 metallic deposits throughout Ecuador and a major oilfield in the Ecuadorian Amazon basin. We used geographic information systems to analyze the spatial distribution of these reservoirs and their mineral compositions. The results indicated a widespread distribution and high concentration of elements potentially harmful for human health, such as mercury, cadmium and arsenic, throughout the metallic deposits in Ecuador. This is particularly true for long-exploited ASGM districts, such as Ponce-Enríquez, Portovelo-Zaruma and Nambija. This study highlights the importance of understanding geological diversity and its potential risks to better protect the biological diversity and public health of its inhabitants. Furthermore, we consider our work not as a call to stop ASGM mining nor petroleum production, but on the contrary as a strong call to plan every mining and petroleum production project considering these risks. Moreover, our work is a call to action by the local government and authorities to stop corruption and fulfill their duties overseeing the activities of mining and petroleum companies, stopping illegal mining, helping ASGM communities to improve their environmental standards, finding alternative income sources and protecting the local environment.

Bismuth Film-Coated Gold Ultramicroelectrode Array for Simultaneous Quantification of Pb(II) and Cd(II) by Square Wave Anodic Stripping Voltammetry

The widespread presence of heavy metals in drinking water sources arises as a major health concern, particularly in developing countries. The development of low-cost and reliable detection techniques is identified as a societal need to provide affordable water quality control. Herein, a bismuth film-coated gold ultramicroelectrode array (BF-UMEA) was used for the detection of Pb(II) and Cd(II) in water samples via square wave anodic stripping voltammetry (SWASV). Experimental parameters such as deposition time, Bi(III) concentration, acetate buffer concentration, pH, square wave frequency, amplitude, and step potential were all varied to determine their effects on the current peak intensities of the target metal ions. Ten-fold excess in the concentration of interferences was found to cause a decrease in the stripping peak areas of Cd(II) and Pb(II) in the following order of magnitude: benzene < NaCl < Ni(II) < Cu(II). Using Box-Behnken design, the optimum SWASV parameters that provided maximum current peak areas were 14.76 Hz (frequency), 50.10 mV (amplitude), and 8.76 mV (step potential). The limits of detection of the as-prepared BF-UMEA were 5 and 7 µg L^-1 for Pb(II) and Cd(II), respectively. These results demonstrate the potential use of a BF-UMEA in SWASV for the trace quantification of Pb(II) and Cd(II) in water samples.

Lead accumulation in photosynthetic Euglena gracilis depends on polyphosphates and calcium

Worldwide increasing levels of lead in water systems require the search for efficient ecologically friendly strategies to remove it. Hence, lead accumulation by the free-living algae-like Euglena gracilis and its effects on cellular growth, respiration, photosynthesis, chlorophyll, calcium, and levels of thiol- and phosphate-molecules were analyzed. Photosynthetic cells were able to accumulate 4627 mg lead/kg_DW after 5 days of culture with 200 μM Pb²⁺. Nevertheless, exposure to 50, 100 and 200 μM Pb²⁺ for up to 8 days did not modify growth, viability, chlorophyll content and oxygen consumption/production. Enhanced biosynthesis of thiol molecules and polyphosphates, i.e. the two canonical metal ion chelation mechanisms in E. gracilis, was not induced under such conditions. However, in cells cultured in the absence of phosphate, lead accumulation and polyphosphate content markedly decreased, while culturing in the absence of sulfate did not modify the accumulation of this metal. In turn, the total amount of intracellular calcium slightly increased as the amount of intracellular lead increased, whereas under Ca²⁺ deficiency lead accumulation doubled. Therefore, the results indicated that E. gracilis is highly resistant to lead through mechanisms mediated by polyphosphates and Ca²⁺ and can in fact be classified as a lead hyperaccumulator microorganism.

Effects of lead exposure on salivary glands of rats: insights into the oxidative biochemistry and glandular morphology

This study aimed to investigate the effects of lead (Pb) exposure on parotid and submandibular glands through morphological aspects as well as the systemic and salivary gland redox state. Male Wistar rats were exposed to 50 mg/kg/day of Pb-acetate or distilled water by intragastric gavage for 55 days (n = 40). Blood samples were used for lipid peroxidation (LPO), glutathione (GSH), and trolox equivalent antioxidant capacity (TEAC) assays. Samples of salivary glands were analyzed by LPO, nitrites (NO), and antioxidant capacity against peroxyl radicals (ACAP) levels. Morphometric analyses (total stromal area [TSA], total parenchyma area [TPA], total ductal area [TDA], and total acinar area [TAA]) and immunohistochemistry for cytokeratin-19 (CK-19), metallothionein I/II (MT I/II), and anti-smooth muscle actin (α-SMA) were performed. The results revealed that exposure to Pb triggered systemic oxidative stress represented by lower GSH levels and increased TBARS/TEAC ratio in blood plasma. ACAP was reduced, while NO and LPO were increased in both parotid and submandibular. The morphological analyses showed increase on MT I/II expression, reduced CK-19 expression in both glands, and α-SMA reduced the immunostaining only in the parotid glands. The morphometric analyses revealed an increase in TPA in both glands, while TAA was reduced only in submandibular glands and TDA was increased only in parotid glands. Our findings are pioneer in showing that long-term exposure to Pb is able to promote blood and glandular oxidative stress associated with cellular, morphological, and biochemical damage in both parotid and submandibular glands.

Lead and zinc interactions - An influence of zinc over lead related toxic manifestations

BACKGROUND

Interaction between metals is known from earlier studies, in which one metal influences the absorption and functional role of other. Lead is known to cause debilitating effects in living organisms and also prevents several essential trace metals from functioning normally.

METHODS

The relevant literature using the key words lead toxicity, lead zinc interaction, zinc nutrition and the ability of zinc to act against lead has been reviewed.

RESULTS

Role of several nutrients in reducing the manifestations of toxic metals have been elucidated recently. Lead damages bio-membranes, causes cognitive disabilities and disturbs the normal process of DNA replication and transcription. Zinc on the other hand helps in proper maintenance of the cellular membranes and plays an important role as a metal cofactor in most of the proteins vital for membrane integrity. Zinc has essential role in cognitive functioning, zinc finger proteins and significantly neutralizes most toxic effects of lead.

