A rationale for lowering the blood lead action level from 10 to 2 microg/dL

Biomonitoring of maternal and fetal exposure to mercury in Sabzevar and its affecting risk factors

Fetuses and young children are sensitive to even low levels of exposure to Hg, which can damage their brain and adversely affect their central nervous system and cognitive development. This study was conducted to determine the maternal and fetal mercury burden levels in mothers presenting to Shahidan Mobini Hospital for delivery. Eighty-nine mothers were included in this study and 360 samples were taken from their placental tissue and blood (maternal blood) as well as their umbilical cord tissue blood (infant blood). Findings revealed a significant strong correlation (r = 0.890, p < 0.001) in blood mercury between mothers and their infants. According to multiple linear regression analysis, there was a significant positive association between living in rural areas and the level of mercury in the placental tissue (β = 11.09, p < 0.001). This positive association was also found in other samples. In addition, there was a significant association between maternal age and mercury level in the placental tissue (β = 5.56, p = 0.049), placental blood (β = 11.67, p = 0.003), umbilical cord tissue (β = 8.33, p = 0.004) and umbilical cord blood (β = 9.51, p < 0.001).

Intelligence gain and social cost savings attributable to environmental lead exposure reduction strategies since the year 2000 in Flanders, Belgium

BACKGROUND

Recent lead (Pb) exposure reduction strategies enabled to lower children's blood lead levels (B-Pb) worldwide. This study reports the estimated intelligence gain and social cost savings attributable to recent exposure reduction based on reported B-Pb levels observed in adolescents sampled within the framework of the Flemish Environment and Health Studies (FLEHS, Belgium), i.e. in 2003-2004 (FLEHSI), in 2008-2009 (FLEHSII), and in 2013-2014 (FLEHSIII).

METHODS

Intelligence Quotient (IQ) loss per 100,000 individuals - attributable to B-Pb above 20 μg/L - was estimated based on widely accepted dose response functions between children's B-Pb and IQ (- 1.88 IQ points for a duplication in B-Pb from 20 μg/L onwards; 95% Confidence Interval (CI): - 1.16;-2.59) and B-Pb exposure distribution parameters of FLEHS studies. The results were translated to the Flemish population of 15-year-olds. Given a 3-year time gap between subsequent sampling periods, the exposure distribution of each study was assumed 3 years prior to the study as well. Economic impact was estimated based on expected decrease in lifetime earnings (€ 19,464 per decreasing IQ point in 2018).

RESULTS

The percentage of the adolescent population exceeding a B-Pb of 20 μg/L decreased from 57% (FLEHSI) to 23% (FLEHSII), and even further to 2.5% (FLEHSIII). The estimated IQ loss per 100,000 individuals was 94,280 (95% CI: 58,427-130,138) in FLEHSI, 14,993 (95% CI: 9289-20,695) in FLEHSII, and 976 (95% CI: 604-1347) in FLEHSIII. This translates into a total loss of 378,962 (95%CI: 234,840-523,091) IQ points within the Flemish population of 15-year-olds between 2000 and 2014. Assuming that current exposure levels do not reincrease, the expected IQ loss during the subsequent period of 15 years is estimated to be maximally 10,275 (95%CI: 6363-14,182) points.

CONCLUSIONS

7176 (95%CI: 4447-9905) million € of social cost savings were achieved by Pb reduction strategies in Flanders over 15 years. If current exposure levels further reduce to B-Pb below 20 μg/L for the whole population, social cost savings may increase up to 7376 (95%CI: 4571-10,181) million €. Given the relatively low lead contamination in Flanders, the global impact of ongoing reduction strategies is expected to be tremendous.

Does low lead exposure affect blood pressure and hypertension?

Objectives

Historically, little was known about the effects of low blood lead level (BLL < 10 μg/dL) on hypertension (HTN). The purpose of this study was to assess the effects of low BLL on blood pressure (BP) and HTN in lead‐exposed male workers in the Republic of Korea.

Methods

From the year 2000 to 2004, 12,060 male workers underwent an Annual Specialised Medical Check‐up for lead; 7,341 subjects had a peak BLL < 10 μg/dL and were selected for the study. The quartiles of peak BLL in lead‐exposed workers were as follows: first (0.01‐3.68 μg/dL), second (3.69‐5.19 μg/dL), third (5.20‐6.86 μg/dL), and fourth (6.87‐10.00 μg/dL). To examine the relationship between BLL and pre‐HTN (systolic BP [SBP] ≥120‐140 mmHg; diastolic BP [DBP] ≥80‐90 mmHg) and between BLL and HTN (SBP ≥ 140 mmHg; DBP ≥ 90 mmHg), the quartiles of BLL were used as independent variables in multiple logistic regression analysis.

Results

In multiple linear regression analyses, SBP (β 0.04, P < .01) and DBP (β 0.06, P < .01) increased in line with a 1 μg/dL increase in BLL. The odds ratio (OR) of HTN in the fourth versus first BLL quartile (1.54; 95% confidence interval [CI]: 1.26, 1.89) was statistically significant.

Conclusion

SBP and DBP were statistically significantly associated with peak BLL. A BLL ≥ 6.87 μg/dL was associated with HTN; thus, even in workers with low BLLs (<10 μg/dL), management of BP is likely to be necessary. Modulation of the current safety standards for BLLs in workers will be needed.

Low-Level Cumulative Lead and Resistant Hypertension: A Prospective Study of Men Participating in the Veterans Affairs Normative Aging Study

Background

Bone lead offers a better method over blood lead measurement to discern long‐term lead exposure and accumulation. We examined the risk of resistant hypertension based on bone lead levels in a prospective cohort study of NAS (Normative Aging Study).

Methods and Results

Participants had clinic data on hypertension (systolic blood pressure, diastolic blood pressure, and antihypertension medication), lead (blood, bone‐patella, bone‐tibia), and demographic and confounding variables. Cases of resistant hypertension were identified by meeting criteria for: (1) inadequate systolic blood pressure (>140 mm Hg) or diastolic blood pressure (>90 mm Hg) while taking 3 medications or (2) requiring >4 medications for blood pressure control. A modified Poisson regression was used for model analysis. Of the 475 participants, 97 cases of resistant hypertension (20.4%) were identified. Among the cases of resistant hypertension, the median tibia and patella lead levels were 20 μg/g and 25 μg/g, respectively, while median tibia and patella lead levels were 20 μg/g and 27.5 μg/g, respectively, in participants without resistant hypertension. Tibia lead demonstrated a significant association with resistant hypertension (relative risk, 1.19; 95% confidence interval, 1.01–1.41 [P=0.04]) per interquartile range increase in tibia lead (13–28.5 μg/g). Patella lead was not associated with resistant hypertension (relative risk, 1.10; 95% confidence interval, 0.92–1.31 [P=0.31]) per interquartile range increase in patella lead (18–40 μg/g). Blood lead levels were not significantly associated with resistant hypertension (relative risk, 1.11; 95% confidence interval, 0.88–1.40 [P=0.38]).

