Blood lead concentrations and children's behavioral and emotional problems: a cohort study

Working with an environmental justice community: Nurse observation, assessment, and intervention

Environmental justice (EJ) is the concept that all people and communities, regardless of their race and socioeconomic status, are entitled to enjoy an equally clean environment and resources. Communities where residents face environmental injustice and a higher risk of being exposed to environmental hazards due to their race, ethnicity, and socioeconomic status are called EJ communities. The purpose of this manuscript is to provide an example of nurses' involvement in observation, assessment, and intervention of an EJ community using a community-based participatory research (CBPR) model. Utilizing a multistage CBPR approach along with a mixed methods design, the project was carried out in three stages. Within the three stages, we conducted a thorough observation of the community, identified possible environmental issues, and collected health data and drinking water samples. Citizens' complaints included coal ash, failed sewer system, health issues, including kidney disorders and neuropathy. Drinking water samples (n = 59) showed lead levels higher than the health limits in 10.4% of samples. We intervened based on our short-term goal, reducing citizens' exposure to lead by education, and our long-term goal, reducing disparities, and exposures. We recommend that nurses increase their knowledge about EJ communities and environmental exposures and their health effects and be advocates for EJ communities.

Airborne manganese exposure and neurobehavior in school-aged children living near a ferro-manganese alloy plant

Excessive exposure to Mn can lead to its accumulation in the brain with neurotoxic consequences. In children, elevated Mn has been associated with deficits in certain neuropsychological domains such as cognition, motor function, memory and attention, and in some instances, hyperactivity and behavioral problems. The aim of this study was to evaluate behavioral effects in school-aged children living near a ferro-manganese alloy plant and examine their association with Mn exposure. Occipital hair, toenails and blood samples were collected from 225 children (7-12 years old) enrolled in four elementary schools with different levels of exposure to Mn, based on dust Mn deposition rates. Full data set collection was completed and run from 165 children. Mn in hair (MnH), toenails (MnTn), blood (MnB) and blood lead levels (PbB) were determined by graphite furnace atomic absorption spectrometry. Children's behavior was assessed with the Child Behavior Check List (CBCL) reported by parents. Median levels and range of MnH, MnT and MnB were, respectively, 0.73 µg/g (0.16-8.79), 0.84 µg/g (0.15-9.29) and 8.98 μg/L (1.51-40.43). Median and range of PbB were 1.2 µg/dL (0.2-15.6). MnH and MnB were not associated with any scale of the CBCL behavior scores. We found a positive association between logMnTn and raw total CBCL score (β = 10.17, p = 0.034), adjusting for sex, age, maternal IQ and logPbB. Analyses using Generalized Additive Model showed non-linear associations between MnTn and externalizing behavior (p = 0.035), as well as with the related subscales: aggressive behavior (p = 0.045) and rule-breaking behavior (p = 0.024). Further positive associations were observed between MnTn and thought problems (p = 0.031) and social problems (p = 0.027). These findings corroborate previous studies showing an association between Mn exposures and externalizing behavior. Our results suggest that toenail Mn, as a biomarker of environmental exposure, is associated with disruptive behavior in children living near a ferro-manganese alloy plant.

Effect of Residential Lead-Hazard Interventions on Childhood Blood Lead Concentrations and Neurobehavioral Outcomes: A Randomized Clinical Trial

IMPORTANCE

Childhood lead exposure is associated with neurobehavioral deficits. The effect of a residential lead hazard intervention on blood lead concentrations and neurobehavioral development remains unknown.

OBJECTIVE

To determine whether a comprehensive residential lead-exposure reduction intervention completed during pregnancy could decrease residential dust lead loadings, prevent elevated blood lead concentrations, and improve childhood neurobehavioral outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal, community-based randomized clinical trial of pregnant women and their children, the Health Outcomes and Measures of the Environment (HOME) Study, was conducted between March 1, 2003, and January 31, 2006. Pregnant women attending 1 of 9 prenatal care clinics affiliated with 3 hospitals in the Cincinnati, Ohio, metropolitan area were recruited. Of the 1263 eligible women, 468 (37.0%) agreed to participate and 355 women (75.8%) were randomized in this intention-to-treat analysis. Participants were randomly assigned to receive 1 of 2 interventions designed to reduce residential lead or injury hazards. Follow-up on children took place at 1, 2, 3, 4, 5, and 8 years of age. Data analysis was performed from September 2, 2017, to May 6, 2018.

