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La contaminación por compuestos tóxicos persistentes (CTP) de la población general es un hecho relevante desde una perspectiva de salud pública. Es, asimismo, importante para el sistema sanitario asistencial y para las políticas ambientales, alimentarias, industriales y económicas. Aunque en España los conocimientos sobre la contaminación de los alimentos por CTP presentan grandes vacíos temporales y geográficos, aún es menor la información sobre sus concentraciones en las personas: no existe ningún estudio representativo de una población general sana efectuado en una zona geográfica amplia. Los estudios disponibles indican que un 80-100% de la población tiene concentraciones detectables de DDE, policlorobifenilos, hexaclorobenceno o lindano. En España el número de estudios sobre los efectos que los CTP tienen en las personas es todavía más exiguo. Los estudios internacionales sugieren que dosis de algunos CTP por debajo de las que normalmente se consideran «seguras» pueden causar efectos biológicos y clínicos relevantes. Los mecanismos de acción no comprenden sólo la disrupción endocrina. La valoración de la significación clínica y social del espectro de efectos más sutiles y con períodos de latencia mayores de los CTP presenta interesantes retos y oportunidades. España y otros países europeos sufren un déficit de indicadores poblacionales sobre el impacto que los procesos ambientales tienen en la salud humana. Los distintos ámbitos de la Administración deben monitorizar los valores biológicos de los CTPs y valorar sus posibles riesgos para la salud. Junto con más de cien otros países, próximamente España intentará implementar el Tratado sobre los Contaminantes Orgánicos Persistentes (Convenio de Estocolmo). Ello constituye un nuevo motivo para desarrollar programas más eficientes de vigilancia y control de los residuos de los CTP en alimentos, humanos y medio ambiente. Como parte de la aplicación del Convenio, es necesario iniciar un informe periódico sobre los factores que condicionan las concentraciones internas de CTP en la población general española.

La población de Flix (comarca de la Ribera del Ebro, Tarragona) se encuentra altamente expuesta a hexaclorobenceno (HCB) debido a la proximidad de una empresa electroquímica. Aunque los niveles de contaminación por HCB en esta población continúan siendo elevados, se ha observado que las concentraciones en sangre venosa de las mujeres de 18-40 años en 1997-1999 fueron un 61% más bajos que en 1994 (4,1 ng/ml frente a 10,6 ng/ml). Las concentraciones de diclorodifenil dicloroetano (p,p'-DDE) y betahexaclorociclohexano (ß-HCH) tambiιn mostraron esta tendencia a la baja, aunque su disminuciσn no fue estadνsticamente significativa. Por el contrario, los niveles de bifenilos policlorados (PCB) en 1997-1999 aumentaron con relaciσn a 1994, aunque la diferencia no fue estadísticamente significativa.

Background: Few consistent data are available in relation to the cognitive and neuropsychological processes involved in sluggish cognitive tempo (SCT) symptoms. The objective of this study was to determine the association of working memory and attentional networks with SCT symptoms in primary schoolchildren. Methods: The participants were schoolchildren aged 7 to 10 years (n = 183) from primary schools in Catalonia (Spain). All the participants completed a working memory task (n-back) and an attentional network task (ANT). Their parents completed an SCT-Child Behavior Checklist self-report and a questionnaire concerning sociodemographic variables. Teachers of the participants provided information on ADHD symptoms and learning determinants. Results: SCT symptoms were correlated with lower scores in both the n-back and ANT. In multivariate regression analysis, SCT symptoms were associated with slower hit reaction times from the ANT. Conclusions: Our results suggest that SCT symptoms are associated with a neuropsychological profile that is different from the classical ADHD profile and characterized by slower reaction times. [ABSTRACT FROM AUTHOR]

Objective: Several studies have shown that some organochlorine compounds (OCs) can interfere with the thyroid system. As thyroid hormones (THs) are essential for normal brain development, it is important to study the association between THs and OCs during pregnancy and childhood. We have evaluated the relationship between thyroid function and OCs in preschool children.Methods: Children from a general population birth cohort in Menorca (n = 259), Spain were assessed at the age of 4 years. Concentrations of THs (free T4 and total T3), thyrotropin (TSH) and a range of OCs were measured in peripheral blood.Results: Blood levels of dichlorodiphenyl trichloroethane (p,p'-DDT), beta-hexachlorocylcohexane (beta-HCH), polychlorinated biphenyls (congeners PCB-138, PCB-153 and PCB-118) were related to lower total T3 levels (p<0.05). In addition, free T4 was inversely associated with PCB-118, while no relationship was found between TSH and any of the measured OCs.Conclusions: This study suggests that even at background levels of exposure, OCs may affect the thyroid system, particularly total T3 levels. [ABSTRACT FROM AUTHOR]

