Both physiology and epidemiology support zero tolerable blood lead levels

Navigating the complexity of spinal cord injuries with retained foreign bodies and the diagnostic challenge of lead toxicity-a case reportaaa

INTRODUCTION

Retained shrapnel from gunshots is a common occurrence; however, retained shrapnel within the spinal canal is exceedingly uncommon. Guidelines for removal and treatment of these cases are a difficult topic, as surgical removal is not necessarily without consequence, and retention can lead to possible further injury or a secondary disease process of plumbism, which can be difficult to diagnose in this population.

CASE PRESENTATION

This case report provides a unique example of a young patient with retained shrapnel from a gunshot. This patient suffered an initial spinal cord injury due to a gunshot and secondarily presented with abdominal pain, fatigue, elevated blood lead levels, and was diagnosed with plumbism. This was addressed with operative removal of shrapnel and posterior instrumented spinal fusion, resulting in decreased lead levels and symptom resolution postoperatively.

DISCUSSION

Lead toxicity risk in patients with retained shrapnel, particularly in the spine, warrants vigilant monitoring. While management guidelines lack consensus, symptomatic lead toxicity may necessitate intervention. Residual neurological deficits complicate evaluation, emphasizing individualized management decisions.

Knowledge, Attitudes, Practices, and Prevention Barriers Related to Childhood Lead Poisoning Among Nepali-Speaking Bhutanese Parents in Northeast Ohio, United States

The study objectives were: (i) to develop and administer a survey to assess childhood lead poisoning (CLP) knowledge, attitudes, practices and prevention barriers (KAP-B) among the Nepali-Speaking Bhutanese (NSB) community in Northeast Ohio; and (ii) to examine the association between socio-demographic characteristics of NSB parents and their understanding of CLP as measured by the constructs of knowledge and attitudes. A Nepali language KAP-B questionnaire was developed and 200 NSB parents with at least one child ≤ 7 years of age from the Akron Metropolitan Area, Ohio were interviewed. NSB parents demonstrated a low level of knowledge about CLP prevention measures. While 82% lived in pre-1978 houses, only 27.5% perceived their house/neighborhood to be potentially lead contaminated. Only 33% of the parents reported understanding lead-related information provided by their child's healthcare provider. Low-level CLP awareness among NSB community emphasizes a need for culturally tailored and linguistically appropriate community-level CLP educational intervention programs in this vulnerable community.

Kaempferol improves Pb-induced cognitive impairments via inhibiting autophagy

Kaempferol (Kam) is a flavonoid antioxidant found in fruits and vegetables, which was discovered as neuroprotective antioxidants. Lead (Pb), an environmental pollution, could induce learning and memory deficits. Nevertheless, little is known about the mechanisms underlying Kam actions in Pb-induced learning and memory deficits. In this study, we investigated the effects of Kam on Pb-induced cognitive deficits. Pb-exposed rats were treated with 50 mg/kg Kam from postnatal day (PND) 30 to PND 60. Then, Y-maze and Morris water maze have been used to detect the spatial memory in all groups of rats. Hematoxylin and eosin (HE) staining and Nissl staining were used to analyze the neuronal structure damages. The results found Kam treatment improved the learning and memory ability and alleviated hippocampal neuronal pathological damages. Besides, Kam could significantly reverse the synaptic transmission related protein expression including PSD95 and NMDAR2B. Further research found that Kam downregulated autophagy markers, P62, ATG5, Beclin1, and LC3-II. Furthermore, 3-MA, autophagy inhibitor, increased the levels of NMDAR2B and PSD95 in Pb-induced PC12 cells, indicating Kam alleviated Pb-induced neurotoxicity through inhibiting autophagy activation. Our results showed that Kam could ameliorate Pb-induced cognitive impairments and neuronal damages by decreasing Pb-induced excess autophagy accumulation.

Protective Effect of Protocatechuic Acid on Oxidative Damage and Cognitive Impairment in Pb-Induced Rats

Protocatechuic acid (PCA), a class of water-soluble phenolic acid abundant in the human diet, has been shown to be of great nutritional interest and to have medicinal value. However, the protective effects against lead (Pb)-induced body injury have not been elucidated. In this study, we explored the protective effect of PCA on Pb-induced oxidative damage and cognitive impairment in rats. The results showed that PCA could reduce the Pb content in rat bodies (blood, bone, brain, liver, and kidney) after Pb exposure. Moreover, PCA may inhibit Pb-induced oxidative damage by increasing the activity of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreasing the level of malondialdehyde (MDA) in the brain, liver, and kidney. In addition, PCA may alleviate Pb-induced learning and memory impairment by upregulating neurotransmitter levels; maintaining the normal function of N-methyl-D-aspartate receptors (NMDARs); and promoting Ca2+ influx, thus activating signaling molecules, related protein kinases, and transcription factors in the cAMP-PKA-CREB pathway. In general, PCA could reduce oxidative stress and ameliorate the learning and memory deficits in Pb-treated rats, indicating that PCA may be an effective preventive agent and treatment or plumbism.