CONCLUSION

Increased lead exposure and limited resources for tackling lead poisoning may cause an increased possibility of future environmental emergencies. Interactions between essential nutrient metals and non-essential toxic metals may act as important factor which can be used to target the metal toxicities. An assumption is made that the lead toxicity can be reduced by maintaining the status of essential trace metals like zinc.

Bacterial tolerance strategies against lead toxicity and their relevance in bioremediation application

Among heavy metals, lead (Pb) is a non-essential metal having a higher toxicity and without any crucial known biological functions. Being widespread, non-biodegradable and persistent in every sphere of soil, air and water, Pb is responsible for severe health and environmental issues, which need appropriate remediation measures. However, microbes inhabiting Pb-contaminated area are found to have evolved distinctive mechanisms to successfully thrive in the Pb-contaminated environment without exhibiting any negative effects on their growth and metabolism. The defensive strategies used by bacteria to ameliorate the toxic effects of lead comprise biosorption, efflux, production of metal chelators like siderophores and metallothioneins and synthesis of exopolysaccharides, extracellular sequestration and intracellular bioaccumulation. Lead remediation technologies by employing microbes may appear as potential advantageous alternatives to the conventional physical and chemical means due to specificity, suitability for applying in situ condition and feasibility to upgrade by genetic engineering. Developing strategies by designing transgenic bacterial strain having specific metal binding properties and metal chelating proteins or higher metal adsorption ability and using bacterial activity such as incorporating plant growth-promoting rhizobacteria for improved Pb resistance, exopolysaccharide and siderophores and metallothionein-mediated immobilization may prove highly effective for formulating bioremediation vis-a-vis phytoremediation strategies.

Symptoms Associated with Low Threshold Lead Poisoning Among Roadside and Organized Panel Beaters in Enugu Metropolis, Nigeria

BACKGROUND

There is no safe level of human exposure to lead (Pb). Detecting common early symptoms of low threshold Pb poisoning can help to prevent the damaging effects of higher doses and chronic low dose exposures. Panel beaters or auto body mechanics are exposed to Pb through their occupational duties.

OBJECTIVES

The present study aimed to determine common early symptoms associated with lower threshold Pb poisoning among roadside and organized panel beaters in Enugu Metropolis, Nigeria.

METHODS

This was a comparative cross-sectional study of 428 panel beaters in Enugu metropolis. A multi-stage sampling method was used to select 214 respondents each from the roadside and organized sectors. A semi-structured interviewer-administered questionnaire was used for data collection. Samples were collected under aseptic procedures. Blood Pb samples were extracted using the conventional wet acid digestion method and analyzed using a flame atomic absorption spectrometer (wavelength 283.3 nm). Comparative analysis was performed using the chi - square and Mann-Whitney U test. Statistical significance was set at P < 0.05.

RESULTS

Median Pb levels were 3.0 ug/dL and 16.0 ug/dL among roadside and organized panel beaters, respectively, with a significant difference. Numbness of limbs (P = 0.010) and fatigue (χ² = 5.294, P = 0.023) were found to be associated with roadside panel beaters, while weakness (χ² = 6.185, P = 0.019) and fatigue (χ² = 4.206, P = 0.046) were associated with organized panel beaters.

CONCLUSIONS

Nonspecific constitutional symptoms were common early symptoms of Pb poisoning irrespective of workplace occupational practices. These symptoms will help in early detection and control of occupational lead exposures.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

Ethics approval was obtained from the Health Research Ethics Committee of the University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu.

COMPETING INTERESTS

The authors declare no competing financial interests.

Heavy Metals and Pesticides Toxicity in Agricultural Soil and Plants: Ecological Risks and Human Health Implications

Environmental problems have always received immense attention from scientists. Toxicants pollution is a critical environmental concern that has posed serious threats to human health and agricultural production. Heavy metals and pesticides are top of the list of environmental toxicants endangering nature. This review focuses on the toxic effect of heavy metals (cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn)) and pesticides (insecticides, herbicides, and fungicides) adversely influencing the agricultural ecosystem (plant and soil) and human health. Furthermore, heavy metals accumulation and pesticide residues in soils and plants have been discussed in detail. In addition, the characteristics of contaminated soil and plant physiological parameters have been reviewed. Moreover, human diseases caused by exposure to heavy metals and pesticides were also reported. The bioaccumulation, mechanism of action, and transmission pathways of both heavy metals and pesticides are emphasized. In addition, the bioavailability in soil and plant uptake of these contaminants has also been considered. Meanwhile, the synergistic and antagonistic interactions between heavy metals and pesticides and their combined toxic effects have been discussed. Previous relevant studies are included to cover all aspects of this review. The information in this review provides deep insights into the understanding of environmental toxicants and their hazardous effects.

Removal of Lead(II) from Aqueous Solution Using Triton X-114 in the Presence of Alanine or Phenylalanine as Biodegradable System

The Cloud Point Extraction (CPE) of Pb(II) ion, using Triton X-114/ alanine and Triton X-114/phenyalanine as biodegradable systems, was carried out. The experimental results are expressed by four responses to surfactant concentration, amino acid concentration and temperature variations: extent of solute extraction (E), remaining solute (Xm,w) and surfactant (Xt,w) concentrations in dilute phase and volume fraction of coacervate (}C) at equilibrium. An empirical smoothing method was used, where the results were represented on three dimensional plots using the Box-Behnken design (BBD) and the response surface methodology (RSM). High extraction efficiencies (94% with alanine and 98% with phenylalanine) are reached in optimal conditions. Thereby, solute concentration reduction in the dilute phase is about 4 and 12 times with alanine and phenylalanine, respectively. The pH effect is also studied. Finally, the possibility of recycling the surfactant/amino acid system by pH change is proved.

