Prenatal Omega-6:Omega-3 Ratio and Attention Deficit and Hyperactivity Disorder Symptoms.

Objective: To evaluate whether higher omega-6:omega-3 (n-6:n-3) long-chain polyunsaturated fatty acid ratio in cord plasma is associated with more symptoms of attention deficit and hyperactivity disorder (ADHD) at 4 and 7 years of age.

Study Design: This study was based on a population-based birth cohort in Spain. N-6 arachidonic acid and n-3 eicosapentaenoic and docosahexaenoic acid concentrations were measured in cord plasma.

Brain Structure and Function in School-Aged Children With Sluggish Cognitive Tempo Symptoms.

Objective: Sluggish cognitive tempo (SCT) is a cluster of symptoms associated with poor function in various domains of major life activities that may comprise a novel attention disorder distinct from attention-deficit/hyperactivity disorder (ADHD). Nevertheless, very little is known about the neural substrate of SCT in children. The present study aimed to examine associations between SCT symptoms and brain structure and function in school-aged children.

Sluggish Cognitive Tempo in a Child and Adolescent Clinical Outpatient Setting.

Sluggish cognitive tempo (SCT) symptoms have largely emerged from investigations of attention-deficit/hyperactivity disorder (ADHD). Recent research has demonstrated the relevance of SCT symptoms in the field of clinical child and adolescent psychiatry. The goal of this research was to study the symptoms of SCT in a clinical child and adolescent sample and to define its features and comorbid conditions.

An evaluation of the sexual differences in the accumulation of organochlorine compounds in children at birth and at the age of 4 years.

This study of the body burden and serum concentrations of organochlorine compounds (OCs), represents a general population in a cohort from Menorca Island (birth 1997-1998) of children at birth and at 4 years of age; the study has shown that the concentrations of hexachlorobenzene (HCB), 4,4'-DDE, 4,4'-DDT, polychlorobiphenyl (PCB) congeners #153, #138 and #180 and total PCBs in sera collected at 4 years are much higher in breastfed children than in those fed with formula, e.g. HCB 0.

Maternal use of folic acid supplements during pregnancy and four-year-old neurodevelopment in a population-based birth cohort.

The use of folic acid supplements during very early pregnancy is recommended in order to reduce the incidence of neural tube defects. Little is known about the possible benefits of folic acid on child neurodevelopment. A total of 420 children (87% of those eligible) from a birth cohort had complete data for final analyses at age 4 years.

Iodine sources and iodine levels in pregnant women from an area without known iodine deficiency.

Objective: An adequate iodine intake during pregnancy is essential for normal development of the foetus. The World Health Organization (WHO) recommends that the median urinary iodine concentration (UIC) in a population of pregnant women should range between 150 and 249 microg/l. The aim of this study was to evaluate iodine status and to examine the main sources of iodine in pregnant women from an apparently iodine-sufficient area.

Influence of glutathione S-transferase polymorphisms on cognitive functioning effects induced by p,p'-DDT among preschoolers.

Background: Early-life exposure to p,p'-DDT [2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane] is associated with a decrease in cognitive skills among preschoolers at 4 years of age. We hypothesized that genetic variability in glutathione S-transferase (GST) genes (GSTP1, GSTM1, and GSTT1) could influence the effects of prenatal exposure to p,p'-DDT.

Methods: We used data from 326 children assessed in a prospective population-based birth cohort at the age of 4 years.

Maternal fish and other seafood intakes during pregnancy and child neurodevelopment at age 4 years.

Objective: To analyse the relationship between maternal intakes of fish and other seafood during pregnancy and child neurodevelopment at age 4 years. Although pregnant women are advised to limit seafood intakes because of possible neurotoxin contamination, several studies suggest that overall maternal seafood intakes are associated with improved child neurodevelopment, perhaps because of higher DHA intakes.

Design: The study uses data from a prospective birth cohort study.

Urinary porphyrin excretion in children is associated with exposure to organochlorine compounds.

Background: Hexachlorobenzene (HCB) and other organochlorines induce porphyria cutanea tarda (PCT) in animal studies. Evidence in humans, however, is contradictory. In neonates and adults from a population historically highly exposed to HCB (Flix, Catalonia, Spain), no relation with PCT or with porphyrin excretion was found.