Effects of Gestational and Lactational Lead Exposure and High Fat Diet Feeding on Cerebellar Development of Postnatal Rat Offspring

Obesity and heavy metals, such as lead (Pb), are detrimental to the adult brain because they impair cognitive function and structural plasticity. However, the effects of co-administration of Pb and a high-fat diet (HFD) on the developing cerebellum is not clearly elucidated. We investigated the effects of Pb exposure (0.3% lead acetate) on developing cerebellum in the pups of an HFD-fed obese rat model. One week before mating, we fed a chow diet (CD) or HFD to the rats for one week and additionally administered Pb to HFD-fed female SD rats. Thereafter, treatment with Pb and a HFD was continued during the gestational and lactational periods. On postnatal day 21, the pups were euthanized to sample the brain tissue and blood for further analysis. Blood Pb levels were significantly higher in HFD-fed rats than in CD-fed rats. Histologically, the prominent degeneration of Purkinje cells was induced by the co-administration of Pb and HFD. The calbindin-28Kd-, GAD67-, NMDAR1-, and PSD95-immunopositive Purkinje cells and inhibitory synapse-forming pinceau structures were significantly decreased following Pb and HFD co-administration. MBP-immunoreactive myelinated axonal fibers were also impaired by HFD but were significantly damaged by the co-administration of HFD and Pb. Oxidative stress-related Nrf2-HO1 signaling was activated by HFD feeding, and Pb exposure further aggravated oxidative stress, as demonstrated by the consumption of endogenous anti-oxidant in HFD-Pb rats. The pro-inflammatory response was also increased by the co-administration of HFD and Pb in the cerebellum of the rat offspring. The present results suggest that HFD and Pb treatment during the gestational and lactational periods are harmful to cerebellar development.

Immune Responses to COVID-19 Vaccines in Patients with Chronic Kidney Disease and Lead Exposure

Literature data regarding the response rate to COVID-19 vaccination in chronic kidney disease (CKD) patients remain inconclusive. Furthermore, studies have reported a relationship between lead exposure and susceptibility to viral infections. This study examined immune responses to COVID-19 vaccines in patients with CKD and lead exposure. Between October and December 2021, 50 lead-exposed CKD patients received two doses of vaccination against COVID-19 at Chang Gung Memorial Hospital. Patients were stratified into two groups based on the median blood lead level (BLL): upper (≥1.30 μg/dL, n = 24) and lower (<1.30 μg/dL, n = 26) 50th percentile. The patients were aged 65.9 ± 11.8 years. CKD stages 1, 2, 3, 4 and 5 accounted for 26.0%, 20.0%, 22.0%, 8.0% and 24.0% of the patients, respectively. Patients in the lower 50th percentile of BLL had a lower proportion of CKD stage 5 than patients in the upper 50th percentile BLL group (p = 0.047). The patients in the lower 50th percentile BLL group also received a higher proportion of messenger RNA vaccines and a lower proportion of adenovirus-vectored vaccines than the patients in the upper 50th percentile BLL group (p = 0.031). Notably, the neutralizing antibody titers were higher in the lower 50th percentile than in the upper 50th percentile BLL group. Furthermore, the circulating levels of granulocyte-colony stimulating factor, interleukin-8, monocyte chemoattractant protein-1 and macrophage inflammatory protein-1α were higher in the upper 50th percentile than in the lower 50th percentile BLL group. Therefore, it was concluded that lead-exposed CKD patients are characterized by an impaired immune response to COVID-19 vaccination with diminished neutralizing antibodies and augmented inflammatory reactions.

Lead toxicity due to retained intracranial bullet fragments: illustrative case

BACKGROUND

Lead toxicity (plumbism) secondary to retained lead bullet fragments is a rare complication in patients with gunshot wounds. To the authors' knowledge, there has been no definitive case reported of lead toxicity due to retained intracranial bullet fragments.

OBSERVATIONS

The authors reported the case of a 23-year-old man who presented after being found down. Computed tomography scanning of the head revealed bullet fragments within the calvaria adjacent to the left transverse sinus. During follow-up, he developed symptoms of plumbism with paresthesias in his bilateral hands and thighs, abdominal cramping, labile mood, and intermittent psychosis. Plumbism was confirmed with sequentially elevated blood lead levels (BLLs). The patient opted for surgical removal of the bullet fragments, which led to reduction in BLLs and resolution of his symptoms.

LESSONS

Although rare, lead toxicity from retained intracranial bullet fragments should be considered in patients who have suffered a gunshot wound to the head and have symptoms of lead toxicity with elevated BLLs. For safe and accessible intracranial bullet fragments in patients with plumbism, surgical intervention may be indicated.

Updated interim reference levels for dietary lead to support FDA's Closer to Zero action plan

The Centers for Disease Control and Prevention (CDC) utilizes a blood lead reference value (BLRV) to identify children with elevated blood lead levels (BLLs). At or above the BLRV, the CDC recommends actions be taken to reduce children's BLLs. In 2021, the CDC updated its BLRV to 3.5 μg/dL. To align with the CDC's updated BLRV, the FDA is updating its interim reference levels (IRLs) for lead from food to 2.2 μg/day for children and 8.8 μg/day for females of childbearing age. The updated FDA IRLs for lead will serve as a benchmark to evaluate whether lead exposure from food is a potential concern. The children's BLL associated with the updated IRL is less than those predicted by other agencies to result in 1 intelligence quotient point loss. Dietary lead exposure estimates for children in the U.S. suggest exposures greater than the mean may exceed the updated FDA IRL for children, indicating a need for additional efforts to reduce lead in foods consumed by young children. The US FDA is addressing this need by implementing its Closer to Zero action plan to reduce babies' and children's dietary exposure to toxic elements (e.g., lead, cadmium, arsenic, mercury) over time.