MAIN OUTCOMES AND MEASURES

Residential dust lead loadings were measured at baseline and when children were 1 and 2 years of age. At 1, 2, 3, 4, 5, and 8 years of age, the children's blood lead concentrations as well as behavior, cognition, and executive functions were assessed.

RESULTS

Of the 355 women randomized, 174 (49.0%) were assigned to the intervention group (mean [SD] age at delivery, 30.1 (5.5) years; 119 [68.3%] self-identified as non-Hispanic white) and 181 (50.9%) to the control group (mean [SD] age at delivery, 29.2 [5.7] years; 123 [67.9%] self-identified as non-Hispanic white). The intervention reduced the dust lead loadings for the floor (24%; 95% CI, -43% to 1%), windowsill (40%; 95% CI, -60% to -11%), and window trough (47%; 95% CI, -68% to -10%) surfaces. The intervention did not statistically significantly reduce childhood blood lead concentrations (-6%; 95% CI, -17% to 6%; P = .29). Neurobehavioral test scores were not statistically different between children in the intervention group than those in the control group except for a reduction in anxiety scores in the intervention group (β = -1.6; 95% CI, -3.2 to -0.1; P = .04).

CONCLUSIONS AND RELEVANCE

Residential lead exposures, as well as blood lead concentrations in non-Hispanic black children, were reduced through a comprehensive lead-hazard intervention without elevating the lead body burden. However, this decrease did not result in substantive neurobehavioral improvements in children.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00129324.

Effect of dietary patterns on the blood/urine concentration of the selected toxic metals (Cd, Hg, Pb) in Korean children

This study was aimed to examine the association the blood/urinary concentration of toxic metal (Hg, Pb, and Cd) with children's dietary patterns. This cross-sectional study included 1026 school children aged 8-17 years. Dietary patterns were defined using factor loading scores for 108 foods from a Semi-Quantitative Food Frequency Questionnaire. A high blood Hg level was found in boys with a high score in the 'fish' pattern (p = 0.02), and in girls with a high score in 'fruit' pattern (p = 0.04). The concentration of Pb was related to the 'imprudent' pattern in high school boys (p = 0.02). The effect of the 'vegetable' pattern on high excretion of urinary Cd was observed in low grade elementary (p = 0.04) and middle school students (p < 0.0001), and the effect of the 'fruit' pattern on the urinary Cd was observed in high grade elementary school students (p = 0.02). This study suggests that the concentration of selected toxic metals in blood/urine could be affected by children's dietary pattern.

Variation in personality traits across a metal pollution gradient in a free-living songbird

Anthropogenic contaminants could alter traits central to animal behavioral types, or personalities, including aggressiveness, boldness and activity level. Lead and other toxic metals are persistent inorganic pollutants that affect organisms worldwide. Metal exposure can alter behavior by affecting neurology, endocrinology, and health. However, the direction and magnitude of the behavioral effects of metal exposure remain equivocal. Moreover, the degree to which metal exposure simultaneously affects suites of correlated behavioral traits (behavioral syndromes) that are controlled by common mechanisms remains unclear, with most studies focusing on single behaviors. Using a model species for personality variation, the great tit (Parus major), we explored differences in multiple behavioral traits across a pollution gradient where levels of metals, especially lead and cadmium, are elevated close to a smelter. We employed the novel environment exploration test, a proxy for variation in personality type, and also measured territorial aggressiveness and nest defense behavior. At polluted sites birds of both sexes displayed slower exploration behavior, which could reflect impaired neurological or physiological function. Territorial aggression and nest defense behavior were individually consistent, but did not vary with proximity to the smelter, suggesting that metal exposure does not concurrently affect exploration and aggression. Rather, exploration behavior appears more sensitive to metal pollution. Effects of metal pollution on exploration behavior, a key animal personality trait, could have critical effects on fitness.