Conclusions

Tibia lead represents a novel risk factor for resistant hypertension. Our study demonstrates an increased association between tibia lead and resistant hypertension status, with an increased risk of 19% per 1 interquartile range increase in tibia lead.

Blood lead levels in children in urban and rural areas: Using multilevel modeling to investigate impacts of gender, race, poverty, and the environment

Many studies of children's exposure to lead (Pb) are carried out in urban and industrialized environments. This study analyzed blood lead level (BLL) data collected from 2011 to 2016 from approximately 140,000 children ages <1 to 6 years across South Carolina (SC), including urban and rural areas. Individual-level characteristics included children's age, and race/ethnicity. Block group variables examined included population by race and ethnicity, households below the poverty level, median year homes built, urban/rural classification, and percent road coverage. BLL were higher in urban compared to rural children but increased to a greater extent in rural children from age < 1 year to 2 years. Road coverage was strongly associated with higher BLL in urban areas, and with home age more weakly, but neither road coverage nor home age was associated with BLL in rural areas. Young urban children may receive greater exposure to Pb from house dust and outdoor legacy Pb contamination, and young rural children through diet and drinking water. Black children had higher BLL in urban areas than white children, and the converse was true in rural areas. Population data indicated that rural areas had more poverty than urban areas, but strong associations between increased children's BLL and either ethnicity or socio-economic status (SES) at the block group level was not observed, likely due to distinct characteristics of poverty and geographic distribution by ethnicity in urban as compared to rural areas of SC. Individual demographics and environmental characteristics may be more closely associated with BLL than geographically aggregated SES and race/ethnicity characteristics. Interventions to reduce children's exposure to Pb should occur at as early an age as possible, and differences between rural and urban areas should be considered as interventions are developed to reduce children's BLL.

Systematic review and meta-analyses of lead (Pb) concentrations in environmental media (soil, dust, water, food, and air) reported in the United States from 1996 to 2016

Environmental lead (Pb) contamination is a persistent public health issue that prominently impacts communities across the United States. Multimedia Pb exposure assessments are utilized to provide a holistic evaluation of Pb exposure and inform the development of programs and regulations that are protective of human health. To conduct multimedia exposure assessments, robust, media-specific environmental Pb concentration data are necessary. To support this effort, systematic review and meta-analysis methods were used to conduct a comprehensive synthesis of research measuring Pb in multiple environmental media (soil, dust, water, food, and air) over a 20-year period within the United States. The breadth of the resulting database allowed for the evaluation of sample characteristics that can serve as indicators of environmental Pb contamination. Random effects models run on literature and national survey datasets generated overall mean estimates of Pb concentrations that can be used for multimedia Pb exposure modeling for general and high-exposure-risk populations. Results from our study highlighted several important trends: 1) The mean estimate of Pb in residential soils is three times higher for urbanized areas than non-urbanized areas; 2) The mean estimate of Pb in produce reported in the literature is approximately three orders of magnitude greater than commercially-sourced raw produce monitored in national surveys; 3) The mean estimate of Pb in soils from shooting ranges is two times greater than non-residential Pb contaminated Superfund sites reported in the literature; 4) Research reporting environmental Pb concentrations for school and daycare sites is very limited; 5) Inconsistent sample collection and reporting of results limited synthesis efforts; and 6) The U.S. EPA's Air Quality System was the most robust, publicly available national survey resource. Results from these analyses will inform future multimedia Pb exposure assessments and be useful in prioritizing future research and program development.

A pharmacokinetic model of lead absorption and calcium competitive dynamics

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

Human biomonitoring to evaluate exposure to toxic and essential trace elements during pregnancy. Part A. concentrations in maternal blood, urine and cord blood

Exposures to toxic elements or deficiencies of essential elements during pregnancy may be associated to various birth complications or even diseases in early life. The aim of this paper was to assess the concentrations of selected toxic (As, Cd, Cr, Hg, Ni, Pb) and essential trace elements (Co, Cu, Mn, Se and Zn) in blood and urine samples of delivering women at different periods of gestation and cord blood, as well as to evaluate the placental permeability for these elements. A total of 53 women participating in the HEALS-EXHES study were enrolled. In particular, 48 blood samples from 1st trimester of pregnancy, 40 blood samples at delivery, and 31 cord blood at delivery were collected. Moreover, mothers' urine were sampled at the 1st (53 samples), 2nd (53 samples) and 3rd trimester (49 samples) of pregnancy. Results showed that Hg and Mn levels in cord blood were about 2.0 times higher than in maternal blood, suggesting that these elements may be transferred from mother to fetus. The cord blood levels of As and Pb were lower (ca. the 65%) than those in maternal blood, showing that the placenta modulates the rate of transfer for these elements. Essential elements as Cu and Zn showed significantly lower levels in cord than in maternal blood suggesting that the transplacental transfer of these nutrients was very limited. In addition, correlation between paired maternal and cord blood samples for As, Hg and Pb was statistically significant indicating that the fetal body burden may reflect the maternal exposure. Cadmium, Co, Cr, Ni and Se levels did not show significant correlations between maternal and cord blood. Maternal urinary concentrations of trace elements, including As, Cr, Cu, Hg, Se and Zn decreased along pregnancy, which may cause variations in fetal exposure. The levels of toxic and essential elements in maternal blood and urine, as well as in cord blood, were for most elements at the lower end of the ranges found in the scientific literature not being of special concern for pregnant women and the unborn.

Assessing the Anxiolytic Properties of Taurine-Derived Compounds in Rats Following Developmental Lead Exposure: A Neurodevelopmental and Behavioral Pharmacological Pilot Study

Lead (Pb²⁺) is a developmental neurotoxicant that causes alterations in the brain's excitation-to-inhibition (E/I) balance. By increasing chloride concentration through GABA-ARs, taurine serves as an effective inhibitory compound for maintaining appropriate levels of brain excitability. Considering this pharmacological mechanism of taurine facilitated inhibition through the GABA-AR, the present pilot study sought to explore the anxiolytic potential of taurine derivatives. Treatment groups consisted of the following developmental Pb²⁺-exposures: Control (0 ppm) and Perinatal (150 ppm or 1000 ppm lead acetate in the drinking water). Rats were scheduled for behavioral tests between postnatal days (PND) 36-45 with random assignments to either solutions of Saline, Taurine, or Taurine Derived compounds (i.e., TD-101, TD-102, or TD-103) to assess the rats' responsiveness to each drug in mitigating the developmental Pb²⁺-exposure through the GABAergic system. Long Evans Hooded rats were assessed using an Open Field (OF) test for preliminary locomotor assessment. Approximately 24-h after the OF, the same rats were exposed to the Elevated Plus Maze (EPM) and were given an i.p. injection of 43 mg/Kg of the Saline, Taurine, or TD drugs 15-min prior to testing. Each rat was tested using the random assignment method for each pharmacological condition, which was conducted using a triple-blind procedure. The OF data revealed that locomotor activity was unaffected by Pb²⁺-exposure with no gender differences observed. However, Pb²⁺-exposure induced an anxiogenic response in the EPM, which interestingly, was ameliorated in a gender-specific manner in response to taurine and TD drugs. Female rats exhibited more anxiogenic behavior than the male rats; and as such, exhibited a greater degree of anxiety that were recovered in response to Taurine and its derivatives as a drug therapy. The results from the present psychopharmacological pilot study suggests that Taurine and its derivatives could provide useful data for further exploring the pharmacological mechanisms and actions of Taurine and the associated GABAergic receptor properties by which these compounds alleviate anxiety as a potential behavioral pharmacotherapy for treating anxiety and other associated mood disorders.