Tartaric acid soil-amendment increases phytoextraction potential through root to shoot transfer of lead in turnip

The phytoextraction potential of turnip and comparative effectiveness of three different organic ligands towards removal of lead (Pb) was investigated under field conditions. The 20 d old turnip seedlings were exposed to different Pb levels (0.0218, 2.42 and 4.83 mM Pb) spiked in the soil. After 10 d of Pb application, the soil was spiked with 2.4 mM concentration of different chelates viz. ethylenediaminetetraacetic acid (EDTA), citric acid (CA) and tartaric acid (TA). The 60 d old plants were harvested for growth analyses and determination of photosynthetic pigments, while Pb-concentration in different plant parts was determined from 60 and 90 d old plants. Yield attributes were recorded at the harvesting stage (HS, 90 d old plants). No suppression (rather a stimulation) in the root and shoot growth was evident upon Pb exposure whereas, a reduction in the chlorophyll content occurred at 4.83 mM Pb level. Soil amendment with TA improved chlorophyll contents irrespective of Pb levels while the effect of CA and EDTA was differential. A reduction in the root length while an increase in its diameter was recorded particularly at 4.83 mM Pb stress in 90 d old plants. The turnip retained maximum Pb-fraction in the roots at early growth stages, while EDTA application further increased its retention in root at 4.83 mM Pb regime. Nonetheless, only TA amendment promoted the transfer of Pb to shoot (∼30%) irrespective of Pb regimes. At the HS, application of both TA and EDTA caused substantial uptake of Pb in the root while the maximum shoot Pb-fraction was recorded again due to TA application, particularly at 4.83 mM Pb level. Above all, TA was identified as the most effective chelate that mobilized Pb from root to shoot leading to better growth possibly due to dilution effect, and thus enhanced phytoextraction efficiency in turnip.

A simple electrochemiluminesecence aptasenor using a GCE/NCQDs/aptamers for detection of Pb

An electrochemiluminescence (ECL) aptasensor was prepared to detect Pb²⁺ with nitrogen-doped carbon quantum dots (NCQDs) as ECL materials. To prepare the working electrode, NCQDs with carboxyl groups were loaded on a glassy carbon electrode (GCE) and then Pb²⁺ aptamers were covalently bound to the NCQDs to form a stable GCE/NCQDs/aptamers. On addition of Pb²⁺, the chain aptamers change to a pb²⁺ G-quadruplex conformation, which lead to a large decrease in the ECL intensity. The variation of intensity and the logarithm of the Pb²⁺ concentration had a good linear relationship (R² = 0.998). The detection range was wide (50 pM to 387.9 nM) with a low detection limit (18.9 pM). In interference experiments, the ECL Pb²⁺ aptasensor did not suffer from interference and it had good stability. The NCQDs ECL aptasensor can detect Pb²⁺ quickly and accurately, and provides a fast and efficient method for detection of Pb²⁺. Compared with literatures, the Pb²⁺ aptasensor has simpler preparation process, lower cost; furthermore, it is more environmentally friendly.

Searching for the Relationship between the Concentration of Heavy Metals in the Blood and the Clinical Course of Multiple Sclerosis: A Cross-Sectional Study in Poland

(1) Background: Of all environmental pollutants, heavy metals have the most detrimental effect on public health because they remain in the ecosystem and are not biodegradable. The neurotoxicity of heavy metals, including cadmium and lead, has been well documented, and blood levels of heavy metals serve as a biomarker of exposure, reflecting their content in soft tissues. Multiple sclerosis (MS) is one of the most common chronic neurodegenerative diseases. The pathogenesis of MS is complex and relies on the interaction between genetic and environmental factors. The aim of this study was to search for the relationship between the values of cadmium and lead concentration in the blood and the health history and functional status of patients with MS. (2) Methods: The study group consisted of 151 patients with a clinical diagnosis of MS. Determination of the presence of tested elements in serum was performed using an ELAN DRC-e ICP mass spectrometer. (3) Results: Statistical analysis demonstrated that an increase in the level of cadmium was accompanied by an increase in the level of lead. There was no significant correlation between the blood lead concentration and the functional status assessed by EDSS among patients with MS in Poland. However, a tendency towards worse functional status of patients with higher blood lead concentration (p = 0.07) was demonstrated. Patients who experienced first MS symptoms at older age had higher blood levels of the tested metals. (4) Conclusions: The concentrations of cadmium and lead in the blood of MS patients in Poland were not factors differentiating their functional status and the course of the disease.

Attention deficit among preschool and school-aged children living near former metal-processing plants in Romania

Industrial areas affected by high and long-term heavy metal pollution have a great impact on health of the resident population. Children represent a group at high-risk with an increased susceptibility to chronic heavy metal intoxication. Our work included the assessment of attention particularities through a case-control study in pre-school and school-aged children (4-6 years and 8-11 years) from two study areas, Copşa Mică and Zlatna, compared to a non-polluted locality with no history of heavy metal pollution. Copşa Mică and Zlatna are two of the most polluted heavy metals regions in Romania due to non-ferrous metallurgy for a long period of time. Recruitment of participants was made by a random selection of an entire class for each age within the schools and kindergartens from the study areas (Copşa Mică and Zlatna) and from the non-polluted region. Interpretation of data was performed using statistical analysis (ANOVA and Student's t-test). Preschool children (4-6 years) were tested using Wechsler Preschool and Primary Scale of Intelligence (WPPSI) tests, Animal House and labyrinth samples. The results of the attention tests applied to pre-school children were lower in the study areas compared to the control group, but no statistical differences were found. The results of the attention tests applied to children aged between 8 and 11 years (Toulouse-Pieron test and Traffic light test) indicate lower average scores within the study groups from polluted areas, compared to the control group. Differences with statistically significance were registered for the 8 years age group (p = 0.037). In these areas efficient strategies and precise intervention measures are needed in order to limit or remove the heavy metal exposure and protect the human health, especially the groups exposed to a high level of risk.