Social determinants of mental disorders and the Sustainable Development Goals: a systematic review of reviews

Mental health has been included in the UN Sustainable Development Goals. However, uncertainty exists about the extent to which the major social determinants of mental disorders are addressed by these goals. The aim of this study was to develop a conceptual framework for the social determinants of mental disorders that is aligned with the Sustainable Development Goals, to use this framework to systematically review evidence regarding these social determinants, and to identify potential mechanisms and targets for interventions. We did a systematic review of reviews using a conceptual framework comprising demographic, economic, neighbourhood, environmental events, and social and culture domains. We included 289 articles in the final Review. This study sheds new light on how the Sustainable Development Goals are relevant for addressing the social determinants of mental disorders, and how these goals could be optimised to prevent mental disorders.

Risk Factors for Antisocial Behavior in Low- and Middle-Income Countries: A Systematic Review of Longitudinal Studies

Violent crime is a major cause of social instability, injury, and death in low- and middle-income countries. Longitudinal studies in high-income countries have provided important evidence on developmental precursors of violence and other antisocial behaviors. However, there may be unique influences or different risk factor effects in other social settings. Extensive searches in seven languages and screening of over 60,000 references identified 39 longitudinal studies of antisocial behavior in low- and middle-income countries. Many risk factors have roughly the same average effects as when studied in high-income countries. Stability of aggression over a 3-year period is almost identical across low- and middle-income countries and high-income countries. Dimensions of comorbid psychopathology such as low self-control, hyperactivity, and sensation seeking are associated with antisocial behavior in low- and middle-income countries, but some early physical health factors have consistently weak or null effects.

Blood lead levels in a group of children: the potential risk factors and health problems

OBJECTIVE

To investigate blood lead levels in schoolchildren in two areas of Egypt to understand the current lead pollution exposure and its risk factors, aiming to improve prevention politicies.

SUBJECTS AND METHOD

This was a cross-sectional study in children (n=400) aged 6-12 years recruited from two areas in Egypt (industrial and urban). Blood lead levels were measured using an atomic absorption method. Detailed questionnaires on sources of lead exposure and history of school performance and any behavioral changes were obtained.

RESULTS

The mean blood lead level in the urban area of Egypt (Dokki) was 5.45±3.90μg/dL, while that in the industrial area (Helwan) was 10.37±7.94μg/dL, with a statistically significant difference between both areas (p<0.05). In Dokki, 20% of the studied group had blood lead levels≥10μg/dL, versus 42% of those in Helwan. A significant association was found between children with abnormal behavior and those with pallor with blood lead level≥10μg/dL, when compared with those with blood lead level<10μg/dL (p<0.05). Those living in Helwan area, those with bad health habits, and those living in housing with increased exposure were at a statistically significantly higher risk of having blood lead level≥10μg/dL.

CONCLUSION

Lead remains a public health problem in Egypt. High blood lead levels were significantly associated with bad health habits and housing with increased exposure, as well as abnormal behavior and pallor.

Glycogen metabolism in brain and neurons - astrocytes metabolic cooperation can be altered by pre- and neonatal lead (Pb) exposure

Lead (Pb) is an environmental neurotoxin which particularly affects the developing brain but the molecular mechanism of its neurotoxicity still needs clarification. The aim of this paper was to examine whether pre- and neonatal exposure to Pb (concentration of Pb in rat offspring blood below the "threshold level") may affect the brain's energy metabolism in neurons and astrocytes via the amount of available glycogen. We investigated the glycogen concentration in the brain, as well as the expression of the key enzymes involved in glycogen metabolism in brain: glycogen synthase 1 (Gys1), glycogen phosphorylase (PYGM, an isoform active in astrocytes; and PYGB, an isoform active in neurons) and phosphorylase kinase β (PHKB). Moreover, the expression of connexin 43 (Cx43) was evaluated to analyze whether Pb poisoning during the early phase of life may affect the neuron-astrocytes' metabolic cooperation. This work shows for the first time that exposure to Pb in early life can impair brain energy metabolism by reducing the amount of glycogen and decreasing the rate of its metabolism. This reduction in brain glycogen level was accompanied by a decrease in Gys1 expression. We noted a reduction in the immunoreactivity and the gene expression of both PYGB and PYGM isoform, as well as an increase in the expression of PHKB in Pb-treated rats. Moreover, exposure to Pb induced decrease in connexin 43 immunoexpression in all the brain structures analyzed, both in astrocytes as well as in neurons. Our data suggests that exposure to Pb in the pre- and neonatal periods results in a decrease in the level of brain glycogen and a reduction in the rate of its metabolism, thereby reducing glucose availability, which as a further consequence may lead to the impairment of brain energy metabolism and the metabolic cooperation between neurons and astrocytes.