Assessment of Pb(II), Cd(II), and Al(III) Removal Capacity of Bacteria from Food and Gut Ecological Niches: Insights into Biodiversity to Limit Intestinal Biodisponibility of Toxic Metals

Toxic metals (such as lead, cadmium, and, to a lesser extent, aluminum) are detrimental to health when ingested in food or water or when inhaled. By interacting with heavy metals, gut and food-derived microbes can actively and/or passively modulate (by adsorption and/or sequestration) the bioavailability of these toxins inside the gut. This “intestinal bioremediation” involves the selection of safe microbes specifically able to immobilize metals. We used inductively coupled plasma mass spectrometry to investigate the in vitro ability of 225 bacteria to remove the potentially harmful trace elements lead, cadmium, and aluminum. Interspecies and intraspecies comparisons were performed among the Firmicutes (mostly lactic acid bacteria, including Lactobacillus spp., with some Lactococcus, Pediococcus, and Carnobacterium representatives), Actinobacteria, and Proteobacteria. The removal of a mixture of lead and cadmium was also investigated. Although the objective of the study was not to elucidate the mechanisms of heavy metal removal for each strain and each metal, we nevertheless identified promising candidate bacteria as probiotics for the intestinal bioremediation of Pb(II) and Cd(II).

High performance Pb+2 detection using CVD-produced high quality multilayer reduced graphene oxide

Detection of heavy metals such as Pb+2 is critical due to their high toxicity as even trace amounts of them pose a serious detrimental risk to human health. Pb2+ is one of the major toxic and persistent pollutants generated from industry and commonly found in soil, drinking water, and aquatic environments. Due to its high-mobility and one-atom thickness, graphene (Gr) based materials have shown great potential for chemical sensors of heavy metals. Recently, a novel conductive reduced-GO obtained by chemical vapor deposition (CVD-rMGO) showed improved layering structure and conductivity over conventional rGO based on chemically exfoliated flakes. Herein, utilizing this novel rGO obtained from chemical vapor deposition, we showed improved Pb2+ detection using both electrochemical and conductivity sensing. For electrochemical sensing, a CVD-rMGO film is used as working electrode and cyclic voltammetry is used to detect Pb+2 ions accumulated on the CVD-rMGO, obtaining a sensitivity of 4.6 nA nM−1cm−2 and a calculated limit of detection of 0.21 nM. For electrical sensing, the drain current through a CVD-rMGO was monitored as the film as exposed to different concentrations of Pb+2, reaching an estimated limit of detection of 0.101 nM. This work shows that high-quality reduced graphene oxide produced by chemical vapor deposition can serve as a basis enable high-sensitivity detectors of Pb2+.

Signal transduction associated with lead-induced neurological disorders: A review

Lead is a heavy metal pollutant that is widely present in the environment. It affects every organ system, yet the nervous system appears to be the most sensitive and primary target. Although many countries have made significant strides in controlling Pb pollution, Pb poisoning continuous to be a major public health concern. Exposure to Pb causes neurotoxicity that ranges from neurodevelopmental disorders to severe neurodegenerative lesions, leading to impairments in learning, memory, and cognitive function. Studies on the mechanisms of Pb-induced nervous system injury have convincingly shown that this metal can affect a plethora of cellular pathways affecting on cell survival, altering calcium dyshomeostasis, and inducing apoptosis, inflammation, energy metabolism disorders, oxidative stress, autophagy and glial stress. This review summarizes recent knowledge on multiple signaling pathways associated with Pb-induced neurological disorders in vivo and in vitro.

Heavy metal and essential elements in beers from turkey market: A risk assessment study

In this study, the level of arsenic (As), lead (Pb) and cadmium (Cd) and also essential elements in beer samples consumed in Turkey were investigated using the inductively coupled plasma mass spectrometry (ICP-MS) method. The heavy metal-induced non-carcinogenic and carcinogenic risks were calculated. For essential elements, the calculated estimated daily intake of iron (Fe), copper (Cu), selenium (Se) and cobalt (Co) from beer consumption were compared with their toxicity reference values. Tukey post-hoc test showed that As was found at a significantly higher level when compared to Pb. Also, a significant correlation was found between As level and alcohol by volume percent. All samples had a hazard quotient and hazard index <1, indicating no non-carcinogenic risk from exposure to single or multiple heavy metals. Some samples exceeded the threshold limit of acceptable cancer risk for As in the high beer consumer group. This assessment showed that in addition to health implications based on the alcohol content of beer, there might be a carcinogenic risk associated with the heavy metals content of these beverages.

Blood lead level and risk of hypertension in the United States National Health and Nutrition Examination Survey 1999-2016

Lead is a heavy metal without a biological role. High level of lead exposure is known to be associated with hypertension, but the risk at low levels of exposure is uncertain. In this study, data from US NHANES 1999–2016 were analyzed. Adults with blood lead and blood pressure measurements, or self-reported hypertension diagnosis, were included. If not already diagnosed, hypertension was defined according to the AHA/ACC 2017 hypertension guideline. Results were analyzed using R statistics version 3.5.1 with sample weight adjustment. Logistic regression was used to study the association between blood lead level and hypertension. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated. Altogether, 39,477 participants were included. Every doubling in blood lead level was associated with hypertension (OR [95%CI] 1.45 [1.40–1.50]), which remained significant after adjusting for demographics. Using quartile 1 as reference, higher blood lead levels were associated with increased adjusted odds of hypertension (Quartile 4 vs. Quartile 1: 1.22 [1.09–1.36]; Quartile 3 vs. Quartile 1: 1.15 [1.04–1.28]; Quartile 2 vs. Quartile 1: 1.14 [1.05–1.25]). In conclusion, blood lead level is associated with hypertension in the general population with blood lead levels below 5 µg/dL. Our findings suggest that reducing present levels of environmental lead exposure may bring cardiovascular benefits by reducing blood pressure.