Early life lead exposure from private well water increases juvenile delinquency risk among US teens

Public health agencies worldwide have determined that there is no safe level for children’s exposure to lead, a neurotoxin. This study shows that lead in drinking water from private wells is significantly associated with juvenile delinquency. Compared to children in homes with public water supplies, those relying on private wells have a 21% higher risk of any delinquency and a 38% increased risk of serious delinquency. The steepest increases in risk occur at the lowest exposure levels. The results highlight the need to prevent lead-leaching from well components, plumbing, and fixtures in the 13% of US households relying on private wells. They also suggest the need to decrease blood and environmental lead thresholds currently used to identify at-risk children.

Early life exposure to environmental lead (Pb) has been linked to decreased IQ, behavior problems, lower lifetime earnings, and increased criminal activity. Beginning in the 1970s, limits on Pb in paint, gasoline, food cans, and regulated water utilities sharply curtailed US environmental Pb exposure. Nonetheless, hundreds of thousands of US children remain at risk. This study reports on how unregulated private well water is an underrecognized Pb exposure source that is associated with an increased risk of teenage juvenile delinquency. We build a longitudinal dataset linking blood Pb measurements for 13,580 children under age 6 to their drinking water source, individual- and neighborhood-level demographics, and reported juvenile delinquency records. We estimate how early life Pb exposure from private well water influences reported delinquency. On average, children in homes with unregulated private wells had 11% higher blood Pb than those with community water service. This higher blood Pb was significantly associated with reported delinquency. Compared to children with community water service, those relying on private wells had a 21% (95% CI: 5 to 40%) higher risk of being reported for any delinquency and a 38% (95% CI: 10 to 73%) increased risk of being reported for serious delinquency after age 14. These results suggest that there could be substantial but as-yet-unrecognized social benefits from intervention programs to prevent children’s exposure to Pb from private wells, on which 13% of the US population relies.

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.

Exposure to metals and metalloids among pregnant women from Spain: Levels and associated factors

BACKGROUND

Humans are regularly exposed to metals and metalloids present in air, water, food, soil and domestic materials. Most of them can cross the placental barrier and cause adverse impacts on the developing foetus.

OBJECTIVES

To describe the prenatal concentrations of metals and metalloids and to study the associated sociodemographic, environmental and dietary factors in pregnant Spanish women.

METHODS

Subjects were 1346 pregnant women of the INMA Project, for whom the following metals arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), thallium (Tl) and zinc (Zn) were determined in urine, at both the first and the third trimesters of gestation. Sociodemographic, dietary and environmental information was collected through questionnaires during pregnancy. Multiple linear mixed models were built in order to study the association between each metal and metalloid concentrations and the sociodemographic, environmental and dietary factors.

RESULTS

The most detected compounds were As, Co, Mo, Sb, Se and Zn at both trimesters. Zn was the element found in the highest concentrations at both trimesters and Tl was detected in the lowest concentrations. We observed significant associations between As, Cd, Cu, Sb, Tl and Zn concentrations and working situation, social class and age. Seafood, meat, fruits, nuts, vegetables and alcohol intake affected the levels of all the metals but Cd and Cu. Proximity to industrial areas, fields and air pollution were related to all metals except Cd, Sb and Se.

CONCLUSIONS

This is the first large prospective longitudinal study on the exposure to metals and metalloids during pregnancy and associated factors to include several cohorts in Spain. The present study shows that some modifiable lifestyles, food intakes and environmental factors could be associated with prenatal exposure to metal(loid)s, which may be considered in further studies to assess their relationship with neonatal health outcomes.

A review of studies on blood lead concentrations of traditional Mexican potters

BACKGROUND

Traditional Mexican potters and their families have been occupationally exposed to lead for centuries; however, studies on blood lead levels (BLL) and their adverse health impact on this population are scarce. There is no safe BLL, even at 1 μg/dL there are associated health effects.

OBJECTIVE

To systematize and characterize Mexican potters' historic lead exposure through their BLL and associated health outcomes.

METHODS

Using PRISMA guidelines, we conducted a systematic review through January 2021 of published studies on BLL and associated health outcomes in Mexican potters.

RESULTS

Fifteen studies containing data from 1980 to 2013 met the inclusion criteria and were published between 1980 and 2018. Study populations ranged from n = 5 to n = 457, and included adult potters (mean BLL 37.9 ± 16.2 μg/dL) and/or their children (mean BLL 22.5 ± 10.5 μg/dL). Studies reported on general lead poisoning symptoms, neurotoxic and nephrotoxic outcomes as well as correlated biomarkers.

CONCLUSIONS

Our results confirm high occupational and para-occupational lead exposure. Despite governmental and non-governmental initiatives to promote lead-free glazes, lead continues to be used by traditional potters and their families.

