Impact of low blood lead concentrations on IQ and school performance in Chinese children

Synergistic susceptibility to environmental lead toxicity in chronic kidney disease

PURPOSE OF REVIEW

While high levels of lead exposure, as occurs accidentally or occupationally, can cause toxicity across multiple organ systems, the hazard of commonly encountered levels of lead in the environment remains unresolved. Challenges to researching the health effects of lead include its complex interplay with renal function, rendering analyses at risk of unaccounted confounding, and the likely small effect size of environmental levels of exposure. While children are known to be disproportionately susceptible to lead toxicity, resulting in appropriately more stringent regulatory surveillance for those under 5 years old, emerging evidence suggests that those with chronic kidney disease (CKD) similarly are at a greater risk. This review summarizes the role of environmental lead toxicity as a potential cause and consequence of CKD.

RECENT FINDINGS

Whether environmental lead exposure causes CKD remains debatable, with little recent research advancing the conflicting, mostly cross-sectional, analyses from years ago. However, an emerging body of evidence suggests that CKD increases the susceptibility to lead toxicity. Higher circulating lead levels and lower urinary excretion result in greater lead accumulation in CKD, with simultaneous greater risk of clinically meaningful disease. Recent studies suggest that levels of lead found commonly in the United States drinking water supply, and currently permissible by the Environmental Protection Agency, associate with hematologic toxicity in those with advanced CKD. Whether environmental lead contamination may have additional negative health impact among this at-risk population, including cardiovascular and neurocognitive disease, warrants further study.

SUMMARY

The underlying pathophysiology of kidney disease synergizes the susceptibility to environmental lead toxicity for those with CKD. Low levels of exposure, as found commonly in the United States water supply, may have adverse health impact in CKD. Further research will be needed to determine if more stringent environmental regulations are warranted to protect the health of all.

Involvement of Nrf2 Signaling in Lead-induced Toxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) is used as one of the main protective factors against various pathological processes, as it regulates cells resistant to oxidation. Several studies have extensively explored the relationship between environmental exposure to heavy metals, particularly lead (Pb), and the development of various human diseases. These metals have been reported to be able to, directly and indirectly, induce the production of reactive oxygen species (ROS) and cause oxidative stress in various organs. Since Nrf2 signaling is important in maintaining redox status, it has a dual role depending on the specific biological context. On the one hand, Nrf2 provides a protective mechanism against metal-induced toxicity; on the other hand, it can induce metalinduced carcinogenesis upon prolonged exposure and activation. Therefore, the aim of this review was to summarize the latest knowledge on the functional interrelation between toxic metals, such as Pb and Nrf2 signaling.

The impact of the 2019/2020 Australian landscape fires on infant feeding and contaminants in breast milk in women with asthma

BACKGROUND

The 2019/2020 Australian landscape fires (bushfires) resulted in prolonged extreme air pollution; little is known about the effects on breastfeeding women and their infants. This study aimed to examine the impact of prolonged landscape fires on infant feeding methods and assess the concentration of polycyclic aromatic hydrocarbons (PAHs) and elements in breast milk samples.

METHODS

From May - December 2020, women with asthma, who were feeding their infants during the fires, were recruited from an existing cohort. Data on infant feeding and maternal concern during the fires were retrospectively collected. Breast milk samples were collected from a sample of women during the fire period and compared with samples collected outside of the fire period for levels of 16 PAHs (gas chromatography coupled with mass spectrometry), and 20 elements (inductively coupled plasma-mass spectrometry).

RESULTS

One-hundred-and-two women who were feeding infants completed the survey, and 77 provided 92 breast milk samples. Two women reported concern about the impact of fire events on their infant feeding method, while four reported the events influenced their decision. PAHs were detected in 34% of samples collected during, versus no samples collected outside, the fire period (cross-sectional analysis); specifically, fluoranthene (median concentration 0.015 mg/kg) and pyrene (median concentration 0.008 mg/kg) were detected. Women whose samples contained fluoranthene and pyrene were exposed to higher levels of fire-related fine particulate matter and more fire days, versus women whose samples had no detectable fluoranthene and pyrene. Calcium, potassium, magnesium, sodium, sulphur, and copper were detected in all samples. No samples contained chromium, lead, nickel, barium, or aluminium. No statistically significant difference was observed in the concentration of elements between samples collected during the fire period versus outside the fire period.

CONCLUSIONS

Few women had concerns about the impact of fire events on infant feeding. Detection of fluoranthene and pyrene in breast milk samples was more likely during the 2019/2020 Australian fire period; however, levels detected were much lower than levels expected to be related to adverse health outcomes.

Childhood lead exposure and sex-based neurobehavioral functioning in adolescence

It is well documented that childhood lead exposure is associated with long-term decreases in intelligence quotients (IQ). Lesser known is the relationship with neurobehavioral domains, especially in adolescence. This study sought to identify cross-sectional and longitudinal associations between lead exposure and adolescent executive and visual-motor functioning and examine sex-based differences. Participants were 681 children from Jintan, China who had their blood lead levels (BLLs) assessed at age 3-5 years and 12 years old and neurobehavioral functioning assessed through the University of Pennsylvania Computerized Neurocognitive Battery (PennCNB) platform http://www.med.upenn.edu/bbl at 12 years old. Mean BLLs were 6.41 mcg/dl at age 3-5 years and 3.10 mcg/dl at 12. BLLs at 3-5 years and 12 years were used as predictors for the individual neurobehavioral domains in general linear models while controlling for father and mother occupation and education, residence location, age, and adolescent IQ. Models were run separately for males and females. In adjusted models, males BLLs at 3-5 years were associated with increased time to correctly complete tasks in multiple domains including abstraction/flexibility (β = 19.90, 95% CI( 4.26, 35.54) and spatial processing (β = 96.00, 95% CI 6.18, 185.82) at 12 years. For females in adjusted models, BLLs at 3-5 years were associated with increasing time to correctly complete tasks on the episodic memory domain task (β = 34.59, 95% CI 5.33, 63.84) at 12 years. Two adolescent cross-sectional relationships remained in the adjusted models for males only, suggesting a positive association between BLLs and increasing time for correct responses on the attentional domain task (β = 15.08, 95% CI 0.65, 29.51) and decreasing time for correct responses on the episodic memory task (β = -73.49, 95% CI -138.91, -8.06) in males at 12 years. These associations remained with and without controlling for IQ. These results suggest that lead exposure is associated with overall deficits in male and female neurobehavioral functioning, though in different domains and different timing of exposure.

Modification by genetic polymorphism of lead-induced IQ alteration: a systematic review

As well as a lead-related environmental factor, genetic factors could also corroborate important changes in intelligence quotient (IQ) through single-nucleotide polymorphisms. Thus, a systematic review was carried out to evaluate the possible influence of polymorphism on blood Pb levels and IQ points in pediatric patients (0-19 years old). Following the PRISMA guideline, the studies were systematically collected on PubMed, Scopus, and Embase databases. Six genes (transferrin (TF); glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A); glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B); dopamine receptor D2/ankyrin repeat and kinase domain containing 1 ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1); aminolevulinate dehydratase (ALAD); vitamin D receptor (VDR)) were found in six selected articles. In these genes, 11 single-nucleotide polymorphisms were searched and six different types of variations (missense variant, intron variant, synonymous variant, stop, stop gained) were observed. Due to the few studies in the literature, there is no conclusive data to point out that there is a direct relationship between polymorphisms, Pb levels, and reduction of IQ points.

Longitudinal association of early childhood lead exposure and adolescent heart rate variability: influence of parental education

Lead exposure has been shown to dysregulate physiological stress responses. However, few studies have investigated the effect of lead exposure on later heart rate variability (HRV), an indicator of a stress response, in large samples of children. Furthermore, the interaction between social environmental factors and lead exposure in childhood, which commonly co-occur, remains understudied. This study examined relationships between childhood lead exposure and early adolescent physiological stress responses at different levels of parental education. Participants were 406 children from Jintan, China. Blood lead levels (BLLs) and parental education data were collected at 3-5 years of age, and HRV outcomes assessed at 12 years via frequency domain measures (LF/HF ratio) collected during an induced stress test. Results show a significant interaction between parental education and BLLs at 3-5 years. This relationship was found to be most consistent for the interaction between BLLs and mother's years of education for both the planning (β = 0.12, p = 0.046) and speaking (β = 0.11, p = 0.043) phase of the stress task, suggesting that increasing years of mother's education may enhance the deleterious influence of lead exposure on the HRV frequency measure, LF/HF ratio. This research highlights the complexity in lead exposure induced outcomes.