Blood lead concentration among oral/inhaled opium users: systematic review and meta-analysis

Lead is a poisonous heavy metal with various known side effects. The effect of opium on raising blood lead concentration (BLC) has been investigated with no general agreement. In Iran, the number of lead poisoning cases has raised among the opium-addicted population. This systematic review and meta-analysis aim to combine the results of previous studies with the Iranian population to investigate the effect of opium on BLC. In this systematic review, PubMed/Medline, Web of Sciences, Embase, and Scopus were searched for studies using the Iranian population to compare the BLC of opium-addicted cases and non-addicted controls till January 2020. A random-effects model was used to pool the results. I-square test was used to assess the heterogeneity of the studies. The effect sizes were standardized mean differences (proxied by Hedges' g) followed by a 95% confidence interval. Of 417 initial articles, 13 studies met the inclusion criteria to be considered in the meta-analysis. The sample size of eligible studies ranged from 40 to 131 (mean 81.83, SD 27.6). All studies were focused on adults with mean age ranged from 33.5 to 65.15 years old (overall mean 49.0, SD 7.66). There were 13 studies included with 18 Hedges' g effect sizes. Using a random effect model, the pooled effect size was g_w = 2.48 (95% CI: 1.58-3.39) and statistically significant in favor of opium-addicted participants. Moreover, heterogeneity was 96.6% (I2=96.6, Q(17) = 504.95, p < 0.001). For studies with large Hedges' g effect sizes (> 4) identified as outliers and removed from meta-analysis. The pooled Hedges' g effect size reduced to 1.39 (95% CI: 0.94-1.85), still highly significant in favor of higher levels of lead in the opium-addicted group. The funnel plot appeared symmetrical confirmed by Egger's test (t = 1.87, p = 0.088), indicating no publication bias present.

Developing a framework for classifying water lead levels at private drinking water systems: A Bayesian Belief Network approach

The presence of lead in drinking water creates a public health crisis, as lead causes neurological damage at low levels of exposure. The objective of this research is to explore modeling approaches to predict the risk of lead at private drinking water systems. This research uses Bayesian Network approaches to explore interactions among household characteristics, geological parameters, observations of tap water, and laboratory tests of water quality parameters. A knowledge discovery framework is developed by integrating methods for data discretization, feature selection, and Bayes classifiers. Forward selection and backward selection are explored for feature selection. Discretization approaches, including domain-knowledge, statistical, and information-based approaches, are tested to discretize continuous features. Bayes classifiers that are tested include General Bayesian Network, Naive Bayes, and Tree-Augmented Naive Bayes, which are applied to identify Directed Acyclic Graphs (DAGs). Bayesian inference is used to fit conditional probability tables for each DAG. The Bayesian framework is applied to fit models for a dataset collected by the Virginia Household Water Quality Program (VAHWQP), which collected water samples and conducted household surveys at 2,146 households that use private water systems, including wells and springs, in Virginia during 2012 and 2013. Relationships among laboratory-tested water quality parameters, observations of tap water, and household characteristics, including plumbing type, source water, household location, and on-site water treatment are explored to develop features for predicting water lead levels. Results demonstrate that Naive Bayes classifiers perform best based on recall and precision, when compared with other classifiers. Copper is the most significant predictor of lead, and other important predictors include county, pH, and on-site water treatment. Feature selection methods have a marginal effect on performance, and discretization methods can greatly affect model performance when paired with classifiers. Owners of private wells remain disadvantaged and may be at an elevated level of risk, because utilities and governing agencies are not responsible for ensuring that lead levels meet the Lead and Copper Rule for private wells. Insight gained from models can be used to identify water quality parameters, plumbing characteristics, and household variables that increase the likelihood of high water lead levels to inform decisions about lead testing and treatment.

Effects of Exposure to Lead and Cadmium on Health of Inhabitants of Abandoned Metal Mine Area in Korea

People living near abandoned mines are at increased risk of exposure to toxic metals. We surveyed 4500 inhabitants with the mean age of 68.5 years old (male: 1768, female: 2732) living near 104 abandoned metal mines from 2013 to 2017 (the 2nd phase health survey in Korea). We conducted personal interviews, blood and urine sampling, and analyzed the concentrations of lead (Pb) and cadmium (Cd) in whole blood and Cd in urine using a graphite furnace atomic absorption spectrometer. The geometric means of blood Pb, blood Cd, and urine Cd were 2.27 μg/dL, 1.42 μg/L, and 1.66 μg/g creatinine, respectively. The level of metal exposure was lower than that reported from the first phase health survey in Korea (2008‒2011) but was higher than in the general population of Korea. Blood Pb was higher in males while blood Cd and urine Cd were significantly higher in females. Blood Pb was highest in the 40‒59 age group, while blood and urine Cd levels continuously increased until age 80 or older. The Cd levels in blood and urine were affected by consumption of locally produced rice and duration of residence near abandoned mines. Furthermore, negative correlations were observed between blood Pb and blood and urine Cd levels. Additionally, 252 of the 4500 subjects exceeded the thresholds of blood Cd or urine Cd levels. Together, these findings suggest that Cd has more sustainable and adverse health effects on the abandoned mine inhabitants, who are mostly aged. Therefore, continuous biomonitoring and risk assessment to environmental health risks are necessary for environmental pollution control and health promotion.

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO₂) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO₂, as well as the toxicity interaction between NPTiO₂ and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO₂ alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO₂ alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO₂. In general, the results of this study indicated that both NPTiO₂ alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.