Exposure and health risk assessment from consumption of Pb contaminated water in Addis Ababa, Ethiopia

Exposure to lead (Pb) through drinking water has been linked to adverse health outcomes. Children are particularly susceptible. This study was designed to measure Pb contamination level in drinking water of the Ethiopian city Addis Ababa and assess the associated health risks. Eighty-eight fully-flushed drinking water samples were collected from all ten sub-cities of Addis Ababa. Pb concentration was measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The chronic daily intake (CDI), the hazard quotient (HQ), and the cancer risk (CR) of Pb were determined to assess exposure levels and health effects. Blood lead level (B-Pb) for children was modelled using the integrated exposure uptake biokinetic model (IEUBK). The mean concentration of Pb in the drinking water was 17.8 μg/l, where >50% of the samples exceeded WHO's 10 μg/l guideline. Significant spatial variation of Pb was noticed among sub-cities. The mean CDI was 1.43 and 0.59 μg/kg/day for children and adults, respectively. The HQ showed that 8% of children and 2.3% of adults exceeded the safe limit. The predicted geometric mean of B-Pb ranged from 3.23 to 14.65 μg/dl. The risk of a child having a B-Pb level >5 μg/dl at the median water Pb concentration (10.5 μg/l) was estimated at 13.4%. Based on the 95^th percentile Pb concentration (75.1 μg/l), 89.6% of children would have B-Pb levels above the 5 μg/dl threshold. The estimated CR was found in the range of 1 × 10^-7 to 9.9 × 10^-5; hence cancer risks are not a concern. The study concluded that Addis Ababa's drinking water is likely to be a source of lead exposure where consumers at specific city locations are at risk of numerous non-cancer health effects. The impacts are expected to be severe in the Ethiopian context; hence further investigations and coordinated interventions are required.

Low dose lead exposure induces alterations on heterochromatin hallmarks persisting through SH-SY5Y cell differentiation

Lead (Pb) is a commonly found heavy metal due to its historical applications. Recent studies have associated early-life Pb exposure with the onset of various neurodegenerative disease. The molecular mechanisms of Pb conferring long-term neurotoxicity, however, is yet to be elucidated. In this study, we explored the persistency of alteration in epigenetic marks that arise from exposure to low dose of Pb using a combination of image-based and gene expression analysis. Using SH-SY5Y as a model cell line, we observed significant alterations in global 5-methycytosine (5 mC) and histone 3 lysine 27 tri-methylation (H3K27me3) and histone 3 lysine 9 tri-methylation (H3K9me3) levels in a dose-dependent manner immediately after Pb exposure. The changes are partially associated with alterations in epigenetic enzyme expression levels. Long term culturing (14 days) after cease of exposure revealed persistent changes in 5 mC, partial recovery in H3K9me3 and overcompensation in H3K27me3 levels. The observed alterations in H3K9me3 and H3K27me3 are reversed after neuronal differentiation, while reduction in 5 mC levels are amplified with significant changes in patterns as identified via texture clustering analysis. Moreover, correlation analysis demonstrates a strong positive correlation between trends of 5 mC alteration after differentiation and neuronal morphology. Collectively, our results suggest that exposure to low dose of Pb prior to differentiation can result in persistent epigenome alterations that can potentially be responsible for the observed phenotypic changes. Our work reveals that Pb induced changes in epigenetic repressive marks can persist through neuron differentiation, which provides a plausible mechanism underlying long-term neurotoxicity associated with developmental Pb-exposure.

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

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

(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.

Human biomonitoring of metals in sub-Arctic Dene communities of the Northwest Territories, Canada

A human biomonitoring project investigating environmental exposures to metals from hair, blood and urine samples was implemented in the Northwest Territories, Canada, between January 2016 and March 2018. This study reports the metal biomarker levels from nine Dene communities located in the Dehcho and Sahtú regions to identify contaminants of interest. Levels of metals in the urine (n = 198), blood (n = 276) and hair (n = 443) samples were generally similar to those seen in other biomonitoring studies in Canada, but lead levels in blood (GM = 16 μg/L; 95th percentile = 71 μg/L) and urine (GM = 0.59 μg/L, 0.69 μg/g of creatinine; 95th percentile = 4.2 μg/L, 4.0 μg/g of creatinine) were higher than those observed in the Canadian Health Measure Survey (CHMS, cycles 2 and 5). Hair mercury (but not blood mercury) appeared higher than observed in participants from the CHMS cycle 5. The vast majority of participants had biomarker levels below the biomonitoring guidance values established for mercury and lead. Based on a comparative analysis of biomarker statistics relative to a nationally-representative survey, metals and essential trace elements of particular interest for follow-up research include: lead, manganese, mercury, and selenium. This project provided baseline biomarker levels in participating regions, which is essential to track changes in the future, and identify the contaminants to prioritize for further investigation of exposure determinants.

