Recent developments in low-level lead exposure and intellectual impairment in children

Investigation of an Optimal Sampling Resolution to Support Soil Management Decisions for Urban Plots

The main objective of the current study was to use seven lots in Hartford, CT that are planned for community reuse to determine the optimal sampling density that allows for the detection of hotspots of lead pollution while limiting the labor of the sampling process. The sampling density was investigated using soil Pb measured by in situ X-ray Fluorescence as the indicator to evaluate soil health, with a new threshold of 200-mg/kg proposed by the USEPA in January of 2024. Even though this study takes place in an urban setting, where the new USEPA policy requires the use of a 100-mg/kg threshold for Pb due to the fact that there are other identifiable sources of the contaminant, only the 200-mg/kg threshold is discussed because it is evident from the analysis that compliance of a 100 mg/kg threshold in urban plots is highly unlikely (five out of seven sites would require complete site excavation prior to reuse). Using the inverse distance weighted geospatial interpolation of in situ pXRF determined lead measurements, grid sampling resolutions of 3-m, 4-m, 5-m, 6-m, 8-m, 10-m, and 12-m were compared. Ultimately, the case study finds that the largest grid resolution that can be implemented for soil screening to maintain hotspots of pollution to properly inform soil management decisions is a 6-m grid, or a density of approximately 1/36-m2.

Insights on Stability Constants and Structures of Complexes between Coumarin Derivatives and Pb(II) in Aqueous Media

In the frame of a systematic study on the sequestering ability of natural antioxidants towards metal cations, here the complexation of coumarin-3-carboxilic acid (HCCA) with Pb(II) and the overall stability constants of the resulting complexes, at 37 °C and in 0.16 M NaClO4, are discussed. Reaction of Pb(ClO4)2 with HCCA in an aqueous medium at a pH range from 2 to 6 and various ratios (1:1-1:10) yielded the Pb-CCA complexes, which were characterized spectrometrically by laser desorption ionization mass spectrometry (LD-MS). LD-MS has provided the composition and structure of Pb-CCA species according to the speciation model proposed on the basis of the potentiometric data. The graphic representation of the complex's concentration curves is given by the distribution diagram, which provides a whole depiction of the species present in the solution at the selected pH ranges.

Early-Life Lead Exposure: Risks and Neurotoxic Consequences

BACKGROUND

Lead (Pb) does not have any biological function in a human, and it is likely no safe level of Pb in the human body. The Pb exposure impacts are a global concern for their potential neurotoxic consequences. Despite decreasing both the environmental Pb levels and the average blood Pb levels in the survey populations, the lifetime redistribution from the tissues-stored Pb still poses neurotoxic risks from the low-level exposure in later life. The growing fetus and children hold their innate high-susceptible to these Pb-induced neurodevelopmental and neurobehavioral effects.

OBJECTIVE

This article aims to evaluate cumulative studies and insights on the topic of Pb neurotoxicology while assessing the emerging trends in the field.

RESULTS

The Pb-induced neurochemical and neuro-immunological mechanisms are likely responsible for the high-level Pb exposure with the neurodevelopmental and neurobehavioral impacts at the initial stages. Early-life Pb exposure can still produce neurodegenerative consequences in later life due to the altered epigenetic imprints and the ongoing endogenous Pb exposure. Several mechanisms contribute to the Pb-induced neurotoxic impacts, including the direct neurochemical effects, the induction of oxidative stress and inflammation through immunologic activations, and epigenetic alterations. Furthermore, the individual nutritional status, such as macro-, micro-, or antioxidant nutrients, can significantly influence the neurotoxic impacts even at low-level exposure to Pb.

CONCLUSION

The prevention of early-life Pb exposure is, therefore, the critical determinant for alleviating various Pb-induced neurotoxic impacts across the different age groups.

Legacies of Pre-1960s Municipal Waste Incineration in the Pb of City Soils

A 1937 street map of Durham, North Carolina, located four city-run waste incinerators that we recognized to be sites of contemporary city parks. We obtained city permission to sample three park's soils, developed a sampling design for geospatial mapping of hypothetical incinerator-ash contamination of park soils, and queried online Durham newspapers to understand histories of incinerator operations, ash disposal, and incinerator-to-park conversions. In 2021-2022, seven decades after parks were created, two parks had soil-Pb > 400 mgPb/kg, EPA's threshold for safe soil in play areas. At Walltown Park, six of 97 surface samples ranged from 416 to 1338 mg Pb/kg within meters of a basketball court and a park path. East Durham Park had a hectare-sized area where 12 samples averaged 1294 mgPb/kg (median 1335 mg/kg). Engineering surveys of United States and Canadian cities in 1941 and 1958 suggest that half incinerated solid wastes. Many records describe how incinerator ash was dumped with little regard for health or environmental hazards. Legacy soil contaminations of incinerator ash can be identified, as we have done in Durham, from historical records of city-waste incinerator operations, online access to newspaper archives that describe incinerator-to-park conversions, and a XRF to screen for soil-Pb contamination.

Bioaccessibility, exposure and risk assessment of potentially toxic elements and essential micronutrients in ayurvedic, traditional Chinese and Ghanaian medicines

Potentially toxic constituents in traditional medicines remain a concern due to health risks posed to consumers. Thirty-six traditional medicines (TM) consisting of 14 Indian Ayurvedic Medicines, 11 Chinese Traditional Medicines and eleven Ghanaian Traditional Medicines were evaluated using Total Reflection X-ray Fluorescence Spectrometer (T-XRF) after microwave assisted acid digestion. Physiologically Based Extraction Test (PBET) was used to obtain bioaccessible elemental concentrations. Merck XVI multi-element standard were used to evaluate the accuracy of the analytical method. The concentrations of the elements were quantified in (mg kg-1): Cr (0.01-698), Mn (0.01-1140), Fe (15-73300), Ni (1-1340), Cu (3-8160), Zn (0.01-224). The greatest bioaccessible concentrations of arsenic was 0.80 mg kg-1 and 0.44 mg kg-1 in the gastric and intestinal phases respectively. In order to evaluate the human health risks from ingesting these TM, the Acceptable Daily Intake (ADI) was calculated for each medicine based on element-specific bioaccessibility-adjusted concentrations and results compared with the United States Environmental Protection Agency (USEPA) Reference Dose (RfD) limits. The Acceptable Daily Intake (ADI) values for risks were within the USEPA RfD. Hazard quotients (HQ) of TM were < 1, meaning elemental concentrations do not pose non-carcinogenic risks to adult consumers. In summary the methods applied in the study gives a new insight on human health risks of potentially toxic and essential micronutrients elements in TM.

Enhanced Cr (VI) removal with Pb (II) presence by Fe2+-activated persulfate and zero-valent iron system

Combined heavy metals such as chromium (Cr (VI)) and lead (Pb (II)) in natural water have globally posed severe environmental and public health risk. Here the removal of Cr (VI) and Pb (II) mixed pollutants using Fe²⁺-activated persulfate (PS) with extra zero-valent iron (ZVI), which was not only a supplementary Fe²⁺ source, but also a high-efficiency absorbent, was investigated. During removal, pivotal factors of initial pollutant concentration, dosages of ZVI and PS, initial pH and temperatures were examined. Interestingly, generating a lot of H⁺ in the process of Fe (II) activating persulfate were helpful to the corrosion of ZVI over a large range of pH (1-9). Under the optimum condition, removal efficiency of Pb (II) and Cr (VI) have reached 100% and 94.26% respectively. The removal mechanism was suggested as a three-step reaction that the Pb (II) boosted the removal of Cr (VI) by co-precipitated in wastewater, and the Pb (II) and Cr (VI) were adsorbed and subsequently reduced to Pb⁰ and Cr³⁺ as Cr(OH)₃ or Cr³⁺-Fe³⁺ hydroxides on ZVI surface. Cr (VI) and Pb (II) adsorption kinetics agreed with the pseudo-second-order reaction rate expression. In addition, we were surprised to found that the contribution effect of chromium and lead co-precipitation for their removal by Fe (II) - PS-ZVI has strong dependence on initial pH and concentration ratio of Cr (VI) and Pb (II). The result indicated that Fe (II)-PS-ZVI system should be a favourable removal technology for Cr (VI) and Pb (II).