Age at Menarche in Urban Girls Exposed to Lead in the Copper Basin, Poland

Lead negatively affects human growth and development. In this research, we aimed to assess the effect of elevated blood lead level on age at menarche (AM), controlling for body mass index (BMI) and estimated fatness. The sample included 490 girls aged 7−16 examined in Polkowice town (Copper Basin, Poland) in 2008. Measurements included height, weight, skinfold thicknesses and estimated percentage of body fat. AM was assessed using the status quo method. Blood samples were taken for lead level assessment. Two groups were defined based on the median blood lead level for the total sample of children (3.7 µg/dL). Logistic regression models were used to assess the association between AM and independent variables. The results indicated that menarche in the higher blood lead level group was significantly later compared to the lower blood lead level group (p < 0.01). This relationship remained only marginally significant when BMI (p < 0.10), sum of skinfolds (p < 0.09) or percentage of fat (p < 0.08) were controlled. The results revealed that a lower blood lead level (3.7 µg/dL) than the currently acceptable threshold (5 µg/dL) is related to a later AM; however, this relationship is moderated by body fatness, which may decrease its significance.

Early childhood lead exposure and adolescent heart rate variability: A longitudinal cohort study

Lead is a known neurotoxicant with many detrimental health effects, including neurocognitive deficits and cardiovascular and metabolic disorders. However, few studies have tested the association between lead exposure and the physiological stress response, which in and of itself may act as a precursor to and/or underlying mechanism of detrimental health outcomes. The purpose of this study was to examine the influence of early childhood and early adolescent low-level lead exposure on early adolescent heart rate variability, a widely-used measure of physiological stress. Participants were 408 children from Jintan, China for whom blood lead levels were measured between 3 and 5 years (early childhood) and again at 12 years (early adolescence). Heart rate variability was assessed at 12 years while participants underwent an induced stress task utilizing the ratio of low to high frequency (LF/HF) ECG measures. Mean blood lead levels in the cohort were 6.63 mcg/dl and 3.10 mcg/dl at 3-5 years and 12 years, respectively. Blood lead levels at 3-5 years of age (β 0.06, p = 0.027), but not at age 12 (β -0.05, p = 0.465), were significantly associated with LF/HF measures while controlling for multiple sociodemographic variables, potentially reflecting a dysregulated stress response with a shift towards sympathetic dominance. These findings suggest that early childhood lead exposure may have a detrimental influence on early adolescent autonomic responses to acute stress, which holds implications for cardiovascular health and overall growth and development.

Heavy metals and neurodevelopment of children in low and middle-income countries: A systematic review

BACKGROUND

The presence of harmful environmental exposures, which disproportionately affects low-and-middle income countries (LMICs), contributes to >25% of deaths and diseases worldwide and detrimentally affects child neurodevelopment. Few resources succinctly summarize the existing literature on this topic. Our objective is to systematically review and characterize the evidence regarding the relationship between heavy metals and neurodevelopment of children in LMICs.

METHODS

We conducted a medical librarian-curated search on multiple online databases to identify articles that included individuals <18 years living in a LMIC, quantitatively measured exposure to a heavy metal (either prenatal or postnatal), and used a standardized measurement of neurodevelopment (i.e. cognitive, language, motor, and behavior). Reviews, editorials, or case studies were excluded. Results were analyzed qualitatively, and quality was assessed.

RESULTS

Of the 18,043 screened articles, 298 full-text articles were reviewed, and 100 articles met inclusion criteria. The included studies represented data from 19 LMICs, only one of which was classified as a low-income country. Ninety-four percent of postnatal lead and all postnatal manganese studies showed a negative association with metal exposure and neurodevelopment, which were the strongest relationships among the metals studied. Postnatal exposure of mercury was associated with poor neurodevelopment in only half of studies. Limited data on postnatal arsenic and cadmium suggests an association with worse neurodevelopment. Findings were mixed for prenatal arsenic and lead, although some evidence supports that the neurotoxicity of lead was amplified in the presence of manganese.

CONCLUSIONS AND POTENTIAL IMPACT

We found that lead and manganese appear to consistently have a detrimental effect on the neurodevelopment of children, and more evidence is needed for mercury, arsenic, and cadmium. Better characterization of these effects can motivate and inform prioritization of much needed international policies and programs to reduce heavy metal exposures for young children within LMICs.

Lead contamination of public drinking water and academic achievements among children in Massachusetts: a panel study

Background

Public drinking water can be an important source exposure to lead, which can affect children’s cognitive development and academic performance. Few studies have looked at the impact of lead exposures from community water supplies or their impact on school achievements. We examined the association between annual community water lead levels (WLLs) and children’s academic performances at the school district level.

Methods

We matched the 90th percentile WLLs with the grade 3–8 standardized test scores from the Stanford Education Data Archive on Geographic School Districts by geographic location and year. We used multivariate linear regression and adjusted for urbanicity, race, socioeconomic characteristics, school district, grade, and year. We also explored potential effect measure modifications and lag effects.

Results

After adjusting for potential confounders, a 5 μg/L increase in 90th percentile WLLs in a GSD was associated with a 0.00684 [0.00021, 0.01348] standard deviation decrease in the average math test score in the same year. No association was found for English Language Arts.

Conclusions

We found an association between the annual fluctuation of WLLs and math test scores in Massachusetts school districts, after adjusting for confounding by urbanicity, race, socioeconomic factors, school district, grade, and year. The implications of a detectable effect of WLLs on academic performance even at the modest levels evident in MA are significant and timely. Persistent efforts should be made to further reduce lead in drinking water.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-12474-1.

Risk-Factor Based Lead Screening and Correlation with Blood Lead Levels in Pregnancy

OBJECTIVES

Lead exposure has devastating neurologic consequences for children and may begin in utero. The American College of Obstetricians and Gynecologists recommends prenatal lead screening using a risk factor-based approach rather than universal blood testing. The clinical utility of this approach has not been studied. We evaluated a risk-factor based questionnaire to detect elevated blood lead levels in pregnancy.

METHODS

We performed a secondary analysis of a cohort of parturients enrolled to evaluate the association of lead with hypertensive disorders of pregnancy. We included participants in this analysis if they had a singleton pregnancy ≥ 34 weeks' gestation with blood lead levels recorded. Participants completed a lead risk factor survey modified for pregnancy. We defined elevated blood lead as ≥ 2 μg/dL, as this was the clinically reportable level.

RESULTS

Of 102 participants enrolled in the cohort, 92 had blood lead measured as part of the study. The vast majority (78%) had 1 or more risk factor for elevated lead using the questionnaire yet none had clinical blood lead testing during routine visits. Only two participants (2.2%) had elevated blood lead levels. The questionnaire had high sensitivity but poor specificity for predicting detectable lead levels (sensitivity 100%, specificity 22%).

CONCLUSIONS FOR PRACTICE

Prenatal risk-factor based lead screening appears underutilized in practice and does not adequately discriminate between those with and without elevated blood levels. Given the complexity of the risk factor-based approach and underutilization, the benefit and cost-effectiveness of universal lead testing should be further explored.

Heavy Metal Contamination of Natural Foods Is a Serious Health Issue: A Review

Heavy metals play an important role in the homeostasis of living cells. However, these elements induce several adverse environmental effects and toxicities, and therefore seriously affect living cells and organisms. In recent years, some heavy metal pollutants have been reported to cause harmful effects on crop quality, and thus affect both food security and human health. For example, chromium, cadmium, copper, lead, and mercury were detected in natural foods. Evidence suggests that these elements are environmental contaminants in natural foods. Consequently, this review highlights the risks of heavy metal contamination of the soil and food crops, and their impact on human health. The data were retrieved from different databases such as Science Direct, PubMed, Google scholar, and the Directory of Open Access Journals. Results show that vegetable and fruit crops grown in polluted soil accumulate higher levels of heavy metals than crops grown in unpolluted soil. Moreover, heavy metals in water, air, and soil can reduce the benefits of eating fruits and vegetables. A healthy diet requires a rational consumption of foods. Physical, chemical, and biological processes have been developed to reduce heavy metal concentration and bioavailability to reduce heavy metal aggregation in the ecosystem. However, mechanisms by which these heavy metals exhibit their action on human health are not well elucidated. In addition, the positive and negative effects of heavy metals are not very well established, suggesting the need for further investigation.