Assessment of Antimicrobic, Antivirotic and Cytotoxic Potential of Alginate Beads Cross-Linked by Bivalent Ions for Vaginal Administration

Antimicrobial agent abuse poses a serious threat for future pharmacotherapy, including vaginal administration. The solution can be found in simple polymeric systems with inherent antimicrobial properties without the need to incorporate drugs, for instance alginate beads cross-linked by bivalent ions. The main goal of the presented study was to provide improvement on the well-documented cytotoxicity of Cu²⁺ cross-linked alginate. Alginate beads were prepared by external ionotropic gelation by cross-linking with Cu²⁺, Ca²⁺ and Zn²⁺ ions, separately and in mixtures. Morphological properties, swelling capacity, ion release and efficacy against the most common vaginal pathogens (C. albicans, E. coli, E. faecalis and virus strain—human herpesvirus type 1) were evaluated. The prepared particles (particle size 1455.68 ± 18.71–1756.31 ± 16.58 µm) had very good sphericity (0.86 ± 0.04–0.97 ± 0.06). In mixture samples, Cu²⁺ hampered second ion loading, and was also released incompletely (18.75–44.8%) compared to the single ion Cu²⁺ sample (71.4%). Efficacy against the selected pathogens was confirmed in almost all samples. Although anticipating otherwise, ion mixture samples did not show betterment over a Cu²⁺ cross-linked sample in cytotoxicity–pathogen efficacy relation. However, the desired improvement was found in a single ion Zn²⁺ sample whose minimal inhibition concentrations against the pathogens (0.6–6.12 mM) were close to, or in the same mathematical order as, its toxic concentration of 50 (1.891 mM). In summary, these findings combined with alginate’s biocompatibility and biodegradability give the combination solid potential in antimicrobial use.

Blood Lead Levels, Hemoglobin, and Liver Enzymes in Opium-Dependent Addicts

BACKGROUND

Opium addiction, as a major health problem, has been reported in Middle East countries. Recently, contaminated opium has been reported as a probable source of lead poisoning. Thus, the aim of this study is to evaluate blood lead levels (BLL), liver enzymes, and hemoglobin (Hb) concentrations in opium-dependent addicts with healthy controls.

METHODS

In a cross-sectional study, 75 opium-addicted men (case group) referred to Zahedan Baharan Hospital were evaluated. A group of 75 nonaddicted men were selected as a control group. BLL, Hb, and liver enzymes levels were measured. Body mass index (BMI) was also calculated.

RESULTS

The case group had elevated BLL compared to the controls (19.1 ± 1.6 vs. 9.1 ± 0.4; P < 0.0001). Hb concentrations were significantly lower in the patients compared to the controls (13.3 ± 1.6 vs. 15.1 ± 1.3; P < 0.0001). A positive correlation was found between BLL and opium addict duration in the case group (r = 0.52, P < 0.0001).

CONCLUSIONS

Due to the contamination of opium to lead, it seems that opiate addicts are at risk of lead poisoning. Thus, it is recommended that the blood lead level is frequently monitored to control the adverse effects of poisoning and prevent lead accumulation.

Lead in Brazilian food: Exposure assessment and risk characterization

A risk assessment was performed to estimate the lead (Pb) dietary intake in the Brazilian population. Data on Pb concentration in food were obtained through a systematic review with meta-analyses and from the GEMS/Food database, both involving data through 2018. Food consumption data were obtained from a Brazilian official dietary survey. Pb dietary intakes were estimated by a deterministic approach. Risk characterisation was conducted using the margin of exposure approach (MOE). The total Pb intake in the Brazilian population ranged from 1.53 to 2.01 μg/kg bw/day. Major contributors to Pb dietary exposure were the vegetable and vegetable products and beverage categories. From the results obtained, a risk of increased systolic pressure, nephrotoxicity and decrease of 0.5 point intelligence quotient can be expected, MOE<1, with greater magnitudes of risk observed for men in rural areas and in the Midwest, Southeast and South Brazilian regions. The dietary risk assessment indicates a health concern for the Brazilian population associated with Pb dietary intake.

Characteristics and mechanisms of Pb(II) sorption onto Fe-rich waste water treatment residue (WTR): A potential sustainable Pb immobilisation technology for soils

Pb contamination of soils is a global problem. This paper discusses the ability of an Fe-rich waste, water treatment residual (WTR), to adsorb Pb(II). This was investigated using batch sorption experiments, X-ray diffraction, electron microprobe microanalysis, PHREEQC modeling and Extended X-ray Absorption Fine Structure (EXAFS) analysis. The WTR is composed of approximately 23 wt. % natural organic matter (NOM), 70 wt. % ferrihydrite and <10 wt. % silicate material. Pb(II) sorption to WTR was dependent on initial Pb(II) load, particle size, time and pH, but not on ionic strength. EXAFS analysis at the Pb L_III-edge confirmed that Pb(II) sorbed to WTR by co-existing bidentate edge-sharing and monodentate or corner-sharing complexes, with 2 O at ∼2.31-2.34 Å, 1 Fe at ∼3.32-3.34 Å, 2 Fe at ∼3.97-3.99 Å and 1 Pb at ∼3.82-3.85 Å. Linear combination showed that the Pb(II)-sorbed spectra were best fit with a ∼0.9 ± 0.1 and 0.1 ± 0.1 contribution from Pb(II)-sorbed ferrihydrite and Pb(II)-sorbed humic acid end members, respectively. Overall, we show that Pb(II) sorbs via strong inner-sphere complexation of Pb(II) to the ferrihydrite component of the WTR, which itself is stable over a wide pH range. Therefore, we suggest that Fe-rich WTR wastes could be used as effective adsorbents in Pb(II)-contaminated soils to help ensure sustainable terrestrial ecosystems.

Co-administration of Luteolin mitigated toxicity in rats' lungs associated with doxorubicin treatment

Doxorubicin (DOX), is a drug against lung malignancies with undesirable side effect including oxidative, inflammatory and apoptotic effects. Luteolin (LUT), present in fruits and vegetables is pharmacologically active against oxido-inflammatory and apoptotic responses. The present study examined the effect of LUT on DOX-induced lungs and blood dysfunction in Wistars rat (sex: male; 10 weeks old, 160 ± 5 g). Randomly grouped (n = 10) rats were treated as follows: control, LUT alone (100 mg/kg; per os), DOX (2 mg/kg; i. p), and co-treated rats with LUT (50 or 100 mg/kg) and DOX for two consecutive weeks. DOX alone adversely altered the final body and relative organ weights, red and white blood cell and platelet counts. DOX significantly (p > 0.05) reduced lungs antioxidant capacity, and anti-inflammatory cytokines; increased biomarkers of oxidative stress, caspase-3 activity, and pro-inflammatory cytokine. Morphological damages accompanied these biochemical alterations in the lung of experimental rats. Co-treatment with LUT, dose-dependently reversed DOX-mediated changes in rats' survival, toxic responses, and diminished oxidative stress in rat's lungs. Furthermore, co-treatment with LUT resulted in the reduction of pro-inflammatory cytokines and apoptotic biomarkers, increased red and white blood cell, platelet counts and abated pathological injuries in rat lungs treated with DOX alone. In essence, our findings indicate that LUT dose-dependently mitigated DOX-induced toxicities in the lungs and haematopoietic systems. Supplementation of patients on DOX-chemotherapy with phytochemicals exhibiting antioxidant activities, specifically LUT, could circumvent the onset of unintended toxic responses in the lungs and haematopoietic system exposed to DOX.