Exposure of preterm neonates to toxic metals during their stay in the Neonatal Intensive Care Unit and its impact on neurodevelopment at 2 months of age

BACKGROUND

Premature neonates might be exposed to toxic metals during their stay in the neonatal intensive care unit (NICU), which could adversely affect neurodevelopment; however, limited evidence is available. The present study was therefore designed to assess the exposure to mercury, lead, cadmium, arsenic, and manganese of preterm neonates who received total parenteral nutrition (TPN) and/or red blood cell (RBC) transfusions during their NICU stay and the risk of neurodevelopment delay at the age of 2 months.

METHODS

We recruited 33 preterm neonates who required TPN during their NICU admission. Blood samples were collected for metal analysis at two different time points (admission and before discharge). Metals in the daily TPN received by preterm neonates were analyzed. Neurodevelopment was assessed using the Ages and Stages Questionnaire Edition 3 (ASQ-3).

RESULTS

All samples of TPN had metal contamination: 96% exceeded the critical arsenic limit (0.3 μg/kg body weight/day); daily manganese intake from TPN for preterm neonates exceeded the recommended dose (1 µg/kg body weight) as it was added intentionally to TPN solutions, raising potential safety concerns. All samples of RBC transfusions exceeded the estimated intravenous reference dose for lead (0.19 µg/kg body weight). Levels of mercury, lead and manganese in preterm neonates at discharge decreased 0.867 µg/L (95% CI, 0.76, 0.988), 0.831 (95%CI, 0.779, 0.886) and 0.847 µg/L (95% CI, 0.775, 0.926), respectively. A decrease in ASQ-3-problem solving scores was associated with higher levels of blood lead in preterm neonates taken at admission (ß = -0.405, 95%CI = -0.655, -0.014), and with plasma manganese (ß = -0.562, 95%CI = -0.995, -0.172). We also observed an association between decreased personal social domain scores with higher blood lead levels of preterm neonates before discharge (ß = -0.537, 95%CI = -0.905, -0.045).

CONCLUSION

Our findings provide evidence to suggest negative impacts on the neurodevelopment at 2 months of preterm infants exposed to certain metals, possibly related to TPN intake and/or blood transfusions received during their NICU stay. Preterm neonates may be exposed to levels of metals in utero.

Intermittent Lead Exposure Induces Behavioral and Cardiovascular Alterations Associated with Neuroinflammation

The nervous system is the primary target for lead exposure and the developing brain appears to be especially susceptible, namely the hippocampus. The mechanisms of lead neurotoxicity remain unclear, but microgliosis and astrogliosis are potential candidates, leading to an inflammatory cascade and interrupting the pathways involved in hippocampal functions. Moreover, these molecular changes can be impactful as they may contribute to the pathophysiology of behavioral deficits and cardiovascular complications observed in chronic lead exposure. Nevertheless, the health effects and the underlying influence mechanism of intermittent lead exposure in the nervous and cardiovascular systems are still vague. Thus, we used a rat model of intermittent lead exposure to determine the systemic effects of lead and on microglial and astroglial activation in the hippocampal dentate gyrus throughout time. In this study, the intermittent group was exposed to lead from the fetal period until 12 weeks of age, no exposure (tap water) until 20 weeks, and a second exposure from 20 to 28 weeks of age. A control group (without lead exposure) matched in age and sex was used. At 12, 20 and 28 weeks of age, both groups were submitted to a physiological and behavioral evaluation. Behavioral tests were performed for the assessment of anxiety-like behavior and locomotor activity (open-field test), and memory (novel object recognition test). In the physiological evaluation, in an acute experiment, blood pressure, electrocardiogram, and heart and respiratory rates were recorded, and autonomic reflexes were evaluated. The expression of GFAP, Iba-1, NeuN and Synaptophysin in the hippocampal dentate gyrus was assessed. Intermittent lead exposure induced microgliosis and astrogliosis in the hippocampus of rats and changes in behavioral and cardiovascular function. We identified increases in GFAP and Iba1 markers together with presynaptic dysfunction in the hippocampus, concomitant with behavioral changes. This type of exposure produced significant long-term memory dysfunction. Regarding physiological changes, hypertension, tachypnea, baroreceptor reflex impairment and increased chemoreceptor reflex sensitivity were observed. In conclusion, the present study demonstrated the potential of lead intermittent exposure inducing reactive astrogliosis and microgliosis, along with a presynaptic loss that was accompanied by alterations of homeostatic mechanisms. This suggests that chronic neuroinflammation promoted by intermittent lead exposure since fetal period may increase the susceptibility to adverse events in individuals with pre-existing cardiovascular disease and/or in the elderly.

Zinc status in public health: exploring emerging research trends through bibliometric analysis of the historical context from 1978 to 2022

The current study aims to provide a roadmap for future research by analyzing the research structures and trends in scholarly publications related to the status of zinc in public health. Only journal articles published between 1978 and 2022 are included in the refined bibliographical outputs retrieved from the Web of Science (WoS) database. The first section announces findings based on WoS categories, such as discipline heterogeneity, times cited and publications over time, and citation reports. The second section then employs VoSViewer software for bibliometric analysis, which includes a thorough examination of co-authorship among researchers, organizations, and countries and a count of all bibliographic databases among documents. The final section discusses the research's weaknesses and strengths in zinc status, public health, and potential future directions; 7158 authors contributed to 1730 papers (including 339 with publications, more than three times). "Keen, C.L." is a researcher with the most publications and a better understanding of zinc status in public health. Meanwhile, the USA has been the epicenter of research on the status of zinc in public health due to the highest percentage of publications with the most citations and collaboration with the rest of the world, with the top institution being the University of California, Davis. Future research can be organized collaboratively based on hot topics from co-occurrence network mapping and bibliographic couplings to improve zinc status and protect public health.

Trends in elemental Pb concentrations within atmospheric PM2.5 and associated risk to human health in major cities of China

High concentrations of elemental lead (Pb) in the atmosphere pose a serious threat to human health. This study presents and summarizes data obtained from relevant literature on Pb concentrations within fine particulate matter (PM_2.5) recorded in major cities in China from 2008 to 2019. An environmental health risk assessment model was then used to evaluate the health hazards of inhaling Pb among adults and children in China. Owing to the promulgation and implementation of a series of air pollution control measures, the Pb concentrations within PM_2.5 measured in major cities in China showed a downward trend after peaking in 2013. The concentrations were higher in winter than in summer, and higher in northern cities than in southern cities. Although the Pb concentrations in most cities did not exceed the limit (500 ng/m³) set by China, they remained much higher than concentrations recorded in developed countries. The results of the environmental health risk analysis showed that the non-carcinogenic risk from atmospheric Pb exposure was higher in children than in adults (adult females > adult males), while the carcinogenic risk was higher in adults than in children. This study shows that even if the health risk of Pb in PM_2.5 does not exceed the acceptable limit, stricter Pb pollution control measures are required to safeguard population health due to the dangers of Pb.

Prepubertal exposure to Pb alters autophagy in the brain of aging mice: A time-series based model

As a ubiquitous toxic heavy metal, lead (Pb) exposure is known to be implicated in the onset and development of neurodegenerative diseases which may cause more serious health hazards with age and the accumulation of Pb in the body. Autophagy is the main degradation route for abnormal aggregated proteins and damaged cell organelles. Here, we aimed to study the effects of adolescent Pb exposure on autophagy at different life nodes. In this study, we developed a time-series model of Pb exposure in mice and randomly divided 4-week-old male C57BL/6 mice into six groups (4 C, 13 C, 16 C, 4Pb, 13Pb and 16Pb). Mice in Pb groups was consumed deionized water containing 0.2 % Pb(Ac)2 for 3 months and then reared to anticipated life nodes, while the control group consumed deionized water. Western blot and Real-time qPCR were used to assess the effects of developmental Pb exposure on individual components of the autophagy machinery and modulation of microtubule-associated protein 1 light chain 3 (LC3) at each age stage. Our results showed that Pb exposure during adolescence reduced the p-mTOR/mTOR ratios with enhanced expression of Beclin-1, Atg12 and Atg7in both the hippocampus (HPC) and prefrontal cortex (PFC) of senescent mice while upregulation of LC3II/LC3I ratios and p62 suggested that autophagy mediates degradation was interrupted. Overall, we confirm that Pb exposure during adolescence promotes autophagic processes in the aged mice brain and that autophagic degradation is hindered, ultimately leading to a failure of autophagic degradation.