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

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

Correlation between lead exposure and cognitive function in 12-year-old children: a systematic review and meta-analysis

Lead exposure as a toxic material especially in children can be recognized as a harmful factor for cognitive function system. This meta-analysis was conducted to estimate the lead exposure effect on cognitive function among 6979 children less than 12 years. The 16 studies were divided into two clusters according to "duration of exposure" and "dose" using k-means partitioning clustering algorithm. Then, subgroup analysis has been performed based on the clustered studies. According to the results of the k-means clustering, dose and duration of exposure were significant factors between all considered variables. A stronger negative significant pooled correlation was observed in higher dose and duration cluster in comparison with another cluster including lower dose and duration (r = - 0.29, P-value < 0.001 vs. r = - 0.08, P-value < 0.001). Overall, a negative significant correlation was observed between lead exposure and cognitive function test score (r = - 0.22, P-value < 0.001). This study confirms the negative effect of lead on cognitive function in children, but needed further investigations to achieve the safe dose and duration of the lead exposure.

Lead and cadmium exposure network in children in a periurban area in India: susceptibility and health risk

To investigate the complex Pb-Cd exposure network in school-going children, a thorough investigation of the probable exposure means (diet, water, and school micro-environments such as paint dust and school courtyard soil) and exposure route (ingestion, inhalation and dermal) was carried out in a periurban area spanning three districts in southern Assam, India. Multivariate statistical analysis was carried out to understand the complex data matrices, and the health risk assessments (carcinogenic and non-carcinogenic) based on US EPA Risk Assessment models were also made. We found the median values to be 0.9-4.0 mg Pb/kg and 0.21-6.2 mg Cd/kg in various food items. Groundwater also had Pb (0.13-0.48 mg/L) and Cd (0.11-0.29 mg/L). Pb levels in paint dust were within the permissible limits, but 50% of the samples had higher than permissible levels of Cd. Approximately 23% of the school courtyard soil had Pb above the global background levels, but all the samples had 4-27 times elevated levels of Cd in them. School micro-environment contributed significantly to the metal load in children due to their typical hand-to-mouth behavior and dietary intake (food and water) via ingestion was the most prominent route of exposure in children. The evaluation of the estimated chronic daily intake and the hazard quotient indicated hazardous exposure over a lifetime to both Pb and Cd, but only Cd posed a prominent cancer risk. It could be concluded that chronic insidious effects of metals would be a noteworthy toxicological threat to children when exposed early on.

Associação da distância da habitação em relação a sítios de reciclagem sobre habilidades cognitivas em escolares

Objetivos: Verificar a associação da distância da habitação em relação a sítios de reciclagem sobre habilidades cognitivas em escolares.Métodos: Estudo transversal, no qual aplicou-se a escala Wechsler Abreviada de Inteligência em 100 escolares de 6 a 14 anos. As crianças foram divididas em um grupo de estudo (expostos), cujas residências estavam situadas a menos de 100 metros de sítios de reciclagem, em um bairro da cidade de Caxias do Sul. Houve um grupo controle, cujas residências estavam a mais de 150 metros de algum sítio de reciclagem, no mesmo bairro ou adjacências.Resultados: A habitação próxima a sítios de reciclagem aumentou a chance de apresentar quociente de inteligência baixo nos escolares na análise univariada (OR 2,19; IC95% 1,21–3,95). No quociente de inteligência total, o escore obtido foi de 84 no grupo exposto e 95 no grupo controle (p≤0,01). Quando ajustadas para outras variáveis potencialmente prejudiciais, a escolaridade materna elevada mostrou-se um fator atenuador do impacto da distância (OR 0,28; IC95% 0,11–0,72). A diferença encontrada entre os escores de quociente de inteligência verbal foi de 14 pontos (p<0,01); no quociente de inteligência de execução a diferença foi de 4 pontos (p=0,04).Conclusões: A distância entre a habitação e os sítios de reciclagem de resíduos pode reduzir habilidades cognitivas em escolares, mas esse efeito parece ser atenuado pela escolaridade materna. Essa associação reforça as preocupações sobre o impacto do manejo inadequado de resíduos urbanos, podendo vir a subsidiar a criação de políticas públicas que visem diminuir exposições ambientais potencialmente danosas.

Blood lead and mercury levels are associated with low resting heart rate in community adolescent boys

While the neurotoxic effects of heavy metals at even low levels have been well-studied, few studies have examined the cardiovascular effects of heavy metals on resting heart rate and these have focused on adult populations. The present study aimed to examine the association between low-level environmental lead and mercury exposure and resting heart rate in community adolescents. As part of the China Jintan Cohort Study, 532 adolescents aged 12 years (SD = 0.6) were tested for blood levels of lead (BLL) and mercury (BML) and resting heart rate (RHR). Generalized linear models were conducted to test the relationship between BLL and BML and RHR, controlling for children's sex, age, and socioeconomic status. Analyses were clustered at the preschool level when the children were recruited to adjust for standard error. The mean (SD) BLL and BML were 3.14 (SD = 1.19) μg/dL and 1.26 (SD = 0.68) μg/L at age 12 years, respectively. After adjusting for confounders, we found a significant interaction between BML and BLL in predicting RHR in boys (B = -1.27, SE = 0.49, p < 0.01, n = 289). We created BLL and BML groups in boys based on median cut-offs. Boys in the High BLL/High BML group had significantly lower RHR (mean = 84.22 beats per minute [bpm], SD = 8.77, n = 61) than boys in the Low BLL/Low BML group (mean = 89.03 bpm, SD = 10.75, n = 69; p < 0.05). BML and BLL did not interact to predict RHR in girls (B = -0.18, SE = 0.88, p > 0.05, n = 242). Combined high BLL and BML were associated with low RHR in community adolescent boys. Low RHR is an indication of chronic under-arousal and has been implicated in psychopathology, particularly for externalizing behavior. Our findings may stimulate further communication and research in this area.

Lactobacillus fermentum CQPC08 protects rats from lead-induced oxidative damage by regulating the Keap1/Nrf2/ARE pathway

In this experiment, Lactobacillus fermentum CQPC08 (LF-CQPC08) isolated from traditionally fermented pickles was used to study its mitigation effect on lead acetate-induced oxidative stress and lead ion adsorption capacity in rats. In vitro experiments showed that the survival rate in artificial gastric juice and the growth efficiency in artificial bile salt of LF-CQPC08 was 93.6% ± 2.2% and 77.2% ± 0.8%, and the surface hydrophobicity rate was 45.5% ± 0.3%. The scavenging rates of hydroxyl radical, superoxide anion, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 47.8% ± 0.9%, 63.9% ± 1.2%, and 83.6% ± 1.5%, respectively, and the reduction power was 107.3 ± 2.8 μmol L-1. LF-CQPC08 could not only adsorb 76.9% ± 1.0% lead ions in aqueous solution but also reduce the lead content in serum, liver, kidneys, and brain tissue of Sprague-Dawley (SD) rats, as well as maintain the cell structure and tissue state of the liver and kidneys. In addition, by examining the indicators of inflammation and oxidation in the serum, liver, and kidneys of SD rats, we found that LF-CQPC08 can reduce the proinflammatory factors interleukin (IL)-1 beta (1β), IL-6, tumor necrosis factor alpha, and interferon gamma in the body, increase the level of anti-inflammatory factor IL-10, enhance the activity of antioxidant enzymes such as superoxide dismutase and catalase and glutathione levels in serum and organ tissues, and reduce the production of reactive oxygen species and accumulation of lipid peroxide malondialdehyde. LF-CQPC08 can also activate the Keap1/Nrf2/ARE signaling pathway to promote high-level expression of the downstream antioxidants heme oxygenase 1 (HO-1), NAD(P)H : quinone oxidoreductase 1 (NQO1), and γ-glutamylcysteine synthetase (γ-GCS). As food-grade lactic acid bacteria, LF-CQPC08 has great potential and research value in removing heavy metals from food and alleviating the toxicity of heavy metals in the future.