The lead story of the fire at the Notre-Dame cathedral of Paris

On 15th April 2019, Parisians watched in shock as Notre-Dame de Paris, the iconic cathedral that has towered over their city for almost 900 years, was engulfed in flames. Although flames destroyed the spire and considerably weakened the structure, no human lives were lost. However, as some amounts of lead volatilized and deposited in the surrounding areas, fears of potential intoxication began to rise. We investigated the impact of this fire on the blood lead levels of adults in Paris according to the distance between the cathedral and where they live or work. The geometric mean of blood lead levels of the study population was 1.49μg/dl (95% CI [1.38-1.62]) with a prevalence of blood lead levels≥5.0μg/dL of 5.0%. Despite the early legitimate fears of intoxication, the fire that destroyed a significant part of the Notre-Dame cathedral did not increase the blood lead levels of adults living and working in the vicinity.

[Blood and faecal lead levels in children with various functional gastrointestinal disorders]

INTRODUCTION

To investigate the blood lead levels (BLLs) and faecal lead levels (FLLs) in children with various functional gastrointestinal disorders (FGIDs) and compare them with controls.

PATIENTS AND METHODS

One hundred and 2children with FGIDs defined by the Rome IV criteria, aged 4 -18 years, and one hundred and 2sex matched healthy children were enrolled in the study. Children with FGIDs were divided into 3subgroups as functional constipation (FC) (n=36), functional abdominal pain (FAP) (n=36) and functional náusea (FN) (n=30). The lead levels were measured using atomic absorption spectrometer.

RESULTS

The median BLLs in the FGIDs group was significantly higher than in controls (5.12 and 1.77μg/dL, respectively). The BLLs were above 5μg/dL in 51,9% of children with FGIDs. There was statistically significant difference in BLLs between FC subgroup and the other subgroups (FAP and FN) (P=.003, P<.001 respectively). The FLLs in the FGIDs group was significantly higher than in controls (28.08 and 0.01μg/g, respectively). There was no significant difference in FLLs between FC subgroup and the other subgroups (P=.992, P=.989 respectively). No significant relation found between BLLs and FLLs of the FGIDs group (P =.123).

CONCLUSION

This study revealed that children with FGIDs had higher BLLs and FLLs than controls and also more than half of children with FGIDs had BLLs ≥5μg/dL which is toxic level. These results might revive the question of whether or not clinician need to evaluate routine BLLs in children with FGIDs.

Synergistic protective effect of Beta vulgaris with meso-2,3-dimercaptosuccinic acid against lead-induced neurotoxicity in male rats

Lead (Pb) toxicity is one of the most prevalent causes of human neurotoxicity. The available chelator drugs used now have many adverse effects. So, in this study, the protective role of Beta vulgaris juice (BVJ) on rat neurotoxicity induced by Pb was evaluated and the results were compared with the results of dimercaptosuccinic acid (DMSA, as used drug). Additionally, the synergistic effect of BVJ and DMSA against Pb-induced neurotoxicity was assessed. The study focused on the determination of the antioxidant, anti-inflammatory, and neurological potential of BVJ (alone, and with DMSA) towards lead-induced neurotoxicity. Also, the characterization of BVJ was studied. The results showed that BVJ contains considerable quantities of polyphenols, triterpenoids, and betalains which play an important role as antioxidants and anti-inflammatory. BVJ exhibited a protective effect against neurotoxicity via the reduction of Pb levels in blood and brain. Moreover, BVJ decreased the oxidative stress, inflammation, and cell death induced by Pb. Also, BVJ regulated the activities of acetylcholine esterase and monoamine oxidase-A which changed by Pb toxicity. BVJ and DMSA combination displayed a synergistic antineurotoxic effect (combination index ˂ 1). These results were in harmony with brain histopathology. Conclusion: BVJ has a powerful efficacy in the protection from brain toxicity via diminishing Pb in the brain and blood circulation, resulting in the prevention of the oxidative and inflammatory stress. Treatment with BVJ in combination with DMSA revealed a synergistic effect in the reduction of neurotoxicity induced by Pb. Also, the antioxidant and anti-inflammatory effects of the BVJ lead to the improvement of DMSA therapy.

Effect of high hydrostatic pressure-assisted pectinase modification on the Pb2+ adsorption capacity of pectin isolated from sweet potato residue

Novel pectin derived from sweet potato residue was modified by high hydrostatic pressure (HHP)-assisted pectinase and then used for Pb²⁺ removal from aqueous solutions. The removal characteristics and mechanisms were also investigated. Results showed that modified sweet potato pectin exhibited greater adsorption performances for Pb²⁺ than that of natural ones, and showed excellent eco-friendly properties and good potential for adsorption of some other heavy metals (such as Cu²⁺). The adsorption curves were much more conformed to Langmuir model, and the highest capacity for Pb²⁺ adsorption was 263.15 mg/g with 1.00% pectin at pH 7. Chemical adsorption process of pectin for Pb²⁺ absorption involved O-containing functional groups (O-H, COO-), cation exchange, and along with electrostatic interactions. Overall, the results in this study indicated that sweet potato pectin modified with HHP-assisted pectinase had the potential to become an environmentally friendly coagulant-flocculant agent for the heavy metal adsorption, especially for Pb²⁺.