Identification of Legacy and Active Sources of Metal Contamination in Soils in Brooklyn, NY

The purpose of this study was to examine the spatial distribution and potential anthropogenic sources of lead (Pb), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) in surface soils throughout Brooklyn, NY. We collected soil samples (n = 1,373) from 176 different New York City parks. Samples were analyzed ex-situ using a portable X-ray fluorescence with a subset of samples laboratory confirmed. The effect of multiple sources on concentrations were determined by multivariable linear regression with generalized estimating equations. Median concentrations of Pb, Zn, Cu, Fe, and Mn were 108 ppm, 145 ppm, 49 ppm, 14,034 ppm, and 279 ppm, respectively. All metals were significantly correlated with one another (p < 0.001), with the strength of the correlation ranging from a low of approximately ρ = 0.3 (Pb-Mn and Zn-Mn) to a high of ρ = 0.7 (Pb-Cu). In final multivariate modeling significant association were observed between scrap yards and Mn concentration (β = 0.075, 0.019), National Priorities List (NPL) sites and Pb, Fe and Mn (β = 0.134, p = 0.004; β = 0.038, p = 0.014; β = 0.057, p = 0.037, respectively), and bridges nearby and Pb and Zn (β = 0.106, p = 0.003; β = 0.076, p = 0.026, respectively). Although manufacturing and industry have mostly left the area, smaller scrap metal recyclers are abundant and associated with increased Cu and Mn soil concentrations. In addition, NPL sites contributed to increased concentrations of all five metals within 800 m. Roadways have long been established to be sources of urban pollution; however, in our study we also found the presence of bridges within 800 m were also strongly predictive of increased Pb, Cu, and Zn concentrations.

Effect of food processing method on heavy metals

The problem of high content of heavy metals in food has spread broadly over the world. The presented study suggests the minimization of heavy metal content in processed food due to different applied techniques such as the frying, boiling, steaming and sous-vide. Three main food products were chosen for investigation – Daucus carota subsp. Sativus (carrot), Solanum tuberosum (potato) and Allium cepa (onion). The concentration of heavy metals (Zn, Pb, Mn, Cd, Cu) was determined in samples investigated by atomic-absorption spectrometer. The health risk index (HRI) was calculated based on obtained data. In all investigated samples, high concentration of lead was identified among the heavy metals. The highest concentration of zinc, lead and manganese was determined in boiled Daucus carota subsp. Sativus, cadmium – in sous - vide Daucus carota subsp. Sativus, copper – in steamed Daucus carota subsp. Sativus. HRI values of cadmium for Solanum tuberosum samples were ranged from 6.8 to 7.1 and for lead are ranged between 3.4 and 4.9.

Legacy Lead in Urban Garden Soils: Communicating Risk and Limiting Exposure

Lead (Pb) exposure has long been recognized as a hazard to human health. Urban garden soils often contain elevated levels of Pb, mainly from legacy sources, which is a main barrier for urban gardening. The capacity of gardeners to access, understand, and act on scientific data related to soil contamination is also variable. This synthesis paper briefly summarizes the current scientific knowledge on soil Pb in urban gardens. Our objective is to produce clear recommendations about assessing actual risks and limiting exposure. First, we synthesize the nature and extent of soil contamination with Pb, and then describe how the bioavailability and risk of this contamination to humans is assessed. We then go on to potential exposure pathway through plants and remediation methods to improve soil health and reduce human exposure. We have developed best management practices for practitioners that include: (1) urban soil testing should be prioritized because of the high probability of Pb contamination, and urban gardening should not begin until thorough testing or remediation has been done; (2) documentation of land-use history should be required in all property transactions so that the potential for soil (and other) contamination can be clearly identified; (3) amendments cannot be relied upon as a treatment for contaminated soils to reduce risk to gardeners because they do not always make contaminants less harmful; (4) certain crops (such as fruiting vegetables) are much less susceptible to contamination than others and thus should be prioritized in urban gardens; (5) wherever feasible, raised beds filled with upcycled local mineral and organic materials are the preferred substrate for urban gardening. Further monitoring of potentially contaminated and remediated soils as well as effective communication with the public are necessary to ensure human safety.

An investigation of heavy metals in edible bird's nest from Indonesia using inductively coupled plasma mass spectrometry

Background and Aim:

In 2020, Indonesia, which has the highest global production of edible bird’s nest (EBNs), exported up to 1312.5 tons of this product at a value of USD 540.4 million. Recently, food safety aspects related to EBNs, including contamination with heavy metals, have become a serious concern. However, data on the presence and concentration of heavy metals in EBNs in Indonesia are not yet available. This study aimed to determine and compare the presence and concentrations of arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), and tin (Sn) in EBNs originating from several primary Indonesian islands. The study also analyzed the effect of washing on the heavy metal content in EBNs.

Materials and Methods:

A study on 44 swiftlet farmhouses (SFHs) was conducted to determine the concentrations of heavy metals in EBNs. The number of samples from the SFHs was allocated proportionally to the main EBN-producing islands in Indonesia, that is, Kalimantan, Sumatera, Sulawesi, and Java (22, 13, 7, and 2, respectively). The concentrations of the above five elements in the samples before washing (raw–unclean EBNs) and after washing (raw–clean EBNs) were determined by inductively coupled plasma mass spectrometry. Washing was conducted according to the general procedures at an EBN processing plant.

Results:

The raw–unclean EBNs from the four islands contained As, Pb, Cd, and Sn at varying concentrations. However, Hg was not detected in the raw–unclean EBN samples from Sulawesi. The raw–unclean EBNs from Kalimantan had lower concentrations of Pb and Cd compared with the other islands. The concentrations of As, Pb, Cd, and Sn in the EBNs decreased significantly after washing with clean water.

Conclusion:

Heavy metals (As, Hg, Pb, Cd, and Sn) were detected at a low level in most of the raw–unclean EBNs originating from the main Indonesian island where they were produced. The concentrations of all the heavy metals reviewed in the raw–unclean EBNs samples decreased significantly after washing.

Risk Factors and Hazards in the Household Environment for Elevated Blood Lead Levels in Urban Preschool Children of Vellore: A Case-Control Approach in the MAL-ED Birth Cohort

OBJECTIVES

To study the household environmental risk factors and hazards associated with elevated blood lead levels (EBLLs) in preschool children in an urban setting of Vellore, South India.

METHODS

A case-control study within the MAL-ED (Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development) birth cohort was conducted between January 2014 and January 2015. The study included 153 pre-school children: 87 cases and 66 controls with elevated and normal BLLs, respectively. A structured questionnaire was used to assess the sociodemographic profile, household environment, breastfeeding practices, children's habits, and the use of cosmetics in them. Household environmental samples of wall and door paint, floor dust, drinking water, and cosmetics were estimated for lead levels using gas flame atomic absorption spectrometry (FAAS).

RESULTS

Children born with low birth weight, those living in houses painted at least once in the last five years and those residing in houses older than ten years had a higher odds of EBLLs [OR (95% CI) = 3.79 (1.24-11.1); 4.84 (1.42-16.53); 5.07 (2.06-12.46), and 2.58 (0.99-6.69)], respectively. Drinking water samples from both cases (88%) and controls (95%) had lead levels more than the Environmental Protection Agency (EPA), USA recommendation of 0.015 ppm.

CONCLUSIONS

Low birth weight and the household environment pose important risk factors/hazards for elevated blood lead levels in urban preschool children. Multipronged interventions that include government legislations, household environmental modification, safe water supply, and community education are pivotal in reducing lead exposure in young children.

Delta-Aminolevulinic Acid Dehydratase, Low Blood Lead Levels, Social Factors, and Intellectual Function in an Afro-Brazilian Children Community

Delta-aminolevulinic acid dehydratase (ALAD) enzyme catalyzes the second phase of the heme biosynthesis and is involved in lead toxicokinetics. This research aimed to evaluate its influence on the relationship between blood lead (PbB) levels and intellectual performance in Afro-Brazilian children. PbB, hemoglobin concentration, ALAD activity, and polymorphism were determined in whole blood. Anthropometric, socioeconomic, and family environment stimuli data were collected with appropriate instruments. The non-verbal intelligence of children and their mothers or guardians was assessed using the correspondent Raven's Progressive Matrix versions. The medians (range) of PbB levels and ALAD activity were 1.0 μg/dL (0.1-21.3) and, 71 U/L (31-113), respectively. ALAD G177C was distributed as follows: 97.9% for ALAD1/1 and 2.1% for ALAD1/2 genotypes. The mean of Raven raw score was 19.3 (± 5.6) points and there were no differences according to sex or environmental Pb exposure. No statistically significant association was observed between PbB level and children's IQ. However, ALAD activity presented an inverse significant association with PbB levels, children's percentile IQ, and children's IQ/Age ratio, suggesting a neuroprotective role of ALAD1 genotype in those with low PbB level.