Epidemiologically-informed cumulative risk hypertension models simulating the impact of changes in metal, organochlorine, and non-chemical exposures in an environmental justice community

Blood pressure is a leading risk factor for cardiovascular disease, influenced by chemical and non-chemical stressors. Exposure reduction strategies can potentially improve public health, but there are analytical challenges in developing quantitative models of health benefits, including the need for detailed multi-stressor exposure models, corresponding health evidence, and methods to simulate changes in exposure and resultant health benefits. These challenges are pronounced in low-income urban communities, where residents are often simultaneously exposed to numerous chemical and non-chemical stressors. For New Bedford (Massachusetts, USA), a low-income community near a Superfund site, we simulated geographically-resolved individual data, and applied previously published structural equation models developed from National Health and Nutrition Examination Survey (NHANES) data. These models simultaneously predict exposures to multiple chemicals (e.g., lead (Pb), cadmium (Cd), and polychlorinated biphenyls (PCBs)) and non-chemical factors (e.g., socioeconomic status), and determine their combined effects on blood pressure. We then modeled counterfactual scenarios reducing exposures and estimated the resulting changes in blood pressure distribution in the community. Results indicated small shifts in mean blood pressure and percentage of normotensive individuals with a reduction of Pb and/or PCB exposure. For example, a reduction in PCB to the lowest 10th percentile exposure in the NHANES resulted in a 2.4 mm Hg shift in systolic blood pressure (SBP), corresponding with 3% fewer individuals with SBP in the Stage 2 hypertension category [SBP ≥140]. Our model also emphasized the importance of the multi-stressor framework by simulating benefits of reductions in smoking rates, given positive associations with Pb and Cd but inverse associations with body mass index and blood pressure. This research demonstrates the ability to jointly consider chemical and non-chemical exposures and their impact on cardiovascular health, using approaches generalizable to other cumulative risk assessment applications.

Status of lead accumulation in agricultural soils across China (1979-2016)

The first national-scale assessment of lead (Pb) contamination in agricultural soils across China was conducted based on >1900 articles published between 1979 and 2016. Pb concentrations, temporal and spatial variations, and influencing factors were analyzed. Children's blood lead levels (BLLs) were also estimated using the integrated exposure uptake biokinetic (IEUBK) model. Pb concentrations in different areas of China varied greatly, which was closely associated with the distribution of Pb-related industries, especially Pb-zinc mine smelting, non-ferrous polymetallic mine smelting, e-waste recycling, and leaded gasoline consumption. The year 2000 was a significant transition year for Pb concentrations, with a rapid increase pre-2000 and a subsequent slow upward trend. Pb concentrations were found to be strongly associated with indicators of economic and social development including gross domestic product (GDP), population size, and vehicle ownership. Leaded gasoline, coal combustion, and non-ferrous smelting were the main sources of atmospheric Pb during the different periods. Predicted BLLs were higher in South China than those in the north. This study details the overall Pb contamination status of agricultural soils in China, and thus provides insights for policymakers with respect to pollution prevention measures.

Long-term consequences of early postnatal lead exposure on hippocampal synaptic activity in adult mice

INTRODUCTION

Lead (Pb) exposure yielding blood lead levels (BLL) as low as 2 µg/dl in children is an international problem. More common in US low-income neighborhoods, childhood Pb exposure can cause behavioral and cognitive deficits, including working memory impairments, which can persist into adulthood. So far, studies characterized short-term effects of high Pb exposure on neuronal structure and function. However, long-term consequences of early chronic Pb exposure on neuronal activity are poorly documented.

METHODS

Here, we exposed male and female mice (PND [postnatal day] 0 to PND 28) to one of three Pb treatments: 0 ppm (sodium-treated water, control), 30 ppm (low dose), and 330 ppm (high dose) lead acetate. Once the male and female mice were 9-12 months old, extracellular field recordings on hippocampal slices were performed.

RESULTS

We show that at CA3 to CA1 synapses, synaptic transmission was decreased and neuronal fiber activity was increased in males exposed to lowest level Pb. In contrast, both synaptic transmission and neuronal fiber activity were increased in females exposed to high Pb. The ventral hippocampus-medial prefrontal cortex (vHPC-mPFC) synapses are crucial for working memory in rodents. The lowest level Pb decreased vHPC-mPFC synaptic transmission, whereas high Pb decreased short-term synaptic depression.

CONCLUSIONS

Overall, we show for the first time that early exposure to either high or lowest level Pb has long-term consequences on different synaptic properties of at least two hippocampal synapses. Such consequences of early Pb exposure might worsen the cognitive decline observed in aging men and women. Our results suggest that additional efforts should focus on the consequences of early Pb exposure especially in at-risk communities.

Neurotoxicity of low-level lead exposure: History, mechanisms of action, and behavioral effects in humans and preclinical models

Lead is a neurotoxin that produces long-term, perhaps irreversible, effects on health and well-being. This article summarizes clinical and preclinical studies that have employed a variety of research techniques to examine the neurotoxic effects of low levels of lead exposure. A historical perspective is presented, followed by an overview of studies that examined behavioral and cognitive outcomes. In addition, a short summary of potential mechanisms of action is provided with a focus on calcium-dependent processes. The current level of concern, or reference level, set by the CDC is 5 μg/dL of lead in blood and a revision to 3.5 μg/dL has been suggested. However, levels of lead below 3 μg/dL have been shown to produce diminished cognitive function and maladaptive behavior in humans and animal models. Because much of the research has focused on higher concentrations of lead, work on low concentrations is needed to better understand the neurobehavioral effects and mechanisms of action of this neurotoxic metal.

Topsoil pollution in highway medians in the State of São Paulo (Brazil): determination of potentially toxic elements using synchrotron radiation total reflection X-ray fluorescence

The presence of metals in vehicle emissions is due to several factors, such as the composition of fuels and lubricating oils, the wear of engine components, and their use in catalytic converters. It is known that the soil near highways is greatly affected by heavy vehicle traffic, since the use of highways is of fundamental importance for the flow of goods and public transport, especially in Brazil, street transport being the main form of transport in the country. Considering the scenario described, the main objective of this study was to monitor the concentration of potentially toxic elements in surface soils located on the medians of the main access highways in the city of Campinas (SP-Brazil) and classify the soils through geoaccumulation index. Using SR-TXRF it was possible to detect and determine the concentrations of 5 elements of toxic-environmental interest (Cr, Ni, Cu, Zn, and Pb) and 11 natural soil composition elements (Al, Si, S, Cl, K, Ca, Ti, Mn, Fe, Rb, and Sr). To evaluate the influence of highway distance on elementary concentrations, ANOVA and Tukey statistical tests were applied. Nickel, Cu, and Zn showed a decrease in their concentrations moving away from the highway, indicating their relation with vehicular emissions. Applying principal components analysis (PCA), it was possible to identify four groups of the quantified elements: those mainly related to the soil itself, those produced by traffic of automotive vehicles, and those emitted by industrial activities.