Association of Urinary and Blood Concentrations of Heavy Metals with Measures of Bone Mineral Density Loss: a Data Mining Approach with the Results from the National Health and Nutrition Examination Survey

Osteoporosis and its consequence of fragility fracture represent a major public health problem. Human exposure to heavy metals has received considerable attention over the last decades. However, little is known about the influence of co-exposure to multiple heavy metals on bone density. The present study aimed to examine the association between exposure to metals and bone mineral density (BMD) loss. Blood and urine concentrations of 20 chemical elements were selected from 3 cycles (2005-2010) NHANES (National Health and Nutrition Examination Survey), in which we included white women over 50 years of age and previously selected for BMD testing (N = 1892). The bone loss group was defined as participants having T-score < - 1.0, and the normal group was defined as participants having T-score ≥ - 1.0. We developed classification models based on support vector machines capable of determining which factors could best predict BMD loss. The model which included the five-best features-selected from the random forest were age, body mass index, urinary concentration of arsenic (As), cadmium (Cd), and tungsten (W), which have achieved high scores for accuracy (92.18%), sensitivity (90.50%), and specificity (93.35%). These data demonstrate the importance of these factors and metals to the classification since they alone were capable of generating a classification model with a high prediction of accuracy without requiring the other variables. In summary, our findings provide insight into the important, yet overlooked impact that arsenic, cadmium, and tungsten have on overall bone health.

Heavy metal associated health hazards: An interplay of oxidative stress and signal transduction

Heavy metal-induced cellular and organismal toxicity have become a major health concern in biomedical science. Indiscriminate use of heavy metals in different sectors, such as, industrial-, agricultural-, healthcare-, cosmetics-, and domestic-sectors has contaminated environment matrices and poses a severe health concern. Xenobiotics mediated effect is a ubiquitous cellular response. Oxidative stress is one such prime cellular response, which is the result of an imbalance in the redox system. Further, oxidative stress is associated with macromolecular damages and activation of several cell survival and cell death pathways. Epidemiological as well as laboratory data suggest that oxidative stress-induced cellular response following heavy metal exposure is linked with an increased risk of neoplasm, neurological disorders, diabetes, infertility, developmental disorders, renal failure, and cardiovascular disease. During the recent past, a relation among heavy metal exposure, oxidative stress, and signaling pathways have been explored to understand the heavy metal-induced toxicity. Heavy metal-induced oxidative stress and its connection with different signaling pathways are complicated; therefore, the systemic summary is essential. Herein, an effort has been made to decipher the interplay among heavy metals/metalloids (Arsenic, Chromium, Cadmium, and Lead) exposures, oxidative stress, and signal transduction, which are essential to mount the cellular and organismal response. The signaling pathways involved in this interplay include NF-κB, NRF2, JAK-STAT, JNK, FOXO, and HIF.

Prenatal and Early Childhood Exposure to Lead and Repeated Measures of Metabolic Syndrome Risk Indicators From Childhood to Preadolescence

Background: Exposure to lead (Pb) during the early life stages has been associated with the development of metabolic syndrome (MetS). Longitudinal studies of Pb exposure in critical developmental windows in children are limited. Methods: Our study included 601 mother-child dyads from the PROGRESS (Programming Research in Obesity, Growth, Environment and Social Stressors) birth cohort. Blood lead levels (BLLs) were assessed during the second and third gestational trimesters, in cord blood at delivery, and at ages 1, 2, and 4 years. Bone lead levels in the patella and tibia were assessed at 1 month postpartum and evaluated in separate models. To account for cumulative exposure (prenatal, postnatal, and cumulative), we dichotomized the BLLs at each stage visit and determined the following: "higher" if a BLL was at least once above the median (HPb) and "lower" if all BLLs were below the median (LPb). We analyzed fasting glucose, HbA1c, triglycerides (TGs), total cholesterol (TC), high-density lipoprotein cholesterol (cHDL), low-density lipoprotein cholesterol (cLDL), body mass index, waist circumference (WC), body fat percentage, and systolic (SBP) and diastolic blood pressure (DBP) at two study visits between 6 and 12 years of age and created cutoff points based on the clinical guidelines for each indicator. Mixed effects models were used to analyze each outcome longitudinally for each BLL score, adjusting for child's sex, size for gestational age, child's age, maternal parity, mother's age, and socioeconomic status. Results: We observed associations for HPb exposure and TC in all stages (OR = 0.53, 95%CI = 0.32-0.86) and postnatally (OR = 0.59, 95%CI = 0.36-0.94) and for prenatal HPb and TGs (OR = 0.65, 95%CI = 0.44-0.95). HPb at all stages was associated with WC (OR = 0.27, 95%CI = 0.08-0.86), BMI (OR = 0.33, 95%CI = 0.11-0.99), SBP (OR = 0.53, 95%CI = 0.32-0.85), and DBP (OR = 0.57, 95%CI = 0.34-0.95). Pb levels in the patella were associated with cHDL (OR = 1.03, 95%CI = 1.00-1.07) and those in the tibia with TGs (OR = 0.95, 95%CI = 0.91-0.99). Conclusion: Early life exposure to Pb may alter early indicators of MetS. A follow-up of these children will allow for more definition on the impact of longer-term exposures.

Review of recent progress on DNA-based biosensors for Pb2+ detection

Lead (Pb) is a highly toxic heavy metal of great environmental and health concerns, and interestingly Pb²⁺ has played important roles in nucleic acids chemistry. Since 2000, using DNA for selective detection of Pb²⁺ has become a rapidly growing topic in the analytical community. Pb²⁺ can serve as the most active cofactor for RNA-cleaving DNAzymes including the GR5, 17E and 8-17 DNAzymes. Recently, Pb²⁺ was found to promote a porphyrin metalation DNAzyme named T30695. In addition, Pb²⁺ can tightly bind to various G-quadruplex sequences inducing their unique folding and binding to other molecules such as dyes and hemin. The peroxidase-like activity of G-quadruplex/hemin complexes was also used for Pb²⁺ sensing. In this article, these Pb²⁺ recognition mechanisms are reviewed from fundamental chemistry to the design of fluorescent, colorimetric, and electrochemical biosensors. In addition, various signal amplification mechanisms such as rolling circle amplification, hairpin hybridization chain reaction and nuclease-assisted methods are coupled to these sensing methods to drive up sensitivity. We mainly cover recent examples published since 2015. In the end, some practical aspects of these sensors and future research opportunities are discussed.