Using Community Science to Better Understand Lead Exposure Risks

Lead (Pb) is a neurotoxicant that particularly harms young children. Urban environments are often plagued with elevated Pb in soils and dusts, posing a health exposure risk from inhalation and ingestion of these contaminated media. Thus, a better understanding of where to prioritize risk screening and intervention is paramount from a public health perspective. We have synthesized a large national data set of Pb concentrations in household dusts from across the United States (U.S.), part of a community science initiative called "DustSafe." Using these results, we have developed a straightforward logistic regression model that correctly predicts whether Pb is elevated (>80 ppm) or low (<80 ppm) in household dusts 75% of the time. Additionally, our model estimated 18% false negatives for elevated Pb, displaying that there was a low probability of elevated Pb in homes being misclassified. Our model uses only variables of approximate housing age and whether there is peeling paint in the interior of the home, illustrating how a simple and successful Pb predictive model can be generated if researchers ask the right screening questions. Scanning electron microscopy supports a common presence of Pb paint in several dust samples with elevated bulk Pb concentrations, which explains the predictive power of housing age and peeling paint in the model. This model was also implemented into an interactive mobile app that aims to increase community-wide participation with Pb household screening. The app will hopefully provide greater awareness of Pb risks and a highly efficient way to begin mitigation.

Lead, Soils, and Children: An Ecological Analysis of Lead Contamination in Parks and Elevated Blood Lead Levels in Brooklyn, New York

Although the prevalence of elevated childhood blood lead levels (BLLs) has been declining, there are still an estimated 500,000 children (1 to 5 years) with BLLs above the CDC's reference value (≥ 5 μg/dL). The objective of this study was to evaluate the ecological association between soil lead (Pb) concentrations in greenspaces in Brooklyn, NY and elevated BLLs of children aged 1 to 5 years old. Soil samples (n = 1504) were collected from a wide variety of parks within 43 neighborhood tabulation areas (NTAs) located in Brooklyn, NY, analyzed with a portable XRF with a subset (n = 350), and also analyzed by ICP-MS. Lead concentrations were right skewed with a mean of 160.4 ppm and a median of 113.1 ppm. The Pb concentration range spanned three orders of magnitude with most samples (66.7%) ≥ 80 ppm and 6.7% of samples ≥ 400 ppm. Elevated BLL (≥ 5ug/dL) data on children 1 to 5 years were obtained from the New York City Department of Health and Mental Hygiene (2011-2015). Weighted median soil Pb concentrations were calculated for each NTA and stratified into quartiles. The overall median rate of children from 1 to 5 years old with BLLs ≥ 5 µg/dL was 28.6 per 1000; the median rate was highest (p = 0.070) in the fourth quartile (Pb concentrations ≥ 150 ppm) compared to the first quartile (Pb concentrations < 88 ppm), 37.2 vs. 28.3 per 1000, respectively. We then used multivariable linear regression to determine the ecological association between BLL rates and soil Pb concentrations. In the final stepwise multivariable regression model, controlling for known risk factors, there was a significant positive association between soil Pb concentrations and increased childhood BLL rates (beta = 0.0008; p = 0.004). Our findings suggest that there is an ecological association between high soil Pb levels and increased rates of elevated childhood BLLs.

Assessment of Urinary Lead (Pb) and Essential Trace Elements in Autism Spectrum Disorder: a Case-Control Study Among Preschool Children in Malaysia

Lead (Pb) is a heavy metal which is abundant in the environment and known to cause neurotoxicity in children even at minute concentration. However, the trace elements calcium (Ca), magnesium (Mg), zinc (Zn) and iron (Fe) are essential to children due to its protective effect on neurodevelopment. The primary objective of this study was to assess the role of Pb and trace elements in the development of autism spectrum disorder (ASD) among preschool children. A total of 81 ASD children and 74 typically developed (TD) children aged between 3 and 6 years participated in the study. Self-administered online questionnaires were completed by the parents. A first-morning urine sample was collected in a sterile polyethene urine container and assayed for Pb, Ca, Mg, Zn and Fe using an inductively coupled plasma mass spectrometry (ICP-MS). Comparisons between groups revealed that the urinary Pb, Mg, Zn and Fe levels in ASD children were significantly lower than TD children. The odds of ASD reduced significantly by 5.0% and 23.0% with an increment of every 1.0 μg/dL urinary Zn and Fe, respectively. Post interaction analysis showed that the odds of ASD reduced significantly by 11.0% and 0.1% with an increment of every 1.0 μg/dL urinary Zn and Pb, respectively. A significantly lower urinary Pb level in ASD children than TD children may be due to their poor detoxifying mechanism. Also, the significantly lower urinary Zn and Fe levels in ASD children may augment the neurotoxic effect of Pb.

Lead-Induced Motor Dysfunction Is Associated with Oxidative Stress, Proteome Modulation, and Neurodegeneration in Motor Cortex of Rats

Lead (Pb) is a toxic metal with great neurotoxic potential. The aim of this study was to investigate the effects of a long-term Pb intoxication on the global proteomic profile, oxidative biochemistry and neuronal density in motor cortex of adult rats, and the possible outcomes related to motor functions. For this, Wistar rats received for 55 days a dose of 50 mg/Kg of Pb acetate by intragastric gavage. Then, the motor abilities were evaluated by open field and inclined plane tests. To investigate the possible oxidative biochemistry modulation, the levels of pro-oxidant parameters as lipid peroxidation and nitrites were evaluated. The global proteomic profile was evaluated by ultraefficiency liquid chromatography system coupled with mass spectrometry (UPLC/MS) followed by bioinformatic analysis. Moreover, it was evaluated the mature neuron density by anti-NeuN immunostaining. The statistical analysis was performed through Student's t-test, considering p < 0.05. We observed oxidative stress triggering by the increase in malonaldehyde and nitrite levels in motor cortex. In the proteomic analysis, the motor cortex presented alterations in proteins associated with neural functioning, morphological organization, and neurodegenerative features. In addition, it was observed a decrease in the number of mature neurons. These findings, associated with previous evidences observed in spinal cord, cerebellum, and hippocampus under the same Pb administration protocol, corroborate with the motor deficits in the rats towards Pb. Thus, we conclude that the long-term administration to Pb in young Wistar rats triggers impairments at several organizational levels, such as biochemical and morphological, which resulted in poor motor performance.

A systematic review of clinical and laboratory findings of lead poisoning: lessons from case reports

Lead is one of the most toxic heavy metals in the environment. The present review aimed to highlight hazardous pollution sources, management, and review symptoms of lead poisonings in various parts of the world. The present study summarized the information available from case reports and case series studies from 2009 to March 2020 on the lead pollution sources and clinical symptoms. All are along with detoxification methods in infants, children, and adults. Our literature compilation includes results from 126 studies on lead poisoning. We found that traditional medication, occupational exposure, and substance abuse are as common as previously reported sources of lead exposure for children and adults. Ayurvedic medications and gunshot wounds have been identified as the most common source of exposure in the United States. However, opium and occupational exposure to the batteries were primarily seen in Iran and India. Furthermore, neurological, gastrointestinal, and hematological disorders were the most frequently occurring symptoms in lead-poisoned patients. As for therapeutic strategies, our findings confirm the safety and efficacy of chelating agents, even for infants. Our results suggest that treatment with chelating agents combined with the prevention of environmental exposure may be an excellent strategy to reduce the rate of lead poisoning. Besides, more clinical studies and long-term follow-ups are necessary to address all questions about lead poisoning management.