Recommendations towards standards for quantitative MRI (qMRI) and outstanding needs

LEVEL OF EVIDENCE

5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.

Effects of single and combined toxic exposures on the gut microbiome: Current knowledge and future directions

Human populations are chronically exposed to mixtures of toxic chemicals. Predicting the health effects of these mixtures require a large amount of information on the mode of action of their components. Xenobiotic metabolism by bacteria inhabiting the gastrointestinal tract has a major influence on human health. Our review aims to explore the literature for studies looking to characterize the different modes of action and outcomes of major chemical pollutants, and some components of cosmetics and food additives, on gut microbial communities in order to facilitate an estimation of their potential mixture effects. We identified good evidence that exposure to heavy metals, pesticides, nanoparticles, polycyclic aromatic hydrocarbons, dioxins, furans, polychlorinated biphenyls, and non-caloric artificial sweeteners affect the gut microbiome and which is associated with the development of metabolic, malignant, inflammatory, or immune diseases. Answering the question 'Who is there?' is not sufficient to define the mode of action of a toxicant in predictive modeling of mixture effects. Therefore, we recommend that new studies focus to simulate real-life exposure to diverse chemicals (toxicants, cosmetic/food additives), including as mixtures, and which combine metagenomics, metatranscriptomics and metabolomic analytical methods achieving in that way a comprehensive evaluation of effects on human health.

Globally temporal transitions of blood lead levels of preschool children across countries of different categories of Human Development Index

In the past decades, efforts to eliminate lead from gasoline, paint and drinking water around the world have substantially reduced human blood lead levels. This study was therefore aimed at examining the global temporal trends in the blood lead levels of preschool children by the category of UN Human Development Index (HDI). In total, 103 blood lead records were retrieved from 51 articles searched from PubMed and Google Scholar, with study subjects aged up to 8years old. Collected preschool children blood lead levels were plotted chronologically by HDI category and their reciprocals were used in regression analysis against calendar year to establish their temporal transition trends in the past decades. Results show that the modes of blood lead level of the preschool children were reduced from 4-6μg/dL to 0.8-1.5μg/dL, from 6-15μg/dL to 3-6μg/dL and from 12-16 to 5-6μg/dL for the very high HDI countries, the high HDI countries and the medium/low HDI countries, respectively. The highest correlation coefficient, 0.849, between the reciprocal of blood lead level and the calendar year was found for the very high HDI countries. Based on the regression lines, the predicted preschool children mean blood lead levels in the year of 2030 are 0.74μg/dL, 2.21μg/dL and 2.86μg/dL, respectively, for the very high HDI countries, the high HDI countries and the medium/low HDI countries. Persistent differences in blood lead level prevailed among countries of different HDI category, suggesting the effects of disparities and inequalities, at the state level, on preschool children blood lead levels. Further action is warranted to reduce the already low environmental lead exposure to eliminate the developmental burden of lead on children through (1) identification of individual local factors for lead exposure and (2) averting health disparity and inequalities at the state level.

Sources of lead exposure in various countries

This review evaluates the sources of lead exposure worldwide. Studies from searches relating to sources of lead exposure in various countries within different regional zones were reviewed. Results indicated that in Nigeria, exposure sources include electronic waste, paint and batteries. In Mexico exposure sources include glazed ceramics, lead contaminated utensils and lead contaminated water, for India lead sources include cosmetics and traditional medicines. Sources of lead exposure in China include e-waste, traditional medicines and industrial emissions. In France, exposure sources included lead paint from older homes, imported ceramics and cosmetics and industrial emissions. Australia's exposure sources include paint, dust, imported toys and traditional medicines. Finally, in the United States exposure sources included paint, the industrial legacy of lead exposure and batteries. In high-income countries (HICs) the legacy of lead exposure keeps populations continuously exposed. In lower- and middle-income countries (LMICs), in addition to the legacy of lead exposure, lack of regulations or the inability to enforce regulations keeps populations exposed. In all, evidence suggests that lead exposure remains an issue of public health significance in both HIC and LMIC.

Spatial distribution of lead contamination in soil and equipment dust at children's playgrounds in Beijing, China

Lead contamination is widespread across China, posing a serious public health concern. In quantifying child lead exposure, established health risk assessment (HRA) approaches often take into account residential soil lead levels. However, this may not constitute a significant exposure source for children in urban mainland China, where the population mainly dwell in high-rise buildings without back or front yards. In this setting, children's playgrounds may represent a more probable exposure source. The present study analyzed lead levels in settled dust on playground equipment and in surficial soils at 71 playgrounds in Beijing, China. Our results reveal that the average playground dust lead concentration was 80.5 mg/kg, more than twice the average soil lead concentration of 36.2 mg/kg. It was found that there are differences in statistical and spatial distributions for lead in playground dust and soils. Lead levels in equipment dust were largely consistent across Beijing, with elevated levels detected at locations in the main city area, the newly developed Tongzhou District, and the rural counties. Whereas average soil lead concentrations were higher at playgrounds in the main city area than other areas of Beijing. Statistical analysis suggests that the lead content in dust and soil may derive from different natural and anthropogenic sources. Equipment dust lead may be associated with long-distance atmospheric transportation and deposition. Whereas lead in soil is more likely to be associated with local traffic. This study also found that, in certain areas of Beijing, the risk of blood lead levels (BLLs) exceeding safe levels was up to 6 times higher when based on dust exposure than when based on playground soil exposure. The results of this study suggests that HRA undertaken for children in urban mainland China should pay closer attention to children's playgrounds as a lead exposure source, and, in particular, playground equipment dust.

Lead-based paint remains a major public health concern: A critical review of global production, trade, use, exposure, health risk, and implications

Human exposure to lead (Pb) is a growing global public health concern. Elevated blood lead is thought to cause the mental retardation of >0.6 million children globally each year, and has recently been attributed to ~18% of all-cause mortality in the US. Due to the severe health risk, the international community, led by the United Nations Environment Programme (UNEP) and the World Health Organization (WHO), is actively supporting the global phase-out of lead-based paint by 2020. However, there are many significant hurdles on the way to achieving this goal. In light of the importance of the lead-based paint issue, and the urgency of achieving the 2020 phase-out goal, this review provides critical insights from the existing scientific literature on lead-based paint, and offers a comprehensive perspective on the overall issue. The global production and international trade of lead-based paints across Asia, Africa, Latin America, and Europe are critically discussed - revealing that lead-based paints are still widely used in many low and middle-income developing countries, and that the production and trade of lead-based paint is still wide-spread globally. In India, as well as many south-east Asian, African, Latin American and European countries, lead concentrations in paints often exceed 10,000 mg/kg. This will certainly pose a serious global threat to public health from surfaces painted with these products for many decades to come. The sources and pathways of exposure are further described to shed light on the associated health risk and socioeconomic costs. Finally, the review offers an overview of the potential intervention and abatement strategies for lead-based paints. In particular, it was found that there is a general lack of consensus on the definition of lead based paint; and, strengthening regulatory oversight, public awareness, and industry acceptance are vital in combating the global issue of lead based paint.