Adverse health effects of lead exposure on physical growth, erythrocyte parameters and school performances for school-aged children in eastern China

We conducted a cross-sectional study with 395 completely matched student samples enrolled from a public primary school in Nanjing of eastern China, including questionnaires, blood samples, growth indexes and school performances, all of which were used for the analysis of variance (ANOVA) and general linear model (GLM). The results showed that factors, such as gender, age, parents' education, residential passive smoking and picky eaters, had significant impacts on the blood lead levels (BPbs). As for the linear and non-linear dose-response relationship between BPbs and erythrocyte parameters, we found a positive association between BPbs and red blood cell count (RBC count) and mean corpuscular hemoglobin concentration (MCHC) but a negative association between BPbs and hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). When BPbs increased by 10 μg/L, the RBC count increased by 0.18 × 10¹²/L, while HGB and HCT decreased by 1.19 g/L and 0.41% for boys, respectively. As for girls, corresponding increases in RBC count was 0.05 × 10¹²/L, while HGB and HCT decreased by 0.82 g/L and 0.23%. Meanwhile, for both boys and girls, MCHC increased by 2.55 g/L, while MCV and MCH levels decreased by 0.41 fL and 0.12 pg each. Furthermore, a remarkable adverse effect (p < 0.05) was observed on children's school performances as a result of increased BPbs. As BPbs increased by 10 μg/L, children's scores for Chinese, Math and English decreased by 0.42 points, 0.39 points and 0.87 points, respectively. In summary, our study indicated that lead exposure can have adverse health effects on children's erythrocyte parameters, BMI, and school performances.

Blood lead levels ≤10 micrograms/deciliter and executive functioning across childhood development: A systematic review

At low levels, the effects of lead on specific neurocognitive processes, such as executive functioning, is not well understood. The aim of this systematic review is to synthesize the empirical literature examining the relationship between prenatal and postnatal low blood lead levels and executive function across childhood development. This review considers the unity and diversity model of executive functioning by assessing the domains of working memory, cognitive flexibility, inhibition, attention, and unitary executive function separately. Nineteen studies met the inclusion criteria and were synthesized in the review. The results suggest an inverse association between postnatal lead exposure and executive function processes across childhood. The inverse relationship between postnatal lead exposure and working memory and cognitive flexibility in middle childhood is most strongly represented. Additionally, a marginal inverse relationship between postnatal lead exposure and unitary executive functioning and attention in middle childhood is suggested. The evidence does not support a relationship between postnatal lead and inhibition in middle childhood. Although there is support for the inverse relationship between low level lead exposure and executive function, lack of repeated exposure and outcome measures limit firm conclusions. Furthermore, the long-term impact of lead exposure on executive function outcomes is relatively unknown given lack of studies on adolescent populations.

Positive and inverse correlation of blood lead level with erythrocyte acetylcholinesterase and intelligence quotient in children: implications for neurotoxicity

Blood lead level (BLL) is insufficiently sensitive for early detection of Lead-induced neurotoxicity (LIN). This study determined the possible role of the combination of BLL, intelligent quotient (IQ) and erythrocyte acetylcholinesterase (AChE) activity in the early detection of LIN in Children. Apparently healthy children (n=309) from eight public primary schools in Ibadan, Nigeria were recruited and classified into: children with Elevated BLL (EBLL) and children with Acceptable BLL (control) based on CDC cut-off for childhood lead exposure. Neurological indices (speech, memory, cranial nerves and cerebellar functions), IQ, BLL and erythrocyte AChE activity were assessed using standard methods, Standard Progressive Matrices, AAS and HPLC respectively. Statistical analysis involved Student’s t-test, Pearson’s correlation and multivariate regression. p<0.05 was considered significant. There were 169 (54.7%) children with EBLL while there were 140 (45.3%) control children. Both groups exhibited normal speech, memory, cranial nerves and cerebellar functions. However, IQ was lower in EBLL children (85.9±11.6) compared with control (91.5±14.0) while BLL and AChE activity were higher in EBLL children (0.4±0.1 μmol/l; 117.5±25.5 μkat/l) compared with control (0.2±0.0 μmol/l; 59.4±10.2 μkat/l). BLL showed inverse correlation with IQ (r=–0.134, p=0.019) but positive correlation with AChE (r=0.978, p≤0.001). 16.2% of the observed variation in BLL could be accounted for by AChE using the equation; [BLL=–0.007+0.003 AChE] p<0.05. Elevated blood lead level is prevalent among the school children and appears to have adverse effect on their IQ. Erythrocyte AChE could be a promising marker for early recognition of significant environmental lead exposure and lead-induced neurotoxicity in children.

Effects of combined administration of calcium, iron, zinc, chrysanthemum flavonoids, and DMSA on the treatment of lead intoxication in mice

The effect of combined administration of calcium (Ca), iron (Fe), zinc (Zn), chrysanthemum flavonoids, and meso-2,3-dimercaptosuccinic acid (DMSA) on the treatment of lead (Pb) intoxication in mice was studied. One hundred ninety female mice (SPF level, aged 18-22 days) were randomly divided into two groups as experimental animals. Mice in group I (10 mice) served as normal control animals, and were administered deionized water containing 12.5 μL/L acetate acid for 6 weeks, whereas mice in group II (180 mice) were exposed to 0.1% (wt/vol) of lead acetate in deionized water for 6 weeks and served as experimental animals. After 6 weeks of successful modeling, 180 mice from group II (lead-exposed) were divided into 18 groups of 10 mice each, 16 of which were treated by the combined administration of Ca, Fe, Zn, chrysanthemum flavonoids, and DMSA by L16 (215 ) orthogonal design. The remaining two groups were given treatment with low and high doses of DMSA, respectively. After three weeks of intervention (ig), the optimal treatment group was identified according to its blood lead level, as well as some antioxidant indices in the blood, liver, and hippocampus. The results indicated that the combined administration of Fe, Zn, chrysanthemum flavonoids, and DMSA with low dosage had the most significant effect on increasing the activities of blood delta-aminolevulinic acid dehydratase and superoxide dismutase (SOD), hepatic SOD and hippocampus nitric oxide synthase while decreasing the blood lead level, the content of hepatic malondialdehyde and hippocampus nitric oxide; this was considered the optimal treatment group. There was no difference in the level of blood hemoglobin between the optimal treatment group and the model control group (the first group of the orthogonal experiment). The activities of blood glutathione (GSH), hepatic GSH and glutathione peroxidase of the optimal treatment group were the same as other groups', and the recovery of the related indexes in the optimal effect group closely resembled the high dosage DMSA group. It can be concluded that the coadministration of Fe, Zn, and chrysanthemum flavonoids along with a low-dose DMSA effectively reduces Pb poisoning and lead-induced oxidative damage in lead-exposed mice; the result may provide a theoretical reference for the treatment of Pb poisoning.

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.

Improving and Expanding Estimates of the Global Burden of Disease Due to Environmental Health Risk Factors

BACKGROUND

The Global Burden of Disease (GBD) study, coordinated by the Institute for Health Metrics and Evaluation (IHME), produces influential, data-driven estimates of the burden of disease and premature death due to major risk factors. Expanded quantification of disease due to environmental health (EH) risk factors, including climate change, will enhance accuracy of GBD estimates, which will contribute to developing cost-effective policies that promote prevention and achieving Sustainable Development Goals.

OBJECTIVES

We review key aspects of the GBD for the EH community and introduce the Global Burden of Disease-Pollution and Health Initiative (GBD-PHI), which aims to work with IHME and the GBD study to improve estimates of disease burden attributable to EH risk factors and to develop an innovative approach to estimating climate-related disease burden-both current and projected.

METHODS

We discuss strategies for improving GBD quantification of specific EH risk factors, including air pollution, lead, and climate change. We highlight key methodological challenges, including new EH risk factors, notably evidence rating and global exposure assessment.