Exposure to hexachlorobenzene during pregnancy increases the risk of overweight in children aged 6 years.

Aim: To determine whether prenatal exposure to hexachlorobenzene (HCB) has potential adverse effects on child's weight and body mass index (BMI) in a general population with no local pollution sources.

Methods: Starting from mid 1997, all mothers presenting for antenatal exposure in Menorca were recruited. Subsequently, 482 children were enrolled.

[Studies conducted in Spain on concentrations in humans of persistent toxic compounds].

No systematic review is available on studies conducted in Spain on human concentrations of persistent toxic substances (PTS). The objectives were: to identify studies conducted in Spain in the past 30 years that determined concentrations in humans of dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDE), hexachlorobenzene (HCB), hexachlorocyclohexane (HCH) and polychlorinated biphenyls (PCBs); and to summarize the main characteristics and results of each study. Studies are highly heterogeneous and most lack population representativeness.

Maternal smoking very early in pregnancy is related to child overweight at age 5-7 y.

Background: Despite being associated with lower birth weight, maternal smoking in the last 2 trimesters of pregnancy has been associated with increased risk of offspring overweight in several studies. To date, only one study has examined whether smoking in the first trimester only, which is not associated with birth weight, is also associated with childhood overweight.

Objective: This study uses prospective data to examine associations between maternal smoking in the first compared with later trimesters of pregnancy and child overweight at age 5-7 y.

Thyroid disruption at birth due to prenatal exposure to beta-hexachlorocyclohexane.

Objective: Thyroid hormones play an important role in human brain development, and some organochlorine compounds (OCs) act as thyroid disruptors. The objective of the present study was to evaluate the association between prenatal exposure to organochlorine compounds and thyroid function in newborns from a general population birth cohort in Menorca, with an a-priori specific focus on beta-HCH.

Methods: Levels of polychlorinated biphenyls (PCB congeners 28, 52, 101, 118, 138, 153 and 180), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (beta-HCH), dichlorodiphenyl dichloroethylene (p'p'-DDE) and dichlorodiphenyl trichloroethane (p'p-DDT) in cord serum, and thyrotropin (TSH) concentration in plasma three days after birth were measured in 387 newborns from Menorca.

Prenatal exposure to mercury in a prospective mother-infant cohort study in a Mediterranean area, Valencia, Spain.

Background: Mercury (Hg) is a ubiquitous pollutant that negatively affects fetal and child neurodevelopment at accidental high-dose exposure. Some studies indicate that Mediterranean populations could be at risk of prenatal exposure to mercury through fish consumption.

Objectives: To assess the prenatal exposure to total mercury (T-Hg), both inorganic and organic, in newborns by analyzing the T-Hg concentration in cord blood, and to evaluate the role of maternal fish consumption in this exposure.

Monitoring concentrations of persistent organic pollutants in the general population: the international experience.

Assessing the adverse effects on human health of persistent organic pollutants (POPs) and the impact of policies aiming to reduce human exposure to POPs warrants monitoring body concentrations of POPs in representative samples of subjects. While numerous ad hoc studies are being conducted to understand POPs effects, only a few countries are conducting nationwide surveillance programs of human concentrations of POPs, and even less countries do so in representative samples of the general population. We tried to identify all studies worldwide that analyzed the distribution of concentrations of POPs in a representative sample of the general population, and we synthesized the studies' main characteristics, as design, population, and chemicals analyzed.

Pentachlorobenzene, hexachlorobenzene, and pentachlorophenol in children's serum from industrial and rural populations after restricted use.

The study of a population of 4-year-old children born between 1997 and 1999 in an urban area under strong inputs of pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) suggested that the measured concentrations of pentachlorophenol (PCP) in serum may essentially result from metabolism of these chlorinated hydrocarbons. In contrast, examination of a rural population of children where the same compounds were present at relatively low levels points to other inputs besides transformation of PeCB and HCB being responsible for the measured PCP concentrations. In both populations, the results showed that a major proportion of the organochlorine compounds present in these children's serum at 4 years of age was incorporated during the lactation period.