Novel Application of Machine Learning Algorithms and Model-Agnostic Methods to Identify Factors Influencing Childhood Blood Lead Levels

Blood lead (Pb) poisoning remains a global concern, particularly for children in their early developmental years. Broken Hill is Australia's oldest operating silver-zinc-lead mine. In this study, we utilized recent advances in machine learning to assess multiple algorithms and identify the most optimal model for predicting childhood blood Pb levels (BLL) using Broken Hill children's (<5 years of age) data (n = 23,749) from 1991 to 2015, combined with demographic, socio-economic, and environmental influencing factors. We applied model-agnostic methods to interpret the most optimal model, investigating different environmental and human factors influencing childhood BLL. Algorithm assessment showed that stacked ensemble, a method for automatically and optimally combining multiple prediction algorithms, enhanced predictive performance by 1.1% with respect to mean absolute error (p < 0.01) and 2.6% for root-mean-squared error (p < 0.01) compared to the best performing constituent algorithm (random forest). By interpreting the model, the following information was acquired: children had higher BLL if they resided within 1.0 km to the central mine area or 1.37 km to the railroad; year of testing had the greatest interactive strength with all other factors; BLL increased faster in Aboriginal than in non-Aboriginal children at 9-10 and 12-18 months of age. This "stacked ensemble + model-agnostic interpretation" framework achieved both prediction accuracy and model interpretability, identifying previously unconnected variables associated with elevated childhood BLL, offering a marked advantage over previous works. Thus, this approach has a clear value and potential for application to other environmental health issues.

Spatial variation, water quality, and health risk assessment of trace elements in groundwater in Beijing and Shijiazhuang, North China Plain

Metal(loid)s pollution of groundwater in northern China is of great concern due to the increasing shortage of fresh water resources. In the present study, total 159 of groundwater samples were collected from the Miyun-Huairou-Shunyi (MHS) districts in Beijing city and the Hutuo River Plain (HRP) in Shijiazhuang city. Nineteen trace elements dissolved in groundwater were measured. Results showed that Al (12.3 %), Mn (5.3%), Zn (1.8%), As (1.8%), and Pb (1.8%) in the MHS samples, and Mn (2.2%) in the HRP samples exceeded their standard threshold of WHO and China. Exceedance of trace elements was attributed to both geochemical background and local human activities. Human health risk assessment showed that local consumers were exposed at a low level of health risk, except in specific area with a high level of arsenic. Elements of arsenic and chromium were important risk contributors in the two regions. The risk of oral exposure was greater than that of skin uptake. Children were more susceptible to non-carcinogenic risk and less to carcinogenic risk than adults. A Nemerow index and CRITIC-weighted WQI were applied to classify groundwater quality. The results from the two methods were comparable to a large extend. More population living in plain rather than mountain resulted in a gradual deterioration trend of groundwater quality from mountain to plain. The samples with poor water quality were almost collected in the area with heavy industrial and agricultural activities. The CRITIC-weighted WQI was recommended for groundwater quality assessment. A simple classification criterion was reformulated based on the MHS hazard index analysis. The groundwaters in the two research fields were not seriously polluted, but potential risks should not be ignored.

Blood lead levels of Chinese children from 1991 to 2020: Based on Monte Carlo simulation

Chinese children have been exposed to high level of lead due to polluted air, dust, contaminated foods and water, etc. In this research, we investigated published blood lead levels (BLLs) reflecting 1,057,832 Chinese children aged at 0-12 and teenagers aged at 13-18 in the past 30 years (1991-2020). The data mining and estimation were performed innovatively by Monte Carlo simulation to remedy the skewed distribution-induced bias. The temporal trend of Chinese children's BLLs showed an obvious decrease in the past decades from 88.74 μg/L (Geometric SD = 4.09) during 1991-1995 to 27.32 μg/L (Geometric SD = 4.18) during 2016-2020. This study also indicated that children's BLLs of Yunnan, Guizhou, Shanxi were at relatively high levels and most provinces showed a downward trend. Chinese boys aged at 1-18 years old had higher BLLs (GM: 44.03 μg/L) compared to girls (GM: 41.32 μg/L) (p < 0.001). At different age groups, Chinese children's BLLs were 42.04 μg/L (1-3 years old), 52.88 μg/L (4-6 years old), 50.49 μg/L (7 and above years old), respectively. Although the BLLs of Chinese children exhibited a continuous declined trend in the past 30 years, it was still higher than that in developed countries, which indicated that more efforts are needed in children's BLLs control.

Effect of chelation therapy on arrhythmogenic and basal ECG parameters of lead exposed workers

Lead exposure has etiological role on cardiovascular system diseases as hypertension, atherosclerosis, stroke, and arrhythmic events. In this study, we aimed to compare the basal and arrhythmogenic ECG parameters of lead exposed workers before and after chelation therapy and to evaluate the effect of acute change of blood lead levels on ECG. Fourty consecutive occupationally lead exposed workers were enrolled, demographic, blood, echocardiographic, and electrocardiographic data's were analyzed before and after chelation therapy. Pmax, P min, P Wave Dispersion, and QT Dispersion values which are arrhythmia predictors were significantly lower after chelation therapy compared to values before chelation therapy. Lead exposed workers are under the risk of ventricular and atrial arrythmias and chelation treatment has a positive effect on these parameters.

Elevated lead levels in relation to low serum neuropeptide Y and adverse behavioral effects in preschool children with e-waste exposure

As a neurotoxicant, lead (Pb) primarily affects central nervous system, and particularly impacts developing brain. This study explores the associations of blood Pb level and children's behavioral health. A total of 213 preschool children aged 3-7 years old were recruited from Guiyu (the e-waste-exposed area) and Haojiang (the reference area). The behavioral health of children was assessed using the 'behavioral symptoms' subscale of the Strengths and Difficulties Questionnaire (SDQ). Results showed that there was a significant difference in percent of children categorized as "at risk" between Guiyu (48.2%) and Haojiang (13.9%) (p < 0.001). The blood Pb level of children in Guiyu was significantly higher than those in Haojiang (median: 5.19 μg/dL vs. 3.42 μg/dL, p < 0.001). The serum Neuropeptide Y (NPY) was significantly lower in Guiyu children than those in Haojiang. Spearman correlation analyses demonstrated that blood Pb levels was negatively correlated with NPY (r_s = -0.25, p < 0.001), but positively correlated with behavioral symptom scores; while serum NPY levels were negatively associated with behavioral symptom scores. Behavioral symptom scores were higher in children with blood Pb level ≥5.00 μg/dL (high) than those with blood Pb level < 5.00 μg/dL (low). After adjusting for confounding factors, children with lower NPY levels were at higher risk of having behavioral difficulties. In conclusion, Pb exposure in e-waste-exposed areas may lead to decrease in serum NPY and increase in the risk of children's behavioral problems. In addition, NPY may mediate the association between Pb exposure and behavioral difficulties.

The Effect of Lead Exposure on Autism Development

Autism Spectrum Disorder (ASD) remains one of the most detrimental neurodevelopmental conditions in society today. Common symptoms include diminished social and communication ability. Investigations on autism etiology remain largely ambiguous. Previous studies have highlighted exposure to lead (Pb) may play a role in ASD. In addition, lead has been shown to be one of the most prevalent metal exposures associated with neurological deficits. A semi-systematic review was conducted using public databases in order to evaluate the extent of lead's role in the etiology of autism. This review examines the relationship between autistic comorbid symptoms-such as deterioration in intelligence scores, memory, language ability, and social interaction-and lead exposure. Specifically, the mechanisms of action of lead exposure, including changes within the cholinergic, dopaminergic, glutamatergic, gamma aminobutyric acid (GABA)ergic systems, are discussed. The goal of this review is to help illustrate the connections between lead's mechanistic interference and the possible furthering of the comorbidities of ASD. Considerations of the current data and trends suggest a potential strong role for lead in ASD.