Chrysin protects against testicular toxicity caused by lead acetate in rats with its antioxidant, anti-inflammatory, and antiapoptotic properties

In the present study, the protective effects of chrysin (CHR) against testicular damage caused by lead acetate (PbAc) were examined. In this way, 30 min after rats were given 25 and 50 mg/kg/b.w CHR orally for seven consecutive days, 30 mg/kg/b.w PbAc was administered orally. In biochemical analysis of testicular tissue, it was found that PbAc-reduced antioxidant parameters [glutathione peroxidase (GPx), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT)], while it increased lipid peroxidation, inflammatory markers [nuclear factor kappa-B (NF-κB), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE-2), and inducible nitric oxide synthase (iNOS)], and 8-hydroxy-2'-deoxyguanosine (8-OHdG). In the immunohistochemical examination, it was determined that PbAc increased the expression of tumor necrosis factor-α (TNF-α) and caspase-3. Accordingly, PbAc was found to cause a decrease in sperm motility and an increase in the percentage of dead sperm. However, it has been observed that CHR relieves oxidative stress due to its antioxidant properties, thus protecting against inflammation and apoptosis. It also allowed the CHR sperm parameters to return to control group levels. The results revealed that CHR could be a natural substance to be used in Pb-induced testicular toxicity. PRACTICAL APPLICATIONS: Lead (Pb) is an important environmental contaminant heavy metal. Pb is believed to reduce fertility in men. Oxidative stress plays a significant role in the damage caused by Pb to testicular tissue. CHR is an antioxidant substance that occurs naturally in various plants and has various pharmacological properties. In the present study, it was investigated whether CHR has a protective effect against testicular toxicity induced by PbAc. The results revealed that in rats, CHR protects the testicular tissue from PbAc toxicity by showing antioxidant, anti-inflammatory and anti-apoptotic effects, thus bringing sperm parameters closer to normal.

(Ascorb)ing Pb Neurotoxicity in the Developing Brain

Lead (Pb) neurotoxicity is a major concern, particularly in children. Developmental exposure to Pb can alter neurodevelopmental trajectory and has permanent neuropathological consequences, including an increased vulnerability to further stressors. Ascorbic acid is among most researched antioxidant nutrients and has a special role in maintaining redox homeostasis in physiological and physio-pathological brain states. Furthermore, because of its capacity to chelate metal ions, ascorbic acid may particularly serve as a potent therapeutic agent in Pb poisoning. The present review first discusses the major consequences of Pb exposure in children and then proceeds to present evidence from human and animal studies for ascorbic acid as an efficient ameliorative supplemental nutrient in Pb poisoning, with a particular focus on developmental Pb neurotoxicity. In doing so, it is hoped that there is a revitalization for further research on understanding the brain functions of this essential, safe, and readily available vitamin in physiological states, as well to justify and establish it as an effective neuroprotective and modulatory factor in the pathologies of the nervous system, including developmental neuropathologies.

Protection of Siganus oramin, rabbitfish, from heavy metal toxicity by the selenium-enriched seaweed Gracilaria lemaneiformis

Seaweed is an inherently important entity in marine ecosystems. It is not only consumed by aquatic animals but also improves environmental quality in the mariculture. Seaweed is also part of the diet of human beings. The purpose of the present study was to evaluate the antagonism of selenium (Se)-enriched Gracilaria lemaneiformis against heavy metals, specifically, the potential of dietary Se-enriched Gracilaria to protect against heavy metal toxicity in rabbitfish (Siganus oramin). Growth rate, heavy metal (Se, Cd, Pb, Cu, Zn and Cr) concentrations, malondialdehyde (MDA), metallothionein (MT), and the activity of the antioxidants, glutathione peroxidase (GPX), catalase (CAT) and superoxide dismutase (SOD) were all assessed. The results showed that the total organic and inorganic Se concentration for the 250 mg L^-1 Se-enriched Gracilaria was significantly higher than those of the 50 and 10 mg L^-1 treatments after 3 days of enrichment. The mean total Se concentrations in Gracilaria were 42.5 μg g^-1 in the 250 mg L^-1 treatment, 13.5 μg g^-1 in the 50 mg L^-1 treatment and 2.5 μg g^-1 in the 10 mg L^-1 treatment, respectively. Organic Se accounts for 80-82% of total Se in Se-enriched Gracilaria. The Se concentration of rabbitfish fed Se-enriched Gracilaria was significantly higher than control. Furthermore, Se increased Cu and Zn absorption, and enhanced MT generation, and improved GPX, CAT, and SOD antioxidant activity, and decreased MDA concentrations and lipid peroxidation levels, all antagonistic to Cd, Pb and Cr. The effects of Se-enriched Gracilaria on waterborne Cd, Pb and Cr-induced toxicity occurred via both enzymatic and non-enzymatic antioxidative mechanisms in rabbitfish. Selenium had synergistic effects on Zn and Cu in rabbitfish. For the 50 mg L^-1 Se-enriched Gracilaria treatment, the Se, Cu, Zn, and antagonistic Cd, Pb, Cr, and the antioxidant enzymes CAT, SOD, GPX activities, and MT concentrations in rabbitfish were higher than that with the 250 mg L^-1 and 10 mg L^-1 Se-enriched Gracilaria treatments. The 50 mg L^-1 Se treatment of Gracilaria was deemed to be the optimum concentration to promote growth of rabbitfish. Therefore, the obtained results suggest Se-enriched Gracilaria can antagonize heavy metal toxicity, and is an advisable Se supplement to improve the edible safety of cultured animals.