Reduction in lead exposures with lead-free ammunition in an advanced urban assault course

The training of soldiers for urban conflict involves marksmanship instruction on outdoor flat ranges and the teaching of close-quarter battle techniques in indoor facilities, referred to as shoot houses, where intense firing exercises can generate high air lead levels from small arms ammunition, flash bang grenades, and explosive devices. Levels of lead and copper in air were evaluated during five training activities of a 45-day training course using both stationary general area and breathing zone sampling over a 2-year period. Individual blood lead values were determined prior to and at course completion. Mean breathing zone lead concentrations for the five training activities ranged from 0.014 on the outdoor flat range to 0.064 mg/m³ inside shoot houses; with a change to lead-free ammunition the values were reduced to a range of 0.006-0.022 mg/m³. Isolated flash bang grenades generated very high general area lead concentrations (2.0 mg/m³), which in training were associated with the highest measured breathing zone concentration (0.16 mg/m³). For copper, mean breathing zone concentrations increased from 0.010 to 0.037 mg/m³ with the change to lead-free frangible ammunition on the outdoor range, but remained below the permissible exposure limit for copper fume. Inside shoot houses, mean breathing zone copper concentrations exceeded the permissible exposure limit with ball and lead-free frangible ammunition, ranging from 0.077-0.13 mg/m³. With the introduction of lead-free ammunition, when comparing the blood lead differences between start and finish of the course, there was a significant reduction in the mean blood lead difference from 13.3 µg/dL to 5.4 µg/dL. Options for mitigation of potentially high exposure areas using improved ventilation designs are discussed. These results advocate for improved designs for shoot house training facilities, stress the importance of removing lead from ammunition and explosive devices for training, and promote the continued need for implementation of controls to mitigate and manage metal exposures during training.

Cadmium and Lead Exposure, Nephrotoxicity, and Mortality

The present review aims to provide an update on health risks associated with the low-to-moderate levels of environmental cadmium (Cd) and lead (Pb) to which most populations are exposed. Epidemiological studies examining the adverse effects of coexposure to Cd and Pb have shown that Pb may enhance the nephrotoxicity of Cd and vice versa. Herein, the existing tolerable intake levels of Cd and Pb are discussed together with the conventional urinary Cd threshold limit of 5.24 μg/g creatinine. Dietary sources of Cd and Pb and the intake levels reported for average consumers in the U.S., Spain, Korea, Germany and China are summarized. The utility of urine, whole blood, plasma/serum, and erythrocytes to quantify exposure levels of Cd and Pb are discussed. Epidemiological studies that linked one of these measurements to risks of chronic kidney disease (CKD) and mortality from common ailments are reviewed. A Cd intake level of 23.2 μg/day, which is less than half the safe intake stated by the guidelines, may increase the risk of CKD by 73%, and urinary Cd levels one-tenth of the threshold limit, defined by excessive ß₂-microglobulin excretion, were associated with increased risk of CKD, mortality from heart disease, cancer of any site and Alzheimer's disease. These findings indicate that the current tolerable intake of Cd and the conventional urinary Cd threshold limit do not provide adequate health protection. Any excessive Cd excretion is probably indicative of tubular injury. In light of the evolving realization of the interaction between Cd and Pb, actions to minimize environmental exposure to these toxic metals are imperative.

Lead Toxicity From Intradiscal Retained Bullet Fragment: Management Considerations and Recommendations

BACKGROUND

Lead toxicity (plumbism) secondary to retained lead missiles in synovial joint spaces is a rare complication after gunshot injuries. Management of lead missiles in the intradiscal space regarding potential lead toxicity is less certain.

CASE DESCRIPTION

We reviewed the literature regarding lead toxicity secondary to intradiscal bullets particularly concerning incidence, management, and outcomes. A lack of high-quality published data precludes a meta-analysis from taking place. Only four reports of lead toxicity secondary to missiles in the intradiscal space have been published. Including an additional case presented in this report, our review of the literature has led us to make several management recommendations, largely based on both the available literature and our current report.

CONCLUSIONS

First, there is insufficient evidence for removing retained lead missiles solely to mitigate the risk of lead toxicity. Second, chelation therapy in addition to surgical removal of the lead source is a valuable adjunct in the perioperative period and should be undertaken with the assistance of medical toxicology. Third, a retained missile does not mandate a simultaneous stabilization procedure in lieu of other indications based on the data available at this time.

A Comparison of the Nephrotoxicity of Low Doses of Cadmium and Lead

Environmental exposure to moderate-to-high levels of cadmium (Cd) and lead (Pb) is associated with nephrotoxicity. In comparison, the health impacts of chronic low-level exposure to Cd and Pb remain controversial. The aim of this study was to therefore evaluate kidney dysfunction associated with chronic low-level exposure to Cd and Pb in a population of residents in Bangkok, Thailand. The mean age and the estimated glomerular filtration rate (eGFR) for 392 participants (195 men and 197 women) were 34.9 years and 104 mL/min/1.73 m², respectively, while the geometric mean concentrations of urinary Cd and Pb were 0.25 μg/L (0.45 μg/g of creatinine) and 0.89 μg/L (1.52 μg/g of creatinine), respectively. In a multivariable regression analysis, the eGFR varied inversely with blood urea nitrogen in both men (β = −0.125, p = 0.044) and women (β = −0.170, p = 0.008), while inverse associations of the eGFR with urinary Cd (β = −0.132, p = 0.043) and urinary Pb (β = −0.130, p = 0.044) were seen only in women. An increased urinary level of Cd to the median level of 0.38 μg/L (0.44 μg/g of creatinine) was associated with a decrease in the eGFR by 4.94 mL/min/1.73 m² (p = 0.011). The prevalence odds of a reduced eGFR rose 2.5-, 2.9- and 2.3-fold in the urinary Cd quartile 3 (p = 0.013), the urinary Cd quartile 4 (p = 0.008), and the urinary Pb quartile 4 (p = 0.039), respectively. This study suggests that chronic exposure to low-level Cd is associated with a decline in kidney function and that women may be more susceptible than men to nephrotoxicity due to an elevated intake of Cd and Pb.