Hydrogen sulfide protects hippocampal CA1 neurons against lead mediated neuronal damage via reduction oxidative stress in male rats

H2S plays vital roles in modulation brain function. It is associated with antioxidant and anti-inflammatory properties. We assessed the H2S impact on spatial learning and memory deficit and cell death due to lead exposure, and probable mechanisms of action. The 36 male Wistar rats that (200-220 g), were in random assigned to 3 groups, control group (12 rats), lead acetate group (12 rats), and lead acetate +H2S groups (NaHS as a H2S donor; 5/6 mg/kg; 12 rats). Administration of lead to rats was performed through acute lead poisoning (25 mg/kg of lead acetate, IP through 3 days). Using male Morris water maze, their spatial learning and memory function were measured. We carried out ELISA method to calculate TNF-α and antioxidant enzymes level. Immunohistochemical staining was applied for evaluating the caspase-3 expression levels. Treatment with H2S improved learning and memory impairment in Pb-exposed rats (P<0.05). H2S treatment suppressed Pb-related apoptosis in the hippocampal CA1 subfield (P<0.01). Also, the TNF-α over-expression in the CA1 region of hippocampus due to lead exposure showed a significant reduction (P<0.05) after administrating H2S. Simultaneously, H2S treatment reduced the MDA levels, enhanced SOD, GSH level than the Pb-exposed group in hippocampus (P<0.05). H2S was able to significantly improve Pb-related spatial learning and memory deficit, and neuronal cell death in the CA1 region of hippocampus in the male rats at least partly by reducing oxidative stress and TNF.

The effect of confounding variables in studies of lead exposure and IQ

Methods proposed to address confounding variables frequently do not adequately distinguish confounding from covariation. A confounder is a variable that correlates both with the outcome and the major exposure variable. Accurate treatment of confounding is crucial to low dose extrapolation of the effects of chemical exposures based on epidemiology studies. This study explores the limitations of current regression models in extrapolation to the low dose region of the dose-response curve due to the existence of unrecognized and uncontrolled confounding, using epidemiological data for lead. Based on the reported data in analyses by Lanphear and colleagues and Crump and colleagues, and drawing on other studies, Wilson and Wilson considered maternal IQ, HOME score, SES, parental education, birthweight, smoking, and race as characteristic variables which may have interaction effects. This analysis identifies confounding variables based on the seven longitudinal cohorts in analyses conducted by Lanphear and colleagues and by Crump and colleagues and confirms maternal IQ, HOME score, maternal education and maternal marital status at birth are "Highly Likely" confounders, while race is a "Likely" confounder. The cohort data were reanalyzed using the methods presented by Crump and colleagues while also considering the interaction among the identified confounding variables. This analysis determined that confounders influence IQ estimates in a quantifiable way that may exceed or at least obscure previously-reported effects of blood lead on IQ with blood lead levels below 5 µg/dL; however, limitations in the datasets make predictions of the low dose dose-response analysis questionable.

Content and Dietary Exposure Assessment of Toxic Elements in Infant Formulas from the Chinese Market

In this study, the content of chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in domestic and imported infant formulas from Beijing, China were analyzed using inductively coupled plasma mass spectrometry. The content of Cr, As, Cd and Pb was 2.51-83.80, 0.89-7.87, 0.13-3.58 and 0.36-5.57 μg/kg, respectively. Even though there were no significant differences in toxic elements content between domestic and imported infant formulas, Cd content was slightly lower in domestic samples. The estimated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI) were calculated for infants between 0.5 and 5 y of age. The EDIs were lower than the oral reference doses. THQ of As, Cr, Cd and Pb was 0.027-0.103, 0.024-0.093, 0.0025-0.0090 and 0.0015-0.0046, respectively. HI values were 0.055-0.192 for boys and 0.056-0.209 for girls and were inversely associated with age with a threshold < 1. The non-carcinogenic risk value were in the safe range, indicating that exposure of As, Pb, Cr and Cd from infant formulas do not represent a health risk in China.

Association between blood lead level during pregnancy and birth weight: A meta-analysis

BACKGROUND

We aimed to provide a quantitative summary of evidence for a relationship between prenatal lead (Pb) exposure and birth weight.

METHODS

PubMed and Web of Science databases were searched for eligible epidemiological studies. We transformed findings in eligible studies with different effect-size metrics to standardized regression coefficients, and used fixed-effects or random-effects models to assess the pooled effects of prenatal Pb exposure on birth weight.

RESULTS

There was a significant negative association between prenatal Pb exposure and birth weight. Birth weight reduction was associated with elevated lead levels in maternal blood (β = -0.094; 95% confidence interval [CI]: -0.157 to -0.030) and cord blood (β = -0.120; 95% CI: -0.239 to -0.001).

CONCLUSIONS

This meta-analysis is the first to provide a quantitative assessment of Pb exposure during pregnancy and an increased risk of lower birth weight.

Effects of early and recent mercury and lead exposure on the neurodevelopment of children with elevated mercury and/or developmental delays during lactation: A follow-up study

This follow-up study of 82 children investigated the potential impact of early and recent exposure to mercury and lead on their neurodevelopmental performance at 5-8 years of age (2017-2018). Early exposure of these children to mercury, methylmercury, and lead was assessed during lactation at 3-12 months old, as well as their mother's exposure using measurements from a cross-sectional study (2011-2013). Only infants who failed to pass the neurodevelopment screening tools and/or had elevated mercury were included in this study. Urine and hair were sampled during the follow-up study to assess the children's recent exposure to mercury, methylmercury, and lead. Their cognitive performance and visual-motor integration were also measured using the Test of Non-Verbal Intelligence (TONI) and the Beery-Visual-Motor Integration (Beery VMI), respectively. The association between alterations in urinary porphyrins excretion and exposure to metals was analyzed and their influence on the children's neurodevelopment was explored. Linear regression models revealed a significant negative association between the infants' mercury exposure during lactation and the TONI Quotient (β = -0.298, 95%CI = -4.677, -0.414) and Beery VMI Age Equivalent scores at age 5-8 (β = -0.437, 95%CI = -6.383, -1.844). The mothers' blood methylmercury was inversely and significantly associated with their children's TONI Quotient (β = -0.231, 95%CI = -8.184, -0.331). In contrast, the children's Beery VMI Age Equivalent scores were positively and significantly associated with the hair methylmercury of the mothers (β = 0.214, 95%CI = 0.088, 3.899) and their infants (β = 0.256, 95%CI = 0.396, 4.488). These relationships suggest the presence of negative confounding that we did not take into account. Unlike mercury, there was some evidence that lead in breast milk had an inverse relationship with the children's visual-motor coordination skills. Our study did not show a clear association between children's recent exposure to metals and neurodevelopment. However, a significant inverse association was observed between the TONI Quotient and the interaction of hair methylmercury × ∑porphyrins (ß = -0.224, 95%CI = -0.86, -0.049), implying that porphyrins are a sensitive measure of low body-mercury burden. Although lead induced higher ∑porphyrins excretion in urine (β = 0.347, 95%CI = 0.107, 0.525), their interaction did not influence children's neurodevelopmental scores. The interactions between metals and porphyrins might provide insights into their potential contributory role in the pathogenesis associated with neurological disorders or other diseases. Despite the small sample size of the present study, its findings about the association between toxic metal exposure and the high risk of poor neurodevelopmental performance are worrying, particularly at an early age, and additional research is needed using larger sample sizes.

Quantificational exposure, sources, and health risks posed by heavy metals in indoor and outdoor household dust in a typical smelting area in China

Contamination of metals in household dust remains a concern for human health. However, few studies to date have been conducted on the contribution of both indoor and outdoor environments to the health risks posed by metals. This study was carried out to assess the potential health risks from both indoor and outdoor household dust and the respective contribution to the health risks for children. The results showed that household dusts were heavily polluted by metal(loid)s, which were up to 30 times higher than the relative background level, and were attributed to smelting activity. However, there are other pollution sources in indoor environments, since the I/O ratio values of Pb, Cd, and As were significantly higher than 1. HI values of Pb and As exceeded the threshold of (1) and accounted for approximately 60% and 24% to the HIt, respectively. The HIts of Zn, Cr, Mn, Hg, and Cu were mainly attributable to indoor dust exposure, particularly for Hg (73.44%), indicating non-carcinogenic health risks could be attributed more to the indoor dust exposure. This study highlights the potential risks of metal contamination in household environment, particularly indoor environment, on the health of children who live in the vicinity of smelting activity.