Concussion History and Cognitive Function in a Large Cohort of Adolescent Athletes

BACKGROUND

The incidence of reported concussions in the adolescent population is increasing, yet research on the effects of concussions in this population is minimal and inconclusive.

PURPOSE

To assess the association between concussion and performance on a cognitive test battery.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Using multivariate models, the authors assessed the association between concussion and performance on a cognitive test battery among 5616 high school and junior high school athletes. The researchers utilized a global cognitive score and scores for 5 domains: verbal memory, visual memory, visual motor, reaction time, and impulse control. Each cognitive score was converted to a z score with the mean and SD of the nonconcussed population. Results from each model were then interpreted as change in the standardized unit score. In the models, concussion was evaluated as ever having a concussion, number of concussions, time since last concussion, and age at first concussion.

RESULTS

Ever having a concussion was associated with a mean decrease of 0.11 standardized units (95% CI, -0.20 to -0.01) on the global cognitive score and lower scores in all cognitive domains. Each additional concussion was associated with lower scores on global cognitive function (effect estimate, -0.06; 95% CI, -0.11 to -0.02), verbal memory, visual memory, and impulse control. Concussion in early childhood was associated with lower global cognition (effect estimate, -0.05; 95% CI, -0.08 to -0.01), visual memory, and motor visual scores as compared with concussions in later childhood. The associations between time since last concussion and cognitive test scores were nonlinear, and on all tests, lower scores were observed even ≥1 year after the concussion.

CONCLUSION

On the basis of objective performance metrics for cognitive function, concussions had a more persistent effect on cognitive function than previously thought. The age at which an individual has his or her first concussion may be an important factor in determining long-lasting cognitive effects.

Lead-based paint in children's toys sold on China's major online shopping platforms

Lead in paint is a major public health concern and has drawn much attention from international organizations such as the World Health Organization (WHO) and the United Nations Environmental Programme (UNEP). However, there is limited research on lead-based paint, especially its use in toys, which poses an explicit health risk to vulnerable children. The present study sampled 100 different toys purchased from the three largest online shopping platforms in China: JD, Taobao (TB) and Tmall (TM). These selected toys have been sold nearly 3 million times in total, suggesting that they may have reached the dwellings of millions of children. It was found that the toys sold by JD and TM, which are considered organized sellers, had average lead concentrations of 25 mg/kg and 32 mg/kg, respectively, much lower than that of toys sold by unorganized sellers on the TB platform, at 219 mg/kg. Approximately 12% of the toys purchased from TB contained paint with total lead concentrations exceeding China's regulatory standard for paints in toy manufacturing, and nearly 36% of the toys purchased from TB exceeded the equivalent US regulatory standard and EU standard. These results suggest that further action is needed to verify the health and safety standards of toys sold by such unorganized sellers. Moreover, this study found that China's regulatory standard (90 mg/kg) based on soluble lead may underestimate the risk posed by lead in paints, and it is suggested that future regulatory thresholds for lead levels in paints for toy manufacture be based on total rather than soluble lead concentrations. The present study also explored various influencing factors on lead concentration, and found that lead concentrations were related to toy price, age group, color, and sales volume.

A Prospective Birth Cohort Study on Early Childhood Lead Levels and Attention Deficit Hyperactivity Disorder: New Insight on Sex Differences

OBJECTIVE

To investigate the prospective associations between early childhood lead exposure and subsequent risk of attention deficit hyperactivity disorder (ADHD) in childhood and its potential effect modifiers.

STUDY DESIGN

We analyzed data from 1479 mother-infant pairs (299 ADHD, 1180 neurotypical) in the Boston Birth Cohort. The child's first blood lead measurement and physician-diagnosed ADHD was obtained from electronic medical records. Graphic plots and multiple logistic regression were used to examine dose-response associations between lead exposure and ADHD and potential effect modifiers, adjusting for pertinent covariables.

RESULTS

We found that 8.9% of the children in the Boston Birth Cohort had elevated lead levels (5-10 µg/dL) in early childhood, which was associated with a 66% increased risk of ADHD (OR, 1.66; 95% CI, 1.08-2.56). Among boys, the association was significantly stronger (OR, 2.49; 95% CI, 1.46-4.26); in girls, the association was largely attenuated (P value for sex-lead interaction = .017). The OR of ADHD associated with elevated lead levels among boys was reduced by one-half if mothers had adequate high-density lipoprotein levels compared with low high-density lipoprotein, or if mothers had low stress compared with high stress during pregnancy.

CONCLUSIONS

Elevated early childhood blood lead levels increased the risk of ADHD. Boys were more vulnerable than girls at a given lead level. This risk of ADHD in boys was reduced by one-half if the mother had adequate high-density lipoprotein levels or low stress. These findings shed new light on the sex difference in ADHD and point to opportunities for early risk assessment and primary prevention of ADHD.

Heads in the sand: public health and ecological risks of lead-based bullets for wildlife shooting in Australia

Lead (Pb) is a toxic element banned from fuel, paint and many other products in most developed countries. Nonetheless, it is still widely used in ammunition, including rifle bullets, and Pb-based bullets are almost universally used in Australia. For decades, poisoning from Pb shot (shotguns) has been recognised as a cause of disease in waterfowl and Pb shot has been subsequently banned for waterfowl hunting in many jurisdictions. However, the risks posed by Pb-based bullets (rifles) have not been similarly recognised in Australia. Pb-based rifle bullets frequently fragment, contaminating the tissue of shot animals. Consuming this Pb-contaminated tissue risks harmful Pb exposure and, thus, the health of wildlife scavengers (carrion eaters) and humans and their companion animals who consume harvested meat (game eaters). In Europe, North America and elsewhere, the environmental and human health risks of Pb-based bullets are widely recognised, and non-toxic alternatives (e.g. copper-based bullets) are increasingly being used. However, Australia has no comparable research despite widespread use of shooting, common scavenging by potentially susceptible wildlife species, and people regularly consuming shot meat. We conclude that Australia has its collective ‘head in the sand’ on this pressing worldwide One Health issue. We present the need for urgent research into this field in Australia.

Blood lead levels and longitudinal language outcomes in children from 4 to 12 years

OBJECTIVES

In this study, the authors aimed to examine the association of a range of blood lead levels on language skills assessed at 4, 6, 10 and 12 years of age using a prospective longitudinal design controlling for potential confounding variables including maternal vocabulary, caregiver's psychological distress and symptomatology, child's race and prenatal drug exposure.