Zhiqi Granules Decreased Lead Level but Increased Iron Level in Serum of Chinese Children with Moderately Elevated Blood Lead Levels

To observe and compare the effects of healthy instruction and Zhiqi granules on lead, calcium, iron, and zinc levels in serum of children with moderately elevated blood lead levels (BLLs). At the same time, the possible mechanisms were discussed. A total of 60 eligible boys aged 4-6 years were selected and divided into two groups (the healthy instruction group and the Zhiqi group) randomly. The boys in the healthy instruction group only received the healthy instruction. Besides the healthy instruction, the boys in the Zhiqi group received 2 g Zhiqi granules orally one time daily. The study lasted for 4 weeks. BLL and serum iron, zinc, and calcium levels of the subjects in the two groups before and after interventions were measured and compared. After the interventions, the BLL in the Zhiqi group lowered significantly, but the decrease of the BLL in the healthy instruction group is not significant, and there was a significant difference in the BLL between the two groups. When the trial was completed, the serum iron level in the Zhiqi group increased significantly, but that in the healthy instruction group changed slightly, and a significant difference was seen between the two groups. There were no significant differences in both serum Ca and Zn levels in these two groups before and after the interventions. Meanwhile, there were no significant differences in serum Ca and Zn levels between the two groups after the interventions. The results suggested that daily intake of Zhiqi granules for 4 weeks together with healthy instruction resulted in a decrease of the BLL and an elevation of the serum iron level.

Prenatal lead exposure and childhood executive function and behavioral difficulties in project viva

BACKGROUND

Lead is an established neurotoxicant and early life exposure to lead is associated with detrimental impacts on IQ and several neurobehavioral domains. Less is known, however, about effects of prenatal lead exposure below 5 μg/dL on executive function and on social, emotional and self-regulatory behaviors in childhood.

OBJECTIVES

To examine the association between prenatal lead exposure and childhood executive function and social, emotional and self-regulatory behaviors.

METHODS

We included 1006 mother-child pairs from the Project Viva prospective pre-birth cohort. We measured prenatal maternal lead in second-trimester erythrocytes. In mid-childhood (median 7.7 years), parents and teachers rated executive function related behaviors using the Behavior Rating Inventory of Executive Function (BRIEF) and behavioral difficulties using the Strengths and Difficulties Questionnaire (SDQ). We used multivariable linear regression models adjusted for maternal, paternal, and child characteristics and metal co-exposures.

RESULTS

Mean maternal erythrocyte lead concentration was 1.2 μg/dL (interquartile range [IQR] 0.8-1.5 μg /dL), equivalent to approximately 0.4 μg/dL in whole blood. In adjusted models, associations with parent and teacher-rated scales were largely null, although effect estimates were consistently positive, suggesting worse scores with increasing lead levels. For an IQR increase in lead, BRIEF Global Executive Composite (GEC) was 0.73 (95% CI: -0.06, 1.52) points higher for parent-rated scores and 0.42 (95% CI: -0.39, 1.23) points higher for teacher-rated scores. Associations were strongest for parent-rated BRIEF plan/organize (β = 0.85; 95% CI: 0.12, 1.59) and shift (β = 0.88; 95% CI: 0.01, 1.75) subscales, as well as the SDQ emotional problems subscale (β = 0.18; 95% CI: 0.03, 0.33).

DISCUSSION

In this cohort with lead levels commonly experienced by U.S. women, there were few statistically significant associations with childhood executive function and behavior. However, there was a trend of worse neurobehavioral scores with increasing prenatal lead concentrations, in particular for childhood emotional problems and capacity to plan/organize and shift. Our results highlight the importance of continuing efforts to eliminate lead exposure in the general population.

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.

An Important Need to Monitor from an Early Age the Neurotoxins in the Blood or by an Equivalent Biomarker

An overwhelming amount of evidence now suggests that some people are becoming overloaded with neurotoxins. This is mainly from changes in their living environment and style, coupled with the fact that all people are different and display a broad distribution of genetic susceptibilities. It is important for individuals to know where they lie concerning their ability to either reject or retain toxins. Everyone is contaminated with a certain baseline of toxins that are alien to the body, namely aluminum, arsenic, lead, and mercury. Major societal changes have modified their intake, such as vaccines in enhanced inoculation procedures and the addition of sushi into diets, coupled with the ever-present lead, arsenic, and traces of manganese. It is now apparent that no single toxin is responsible for the current neurological epidemics, but rather a collaborative interaction with possible synergistic components. Selenium, although also a neurotoxin if in an excessive amount, is always present and is generally more present than other toxins. It performs as the body’s natural chelator. However, it is possible that the formation rates of active selenium proteins may become overburdened by other toxins. Every person is different and it now appears imperative that the medical profession establish an individual’s neurotoxicity baseline. Moreover, young women should certainly establish their baselines long before pregnancy in order to identify possible risk factors.

Factors Associated With High Blood Lead Levels in a Sample of 100 Children in Tehran

Background:

Lead is considered a neurotoxic agent. We aimed to evaluate the blood lead level (BLL) in young population and determine probable risk factors of lead exposure in Iran.

Methods:

In a cross-sectional study, a total of 100 children were entered and their BLLs were checked.

Results:

In all, 25 and 8 patients had BLLs above 5 and 10 µg/dL, respectively. There was a significant univariate correlation between BLL and place of living, water pipe type, using dairy products, and stature in both cut-offs of 5 and 10 µg/dL. Binary regression analysis showed that pipe type was associated with high BLLs at cut-offs of 5 and 10 µg/dL, respectively. Also, there was an association between 50th percentile of stature for age and cut-off of 5 µg/dL.