Armour GE, Thakkar E, Mackay TFC, Anholt RRH. A Drosophila model for toxicogenomics: Genetic variation in susceptibility to heavy metal exposure

The genetic factors that give rise to variation in susceptibility to environmental toxins remain largely unexplored. Studies on genetic variation in susceptibility to environmental toxins are challenging in human populations, due to the variety of clinical symptoms and difficulty in determining which symptoms causally result from toxic exposure; uncontrolled environments, often with exposure to multiple toxicants; and difficulty in relating phenotypic effect size to toxic dose, especially when symptoms become manifest with a substantial time lag. Drosophila melanogaster is a powerful model that enables genome-wide studies for the identification of allelic variants that contribute to variation in susceptibility to environmental toxins, since the genetic background, environmental rearing conditions and toxic exposure can be precisely controlled. Here, we used extreme QTL mapping in an outbred population derived from the D. melanogaster Genetic Reference Panel to identify alleles associated with resistance to lead and/or cadmium, two ubiquitous environmental toxins that present serious health risks. We identified single nucleotide polymorphisms (SNPs) associated with variation in resistance to both heavy metals as well as SNPs associated with resistance specific to each of them. The effects of these SNPs were largely sex-specific. We applied mutational and RNAi analyses to 33 candidate genes and functionally validated 28 of them. We constructed networks of candidate genes as blueprints for orthologous networks of human genes. The latter not only provided functional contexts for known human targets of heavy metal toxicity, but also implicated novel candidate susceptibility genes. These studies validate Drosophila as a translational toxicogenomics gene discovery system.

Although physiological effects of environmental toxins are well documented, we know little about the genetic factors that determine individual variation in susceptibility to toxins. Such information is difficult to obtain in human populations due to heterogeneity in genetic background and environmental exposure, and the diversity of symptoms and time lag with which they appear after toxic exposure. Here, we show that the fruit fly, Drosophila, can serve as a powerful genetic model system to elucidate the genetic underpinnings that contribute to individual variation in resistance to toxicity, using lead and cadmium exposure as an experimental paradigm. We identified genes that harbor genetic variants that contribute to individual variation in resistance to heavy metal exposure. Furthermore, we constructed genetic networks on which we could superimpose human counterparts of Drosophila genes. We were able to place human genes previously implicated in heavy metal toxicity in biological context and identify novel targets for heavy metal toxicity. Thus, we demonstrate that based on evolutionary conservation of fundamental biological processes, we can use Drosophila as a powerful translational model for toxicogenomics studies.

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.

Sex differences in the effects of prenatal lead exposure on birth outcomes

Studies on the associations between prenatal lead exposure and birth outcomes have been inconsistent, and few data are available on the sex differences in these associations. We measured the cord blood lead levels of newborns in Shanghai and determined their associations with birth outcomes, which included birth weight, birth length, head circumference, and the ponderal index, in the total sample and within sex subgroups. A total of 1009 mother-infant pairs were enrolled from 10 hospitals in Shanghai between September 2008 and October 2009. The geometric mean of the cord blood lead concentrations was 4.07 μg/dl (95% CI: 3.98-4.17 μg/dl). A significant inverse association was found between cord blood lead levels and head circumference only in the male subgroup, and increasing cord blood lead levels were related to significant decreases in the ponderal index only in females. The birth weights of the male infants were positively associated with cord blood lead levels; after adjusting for the maternal intake frequency of preserved eggs, the estimated mean differences in birth weights decreased by 11.7% for each 1-unit increase in the log10-transformed cord blood lead concentration. Our findings suggest that prenatal lead exposure may have sex-specific effects on birth outcomes and that maternal dietary intake may be a potential confounder in these relationships. Further studies on this topic are highly warranted.

