Attention-deficit hyperactivity disorder symptoms and lead exposure in children: A systematic review of literature

Blood lead levels > 10 µg/dL are known to affect various areas of the brain that influence behavior and cause many other health problems in children. As a result, the Centers for Disease Control and Prevention (CDC) set the blood lead action level at 10 µg/dL. However, recent research provides evidence that blood lead levels <10 µg/dL also may lead to behavioral problems in children. With the recent increase in diagnosis of Attention-Deficit Hyperactivity Disorder (ADHD) in children in the U.S. it is important to determine possible environmental toxins such as lead that may play a role in causing ADHD symptoms. The aim of this systematic review of the literature was to identify recent published studies that examine an association between blood lead levels < 10 µg/dL and ADHD symptoms in children in order to summarize their findings and describe major gaps in the literature. Although available research is limited, the articles reviewed indicate that blood lead at levels much below the CDC action level of 10 µg/dL may affect a child's level of attention, hyperactivity, impulsivity and ADHD diagnosis. Additional prospective research is warranted in order to inform the revision of current blood lead action levels as well as better elucidate the relationship between lead and ADHD diagnoses.^

Prevalence of secondhand smoke exposure in asthmatic children at home and in the car: A cross-sectional study

OBJECTIVE: To compare secondhand smoke exposure (SHSe) prevalence at home and inside the car between asthmatic and non-asthmatic Portuguese children. MATERIALS AND METHODS: This is a cross-sectional study that assessed children's SHSe in a representative sample of nine Portuguese cities. A validated self-reported questionnaire was administered to a random sample of 4th grade students during the school year of 2010/2011. The asthma prevalence was defined by the answers to three questions regarding asthma symptoms, medication and inhaler use. We performed chi-square tests and analysed frequencies, contingency tables, confidence intervals, and odd-ratios. RESULTS: The self-reported questionnaire was administered to 3187 students. Asthma prevalence was 14.8% (472 students). Results showed that 32.3% of non-asthmatic children and 32.4% of asthmatic children were exposed to secondhand smoke as at least one of their household members smoked at home. The prevalence of parental smoking, smoking among fathers and smoking among mothers at home was also similar in both groups (asthmatic and non-asthmatic children). SHSe inside the car was 18.6% among non-asthmatic children and 17.9% among asthmatic children. CONCLUSIONS: Asthmatic and non-asthmatic children were equally exposed to secondhand smoke, because no significant differences were found between the two groups concerning the prevalence of SHSe at home and inside the car. These findings highlight the need to include SHSe brief advice in paediatric asthma management.

Predicting posttraumatic stress reactions in children prior to traumatic exposure

The present study examined the relations among previously identified risk and protective variables associated with traumatic exposure and evaluated a model of resilience to traumatic events among Latino youth prior to traumatic exposure using structural equation modeling. Model tests were pursued in the context of Full Information Maximum Likelihood (FIML) methods as implemented in Mplus. The model evaluated the role of the following variables: (a) intervening life events; (b) child characteristics; (c) social support from significant others; and (d) children's coping. Data were collected from 181 Latino youth (M age = 9.22, SD = 1.38; 49.0% female) participants. Data analyses revealed that children's perceived available social support and use of coping strategies predicted low state anxiety following exposure to cues of disaster. Life events and preexisting depression symptoms did not significantly predict social support and coping, whereas preexisting anxiety was a significant predictor of perceived social support. This study represents an important initial step towards establishing and empirically evaluating a resilience model. Implications for preparedness interventions and a framework for the etiology of resilient reactions to disaster exposure are discussed.

Dietary exposure assessments for children in Europe (the EXPOCHI project): rationale, methods and design

[EN]The number of dietary exposure assessment studies focussing on children is very limited. Children are however a vulnerable group due to their higher food consumption level per kg body weight. Therefore, the EXPOCHI project aims [1] to create a relational network of individual food consumption databases in children, covering different geographical areas within Europe, and [2] to use these data to assess the usual intake of lead, chromium, selenium and food colours.