Aims: To assess the association between prenatal exposure to organochlorine compounds and thyroid status in newborns from an area with high levels of hexachlorobenzene (HCB).Methods: A total of 98 mother-infant pairs (83.1% of all children born during the period 1997-99 in a specific area polluted with HCB) were recruited. Levels of organochlorine compounds were measured in 70 cord serum samples. Concentrations of thyroid stimulating hormone (TSH) were measured in plasma of all newborns three days after birth.Results: All newborns had concentrations of TSH within the range of normal reference values (<25 mU/l). Dichlorodiphenyl dichloroethylene (p,p'DDE), beta-hexachlorocyclohexane (beta-HCH), polychlorinated biphenyl (PCB) 138 and 118 were related to higher concentrations of TSH, although only significant for beta-HCH. Levels of HCB were not associated with TSH.Conclusions: Although this community is highly exposed to HCB, no association was found between this organochlorine and TSH concentrations at birth. [ABSTRACT FROM AUTHOR]

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. In that study, the McCarthy Scales of Children's Abilities were administrated by psychologists, organochlorine compounds were measured in cord serum, and genotyping was conducted for the coding variant Ile105Val from GSTP1 and for null alleles from GSTM1 and GSTT1. We used linear regression models to measure the association between organochlorines and neurodevelopmental scores by GST polymorphisms.Results: p,p´-DDT cord serum concentration was inversely associated with general cognitive, memory, quantitative, and verbal skills, as well as executive function and working memory, in children who had any GSTP1 Val-105 allele. GSTP1 polymorphisms and prenatal p,p´-DDT exposure showed a statistically significant interaction for general cognitive skills (p = 0.05) , quantitative skills (p = 0.02) , executive function (p = 0.01) , and working memory (p = 0.02) . There were no significant associations between p,p´-DDT and cognitive functioning at 4 years of age according to GSTM1 and GSTT1 polymorphisms.Conclusions: Results indicate that children with GSTP1 Val-105 allele were at higher risk of the adverse cognitive functioning effects of prenatal p,p´-DDT exposure. [ABSTRACT FROM AUTHOR]

Abstract Background Porphyria cutanea tarda (PCT) is caused by hexachlorobenzene (HCB) in several species of laboratory mammals, but the human evidence is contradictory. In a study among adults of a population highly exposed to HCB (Flix, Catalonia, Spain), the prevalence of PCT was not increased. We aimed at analysing the association of individual urinary porphyrins with the serum concentrations of HCB and other organochlorine compounds in this highly exposed population. Methods A cross-sectional study on total porphyrins was carried out in 1994 on 604 inhabitants of the general population of Flix, older than 14 years. Of them, 241 subjects (comprising a random sample and the subgroup with the highest exposure) were included for the present study. The porphyrin profile was determined by high-pressure liquid chromatography. Serum concentrations of HCB, as well as common organochlorine compounds, were determined by gas chromatography coupled to electron capture detection. Results Coproporphyrin I (CPI) and coproporphyrin III (CPIII) were the major porphyrins excreted, while uroporphyrins I and III were only detected in 2% and 36% of the subjects respectively, and heptaporphyrins I and III in 1% and 6%, respectively. CPI and CPIII decreased with increasing HCB concentrations (p < 0.05). This negative association was not explained by age, alcohol, smoking, or other organochlorine compounds. No association was found between uroporphyrin I and III excretion, nor heptaporphyrin excretion, and HCB. CPIII increased with smoking (p < 0.05). Conclusion HCB exposure in this highly exposed population did not increase urinary concentrations of individual porphyrins.