METHODS

The participants (N = 278) were a subsample of a large longitudinal study that examined the association of prenatal drug exposure on children who were followed prospectively from birth and assessed for receptive and expressive language skills at 4, 6, 10 and 12 years of age. Blood lead levels were determined at 4-years of age by atomic absorption spectrometry. A mixed model approach with restricted maximum likelihood procedures was used to assess the association of lead on language outcomes.

RESULTS

Longitudinal mixed model analyses suggested a negative effect of lead exposure on both receptive and expressive language, with the adverse outcomes of lead exposure appearing to become more prominent at 10 and 12 years. Higher caregiver vocabulary was positively associated with child's language scores whereas caregiver psychological distress appeared to negatively affect language scores. Prenatal drug exposure was not related to the effects of lead on language skills.

CONCLUSIONS

These findings suggest that elevated blood lead levels occurring early in life may be associated with poorer language skills at older ages. A language rich environment may minimize the negative influence of early lead exposure on language skills, with psychological distress seemingly exacerbating the negative outcome.

Reducing occupational lead exposures: Strengthened standards for a healthy workforce

Outdated federal and state occupational lead standards leave workers and their families vulnerable to the adverse effects of lead. Standards should be updated to reflect the best available scientific and medical evidence, which documents harm to multiple organ systems even at low levels of exposure. This commentary will review the inadequacies of existing policies, highlight susceptible populations, and briefly summarize state revision efforts to date. Federal policies must be strengthened to protect all workers and their families from this well-documented hazard.

Gut Dysbiosis in Animals Due to Environmental Chemical Exposures

The gut microbiome consists of over 10³–10⁴ microorganism inhabitants that together possess 150 times more genes that the human genome and thus should be considered an “organ” in of itself. Such communities of bacteria are in dynamic flux and susceptible to changes in host environment and body condition. In turn, gut microbiome disturbances can affect health status of the host. Gut dysbiosis might result in obesity, diabetes, gastrointestinal, immunological, and neurobehavioral disorders. Such host diseases can originate due to shifts in microbiota favoring more pathogenic species that produce various virulence factors, such as lipopolysaccharide. Bacterial virulence factors and metabolites may be transmitted to distal target sites, including the brain. Other potential mechanisms by which gut dysbiosis can affect the host include bacterial-produced metabolites, production of hormones and factors that mimic those produced by the host, and epimutations. All animals, including humans, are exposed daily to various environmental chemicals that can influence the gut microbiome. Exposure to such chemicals might lead to downstream systemic effects that occur secondary to gut microbiome disturbances. Increasing reports have shown that environmental chemical exposures can target both host and the resident gut microbiome. In this review, we will first consider the current knowledge of how endocrine disrupting chemicals (EDCs), heavy metals, air pollution, and nanoparticles can influence the gut microbiome. The second part of the review will consider how potential environmental chemical-induced gut microbiome changes might subsequently induce pathophysiological responses in the host, although definitive evidence for such effects is still lacking. By understanding how these chemicals result in gut dysbiosis, it may open up new remediation strategies in animals, including humans, exposed to such chemicals.

Accumulation, elimination, sequestration, and genetic variation of lead (Pb2+) loads within and between generations of Drosophila melanogaster

We examined accumulation, sequestration, elimination, and genetic variation for lead (Pb) loads within and between generations of Drosophila melanogaster. Flies were reared in control or leaded medium at various doses and tested for their Pb loads at different stages of development (larvae, eclosion, newly-eclosed adults, and mature adults). Pb loads were tested using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). We found that D. melanogaster readily accumulated Pb throughout their lifespan and the levels of accumulation increased with Pb exposure in the medium. Wandering third-instar larvae accumulated more Pb than mature adults; this phenomenon may be due to elimination of Pb in the pupal cases during eclosion and/or depuration in adults post-eclosion. The accumulated Pb in mature adults was not transferred to F1 mature adult offspring. Using a set of recombinant inbred strains, we identified a quantitative trait locus for adult Pb loads and found that genetic variation accounted for 34% of the variance in Pb load. We concluded that D. melanogaster is a useful model organism for evaluating changes in Pb loads during development, as well as between generations. Furthermore, we found that genetic factors can influence Pb loads; this provides an essential foundation for evaluating phenotypic variation induced by the toxic effects of Pb.

A review: Aptamer-based analytical strategies using the nanomaterials for environmental and human monitoring of toxic heavy metals

Recent developments in biotechnology offer the new methods for the sensitive detection of heavy metals based on the affinity and specificity of aptamers, as nucleic acid ligands selected from random sequence pools in vitro. Heavy metals have received considerable importance as the most toxic metallic pollutants which may cause serious environmental damages. They are classified as trace elements because of their presence in trace concentrations in various environmental matrices. Thus, the precise and sensitive methods to detect heavy metals are important to ensure human and environment safety. Aptamers as the biological probes, show high binding affinity which can often be directly translated into high detection sensitivity. On the other hand, high selectivity and stability make them possible to detect a wide range of targets, especially metallic ions. This review provides current progress of aptamers for environmental and biological monitoring of heavy metals using the nanomaterials mainly in two groups: (i) aptamer based biosensors (aptasensors) and (ii) aptamer based biosorbents (aptasorbents). The introduction of nanomaterials can efficiently increase the immobilization quantity of aptamers. Furthermore, they play an important role in the orientation and assembly density controlling of aptamers for the optimized recognition ability.

High prevalence of elevated blood lead levels in both rural and urban Iowa newborns: Spatial patterns and area-level covariates

Lead in maternal blood can cross the placenta and result in elevated blood lead levels in newborns, potentially producing negative effects on neurocognitive function, particularly if combined with childhood lead exposure. Little research exists, however, into the burden of elevated blood lead levels in newborns, or the places and populations in which elevated lead levels are observed in newborns, particularly in rural settings. Using ~2300 dried bloods spots collected within 1-3 days of birth among Iowa newborns, linked with the area of mother's residence at the time of birth, we examine the spatial patterns of elevated (>5 μg/dL) blood lead levels and the ecological-level predictors of elevated blood lead levels. We find that one in five newborns exceed the 5 μg/dL action level set by the US Centers for Disease Control & Prevention (CDC). Bayesian spatial zero inflated regression indicates that elevated blood lead in newborns is associated with areas of increased pre-1940s housing and childbearing-age women with low educational status in both rural and urban settings. No differences in blood lead levels or the proportion of children exceeding 5 μg/dL are observed between urban and rural maternal residence, though a spatial cluster of elevated blood lead is observed in rural counties. These characteristics can guide the recommendation for testing of infants at well-baby appointments in places where risk factors are present, potentially leading to earlier initiation of case management. The findings also suggest that rural populations are at as great of risk of elevated blood lead levels as are urban populations. Analysis of newborn dried blood spots is an important tool for lead poisoning surveillance in newborns and can direct public health efforts towards specific places and populations where lead testing and case management will have the greatest impact.