DISCUSSION

A number of issues present challenges to the scope and accuracy of current GBD estimates for EH risk factors. For air pollution, minimal data exist on the exposure-risk relationships associated with high levels of pollution; epidemiological studies in high pollution regions should be a research priority. For lead, the GBD's current methods do not fully account for lead's impact on neurodevelopment; innovative methods to account for subclinical effects are needed. Decisions on inclusion of additional EH risk-outcome pairs need to be guided by findings of systematic reviews, the size of exposed populations, feasibility of global exposure estimates, and predicted trends in exposures and diseases. Neurotoxicants, endocrine-disrupting chemicals, and climate-related factors should be high priorities for incorporation into upcoming iterations of the GBD study. Enhancing the scope and methods will improve the GBD's estimates and better guide prevention policy. https://doi.org/10.1289/EHP5496.

Iron-related dietary pattern increases the risk of poor cognition

INTRODUCTION

High iron intake has been shown to be associated with poor cognition. We aimed to examine the association between iron-related dietary pattern (IDP) and cognitive function in Chinese adults.

METHOD

Longitudinal study data from the China Health and Nutrition Survey (CHNS) during 1991-2006 were used (N = 4852, ≥55 years old). Dietary intake was obtained from a 3-day food record during home visits. Reduced rank regression was used to construct IDP with iron intake as a response variable. Cognitive function was assessed in 1997, 2000, 2004 and 2006. Multivariable mixed linear regression and logistic regression were used in the analyses.

RESULTS

IDP was characterised by high intake of fresh vegetable, wheat, legume, beverage, offal, rice and whole grain. High IDP intake was associated with poor cognition. In fully adjusted models, across the quartiles of IDP, the odds ratio (95% CI) for poor cognitive function were: 1.00, 1.06 (0.86-1.30), 1.24 (0.99-1.54), and 1.50 (1.17-1.93), respectively. There was a borderline significant interaction between IDP and meat intake (p interaction 0.085). The association between high IDP and poor cognition was only observed among those with no or low intake of meat. With the adjustment of carbohydrate or iron intake, the IDP and cognition association became non-significant. IDP was positively associated with lead intake. The association between IDP and poor cognition was partly mediated by lead intake.

CONCLUSIONS

Iron-related dietary pattern is associated with poor cognition in Chinese adults, partly due to high intake of carbohydrate, iron and lead.

Childhood lead poisoning from domestic products in China: A case study with implications for practice, education, and policy

OBJECTIVE

This study aimed to report three representative childhood lead poisoning cases in China from domestic products exposure and to highlight their critical implications for practice, education, and policy in prevention and treatment of childhood lead poisoning by health care providers, especially public health nurses.

DESIGN AND SAMPLE

Three representative childhood lead poisoning cases occurring in 2017 were collected and analyzed.

RESULTS

The lead exposure sources of three cases were evaluated by experts in the field and determined to be tin pots, home factories for tinfoil, and contamination of folk medicine, respectively. These cases demonstrated that the lack of lead exposure risk assessment, insufficient knowledge of potential lead exposure sources, underdeveloped policy, and regulations were areas for improvement.

CONCLUSIONS

The best strategies for preventing lead poisoning include an appropriate risk assessment of lead exposure, implementation of comprehensive parental health education, conduction of further research by public health providers, and the application of policy strategies by the government. It was determined that public health nurses are at the frontline of prevention of lead poisoning in children.

Neurocognitive impact of metal exposure and social stressors among schoolchildren in Taranto, Italy

BACKGROUND

Metal exposure is a public health hazard due to neurocognitive effects starting in early life. Poor socio-economic status, adverse home and family environment can enhance the neurodevelopmental toxicity due to chemical exposure. Disadvantaged socio-economic conditions are generally higher in environmentally impacted areas although the combined effect of these two factors has not been sufficiently studied.

METHODS

The effect of co-exposure to neurotoxic metals including arsenic, cadmium, manganese, mercury, lead, selenium, and to socio-economic stressors was assessed in a group of 299 children aged 6-12 years, residing at incremental distance from industrial emissions in Taranto, Italy. Exposure was assessed with biological monitoring and the distance between the home address and the exposure point source. Children's cognitive functions were examined using the Wechsler Intelligence Scale for Children (WISC) and the Cambridge Neuropsychological Test Automated Battery (CANTAB). Linear mixed models were chosen to assess the association between metal exposure, socio-economic status and neurocognitive outcomes.

RESULTS

Urinary arsenic, cadmium and hair manganese resulted inversely related to the distance from the industrial emission source (β - 0.04; 95% CI -0.06, - 0.01; β - 0.02; 95% CI -0.05, - 0.001; β - 0.02 95% CI -0.05, - 0.003) while the WISC intellectual quotient and its sub-scores (except processing speed index) showed a positive association with distance. Blood lead and urinary cadmium were negatively associated with the IQ total score and all sub-scores, although not reaching the significance level. Hair manganese and blood lead was positively associated with the CANTAB between errors of spatial working memory (β 2.2; 95% CI 0.3, 3.9) and the reaction time of stop signal task (β 0.05; 95% CI 0.02, 0.1) respectively. All the other CANTAB neurocognitive tests did not show to be significantly influenced by metal exposure. The highest socio-economic status showed about five points intellectual quotient more than the lowest level on average (β 4.8; 95% CI 0.3, 9.6); the interaction term between blood lead and the socio-economic status showed a significant negative impact of lead on working memory at the lowest socio-economic status level (β - 4.0; 95% CI -6.9, - 1.1).

CONCLUSIONS

Metal exposure and the distance from industrial emission was associated with negative cognitive impacts in these children. Lead exposure had neurocognitive effect even at very low levels of blood lead concentration when socio-economic status is low, and this should further address the importance and prioritize preventive and regulatory interventions.

A study protocol to determine the association between lifetime lead exposure and violent criminal behaviour in young males in conflict with the law

Background

Low-level lead exposure has harmful and persistent effects on behaviour. Recent studies have linked environmental lead exposure and the development of aggressive, violent and criminal behaviour. This protocol is designed to study an association between lifetime (bone) lead levels and violent criminal behaviour among young males in conflict with the law in Gauteng youth development centres.

Methods

This paper describes a study to determine a link between lifetime lead exposure and violent criminal behaviour. Lifetime lead exposure will be measured using bone lead measurement, while blood lead levels will be observed for current exposure. Thereafter, criminal records of participants will be reviewed whereas violent behaviour and risk factors will be observed using a questionnaire. The study focused on young males in conflict with the law in three centres within Gauteng Provence, South Africa. After stratifying the centres, we randomly selected participants. The researcher shall adhere to ethical requirements throughout the study. Data will be analysed for descriptive and inferential analysis using Statistical Package for Social Science (SPSS).

Discussion

The study will provide a strong foundation for an improved understanding of the relationship between environmental contamination from lead exposure and aggression/violent criminal behaviour. Beyond the health sector, the study findings may be able to inform new approaches to crime prevention through environmental action with an emphasis on the role of non-health sectors.

Childhood lead poisoning in Gaza Strip, the Palestinian Authority

PURPOSE

To assess lead poisoning among a pediatric population in Gaza Strip, the Palestinian Authority.

METHODS

A total of 1705 questionnaires and blood samples were collected from children aged 2-6 years, by the finger stick capillary procedure, for the assessment of blood lead level (BLL), using the LeadCare kits. The samples were collected from children living close to lead processing units (hotspots) and far 100-500 m away (general population). Management of elevated BLL was achieved by gavage of chelating agent d-penicillamine at a dose of 30 mg kg^-1 body weight/day for two weeks for children having BLL above 20 μg/dl. Data were statistically analyzed using SPSS computer program version 22.

RESULTS

Distribution of children in Gaza Strip by sampling process illustrated those 326 children (19.1%) living in lead processing units (hot spots) and 1379 children (80.9%) from location far away 100-500 m from host spot (general population). The mean BLL was 10.4 μg/dl. A total of 440 children (25.8%) were found to be having BLL ≥ 10 μg/dl while 1265 children (74.2%) have BLL < 10 μg/dl. BLL < 10 μg/dl was taken as a cut point due to CDC standards. The prevalence of BLL in hotspot areas in children who were exposed to lead and have BLL ≥ 10 μg/dl was 95.7% while in general population it was 9.3%. The difference between the study population was statistically significant (p < 0.01). Statistical significant differences between the study populations were found among several independent variables of risk factors such as household location and exposure sources, and occupational exposure. Gavage of d-penicillamine significantly reduced BLL to the acceptable level (BLL < 10 μg/dl).