Carvacrol reduces hippocampal cell death and improves learning and memory deficits following lead-induced neurotoxicity via antioxidant activity

Carvacrol is a monoterpene with neuroprotective effects in several animal models of neurodegeneration, including epilepsy, ischemia, and traumatic neuronal events. In this study, we aimed to examine the effects of carvacrol on neurodegeneration induced by lead acetate in rats. A total of 50 male Wistar rats were divided into five equal groups. The control group received drinking water, while the neurotoxic group was exposed to 500 ppm of lead acetate in drinking water for 40 days. The three remaining groups, which were also exposed to 500 ppm of lead acetate, received carvacrol at doses of 25, 50, and 100 mg/kg orally for 40 days. The Morris water maze test was employed to examine spatial learning and memory. Pathological damage to the hippocampus was determined by Nissl staining. The level of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were detected using biochemical analysis and the free radical scavenging activity as evaluated by the DPPH test. Administration of carvacrol significantly restored learning and memory impairment induced by lead acetate. Moreover, carvacrol ameliorated neurodegeneration, antioxidative capacity, and lipid peroxidation in the hippocampus of rats exposed to lead. The present results provide a rationale for the inhibitory role of carvacrol in the attenuation of lead-induced neurotoxicity.

Lead in New York City's soils: Population growth, land use, and contamination

Soil is an important exposure pathway for lead (Pb) and predictor of blood lead levels (BLL) among children. Over the past two decades, many areas within New York City (NYC) have undergone a transition from industrial and manufacturing land use to residential housing. This can bring new residents to areas which contain the legacy of historic Pb contamination. The objective of this study was to evaluate the difference in soil Pb concentrations between community parks and greenspaces in areas undergoing rapid redevelopment and land use changes and stable areas without redevelopment. Three high- and three low-risk Pb contaminated areas within NYC were identified based on an additive index that included population growth, industrial land use, and new construction. Soil samples (n=358) were collected across 34 parks and analyzed with an XRF with a subset also analyzed by ICP-MS. Areas within NYC, evaluated in this study, with a high-risk index had significantly (p<0.0001) larger mean concentrations of Pb in soil (374 mg/kg vs. 150 mg/kg, respectively) and double the rate of children under the age of six years with BLL > 5ug/dL (37.94 vs. 18.72 per 1000, respectively) compared to low-risk areas. There was a statistically significant (p <0.05) positive correlation between street density, manufacturing/industrial land density and population density change within 0.40 km of a park and soil Pb concentrations. However, we were unable to estimate the source-specific contribution of Pb concentrations in soil, since many of the variables assessed were correlated with one another. Regardless of the source, large population increases are occurring in areas with elevated soil Pb levels. In the three high-risk areas investigated in this study, the population has increased by over 35,000 residents between 2010 to 2017 compared to just 8,500 in the low-risk areas.

Chronic exposure to heavy metals from informal e-waste recycling plants and children's attention, executive function and academic performance

E-waste contains valuable metals that require appropriate waste management plans. However, rudimentary e-waste processing methods are a source of heavy metals environmental pollution. This study has characterised concentrations of heavy metals in soil (n = 10), water (n = 10) and hair (n = 44) of children in areas surrounding Jakarta (Indonesia), where e-waste is being or has been conducted in the past, and in a reference unexposed site. Chronic exposure to Mn, Pb, Hg, As and Cd and its associations with attention and executive function, characterised with the Trail Making Test (TMT), along with academic performance scores was conducted using multivariate regression analysis. Models were adjusted for age, gender, parental education, environmental tobacco smoke and residential traffic. Lead (3653 ± 3355 mg/kg), cadmium (3.4 ± 0.9 mg/kg) and mercury (15.2 ± 28.5 mg/kg) concentrations from soil and manganese concentrations in water (1.43 ± 0.64 mg/L) in the exposed sites were higher than current regulations. Heavy metal concentrations in hair of children living near e-waste facilities was higher than for children living in non-exposed areas (Pb: 0.155 ± 0.187 vs 0.0729 ± 0.08 mg/g; Mn: 0.130 ± 0.212 vs 0.018 ± 0.045 mg/g; Hg: 0.008 ± 0.0042 vs 0.002 ± 0.0011 mg/g) suggesting chronic exposure to heavy metals. Manganese exposure was associated with worse cognitive performance in the domains of attention (TMT-A score: 66 s, 95% CI 0.09, 132), executive function (TMT-B score: 105 s, 95% CI 11.5, 198) and social sciences (-29%, 95% CI -54, -4.7) (per unit of Mn in hair mg/g). These results suggest that informal e-waste activities contribute to local heavy metal soil contamination, and could be an important source of metal exposure to children living in the vicinity of these facilities with putative impacts on their cognitive performance. E-waste management regulation and remediation programmes should be implemented to reduce environmental pollution and associated health effects.

Environmental exposure to lead and hematological parameters in Afro-Brazilian children living near artisanal glazed pottery workshops

This study aimed to evaluate the exposure to environmental lead (Pb) of children from a traditional community of African descent in Brazil and the effects on hematological parameters. Children (n = 75) aged 5.5-13 years from the exposed areas classified as low (LEx) and moderately (MEx) exposed were compared with children (n = 75) of a control group (CG). Dust Pb loading rates (RtPbs) at children's homes were measured. Peripheral venous blood samples were collected to assess Pb biomarkers of exposure and effects. All Pb determinations were performed by graphite furnace atomic absorption spectrometry. The median (IQR) of RtPb, PbB level, and ALA-D activity were 65 (25-137) μgPb/m²/30 days, 1.0 (0.1-2.8) μg/dL, and 71 (55-86) U/L, respectively. Spearman correlation evidenced the relationship of PbB with RtPb (rho = 0.368, P < 0.001) and ALA-D activity (rho = -0.587; P ˂ 0.001). After adjusting for exposure degree and child's age, a decline of 7.4 U/L in ALA-D activity was associated with a 10-fold increase in PbB. The prevalence ratio of elevated PbB (>5 μg/dL) in LEx and MEx areas were 1.5 and 3.7, respectively. Indoor dust exposure, living near pottery workshops and the secondary exposure were the main determinants of elevated PbB levels, which were associated with hematological effects.

Current trends of blood lead levels, distribution patterns and exposure variations among household members in Kabwe, Zambia

Childhood lead (Pb) poisoning has devastating effects on neurodevelopment and causes overt clinical signs including convulsions and coma. Health effects including hypertension and various reproductive problems have been reported in adults. Historical Pb mining in Zambia's Kabwe town left a legacy of environmental pollution and childhood Pb poisoning. The current study aimed at establishing the extent of Pb poisoning and exposure differences among family members in Kabwe as well as determining populations at risk and identify children eligible for chelation therapy. Blood samples were collected in July and August 2017 from 1190 household members and Pb was measured using a portable LeadCare-II analyser. Participants included 291 younger children (3-months to 3-years-old), 271 older children (4-9-years-old), 412 mothers and 216 fathers from 13 townships with diverse levels of Pb contamination. The Blood Lead Levels (BLL) ranged from 1.65 to 162  μg/dL, with residents from Kasanda (mean 45.7  μg/dL) recording the highest BLL while Hamududu residents recorded the lowest (mean 3.3  μg/dL). Of the total number of children sampled (n = 562), 23% exceeded the 45  μg/dL, the threshold required for chelation therapy. A few children (5) exceeded the 100  μg/dL whereas none of the parents exceeded the 100  μg/dL value. Children had higher BLL than parents, with peak BLL-recorded at the age of 2-years-old. Lead exposure differences in Kabwe were attributed to distance and direction from the mine, with younger children at highest risk. Exposure levels in parents were equally alarming. For prompt diagnosis and treatment, a portable point-of-care devise such as a LeadCare-II would be preferable in Kabwe.