The physical, social and intellectual development of children from conception to the end of adolescence requires an environment which is both protected and protective of their health. A growing number of diseases in children are linked to the unsafe environments. Prenatal and early life exposures including diet are associated with child health and human development and predispose to late adult effects. Children are more vulnerable than adults to environmental exposures. Children are not little adults-since they are still growing and their immune system and detoxification mechanisms are not fully developed, they are especially vulnerable to chemical, physical and biological hazards in air, water and soil. The project INfancia y Medio Ambiente (INMA) will follow up a life-stage approach and prospectively enroll a population sample of 5.000 pregnant mothers and newborns. Existing and new cohorts of pregnant women will be incorporated from seven different Spanish regions. The INMA project aims to transfer knowledge and methodology between the different Spanish groups that are studying environment and health; to describe the degree of individual contamination to persistent organic pollutants and metals and the burden of exposure during pregnancy and early infancy; to evaluate the impact of the exposure to different contaminants and both the protective and negative factors of diet on infants' growth and development; and to contrast the hypothesis generated from other ongoing cohorts. Environmental, nutrition, biological and psychosocial exposures at the prenatal and postnatal periods will be evaluated. Outcomes include prenatal and birth health events, neurodevelopment, behavioural functioning, immunity and hormonal disruption. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Exposure to organochlorine compounds (OCs) occurs both in utero and through breastfeeding. Levels of hexachlorobenzene (HCB) found in the cord serum of newborns from a population located in the vicinity of an electrochemical factory in Spain were among the highest ever reported. We studied the association between exposure to OCs and breastfeeding on neurodevelopment in the 1-year-old infants of this population. METHODS: A birth cohort including 92 mother-infant pairs was recruited between 1997 and 1999 in 5 neighboring villages (84% of possible recruits). The mental and psychomotor development of each infant was assessed at 13 months using the Bayley and the Griffiths Scales of Infant Development. OCs were measured in cord serum. RESULTS: Dichlorodiphenyl dichloroethylene (p,p'DDE) cord serum levels were negatively associated with both mental and psychomotor development. For each doubling of a dose of p,p'DDE, we found a resultant decrease of 3.50 points (standard error: 1.39) on the mental scale and 4.01 points (standard error: 1.37) on the psychomotor scale. Exposure to polychlorinated biphenyls was only marginally associated with psychomotor development. Prenatal exposure to HCB had no effect on child neurodevelopment. Long-term breastfeeding was associated with better performance on both the mental and motor scales. Short-term breastfed infants with higher p,p'DDE levels in cord serum were associated with the lowest scores on both the mental and the psychomotor scales. CONCLUSIONS: Prenatal exposure to p,p'DDE was associated with a delay in mental and psychomotor development at 13 months. No association was found for exposure to HCB. Long-term breastfeeding was found to be beneficial to neurodevelopment, potentially counterbalancing the impact of exposure to these chemicals through breast milk. [ABSTRACT FROM AUTHOR]

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. At 4 years old, ADHD symptoms were reported by teachers through the ADHD Diagnostic and Statistical Manual of Mental Disorders, 4th ed checklist (n = 580). At 7 years old, ADHD symptoms were reported by parents through the Conners' Rating Scale-Revised (short form; n = 642). The ADHD variable was treated as continuous (score) and as dichotomous (symptom diagnostic criteria). Child and family general characteristics were prospectively collected through questionnaires. We applied pooled zero-inflated negative binomial and logistic regressions adjusted for covariates., Results: A higher omega-6:omega-3 long-chain polyunsaturated fatty acid ratio in cord plasma was associated with a higher ADHD index (incidence rate ratio, 1.13; 95% CI, 1.03, 1.23) at 7 years old. The association was not observed at 4 years old (incidence rate ratio, 1.04; 95% CI, 0.92-1.18). No associations were found using ADHD symptom diagnostic criteria., Conclusions: High prenatal omega-6:omega-3 long-chain polyunsaturated fatty acid ratio preceded the appearance of subclinical ADHD symptoms during mid-childhood. Our findings suggest that maternal diet during pregnancy may modulate the risk to develop long-term ADHD symptoms in the offspring., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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. We reviewed 834 clinical records of patients referred to Child and Adolescent Mental Health Services and examined SCT symptoms and their relation with sociodemographic data, clinical diagnosis, comorbid conditions, Child Behavior Checklist dimensions, and intelligence quotient. Of the 515 patients (age range, 4 to 17 y, 62.5% male) for whom a fully completed Child Behavior Checklist for Children and Adolescents was available, 20.8% showed high levels of SCT symptoms. SCT symptoms were strongly associated with age, internalizing symptoms, learning disabilities, and ADHD inattentive subtype (ADHD-I). No significant correlations with intelligence quotient were found. We concluded that SCT symptoms are highly prevalent in a clinical sample, and that these symptoms might be related to the difficulties that some individuals have in responding to demands in their environments, such as academic or social demands, as they increase over time.