Conclusions:

Higher BLLs may be seen in short stature pediatric population. Polyvinyl chloride (PVC) and polypropylene water pipes may even cause more release of lead and result in higher absorption of this metal in the pediatric population.

Early chronic exposure to low-level lead alters total hippocampal microglia in pre-adolescent mice

Developmental lead (Pb) exposure alters brain function through mechanisms that are not yet understood. A previous study showed that early lead exposure reduced microglia number in the dentate gyrus region of the hippocampus. Given the critical role of microglia in brain development, it is important to determine whether these differences are unique to the dentate gyrus, or occur throughout the hippocampus. Unbiased stereology was used to quantify microglia mean cell body number in total hippocampus, and compare the proportion of microglia in the ventral vs. dorsal regions. Total hippocampal volume was also measured and compared. The study included brain tissue from 30 pre-adolescent C57BL/6 J mice, exposed to 30 ppm Pb acetate (n = 10, mean BLL 3.4 μg/dL at sacrifice), 330 ppm Pb acetate (n = 10, mean BLL 14.1 μg/dL at sacrifice), or 0 ppm Pb acetate (n = 10, negative controls). In lead exposed animals, microglia mean cell body number was reduced in total hippocampus; total hippocampal volume was reduced. Importantly, effects in low- and high-dose exposure groups did not differ. Contrary to study hypotheses, the distribution of hippocampal microglia in the ventral vs. dorsal hippocampal regions did not differ. Overall, lowest and higher levels of lead exposure during development had strikingly similar disruptive effects in the neuroimmune system. Studies are needed to determine the immune and other mechanisms responsible for these effects. Future studies would benefit from larger samples to determine whether in fact there is a group by sex interaction driving the effects of early lead exposure on microglia.

Metabolic profiling of metformin treatment for low-level Pb-induced nephrotoxicity in rat urine

Chronic kidney disease is a worldwide problem, and Pb contamination is a potential risk factor. Since current biomarkers are not sensitive for the diagnosis of Pb-induced nephrotoxicity, novel biomarkers are needed. Metformin has both hypoglycaemic effects and reno-protection ability. However, its mechanism of action is unknown. We aimed to discover the early biomarkers for the diagnosis of low-level Pb-induced nephrotoxicity and understand the mechanism of reno-protection of metformin. Male Wistar rats were randomly divided into control, Pb, Pb + ML, Pb + MH and MH groups. Pb (250 ppm) was given daily via drinking water. Metformin (50 or 100 mg/kg/d) was orally administered. Urine was analysed by nuclear magnetic resonance (NMR)-based metabolomics coupled with multivariate statistical analysis, and potential biomarkers were subsequently quantified. The results showed that Pb-induced nephrotoxicity was closely correlated with the elevation of 5-aminolevulinic acid, D-lactate and guanidinoacetic acid in urine. After co-treatment with metformin, 5-aminolevulinic acid and D-lactate were decreased. This is the first demonstration that urinary 5-aminolevulinic acid, D-lactate and guanidinoacetic acid could be early biomarkers of low-level Pb-induced nephrotoxicity in rats. The reno-protection of metformin might be attributable to the reduction of D-lactate excretion.

Developmental lead (Pb)-induced deficits in hippocampal protein translation at the synapses are ameliorated by ascorbate supplementation

BACKGROUND

Lead (Pb) is a persistent environmental neurotoxin and its exposure even in minute quantities has been known to induce neuronal defects. The immature brain is singularly sensitive to Pb neurotoxicity, and its exposure during development has permanent detrimental effects on the brain developmental trajectory and neuronal signaling and plasticity, culminating into compromises in the cognitive and behavioral attributes which persists even later in adulthood. Several molecular pathways have been implicated in the Pb-mediated disruption of neuronal signaling, including elevated oxidative stress, alterations in neurotransmitter biology, and mitochondrial dysfunction. Nevertheless, the neuronal targets and biochemical pathways underlying these Pb-mediated alterations in synaptic development and function have not been completely deduced. In this respect, recent studies have shown that synaptic signaling and its maintenance and plasticity are critically dependent on localized de novo protein translation at the synaptic terminals.

MATERIALS AND METHODS

The present study hence aimed to assess the alterations in the synapse-specific translation induced by developmental Pb exposure. To this end, in vitro protein translation rate was analyzed in the hippocampal synaptoneurosomal fractions of rat pups pre- and postnatally exposed to Pb using a puromycin incorporation assay. Moreover, we evaluated the therapeutic effects of ascorbic acid supplementation against Pb-induced deficits in synapse-localized protein translation.

RESULTS

We observed a significant loss in the rates of de novo protein translation in synaptoneurosomes of Pb-exposed pups compared to age-matched control pups. Interestingly, ascorbate supplementation lead to an appreciable recovery in Pb-induced translational deficits. Moreover, the deficit in activity-dependent synaptic protein translation was found to correlate significantly with the increase in the blood Pb levels.

CONCLUSION

Dysregulation of synapse-localized de novo protein translation is a potentially critical determinant of Pb-induced synaptic dysfunction and the consequent deficits in behavioral, social, and psychological attributes of the organisms. In addition, our study establishes ascorbate supplementation as a key ameliorative agent against Pb-induced neurotoxicity.