Elevated Serum Pb, Ni, Cd, and Cr Levels and DNA Damage in Exfoliated Buccal Cells of Teenage Scavengers at a Major Electronic Waste Dumpsite in Lagos, Nigeria

This study investigated the levels of Pb, Ni, Cd, and Cr in the blood, and DNA damage in exfoliated buccal cavity of scavenging teenagers at Alaba International electronic market, Nigeria. One hundred and ninety-nine blood samples were collected from scavenging teenagers in Alaba International market (n = 95) and the control group (n = 104). Blood Pb, Ni, Cd, and Cr concentrations were analyzed using graphite furnace atomic absorption spectrometry. Genotoxicity assessment was through exfoliated buccal cell micronucleus assay, while questionnaire was used to collect data on factors that can contribute to the blood heavy metal levels. The blood Pb of scavenging teenagers from Alaba International market varied from 2.84 to 189.44 μg/L compared to the control group with a range of 0.01 to 4.21 μg/L. The blood Cd (range = 0.38-12.35 μg/L), Cr (range = 0.20-19.03 μg/L), and Ni (range = 0.24-21.01 μg/L) were higher significantly in the Alaba group compared to the control group (Cd: range = 0.00-0.96 μg/L; Cr: range = 0.01-0.72 μg/L; and Ni: range = 0.00-0.28 μg/L). Frequencies of micronucleus, karyolysis, and pycnosis in the exfoliated buccal cells in Alaba group also increased significantly compared with the control group. Spearman correlation analyses indicated a positive correlation between the blood Pb, Ni, Cd, and Cr and induced micronucleus in the buccal exfoliated cells. Furthermore, data showed a positive correlation between Pb, Ni, Cd, and Cr and the duration of scavenging of the teenagers. However, a negative correlation was observed between educational status and Pb, Ni, Cd, and Cr. E-waste indiscriminate disposal and primitive recycling processes may be responsible for the high blood heavy metal levels, and consequently an increased DNA damage in exfoliated buccal cells in scavenging teenagers at Alaba International market. Graphical Abstract.

Blood lead levels among Chinese children: The shifting influence of industry, traffic, and e-waste over three decades

In China, data relating to the historic prevalence of childhood lead poisoning suggest its pervasiveness. This review analysed published epidemiological data on blood lead levels (BLLs) of 735,271 Chinese children aged 0-6 between 1987 and 2017. Among these children, the geometric mean (GM) BLL was 95.1 μg/L (geometric SD = 1.62), and 24.1% suffered lead poisoning (BLL ≥ 100 μg/L). Importantly, there was a temporal decrease in the GM BLL value, from 182.9 μg/L in 1987-1991 to 42.4 μg/L in 2012-2017. However, a rebound was seen in the most recent two years (2016 and 2017). Moreover, the GM BLL among Chinese children has not fallen as low as U.S. children. This indicates that either (1) leaded petrol or lead based-paint exposure sources have not been adequately controlled in China, or (2) other pollution sources, such as industry, traffic, and e-waste, are impacting Chinese children. Drivers behind spatio-temporal variations were explored to provide scientific evidence regarding the prevention of childhood lead poisoning. We found that BLLs among children in the central and eastern areas of China have dropped lower than those in the western area, and that the GM BLL of children living in rural areas now exceeds children in urban areas. These reversals may be associated with the industrial decentralization policy of the late 1980s, when many heavily polluting industries and manufacturers moved away from cities on the east coast. It was discovered that the BLLs of children living in areas associated with mining have remained high (GM BLL = 155.0 μg/L for 2007-2017), and that the lead poisoning rate (LPR) has become exceptionally high in areas associated with e-waste. Finally, the review offers a data comparison with other countries, an overview of potentially influencing factors and sources, as well as some suggested prevention strategies to reduce childhood lead exposure.

A comparison of blood and toenails as biomarkers of children's exposure to lead and their correlation with cognitive function

This study sought to compare lead (Pb) concentrations in toenails and blood and to investigate the association of each biomarker with children's cognitive function. Toenails and whole blood samples were collected from 224 twelve-year-old children, and their full-scale intelligence quotient (FSIQ) was assessed using the Wechsler Intelligence Scale for Children-4th edition. Inductively coupled plasma-mass spectrometry was used to determine blood (BPb) and toenail (TPb) Pb concentrations. Log BPb and Log TPb were significantly correlated (r² = 0.49, p < 0.001). In unadjusted analyses, both log-transformed BPb and TPb were significantly associated with decreased FSIQ, but BPb accounted for approximately quadruple the FSIQ scores' variability than log-transformed TPb (model R² = 0.12 and R² = 0.03, respectively). After adjusting for neighborhood deprivation, caregiver intelligence (assessed with the Wechsler Abbreviated Scale of Intelligence-2nd edition), and child BMI, BPb remained significantly associated with decreased FSIQ, while TPb did not (p = 0.16). These results suggest that while concentrations of Pb in blood and toenails are correlated, TPb does not predict cognitive outcomes at these exposure levels. With caution and in conjunction with BPb, TPb may be used as a population-based biomarker of Pb exposure.

Chronic lead (Pb) exposure results in diminished hemocyte count and increased susceptibility to bacterial infection in Drosophila melanogaster

Heavy metal Pb is a common toxic pollutant present in our environment adversely affecting health of the living organisms. Recent studies suggest positive correlation between heavy metal exposure and immune dysfunction and present work utilizes Drosophila to address this issue in relation to Pb exposure. In-vivo Pb toxicity was established by dietary intake where essential parameters like development and life span were found to be hampered and augmented upon metallothionein B (mtnB) downregulation hinting towards potential role of mtnB in Pb detoxification. Further response of Drosophila to B. subtilis bacterial infection was monitored by carrying out oral infections. Pb fed flies showed increased susceptibility to infection as compared to their controls. Since Drosophila hemocytes play dual role as immune cells, we checked for the total hemocyte count and found significant decrease in hemocyte numbers in Pb fed larvae. Both crystal cells and plasmatocytes, the two major hemocytes in third instar larval hemolymph were reduced. However we did not find any visible morphological changes in Giemsa stained hemocytes. Crystal cells are crucial for synthesis and release of phenoloxidase (PO), an enzyme required for melanin clot synthesis and deposition. PO activity assessed from total hemolymph protein isolates was found to be substantially decreased in Pb raised animals. Results were also confirmed by spot test and native gel activity assay of PO. Overall our results suggest immunotoxic effect of Pb through decrease in hemocyte count including crystal cell which in turn leads to decreased PO activity and increased susceptibility to B. subtilis.

The pathway of lead through the mother's body to the child

Placenta, the organ on which great attention is concentrated during pregnancy, represents an ineffective barrier to the transfer of hazardous heavy metals, mainly lead, into the foetus. The presence of lead in the placenta is an environmental hazard for a person's future. Due to hormonal changes, lead is released during pregnancy into the bloodstream of the mother from deposits in the bones and in the teeth, where it has accumulated for years as a result of a contaminated environment. Since lead is a neurotoxic metal, exposure to lead during prenatal and postnatal development can cause serious neurocognitive damage and hence the development of an Attention Deficit Hyperactivity Disorder (ADHD) in a developing human. Our work provides an overall picture of the "toxic pathway" of lead through the mother's body, the risks arising from its transplacental transfer and its accumulation in the developing foetus as well as effective prevention to protect all newborns.

Human Blood Lead Levels and the First Evidence of Environmental Exposure to Industrial Pollutants in the Amazon

The main routes of lead (Pb) absorption are through the airways and orally, and through consumption of contaminated food and beverage, with Pb mainly being absorbed in the atmospheric particulate form. In 2012, a cross-sectional study was performed to evaluate the Pb environmental exposure in two Amazonian districts, Dom Manuel (DMN) and Laranjal (CLA), located in Barcarena City, northern Brazil. CLA is located outside the industrial area of Barcarena (control population), whereas DMN is an old community located in the vicinity of industrial activities. A significant number of residents in these districts participated in an epidemiological inquiry and blood sampling. Total Pb blood levels were quantified using inductively coupled plasma mass spectrometry (ICP-MS). The mean Pb blood level in people that live in DMN was 281.60 (98.73-570.80) μg·L-1, approximately nine times higher than the level found in CLA (32.77 μg·L-1). In these districts, the Pb blood levels showed statistically significant differences (p < 0.05) based on gender, schooling, residence time, and smoking. This is the first evidence of industrial environmental pollutant exposure in the Amazon.

Lead Levels in the Eggs of a Chicken With Lead Toxicosis

A 1.5-year-old Polish hen was presented with a history of watery droppings and poor vent tone. Results of diagnostic tests revealed blood lead at levels considered to be toxic. Chelation therapy was started with calcium ethylenediaminetetraacetate. The hen was laying eggs before, during, and after chelation therapy. Eggs were tested for the presence of lead by combining yolk and albumen together. Before chelation therapy, the level of lead in the egg tested was 14 μg. Two days after the end of chelation therapy, results of a second blood lead test revealed a drop to nontoxic levels. No lead was detected in the combined yolks and albumen of eggs collected 7-11 days after the end of chelation therapy. Four weeks after the end of chelation therapy, no lead was identified in the shells of tested eggs.