Exposure of children to ultrafine particles in primary schools in Portugal

Children spend a large part of their time at schools, which might be reflected as chronic exposure. Ultrafine particles (UFP) are generally associated with a more severe toxicity compared to fine and coarse particles, due to their ability to penetrate cell membranes. In addition, children tend to be more susceptible to UFP-mediated toxicity compared to adults, due to various factors including undeveloped immune and respiratory systems and inhalation rates. Thus, the purpose of this study was to determine indoor UFP number concentrations in Portuguese primary schools. Ultrafine particles were sampled between January and March 2014 in 10 public primary schools (35 classrooms) located in Porto, Portugal. Overall, the average indoor UFP number concentrations were not significantly different from outdoor concentrations (8.69 × 10(3) vs. 9.25 × 10(3) pt/cm(3), respectively; considering 6.5 h of indoor occupancy). Classrooms with distinct characteristics showed different trends of indoor UFP concentrations. The levels of carbon dioxide were negatively correlated with indoor UFP concentrations. Occupational density was significantly and positively correlated with UFP concentrations. Although the obtained results need to be interpreted with caution since there are no guidelines for UFP levels, special attention needs to be given to source control strategies in order to reduce major particle emissions and ensure good indoor air quality.

Balance ability in 7- and 10-year-old children:associations with prenatal lead and cadmium exposure and with blood lead levels in childhood in a prospective birth cohort study

OBJECTIVES: Most studies reporting evidence of adverse effects of lead and cadmium on the ability to balance have been conducted in high-exposure groups or have included adults. The effects of prenatal exposure have not been well studied, nor have the effects in children been directly studied. The aim of the study was to identify the associations of lead (in utero and in childhood) and cadmium (in utero) exposure with the ability to balance in children aged 7 and 10 years. DESIGN: Prospective birth cohort study. PARTICIPANTS: Maternal blood lead (n=4285) and cadmium (n=4286) levels were measured by inductively coupled plasma mass spectrometry in women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) during pregnancy. Child lead levels were measured in a subsample of 582 of ALSPAC children at age 30 months. MAIN OUTCOME MEASURES: Children completed a heel-to-toe walking test at 7 years. At 10 years, the children underwent clinical tests of static and dynamic balance. Statistical analysis using SPSS V.19 included logistic regression modelling, comparing categories of ≥ 5 vs <5 µg/dL for lead, and ≥ 1 vs <1 µg/L for cadmium. RESULTS: Balance at age 7 years was not associated with elevated in utero lead or cadmium exposure (adjusted OR for balance dysfunction: Pb 1.01 (95% CI 0.95 to 1.01), n=1732; Cd 0.95 (0.77 to 1.20), n=1734), or with elevated child blood lead level at age 30 months (adjusted OR 0.98 (0.92 to 1.05), n=354). Similarly, neither measures of static nor dynamic balance at age 10 years were associated with in utero lead or cadmium exposure, or child lead level. CONCLUSIONS: These findings do not provide any evidence of an association of prenatal exposure to lead or cadmium, or lead levels in childhood, on balance ability in children. Confirmation in other cohorts is needed.

Association of dental enamel lead levels with risk factors for environmental exposure

OBJECTIVE: To analyze household risk factors associated with high lead levels in surface dental enamel. METHODS: A cross-sectional study was conducted with 160 Brazilian adolescents aged 14-18 years living in poor neighborhoods in the city of Bauru, southeastern Brazil, from August to December 2008. Body lead concentrations were assessed in surface dental enamel acid-etch microbiopsies. Dental enamel lead levels were measured by graphite furnace atomic absorption spectrometry and phosphorus levels were measured by inductively coupled plasma optical emission spectrometry. The parents answered a questionnaire about their children's potential early (05 years old) exposure to well-known lead sources. Logistic regression was used to identify associations between dental enamel lead levels and each environmental risk factor studied. Social and familial covariables were included in the models. RESULTS: The results suggest that the adolescents studied were exposed to lead sources during their first years of life. Risk factors associated with high dental enamel lead levels were living in or close to a contaminated area (OR = 4.49; 95% CI: 1.69;11.97); and member of the household worked in the manufacturing of paints, paint pigments, ceramics or batteries (OR = 3.43; 95% CI: 1.31;9.00). Home-based use of lead-glazed ceramics, low-quality pirated toys, anticorrosive paint on gates and/or sale of used car batteries (OR = 1.31; 95% CI: 0.56;3.03) and smoking (OR = 1.66; 95% CI: 0.52;5.28) were not found to be associated with high dental enamel lead levels. CONCLUSIONS: Surface dental enamel can be used as a marker of past environmental exposure to lead and lead concentrations detected are associated to well-known sources of lead contamination.

Magnetic fields and acute lymphoblastic leukemia in children: a systematic review of case-control studies

Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.