Neurodevelopmental Disorders and Environmental Toxicants: Epigenetics as an Underlying Mechanism

The increasing prevalence of neurodevelopmental disorders, especially autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), calls for more research into the identification of etiologic and risk factors. The Developmental Origin of Health and Disease (DOHaD) hypothesizes that the environment during fetal and childhood development affects the risk for many chronic diseases in later stages of life, including neurodevelopmental disorders. Epigenetics, a term describing mechanisms that cause changes in the chromosome state without affecting DNA sequences, is suggested to be the underlying mechanism, according to the DOHaD hypothesis. Moreover, many neurodevelopmental disorders are also related to epigenetic abnormalities. Experimental and epidemiological studies suggest that exposure to prenatal environmental toxicants is associated with neurodevelopmental disorders. In addition, there is also evidence that environmental toxicants can result in epigenetic alterations, notably DNA methylation. In this review, we first focus on the relationship between neurodevelopmental disorders and environmental toxicants, in particular maternal smoking, plastic-derived chemicals (bisphenol A and phthalates), persistent organic pollutants, and heavy metals. We then review studies showing the epigenetic effects of those environmental factors in humans that may affect normal neurodevelopment.

Project TENDR

: Chemicals are ubiquitous in the food we eat, the water we drink, the air we breathe, and the products we use at work and in our personal lives. Toxic chemicals increase the risk of cognitive, behavioral, and neurodevelopmental disorders throughout the life span. The Toxic Substances Control Act of 1976 was intended to allow for the collection of data on and regulation of these chemicals but has been criticized for its significant limitations in protecting the public's health. In recognition of the scientific evidence demonstrating the connection between toxic environmental chemicals and neurodevelopmental disorders, Project TENDR (Targeting Environmental Neuro-Developmental Risks)-a collaborative initiative of scientists, health professionals, and children's health advocates-produced a call to action last July with the aim of reducing exposure to chemicals and pollutants that contribute to the development of these disorders.

The non-linear association between low-level lead exposure and maternal stress among pregnant women

BACKGROUND

Neuro-developmental impairments in the developing fetus due to exposure to low-level lead have been well documented. However, few studies have investigated the relation between maternal stress levels and low-level lead exposure among pregnant women.

OBJECTIVES

To investigate the relation between maternal blood lead and stress levels during index pregnancy.

METHODS

1931 pregnant women (gestational week 28-36) were investigated using stratified-cluster-sampling in Shanghai in 2010. Maternal life event stress and emotional stress were assessed using "Life-Event-Stress-Scale-for-Pregnant-Women" (LESPW) and "Symptom-Checklist-90-Revised" (SCL-90-R), respectively. Maternal whole blood lead levels were determined, and other data on covariates were obtained from maternal interviews and medical records. Two piecewise linear regression models were applied to assess the relations between blood lead and stress levels using a data-driven approach according to spline smoothing fitting of the data.

RESULTS

Maternal blood lead levels ranged from 0.80 to 14.84μg/dL, and the geometric mean was 3.97μg/dL. The P-values for the two piecewise linear models against the single linear regression models were 0.010, 0.003 and 0.017 for models predicting GSI, depression and anxiety symptom scores, respectively. When blood lead levels were below 2.57μg/dL, each unit increase in log10 transformed blood lead levels (μg/dL) was associated with about 18% increase in maternal GSI, depression and anxiety symptom scores (P_GSI=0.013, P_depression=0.002, P_anxiety=0.019, respectively). However, no significant relation was found when blood lead levels were above 2.57μg/dL (all P-values>0.05).

CONCLUSION

Our findings suggested a nonlinear relationship between blood lead and emotional stress levels among pregnant women. Emotional stress increased along with blood lead levels, and appeared to be plateaued when blood lead levels reached 2.57μg/dL.