Beneficial effects of breastfeeding on cognition regardless of DDT concentrations at birth.

The authors previously reported that intrauterine exposure to background concentrations of p,p'-dichlorodiphenyltrichloroethane (DDT) reduces cognitive performance among preschoolers. Breastfeeding has been associated with both increased exposure to certain pollutants during infancy and better performance on cognitive tests. Thus, the authors examined the role of breastfeeding in cognitive function among preschoolers, taking prenatal DDT exposure into account.

Influence of breastfeeding in the accumulation of polybromodiphenyl ethers during the first years of child growth.

The concentrations of polybromodiphenyl ethers (PBDEs) in children at birth (cord blood sera, n = 92) and at the age of 4 years (sera, n = 244) from a cohort established in Menorca Island (Balearic Island, Spain) were studied. This cohort is representative of a general European population that is fed a typical Mediterranean diet. Among the 13 congeners analyzed, BDE #47 was the most abundant in both types of samples, with mean values of 2.

In utero and post-natal accumulation of organochlorine compounds in children under different environmental conditions.

A study of intake of organochlorine compounds (OCs) in children both in utero and at the age of four years has been performed in two cohorts. One encompasses children born in Menorca Island between 1997 and 1998, and the other those born between 1997-1999 in Ribera d'Ebre, an in-land industrial-agricultural area of Catalonia. Comparison of the OC concentrations in serum samples from both populations, including those obtained from cord blood and blood collected at four years, provides information on the influence of local pollution sources in the accumulation of these compounds.

Maternal smoking habits and cognitive development of children at age 4 years in a population-based birth cohort.

Background: Active maternal smoking during pregnancy has been associated with a higher risk of behavioural disorders in children, but a few cohort studies measuring smoking data prospectively have studied its specific effects on the cognitive abilities of pre-schoolers.

Method: A birth cohort was set up in Menorca Island in 1997 within the Asthma Multicenter Infants Cohort Study. A total of 420 (87% of those eligible) children had complete data for final analyses at age 4 years.

Attention behaviour and hyperactivity at age 4 and duration of breast-feeding.

Aim: The relation of longer duration of breast-feeding to cognitive development was been demonstrated in several previous studies, however its potential impact on behaviour is unknown. We assess which behavioural areas (executive function, social competence, attention behaviour and hyperactivity) are related to long-term breast-feeding in young children.

Methods: Two prospective population-based birth cohorts, one from the island of Menorca (N = 421) and the second from Ribera d'Ebre county (N = 79) in Spain were followed up at the age of 4 years during a two year period (2001-2003).

TSH concentration within the normal range is associated with cognitive function and ADHD symptoms in healthy preschoolers.

Objective: Thyroid hormone concentrations outside the normal range affect brain development, but their specific influence on behaviour and mental abilities within normal values is unknown. The objective of this study was to investigate whether thyroid hormone concentrations are related to neurodevelopment and ADHD (attention deficit and hyperactivity disorder) symptoms in healthy preschoolers. DESIGN SUBJECTS AND MEASUREMENTS: Children from two general population birth cohorts in Menorca (n = 289) and Ribera d'Ebre (n = 53), Spain, were assessed in a cross-sectional study at the age of 4.

[Measurement of drinking water contaminants and water use activities during pregnancy in a cohort study in Spain].

Objectives: Exposure to chlorination by-products during pregnancy has been associated with reproductive outcomes but the evidence remains inconclusive. Levels of trihalomethanes, the most prevalent chlorination by-products, are high in some areas of Spain. Within the framework of a follow-up study in pregnant women, we describe: 1) the personal habits of water use and consumption, and 2) trihalomethane levels in the drinking water of the study areas.

Exposure to hexachlorobenzene during pregnancy and children's social behavior at 4 years of age.

Background: Hexachlorobenzene (HCB) is an organochlorine chemical that has been used in agriculture and industrial processes. Behavioral impairment after HCB exposure has been described in animal models, but little information is available in humans.

Objectives: Our goal was to study the association of prenatal exposure to HCB with the social behavior of preschool children.