Respiratory infection, exposure to mouse allergen and breastfeeding: role in recurrent wheezing in early life

Background: Environmental factors may influence the development of allergen sensitization and asthma. The aim of this study was to evaluate the role of endotoxin and allergen exposure in early life as a risk factor for recurrent wheezing. Methods: One hundred and four infants from low-income families, at high risk of asthma, were enrolled at birth. Dust samples were collected from the bedding and bedroom floor within 6 months after birth. Recurrent wheezing was defined as 3 or more wheezing episodes in the past year. Endotoxin was determined by Limulus amebocyte lysate assay, and major indoor allergens were quantitated by ELISA in dust extracts. IgE antibodies were measured by ImmunoCAP at 30 months of age. Results: At 30 months, 51 of the 99 infants who completed the study (51.5 per cent) had recurrent wheezing. Respiratory infection was strongly associated with recurrent wheezing (OR 6.67, 95 per cent CI 1.96-22.72), whereas exclusive breastfeeding for at least 1 month was a protective factor (OR 0.09, 95 per cent CI 0.01-0.51). Exposure to high levels of mouse allergen was more frequent among non-recurrent wheezers, approaching significance (OR 0.12, 95 per cent CI 0.01-1.13; p = 0.064). None of the children were sensitized to mouse. Sensitization to mite was found in 26/90 (28.8 per cent) children, with no association with recurrent wheezing. Conclusion: Respiratory infection was strongly associated with recurrent wheezing in the first 30 months of life, in children at high risk of asthma, living in a socially deprived community in Brazil

Neurotoxicity and aggressiveness triggered by low-level lead in children: a review

Lead-induced neurotoxicity acquired by low-level long-term exposure has special relevance for children. A plethora of recent reports has demonstrated a direct link between low-level lead exposure and deficits in the neurobehavioral-cognitive performance manifested from childhood through adolescence. In many studies, aggressiveness and delinquency have also been suggested as symptoms of lead poisoning. Several environmental, occupational and domestic sources of contaminant lead and consequent health risks are largely identified and understood, but the occurrences of lead poisoning remain numerous. There is an urgent need for public health policies to prevent lead poisoning so as to reduce individual and societal damages and losses. In this paper we describe unsuspected sources of contaminant lead, discuss the economic losses and urban violence possibly associated with lead contamination and review the molecular basis of lead-induced neurotoxicity, emphasizing its effects on the social behavior, delinquency and IQ of children and adolescents

Pre and post-natal exposure to ambient level of air pollution impairs memory of rats: the role of oxidative stress

The aims of this study were to evaluate whether air pollution during pre-natal and post-natal phases change habituation and short-term discriminative memories and if oxidants are involved in this process. As secondary objectives, it was to evaluate if the change of filtered to nonfiltered environment could protect the cortex of rats against oxidative stress as well as to modify the behavior of these animals. Wistar, male rats were divided into four groups (n = 12/group): pre and post-natal exposure until adulthood to filtered air (FA); pre-natal period to nonfiltered air (NFA-FA); until (21st post-natal day) and post-natal to filtered air until adulthood (PND21); prenatal to filtered air until PND21 and post-natal to nonfiltered air until adulthood (FA-NFA); pre and post-natal to nonfiltered air (NFA). After 150 days of air pollution exposure, animals were tested in the spontaneous object recognition test to evaluate short-term discriminative and habituation memories. Rats were euthanized; blood was collected for metal determination; cortex dissected for oxidative stress evaluation. There was a significant increase in malondialdehyde (MDA) levels in the NFA group when compared to other groups (FA: 1.730 +/- 0.217; NFA-FA: 1.101 +/- 0.217; FA-NFA: 1.014 +/- 0.300; NFA: 5.978 +/- 1.920 nmol MDA/mg total proteins; p = 0.007). NFA group presented a significant decrease in short-term discriminative (FA: 0.603 +/- 0.106; NFA-FA: 0.669 +/- 0.0666; FA-NFA: 0.374 +/- 0.178; NFA: -0.00631 +/- 0.106 sec; p = 0.006) and an improvement in habituation memories when compared to other groups. Therefore, exposure to air pollution during both those periods impairs short-term discriminative memory and cortical oxidative stress may mediate this process.