Effects of low level lead exposure on associative learning and memory in the rat: Influences of sex and developmental timing of exposure

Lead (Pb) exposure during development impairs a variety of cognitive, behavioral and neurochemical processes resulting in deficits in learning, memory, attention, impulsivity and executive function. Numerous studies have attempted to model this effect of Pb in rodents, with the majority of studies focusing on hippocampus-associated spatial learning and memory processes. Using a different paradigm, trace fear conditioning, a process requiring coordinated integration of both the medial prefrontal cortex and the hippocampus, we have assessed the effects of Pb exposure on associative learning and memory. The present study examined both female and male long evans rats exposed to three environmentally relevant levels of Pb (150 ppm, 375 ppm and 750 ppm) during different developmental periods: perinatal (PERI; gestation-postnatal day 21), early postnatal (EPN; postnatal days 1-21) and late postnatal (LPN; postnatal days 1-55). Testing began at postnatal day 55 and consisted of a single day of acquisition training, and three post training time points (1, 2 and 10 days) to assess memory consolidation and recall. All animals, regardless of sex, developmental window or level of Pb-exposure, successfully acquired conditioned-unconditioned stimulus association during training. However, there were significant effects of Pb-exposure on consolidation and memory recall at days 1-10 post training. In females, EPN and LPN exposure to 150 ppm Pb (but not PERI exposure) significantly impaired recall. In contrast, only PERI 150 ppm and 750 ppm-exposed males had significant recall deficits. These data suggest a complex interaction between sex, developmental window of exposure and Pb-exposure level on consolidation and recall of associative memories.

Exposure to Power-Frequency Magnetic Fields and the Risk of Infertility and Adverse Pregnancy Outcomes: Update on the Human Evidence and Recommendations for Future Study Designs

Infertility and adverse pregnancy outcomes are significant public health concerns with global prevalence. Over the past 35 years, research has addressed whether exposure to power-frequency magnetic fields is one of the etiologic factors attributed to these conditions. However, no apparent authoritative reviews on this topic have been published in the peer-reviewed literature for nearly 15 years. This review provides an overview and critical analysis of human studies that were published in the peer-reviewed literature between 2002 and July 2015. Using PubMed, 13 epidemiology studies published during this time frame that concern exposure to magnetic fields and adverse prenatal (e.g., miscarriage), neonatal (e.g., preterm birth or birth defects), and male fertility (e.g., poor semen quality) outcomes were identified. Some of these studies reported associations whereas others did not, and study design limitations may explain these inconsistencies. Future investigations need to be designed with these limitations in mind to address existing research gaps. In particular, the following issues are discussed: (1) importance of selecting the appropriate study population, (2) need for addressing confounding due to unmeasured physical activity, (3) importance of minimizing information bias from exposure measurement error, (4) consideration of alternative magnetic field exposure metrics, and (5) implications and applications of personal exposure data that are correlated within female-male couples. Further epidemiologic research is needed, given the near ubiquitous exposures to power-frequency magnetic fields in the general population.

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.

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.

Metallic Profile of Whole Blood and Plasma in a Series of 99 Healthy Children

In recent years, special emphasis has been put on heavy metals. Children are very sensitive to accumulation of metals. Furthermore, as regards elements, the reference values in children are scarce in the literature as it is difficult to obtain the large quantity of blood necessary to analyze many metals by the conventional atomic absorption spectrometry technique. An inductively coupled plasma mass spectrometry (ICP-MS) procedure that uses a reduced sample of 0.3 mL whole blood or plasma is adapted to multielemental determinations. We applied a previously validated technique for adults that simultaneously quantifies 25 elements by ICP-MS in whole blood and 23 in plasma in a series of 99 healthy children ranging from under 5 years to <18 years, without exposure to metal or drug-containing metals. The aims of the study were to compare metallic concentrations according to the age among children and metallic concentration differences between children and adults. The blood and plasma pediatric metallic profile is a practical useful tool for many purposes in clinical toxicology, forensic toxicology and any cases of metal environmental exposure.

Neurological and Epigenetic Implications of Nutritional Deficiencies on Psychopathology: Conceptualization and Review of Evidence

In recent years, a role for epigenetic modifications in the pathophysiology of disease has received significant attention. Many studies are now beginning to explore the gene-environment interactions, which may mediate early-life exposure to risk factors, such as nutritional deficiencies and later development of behavioral problems in children and adults. In this paper, we review the current literature on the role of epigenetics in the development of psychopathology, with a specific focus on the potential for epigenetic modifications to link nutrition and brain development. We propose a conceptual framework whereby epigenetic modifications (e.g., DNA methylation) mediate the link between micro- and macro-nutrient deficiency early in life and brain dysfunction (e.g., structural aberration, neurotransmitter perturbation), which has been linked to development of behavior problems later on in life.

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.