CONCLUSIONS

Childhood lead poisoning accounts for a substantial burden in Gaza Strip. Hotspots of lead-related industries are the high risk areas that contributing to high BLLs in children. d-Penicillamine was effective in the treatment of lead poisoning among children. Health education and treatment campaigns should be designed to minimize or prevent childhood lead poisoning in Gaza Strip.

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.

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.

Heavy Metals' Effect on Susceptibility to Attention-Deficit/Hyperactivity Disorder: Implication of Lead, Cadmium, and Antimony

Background: Heavy metals are known to be harmful for neurodevelopment and they may correlate to attention deficit/hyperactivity disorder (ADHD). In this study, we aim to explore the relationships between multiple heavy metals (manganese, lead, cadmium, mercury, antimony, and bismuth), neurocognitive function, and ADHD symptoms. Methods: We recruited 29 patients with ADHD inattentive type (ADHD-I), 47 patients with ADHD hyperactivity/impulsivity type (ADHD-H/I), and 46 healthy control children. Urine samples were obtained to measure the levels of the aforementioned heavy metals in each child. Participants’ cognitive function and clinical symptoms were assessed, respectively. Results: We found ADHD-H/I patients demonstrated the highest antimony levels (p = 0.028), and ADHD-I patients demonstrated the highest cadmium levels (p = 0.034). Antimony levels were positively correlated with the severity of ADHD symptoms that were rated by teachers, and cadmium levels were negatively correlated with the Full Scale Intelligence Quotient. Lead levels were negatively correlated with most indices of the Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV), but positively correlated with inattention and hyperactivity/impulsivity symptoms (p < 0.05). Conclusion: Lead, cadmium and antimony were associated with susceptibility to ADHD and symptom severity in school-age children. Eliminating exposure to heavy metals may help to prevent neurodevelopmental disorders in children.

Effects of lead, cadmium, arsenic, and mercury co-exposure on children's intelligence quotient in an industrialized area of southern China

Exposure to metal(loid)s can lead to adverse effects on nervous system in children. However, little is known about the possible interaction effects of simultaneous exposure to multiple metal(loid)s on children's intelligence. In addition, relationship between blood lead concentrations (<100 μg/L) and the intelligence of children over 5 years needs further epidemiological evidence. We recruited 530 children aged 9-11 years, including 266 living in a town near an industrialized area and 264 from another town in the same city in South China as a reference. The levels of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in blood (BPb, BCd, BAs, BHg) and urine (UPb, UCd, UAs, UHg) were assessed, as well as children's intelligence quotient (IQ). A significant decrease in IQ scores was identified in children from the industrialized town (p < .05), who had statistically higher geometric mean concentrations of BPb, BCd, UPb, UCd and UHg (65.89, 1.93, 4.04, 1.43 and 0.37 μg/L, respectively) compared with children from the reference town (37.21, 1.07, 2.14, 1.02 and 0.30 μg/L, respectively, p < .05). After adjusting confounders, only BPb had a significant negative association with IQ (B = -0.10, 95% confidence interval: -0.15 to -0.05, p < .001), which indicated that IQ decreased 0.10 points when BPb increased 1 μg/L. Significant negative interactions between BAs and BHg, positive interaction between UPb and UCd on IQ were observed (p < .10), and BPb <100 μg/L still negatively affected IQ (p < .05). Our findings suggest that although only BPb causes a decline in children's IQ when simultaneously exposed to these four metal(loid)s at relatively low levels, interactions between metal(loid)s on children's IQ should be paid special attention, and the reference standard in China of 100 μg/L BPb for children above 5 years old should be revised.

The Relationship of Children's Intelligence Quotient and Blood Lead and Zinc Levels: a Meta-analysis and System Review

The purpose of this study was to analyze the existing studies and to investigate the relationship between children's full-scale intelligence quotient (FIQ), verbal IQ (VIQ), and performance IQ (PIQ) and their blood lead (Pb) and zinc (Zn) levels. All documents in Chinese and English were collected from the PubMed, Web of Science, and Chinese National Knowledge Infrastructure (CNKI) databases from inception date to December 30, 2016. RevMan software (version 5.2) was used for the meta-analysis and Stata software (version 12.0) for the meta-regression and sensitivity analyses. A total of 32 eligible literatures was included in the study. Seven prevalence studies showed that the blood Pb level was negatively correlated with children's IQ. The results of the meta-analysis from 22 case-control studies indicate a significant difference between FIQ and PIQ with blood Pb levels, detailed as the FIQ score with a weighted mean difference (WMD) = -6.60 (95% CI: -9.01, -4.20), P < 0.001; PIQ WMD = -8.85 (95% CI: -12.651, -5.05), P < 0.001; but VIQ WMD = -3.32 (95% CI: -6.98, 0.33), P > 0.05. Three studies on the blood Zn concentrations were with a FIQ WMD = 7.88 (95% CI: -0.07, 15.83), VIQ WMD = 7.73 (95% CI: -7.40, 22.86), and PIQ WMD = 6.69 (95% CI: -7.13, 20.51), all P > 0.05. The results indicate that Pb is harmful to children's intelligence development, especially in PIQ. Zn is beneficial to intelligence, although more studies are needed.

Blood Lead Levels in Children of Southwest Iran, Aged 2-6 Years and Associated Factors

INTRODUCTION

Lead is one of the toxic metals that can cause several complications in children.

AIM

This study was conducted to determine Blood Lead Levels (BLLs) in healthy children and its association with individual and environmental factors.

MATERIALS AND METHODS

This descriptive-analytical study was conducted on 262 healthy children aged 2-6 years in Shahrekord, Southwest Iran in 2013. After taking serum samples from the children, the checklists of effective environmental factors on lead toxicity were completed after interviewing the parents. BLLs were determined by ICP-MS. Data were analysed by descriptive and analytical statistics (chi-square and ANOVA) in SPSS 16.

RESULTS

BLLs ranged 0.4-52.8 (mean: 6.9±7.9) ng/ml. BLL was significantly associated with father's education level, house colour damage, canned food use and soil eating (p<0.05), but not with age, gender, economic status, proximity to factory and kohl use (p>0.05).

CONCLUSION

BLL can cause serious health risks for children in Shahrekord and is associated with certain risk factors. It is necessary to screen for these risk factors.

High blood levels of lead in children aged 6-36 months in Kathmandu Valley, Nepal: A cross-sectional study of associated factors

Young children are at greatest risk of exposure to lead and its effects. Although lead is one of the most widely used elements with known health hazard, there is little data on the blood lead level (BLL) of children in the Kathmandu Valley. Thus, this study aimed to assess factors associated with high BLL in children who were 6–36 months of age and resided in the Kathmandu Valley. In this hospital-based cross-sectional study 6–36 month-old children visiting the Paediatrics Outpatient Department of Tribhuvan University Teaching Hospital, Patan Hospital, and Siddhi Memorial Hospital were enrolled. All three hospitals are located in different areas inside the Kathmandu Valley. Written informed consent was obtained from the parents, and exposure data were collected using a structured questionnaire. Portable Anodic Stripping Voltammetry (ASV) was used to determine BLLs in children. Data were analyzed using SPSS version 16. Of 312 children enrolled in the study, 64.4% had BLLs ≥5μg/dl. A significant association was found between BLL and exposure to enamel paints in the household in the form of painting materials used in different parts of the house like walls, windows and doors (p = 0.001). Furthermore, multivariate analyses showed that BLLs were 4.5 times higher in children playing with dirt and dust (p = 0.006) and that children belonging to the community of lower caste/ethnicity groups had significantly higher BLLs compared to those from the upper caste groups (p = 0.02). Our study demonstrated that children living in households that have used enamel paints, children belonging to lower caste/ethnic groups, and children frequently playing with dirt and dust had significantly higher BLLs. The results of this study highlight the importance of policy decisions to limit environmental lead contamination, and to roll out awareness building measures designed to limit lead exposure and break the poverty cycle associated with chronic lead poisoning.

Clinical and laboratory evaluation of new immigrant and refugee children arriving in Greece

Background

Migrant children are a population at risk for various health problems. Despite the increased inflow of migrants in Greece, data regarding their health assessment are lacking. This study aims to describe the clinical and certain laboratory characteristics and identify possible associations in a group of new immigrant (I) and refugee (R) children, arriving in Athens, Greece.