Lead in saliva from lead-exposed and unexposed children

Introduction: Whole blood is used for diagnosis of lead exposure. A non-invasive method to obtain samples for the biomonitoring of lead contamination has become a necessity. This study 1) compares the lead content in whole saliva samples (Pb-saliva) of children from a city with no reported lead contamination (Ribeirao Preto, Sao Paulo State, Brazil) and children of a region notoriously contaminated with lead (Bauru, Sao Paulo State, Brazil), and 2) correlates Pb-saliva with the lead content in the enamel microbiopsy samples (Pb-enamel) in the case of these two populations. Methods: From a population of our previous study that had included 247 children (4- to 6-year-old) from Ribeirao Preto, and 26 children from Bauru, Pb-saliva was analyzed in 125 children from Ribeirdo Preto and 19 children from Bauru by inductively coupled plasma mass spectrometry (ICPMS). To correlate Pb-saliva with Pb-enamel, we used Pb-enamel data obtained in our previous study. The Mann-Whitney test was employed to compare the Pb-saliva data of the two cities. Pb-saliva and Pb-enamel values were then Log(10) transformed to normalize data, and Pb-saliva and Pb-enamel were correlated using Pearson`s correlation coefficient. Results: Median Pb-saliva from the Ribeirao Preto population (1.64 mu g/L) and the Bauru population (5.85 mu g/L) were statistically different (p<0.0001). Pearson`s correlation coefficient for Log(10) Pb-saliva versus Log(10) Pb-enamel was 0.15 (p=0.08) for Ribeirao Preto and 0.38 (p=0.11) for Bauru. Conclusions: A clear relationship between Pb-saliva and environmental contamination by lead is shown. Further studies on Pb-saliva should be undertaken to elucidate the usefulness of saliva as a biomarker of lead exposure, particularly in children. (C) 2008 Elsevier B.V. All rights reserved.

Long-Term Results of Percutaneous Bilioenteric Anastomotic Stricture Treatment in Liver-Transplanted Children

The purpose of this study was to evaluate the mid- and long-term results of percutaneous transhepatic cholangiography (PTC) and biliary drainage in children with isolated bilioenteric anastomotic stenosis (BAS) after pediatric liver transplantation. Sixty-four children underwent PTC from March 1993 to May 2008. Nineteen cholangiograms were normal; 10 showed intrahepatic biliary stenosis and BAS, and 35 showed isolated BAS. Cadaveric grafts were used in 19 and living donor grafts in 16 patients. Four patients received a whole liver, and 31 patients received a left lobe or left lateral segment. Roux-en-Y hepaticojejunostomy was performed in all patients. Indication for PTC was based on clinical, laboratory, and histopathologic findings. In patients with isolated BAS, dilation and biliary catheter placement, with changes every 2 months, were performed. Patients were separated into 4 groups according to number of treatment sessions required. The drainage catheter was removed if cholangiogram showed no significant residual stenosis and normal biliary emptying time after a minimum of 6 months. The relationship between risk factors (recipient`s weight < 10 kg, previous exposure to Cytomegalovirus, donor-recipient sex and weight relations, autoimmune disease as indication for transplantion, previous Kasai`s surgery, use of reduced liver grafts, chronic or acute rejection occurrence) and treatment was evaluated. Before PTC, fever was observed in 46%, biliary dilation in 23%, increased bilirubin in 57%, and increased gamma-glutamyltransferase (GGT) in 100% of patients. In the group with BAS, 24 of 35 (69%) patients had histopathologic findings of cholestasis as did 9 of 19 (47%) patients in the group with normal PTC. Of the 35 patients, 23 (65.7%) needed 1 (group I), 7 needed 2 (group II), 4 needed 3 (group III), and 1 needed 4 treatment sessions (group IV). The best results were observed after 1 treatment session, and the mean duration of catheter placement and replacement was 10 months. The primary patency rate was 61.2%, and the recurrence rate was 34.3% (group I). Seven patients (7 of 35; 20%) had their stricture treated with a second treatment session (group II). The average drainage time in group II was 24 months. During a period > 20 months, 4 patients (4 of 35; 11.4%) required 1 additional treatment session (group III), and 1 patient (1 of 35; 2.9%) had a catheter placed at the end of the study period (group IV). Drainage time in group I was significantly shorter than those in groups II, III, and IV (p < 0.05). There was no statistically significant relation between therapeutic response and the selected risk factors (p > 0.05). The majority of complications, such as catheter displacement and leakage, were classified as minor; however, 2 patients (5.7%) with hemobilia were noted. Complications increased according to the need for reintervention. In conclusion, balloon dilation and percutaneous drainage placement is safe and effective, and it has long-term patency for children with BAS after liver transplantation. Because of prolonged treatment time, reintervention may be necessary, thereby increasing the complication rate. Balloon dilation and percutaneous drainage placement should be considered as the first treatment option because of its minimally invasive nature.