Exposure to lead in South African shooting ranges

INTRODUCTION

Lead exposure in shooting ranges has been under scrutiny for decades, but no information in this regard is available in respect of African settings, and in South Africa specifically. The aim of this study was to determine the blood lead levels in the users of randomly selected private shooting ranges in South Africa's Gauteng province.

METHODS

An analytical cross sectional study was conducted, with participants recruited from four randomly selected shooting ranges and three archery ranges as a comparator group.

RESULTS

A total of 118 (87 shooters and 31 archers) were included in the analysis. Shooters had significantly higher blood lead levels (BLL) compared to archers with 36/85 (42.4%) of shooters versus 2/34 (5.9%) of archers found to have a BLL ≥10μg/dl (p<0.001).

CONCLUSION

Shooting ranges may constitute an import site of elevated exposure to lead. Improved ventilation, low levels of awareness of lead hazards, poor housekeeping, and inadequate personal hygiene facilities and practices at South African shooting ranges need urgent attention.

Chemical assessment of lead, cadmium, nitrate, and nitrite intakes with daily diets of children and adolescents from orphanages in Krakow, Poland

The aim of this study has been to measure the level of lead, cadmium, nitrates, and nitrites in the daily diets of children and adolescents from orphanages located in Krakow (Poland). Diets were collected over four seasons of 2009. The content of cadmium and lead was measured with flameless atomic absorption spectrometry. Nitrates and nitrites in diets were measured using the Griess colorimetric method. In all orphanages, the average intake of lead with daily diets, regardless of the season, ranged from 1.11 ± 0.15 to 22.59 ± 0.07 μg/kg bw/week. The average cadmium intake by children and adolescents ranged between 3.09 ± 0.21 and 20.36 ± 2.21 μg/kg bw/week and, for all orphanages, exceeded the tolerable weekly intake (TWI) level. Daily intake of nitrates and nitrites ranged respectively from 27 to 289 % and from 9 to 99 % of the acceptable daily intake (ADI). The youngest children, with lower body mass, were particularly sensitive to the excessive intakes of cadmium and nitrates.

Urinary t,t-muconic acid as a proxy-biomarker of car exhaust and neurobehavioral performance in 15-year olds

INTRODUCTION

Traffic-related air pollution has been shown to induce neurotoxicity in rodents. Several recent epidemiological studies reported negative associations between residential outdoor air pollution and neurobehavioral performance. We investigated in a population of non-smoker adolescents the associations between the urinary concentration of trans, trans-muconic acid (t,t-MA-U), a metabolite of benzene and used as proxy-biomarker of traffic exposure, and two neurobehavioral domains, i.e. sustained attention and short-term memory.

METHODS

In the framework of an environmental health surveillance study in Flanders (Belgium), we examined between 2008 and 2014 grade nine high school students (n=895). We used reaction time, number of omission errors, and number of commission errors in the Continuous Performance Test to evaluate sustained attention, and for the evaluation of short-term memory we used maximum digit span forward and backward of the Digit Span Test. We measured blood lead (PbB) to assess the independent effect of t,t-MA-U on neurobehavioral outcomes.

RESULTS

This neurobehavioral examination study showed that a ten-fold increase in t,t-MA-U was associated with a 0.14 SD lower sustained attention (95% Confidence Interval: -0.26 to -0.019; p=0.02) and a 0.17 SD diminished short-term memory (95% CI: -0.31 to -0.030; p=0.02). For the same increment in t,t-MA-U, the Continuous Performance Test showed a 12.2ms higher mean reaction time (95% CI: 4.86-19.5; p=0.001) and 0.51 more numbers of errors of omission (95% CI: 0.057-0.97; p=0.028), while no significant association was found with errors of commission. For the Digit Span Tests, the maximum digit span forward was associated with a 0.20 lower number of digits (95% CI: -0.38 to -0.026; p=0.025) and maximum digit span backward with -0.15 digits (95% CI: -0.32 to 0.022; p=0.088). These associations were independent of PbB, parental education and other important covariates including gender, age, passive smoking, ethnicity, urinary creatinine, time of the day, and examination day of the week. For PbB, an independent association was only found with mean reaction time of the Continuous Performance Test (19.1ms, 95% CI: 2.43-35.8; p=0.025).

CONCLUSIONS

In adolescents, a ten-fold increase in the concentration of t,t-MA-U, used as a proxy-biomarker for traffic-related exposure, was associated with a significant deficit in sustained attention and short-term memory. The public health implications of this finding cannot be overlooked as the effect-size for these neurobehavioral domains was about 40% of the effect-size of parental education.

Heavy metal content of selected personal care products (PCPs) available in Ibadan, Nigeria and their toxic effects

There is a growing concern on heavy metals in consumer products due to their potential human health risks and environmental effects. In this study, the levels of zinc, cadmium, lead and nickel were assessed in 3 different classes of personal care products commonly used in Ibadan, Nigeria. Samples were analysed for heavy metals using Atomic Absorption Spectrophotometer (AAS) after acid digestion. Estimated daily intake (EDI) of the metals and Health Risk Index (HRI) were calculated to assess the human health risks associated with the use of these PCPs. The concentrations (mg/kg) of zinc ranged from 3.75 to 19.3, 1.88 to 112,000 and 19.8 to 217 respectively in creams, powders and eyeliners. Cadmium ranged from ND-0.50, ND-36.3 and ND-0.50 mg/kg while lead ranged from ND-6.25, ND-468 and 3.73-27.5 mg/kg and nickel ranged from ND-6.25, 0.13-107 and 2.75-22.7 mg/kg respectively. There were high concentrations of Cd, Pb and Ni in some of the samples when compared with the available permissible limits in cosmetics (Cd: 0.3 ppm, Pb: 10 ppm and Ni: 0.6 ppm while there is no permissible limit for Zn in cosmetics currently available). Prolonged use of PCPs may pose human health and environmental risks due to toxic metal loading through dermal contact and accumulation over a period of time. Hence, the need for necessary government agencies to regulate and enforce toxic metals in consumer products including cosmetics produced and imported into Nigeria to safeguard public health and the environment, which is the final sink.

Perinatal Lead Exposure Alters Gut Microbiota Composition and Results in Sex-specific Bodyweight Increases in Adult Mice

Heavy metal pollution is a principle source of environmental contamination. Epidemiological and animal data suggest that early life lead (Pb) exposure results in critical effects on epigenetic gene regulation and child and adult weight trajectories. Using a mouse model of human-relevant exposure, we investigated the effects of perinatal Pb exposure on gut microbiota in adult mice, and the link between gut microbiota and bodyweight changes. Following Pb exposure during gestation and lactation via maternal drinking water, bodyweight in A(vy) strain wild-type non-agouti (a/a) offspring was tracked through adulthood. Gut microbiota of adult mice were characterized by deep DNA sequencing of bacterial 16S ribosomal RNA genes. Data analyses were stratified by sex and adjusted for litter effects. A Bayesian variable selection algorithm was used to analyze associations between bacterial operational taxonomic units and offspring adult bodyweight. Perinatal Pb exposure was associated with increased adult bodyweight in male (P < .05) but not in female offspring (P = .24). Cultivable aerobes decreased and anaerobes increased in Pb-exposed offspring (P < .005 and P < .05, respectively). Proportions of the 2 predominant phyla (Bacteroidetes and Firmicutes) shifted inversely with Pb exposure, and whole bacterial compositions were significantly different (analysis of molecular variance, P < .05) by Pb exposure without sex bias. In males, changes in gut microbiota were highly associated with adult bodyweight (P = .028; effect size = 2.59). Thus, perinatal Pb exposure results in altered adult gut microbiota regardless of sex, and these changes are highly correlated with increased bodyweight in males. Adult gut microbiota can be shaped by early exposures and may contribute to disease risks in a sex-specific manner.