Methods

A prospective, cross- sectional study was performed in a migrant outpatient clinic of a tertiary Children’s hospital. All immigrant and refugee children, examined to obtain a health certificate, within 3 months of their arrival in the country, were enrolled. Clinical and laboratory information was collected in a pre- designed form. We applied multiple logistic regression models to investigate the association between the child’s status (immigrant vs refugee) and health indicators controlling for possible confounding effects, mainly of age and area of origin.

Results

From 2010 to 2013, a total of 300 children (I/R:138/162) with a mean age of 7.08 (range 1–14) years were included. Overall, 79.3% presented unknown vaccination status, 21.3% dental and 7.3% additional clinical problems. Latent tuberculosis was identified in 2.7%, while anemia, low serum ferritin and eosinophilia were found in 13.7%, 17.3%, and 22.7% of subjects, respectively. 57.7% had protective antibodies to hepatitis B surface antigen (anti-HBs ≥ 10 IU/L) and 30.6% elevated blood lead levels (EBLLs). Immigrants had less likely unknown immunization (OR = 0.25, p < 0.001), but had increased odds of low ferritin (OR = 1.97, p = 0.043), EBLLs (OR = 2.97, p = 0.001) and protective anti-HBs (OR = 1.79, p = 0.03). Age was inversely associated with anemia (OR = 0.0.89, p = 0.017), low ferritin (OR = 0.91, p = 0.027), EBLLs (OR = 0.86, p = 0.001) or positive anti-HBs (OR = 0.92, p = 0.025). Children from Europe or Africa presented decreased probability of EBLLs (OR = 0.31, p = 0.001, and OR = 0.15, p = 0.005, respectively) compared to those from Asia.

Conclusions

New immigrant and refugee children presented distinct clinical problems and certain laboratory abnormalities. Some of these health issues differed according to their migration status, age and geographic area of origin. These findings provide evidence that may assist the optimal approach of this vulnerable population.

Neurocognitive Function Is Associated With Serum Iron Status in Early Adolescents

OBJECTIVE

The association between iron and neurocognition remains underexplored in adolescents, and the neurocognitive effects of low and high iron levels have yet to be established. The aim of this study was to investigate the relationships of low and high iron levels with neurocognitive domains in early adolescents.

METHOD

The sample comprised 428 adolescents (12.0 ± 0.4 years) from Jintan, China. Serum iron concentrations were analyzed from venous blood samples and classified into low, normal, and high levels according to the clinical reference range 75-175 μg/dl. Neurocognition was measured by the Penn Computerized Neurocognitive Battery and Wechsler Intelligence Scale. Generalized linear regression was used to analyze relationships.

RESULTS

Prevalence rates of iron deficiency, normal iron, and high iron were 13.8%, 76.4%, and 9.8%, respectively. Compared with normal levels, iron deficiency was associated with slower performance in tasks that measured abstraction and mental flexibility (β = 107.5, p = .03) and spatial processing ability (β = 917.2, p = .04). High serum iron was associated with less accuracy in the spatial processing ability task (β = -2.2, p = .03) and a longer reaction time in the task assessing abstraction and mental flexibility (β = 702.8, p = .046) compared to normal levels.

CONCLUSION

Both iron deficiency and high iron levels contribute to reduced neurocognitive performance in a domain-specific manner in early adolescents. The dual burden of iron under- and overnutrition should be incorporated into future interventions for improving brain development and cognitive function in adolescents, especially in a Chinese context.

Lead exposure and early child neurodevelopment among children 12-24 months in Kinshasa, the Democratic Republic of Congo

Childhood lead exposure remains a problem in developing countries, and little is known about its effects on early child neurodevelopment and temperament in the Democratic Republic of Congo (DRC). We, therefore, conducted this study to determine the association between lead exposure and the neurodevelopment and behaviour of children aged 12-24 months in Kinshasa, DRC. A cross-sectional study was conducted between February and June 2012, and parents of 104 children were invited to participate. Blood lead levels (BLLs) of each child were tested using the flame atomic spectrophotometry method. All children were subject to a clinical examination and assessed with two selected early child neurodevelopmental tools, the Gensini-Gavito and the baby characteristics questionnaire, to measure their neurodevelopment and temperament. Detectable BLLs ranged from 1 to 30 μg/dl with a geometric mean of 6.9 (SD 4.8) μg/dl. BLLs at 5-9 and ≥10 μg/dl were significantly associated with the child temperament (p <0.05). Perinatal and maternal factors did not seem to affect early child neurodevelopment and temperament. Children exposed to lead were reported with more temperament difficulties at even blood lead levels <10 μg/dl, suggesting the need for preventive and intervention measures to reduce lead exposure among children in Kinshasa, DRC.

Early Blood Lead Levels and Sleep Disturbance in Preadolescence

STUDY OBJECTIVES

Little is known about the effect of lead exposure on children's sleep. This study examined the association between blood lead levels (BLL) and sleep problems in a longitudinal study of children.

SETTING

Four community-based elementary schools in Jintan City, China.

PARTICIPANTS

1,419 Chinese children.

MEASUREMENT AND RESULTS

BLL were measured when children were aged 3-5 y, and sleep was assessed at ages 9-13 y. Sleep was assessed by both parents' report, using the Children's Sleep Habits Questionnaire (CSHQ), and children's report, using an adolescent sleep questionnaire. A total of 665 children with complete data on BLL and sleep at both ages were included in the current study. Mean age of the sample at BLL assessment was 4.74 y (standard deviation [SD] = 0.89) and at sleep assessment was 11.05 y (SD = 0.88). Mean BLL was 6.26 μg/dL (SD = 2.54). There were significant positive correlations between BLL and 3 CSHQ subscales: Sleep onset delay (r = 0.113, P < 0.01), sleep duration (r = 0.139, P < 0.001), and night waking (r = 0.089, P < 0.05). Excessive daytime sleepiness (EDS) (26.1% versus 9.0%, P < 0.001) and use of sleeping pills (6.5% versus 1.8%, P = 0.03) were more prevalent in children BLL ≥ 10.0 μg/dL than in those children BLL < 10.0 μg/dL. After adjusting for demographics, BLL ≥ 10.0 μg/dL was significantly associated with increased risk for insomnia symptoms (odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.03-3.95) and EDS (OR = 2.90, 95% CI = 1.27-6.61).

CONCLUSION

The findings indicate that elevated blood lead levels in early childhood are associated with increased risk for sleep problems and excessive daytime sleepiness in later childhood.

Relationship of lead and essential elements in whole blood from school-age children in Nanning, China

OBJECTIVES

The aim of this study was to investigate blood lead level and its relationship to essential elements (zinc, copper, iron, calcium and magnesium) in school-age children from Nanning, China.

METHODS

A total of 2457 children aged from 6 to 14 years were enrolled in Nanning, China. The levels of lead (Pb), zinc (Zn), copper (Cu), iron (Fe), calcium (Ca) and magnesium (Mg) were determined by an atomic absorption spectrometer.

RESULTS

The mean blood lead level (BLL) was 57.21±35.00μg/L. 188 (7.65%) asymptomatic children had toxic lead level higher than 100μg/L. The school-age boys had similar lead level among different age groups, while the elder girls had less BLL. The blood Zn and Fe were found to be increased in the boys with elevated BLL, but similar trends were not observed in the girls. Positive correlations between Pb and Fe or Mg (r=0.112, 0.062, respectively, p<0.01) and a negative correlation between Pb and Ca (r=-0.047, p<0.05) were further established in the studied children.

CONCLUSIONS

Lead exposure in school-age children was still prevalent in Nanning. The boys and girls differed in blood levels of lead and other metallic elements. Lead exposure may induce metabolic disorder of other metallic elements in body.

Cohort Profile Update: The China Jintan Child Cohort Study

The China Jintan Child Cohort study began in 2004 with 1656 pre-school participants and a research focus on studying the impact of environmental exposures, such as lead, on children's neurobehavioural outcomes. This population cohort now includes around 1000 of the original participants, who have been assessed three times over a period of 10 years. Since the original IJE cohort profile publication in 2010, participants have experienced a critical developmental transition from pre-school to school age and then adolescence. The study has also witnessed an increase in breadth and depth of data collection from the original aim of risk assessment. This cohort has added new directions to investigate the mechanisms and protective factors for the relationship between early health factors and child physical and mental health outcomes, with an emphasis on neurobehavioural consequences. The study now encompasses 11 domains, composed of repeated measures of the original variables and new domains of biomarkers, sleep, psychophysiology, neurocognition, personality, peer relationship, mindfulness and family dynamics. Depth of evaluation has increased from parent/teacher report to self/peer report and intergenerational family report. Consequently, the cohort has additional directions to include: (i) classmates of the original cohort participants for peer relationship assessment; and (ii) parental and grandparental measures to assess personality and dynamics within families. We welcome interest in our study and ask investigators to contact the corresponding author for additional information on data acquisition.

Mediation analysis in nursing research: a methodological review

Mediation statistical models help clarify the relationship between independent predictor variables and dependent outcomes of interest by assessing the impact of third variables. This type of statistical analysis is applicable for many clinical nursing research questions, yet its use within nursing remains low. Indeed, mediational analyses may help nurse researchers develop more effective and accurate prevention and treatment programs as well as help bridge the gap between scientific knowledge and clinical practice. In addition, this statistical approach allows nurse researchers to ask - and answer - more meaningful and nuanced questions that extend beyond merely determining whether an outcome occurs. Therefore, the goal of this paper is to provide a brief tutorial on the use of mediational analyses in clinical nursing research by briefly introducing the technique and, through selected empirical examples from the nursing literature, demonstrating its applicability in advancing nursing science.

Inverse association between intelligence quotient and urinary retinol binding protein in Chinese school-age children with low blood lead levels: results from a cross-sectional investigation

OBJECTIVES

Examine the relationship between blood lead concentration and children's intelligence quotient (IQ) in Chinese children 8-12 years old.

PARTICIPANTS AND METHODS

This is a cross-sectional study, and participants included 446 children from three primary schools in Jiangsu, China. We collected environmental and genetic information from questionnaires. Blood lead (Pb), manganese (Mn), cadmium (Cd) and selenium (Se) concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). IQ was assessed using the Combined Raven's Test and then converted to a standard IQ score according to Chinese children's norm. Morning urine samples were collected to measure retinol binding protein (RBP).

RESULTS

The average blood lead concentration was 33.13 μg L(-1) (geometric mean), and the blood lead concentration (BoxCox transform) was inversely and significantly associated with IQ (r=-0.11, p=0.02). The geometric mean of blood Mn, Cd and Se was 7.02 μg L(-1), 0.18 μg L(-1) and 94.77 μg L(-1), respectively. Blood Mn, Cd and Se showed no association with IQ, but all of them associated with urinary RBP. Urinary RBP was identified as a new factor associated with IQ (β=-6.49, p=0.011).

CONCLUSIONS

Urinary RBP was recognized as a new indicated factor associated with children's IQ. Mn, Cd and Se exposure might affect urinary RBP concentration and further IQ. Findings also support that blood lead concentrations in 8-12 years old children, even <44 μg L(-1), have a negative association with IQ.

Blood lead levels in children aged 0-6 years old in Hunan Province, China from 2009-2013

Objectives

The aim of this study is to describe blood lead levels (BLLs) and the prevalence of elevated blood lead levels (EBLLs) in children aged 0–6 years old and to analyze the BLL trend in children from 2009 to 2013 in China.

Methods

A total of 124,376 children aged 0–6 years old were recruited for this study from January 1^st 2009 to December 31^st 2013. Their blood lead levels were analyzed using atomic absorption spectrometry.

Results

The median BLL was 64.3 μg/L (IQR: 49.6–81.0), and the range was 4.3–799.0 μg/L. Blood lead levels were significantly higher in boys (66.0 μg/L) than in girls (61.9 μg/L) (P<0.001). The overall prevalence of BLLs≥100 μg/L was 10.54% in children aged 0–6 years in Hunan Province. Between 2009 and 2013, the prevalence of EBLLs (≥100 μg/L) decreased from 18.31% to 4.26% in children aged 0–6 years and increased with age. The prevalence of EBLLs has dramatically decreased in two stages (2009–2010 and 2012–2013), with a slight fluctuation in 2010 and 2011.

Conclusions

Both BLLs and the prevalence of EBLLs in children aged 0–6 years old declined substantially from 2009 to 2013 in Hunan Province; however, both remain at unacceptably high levels compared to developed countries. Comprehensive strategies are required to further reduce blood lead levels in children.

Screening for childhood lead poisoning in the industrial region of Fez, Morocco

The study objectives were to estimate lead poisoning prevalence among children living next to an industrial area, to compare it to that in a control population, and to establish clinical and biological follow-up of the poisoned children. This is a descriptive cross-sectional study including 150 children (exposed and unexposed) performed between January 2012 and April 2013. It was meant to determine blood lead levels (BLLs) in children considered to be an exposed population (EP N 90), living in the industrial area Ain Nokb Fez compared with BLLs of children of other areas belonging to the same city supposed to be unexposed [UP (N = 60)]. A sociodemographic questionnaire was obtained, and a blood lead analysis was performed. Clinical and biological follow-up has been performed of poisoned children. The sample consisted of 90 EP children with an average age of 6.82 ± 3.32 years and male-to-female sex ratio (SR) of 1.5 and 60 UP children with an average age of 6.45 ± 3.29 years and an SR of 1.2. Among the 150 children recruited, the average of BLLs was 58.21 ± 36 µg/L (18-202.3 μg/L). The average of BLLs in EP children (71 ± 40 µg/L) was statistically greater (p < 0.0001) than that registered in UP children (38 ± 13 µg/L). All poisoned children belonged to the EP group at a prevalence of 21.1 %. The clinical and biological examinations of poisoned children showed a few perturbations such as anemia, hypocalcaemia, and deficiencies in magnesium and iron. No renal disease or objective neurological disorders were observed. In the follow-up of the children with BLL ≥100 µg/L (19 cases). BLL monitoring showed a significant decrease in average of blood concentration ranging from 136.75 ± 32.59 to 104.58 ± 32.73 µg/L (p < 0.0001) and in lead poisoning prevalence (p < 0.001), which decreased to 7.8 % from 21.1. Our study showed a high prevalence of lead poisoning (21.1 %) in EP children. The relocation of the industrial site associated with corrective and preventive measures has contributed to a decrease of exposure and lead poisoning prevalence in the aforementioned population.

Early-life lead exposure recapitulates the selective loss of parvalbumin-positive GABAergic interneurons and subcortical dopamine system hyperactivity present in schizophrenia

Environmental factors have been associated with psychiatric disorders and recent epidemiological studies suggest an association between prenatal lead (Pb(2+)) exposure and schizophrenia (SZ). Pb(2+) is a potent antagonist of the N-methyl-D-aspartate receptor (NMDAR) and converging evidence indicates that NMDAR hypofunction has a key role in the pathophysiology of SZ. The glutamatergic hypothesis of SZ posits that NMDAR hypofunction results in the loss of parvalbumin (PV)-positive GABAergic interneurons (PVGI) in the brain. Loss of PVGI inhibitory control to pyramidal cells alters the excitatory drive to midbrain dopamine neurons increasing subcortical dopaminergic activity. We hypothesized that if Pb(2+) exposure in early life is an environmental risk factor for SZ, it should recapitulate the loss of PVGI and reproduce subcortical dopaminergic hyperactivity. We report that on postnatal day 50 (PN50), adolescence rats chronically exposed to Pb(2+) from gestation through adolescence exhibit loss of PVGI in SZ-relevant brain regions. PV and glutamic acid decarboxylase 67 kDa (GAD67) protein were significantly decreased in Pb(2+) exposed rats with no apparent change in calretinin or calbindin protein levels suggesting a selective effect on the PV phenotype of GABAergic interneurons. We also show that Pb(2+) animals exhibit a heightened locomotor response to cocaine and express significantly higher levels of dopamine metabolites and D2-dopamine receptors relative to controls indicative of subcortical dopaminergic hyperactivity. Our results show that developmental Pb(2+) exposure reproduces specific neuropathology and functional dopamine system changes present in SZ. We propose that exposure to environmental toxins that produce NMDAR hypofunction during critical periods of brain development may contribute significantly to the etiology of mental disorders.