Early-life lead exposure results in dose- and sex-specific effects on weight and epigenetic gene regulation in weanling mice

AIMS

Epidemiological and animal data suggest that the development of adult chronic conditions is influenced by early-life exposure-induced changes to the epigenome. This study investigates the effects of perinatal lead (Pb) exposure on DNA methylation and bodyweight in weanling mice.

MATERIALS & METHODS

Viable yellow agouti (A(vy)) mouse dams were exposed to 0, 2.1, 16 and 32 ppm Pb acetate before conception through weaning. Epigenetic effects were evaluated by scoring coat color of A(vy)/a offspring and quantitative bisulfite sequencing of two retrotransposon-driven (A(vy) and CDK5 activator-binding protein intracisternal A particle element) and two imprinted (Igf2 and Igf2r) loci in tail DNA.

RESULTS

Maternal blood Pb levels were below the limit of detection in controls, and 4.1, 25.1 and 32.1 µg/dl for each dose, respectively. Pb exposure was associated with a trend of increased wean bodyweight in males (p = 0.03) and altered coat color in A(vy)/a offspring. DNA methylation at A(vy) and the CDK5 activator-binding protein intracisternal A-particle element was significantly different from controls following a cubic trend (p = 0.04; p = 0.01), with male-specific effects at the A(vy) locus. Imprinted genes did not shift in methylation across exposures.

CONCLUSION

Dose- and sex-specific responses in bodyweight and DNA methylation indicate that Pb acts on the epigenome in a locus-specific fashion, dependent on the genomic feature hosting the CpG site of interest, and that sex is a factor in epigenetic response.

Validation and Assessment of Pediatric Lead Screener Questions for Primary Prevention of Lead Exposure

OBJECTIVE

Pediatric lead screener questions have previously been evaluated for their ability to identify children whose blood lead levels (BLLs) are greater than 10 µg/dL. Based on recent policy changes stressing that there is no safe BLL for children, the current study reevaluates the screener questions for their ability to identify children with BLLs less than 2 µg/dL and the validity of the questions in positively identifying those at greater risk for exposure.

METHOD

A total of 202 parents of children enrolled in Head Start programs were administered the pediatric lead screener, questions to validate the screener questions, and children's BLLs were collected in Summer 2013. Pediatric screener questions were validated against children's BLL and the more comprehensive questions on lead risk.

RESULTS

In predicting BLL greater than 2 µg/dL, the pediatrician screener tool had a sensitivity of 26.3% and specificity of 72.2%. Each of the screener questions had low sensitivities for identifying children with BLLs above 2 µg/dL. The screener questions did not demonstrate adequate validity when compared against a more comprehensive battery of lead exposure risk indicators. The validation questions improved sensitivity to detect children with BLL >2 µg/dL and reduced the number of false positives.

CONCLUSION

The pediatrician screener questions in their current format are not a useful primary prevention tool in identifying children at greater risk for lead exposure and in need of secondary prevention through the receipt of a blood lead test. A revision to the protocol for identifying children at risk could result in better primary and secondary prevention efforts.

Lead concentration in the blood of the general population living near a lead-zinc mine site, Nigeria: Exposure pathways

Lead (Pb) poisoning in children is a major public health catastrophe worldwide. This report summarises both exposure pathways and blood Pb levels in children below 7 years of age and adults (above 18 years) from the Adudu community living near a lead-zinc mine in Nasawara, Nigeria. The average and median blood Pb levels in children and adults were 2.1 and 1.3 μg/dL, 3.1 and 1.8 μg/dL, respectively. However, Pb in 14% of adults' blood exceeded 5 μg/dL, which is the recommended threshold blood Pb concentration in adults as established by the Centers for Disease Control and Prevention (CDC). Furthermore 68% of adults' blood exceeded blood Pb action level of 2 μg/dL. For children, 11.4% and 31% of the blood samples exceeded 5 μg/dL and 2 μg/dL, respectively, while no safe blood Pb level in children has been recommended. In Nasawara, a significant difference (p<0.05) was observed between the various age groups in children with 2-4 years old having the highest levels and 6 year old children having the lowest Pb levels. Although this study did not detect elevated levels of Pb in children's blood in regions such as Zamfara, Nigeria and Kabwe, Zambia, a high percentage of samples exceeded 2 μg/dL. Soils, floor dusts, water and crops also reveal that Pb contamination in the study area could potentially be the major cause of blood Pb in the community exposed to mining. This study also observed a significant correlation between water Pb levels of adults and blood Pb levels, suggesting that water is the major exposure pathway. This analysis highlights the need to properly manage mining activities so that the health of communities living in the vicinity of a Pb-Zn mine is not compromised.

Cytotoxic, genotoxic, and neurotoxic effects of Mg, Pb, and Fe on pheochromocytoma (PC-12) cells

Metals such as lead (Pb), magnesium (Mg), and iron (Fe) are ubiquitous in the environment as a result of natural occurrence and anthropogenic activities. Although Mg, Fe, and others are considered essential elements, high level of exposure has been associated with severe adverse health effects including cardiovascular, hematological, nephrotoxic, hepatotoxic, and neurologic abnormalities in humans. In the present study we hypothesized that Mg, Pb, and Fe are cytotoxic, genotoxic and neurotoxic, and their toxicity is mediated through oxidative stress and alteration in protein expression. To test the hypothesis, we used the pheochromocytoma (PC-12) cell line as a neuro cell model and performed the LDH assay for cell viability, Comet assay for DNA damage, Western blot for oxidative stress, and HPLC-MS to assess the concentration levels of neurological biomarkers such as glutamate, dopamine (DA), and 3-methoxytyramine (3-MT). The results of this study clearly show that Mg, Pb, and Fe, respectively in the form of MgSO4 , Pb(NO3 )2 , FeCl2 , and FeCl3 induce cytotoxicity, oxidative stress, and genotoxicity in PC-12 cells. In addition, exposure to these metallic compounds caused significant changes in the concentration levels of glutamate, dopamine, and 3-MT in PC-12 cells. Taken together the findings suggest that MgSO4 , Pb(NO3 )2 , FeCl2 , and FeCl3 have the potential to induce substantial toxicity to PC-12 cells.