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., Methods: Six hundred pregnant women in the third trimester completed a food frequency questionnaire, and iodine was measured in urine samples. Urinary iodine concentrations were described in the whole population and in subgroups according to their frequency of intake of milk, fish, eggs, bread and iodized salt, as iodine supplements., Results: The median UIC was 104 microg/l (n = 600), however, the median was higher among women who had a high milk intake (117 microg/l), used iodized salt (117 microg/l) or who were supplemented with iodine (141 microg/l). Women receiving iodine supplementation who also consumed more than one cup of milk per day had median UIC higher than 150 microg/l. In multivariate models, women with moderate and high milk intake had lower risk of having UIC below 150 microg/l [OR (95% CI): 0.42 (0.22-0.82) and 0.29 (0.15-0.55) respectively], after adjustment for potential confounders., Conclusions: On the basis of WHO criteria, the iodine status of pregnant women was inadequate in this area. Milk was the most important dietary source of iodine, and iodine supplementation was also an important source of iodine, although not enough to reach the current recommendations.

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. Maternal seafood intakes were assessed using a semi-quantitative FFQ administered shortly after delivery. Multivariate linear regression was used to estimate associations between seafood consumption and scores on the McCarthy Scales of Children's Abilities (MCSA). Analyses were stratified by breast-feeding duration as breast milk is a source of DHA during the postnatal phase of the brain growth spurt., Setting: Menorca, Spain, 1997-2001., Subjects: Full-term children (n 392) with data on maternal diet in pregnancy, breast-feeding duration and neurodevelopment at age 4 years., Results: Among children breast-fed for <6 months, maternal fish intakes of >2-3 times/week were associated with significantly higher scores on several MCSA subscales compared with intakes < or =1 time/week. There was no association among children breast-fed for longer periods. Maternal intakes of other seafood (shellfish/squid) were, however, inversely associated with scores on several subscales, regardless of breast-feeding duration., Conclusions: The study suggests that moderately high intakes of fish, but not other seafood, during pregnancy may be beneficial for neurodevelopment among children breast-fed for <6 months. Further research in other populations with high seafood intakes and data on additional potential confounders are needed to confirm this finding.

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. Information about folic acid and other over-the-counter dietary supplements was obtained prospectively using interviewer-administered questionnaires at the end of the first trimester of pregnancy. Psychological outcomes were assessed by two psychologists and teachers 4 years later. Low maternal socio-economic status, smoking, high parity and short duration of breast feeding were associated with lower prevalence of folic acid supplement use. Verbal (b = 3.98, SE = 1.69), motor (b = 4.54, SE = 1.66) and verbal-executive function (b = 3.97, SE = 1.68) scores, social competence (b = 3.97, SE = 1.61) and inattention symptom [OR = 0.46; 95% CI 0.22, 0.95] scores were associated with reported folic acid use. Reported folic acid supplement use during pregnancy was associated with improved neurodevelopment in children after adjusting for a number of sociodemographic and behavioural factors.

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., Objectives: We aimed to analyze the association between urinary porphyrin excretion and exposure to HCB and other organochlorinated compounds in children 4 years of age., Methods: Our birth cohort included all newborns from Flix and the five surrounding towns (where no airborne pollution occurred). Among the 68 children with porphyrins we measured in cord blood, 52 children 4 years of age provided blood to measure organochlorine compounds, hair for methylmercury, and urine for porphyrin excretion pattern., Results: Quantitative porphyrin excretion was within the normal values. However, total porphyrins, coproporphyrin I (CPI), and coproporphyrin III (CPIII) adjusted to creatinine excretion increased with increasing levels of HCB, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT), and polychlorinated biphenyl congener 153 (PCB-153). We found no association with methylmercury. When we fitted multiple pollutant models, p,p'-DDE had the strongest association. We found these associations in children from both Flix and other towns, and they were independent of breast-feeding and of organochlorine and porphyrin levels at birth., Conclusion: HCB at current levels did not induce porphyria or increase uroporphyrins. However, the increase of urinary coproporphyrins suggests an incipient toxic effect of the organochlorines, especially for p,p'-DDE, on the hepatic heme-synthesis pathway that differs from the major effects seen in PCT.

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. The TSH concentration was categorized (high or low), except for 27 children whose TSH levels were quantified., Results: Levels of beta-HCH and PCB-153 were positively related to TSH concentrations (gestational age-adjusted coefficient (p-value): 0.26 (p = 0.006) and 0.31 (p = 0.050), respectively)., Conclusions: beta-HCH is potentially a new thyroid disrupting compound, deserving special interest in future studies given its high body burden in humans.

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., Design: Data from a prospective cohort of 369 Spanish children born in 1997-1998 were used. Logistic regression was used to estimate associations between maternal smoking during different time periods and odds of child overweight later in life., Results: Maternal smoking during the first trimester was more strongly associated with overweight (adjusted odds ratio: 2.65; 95% CI: 1.26, 5.54) than smoking later in pregnancy (1.88, 0.85, 4.15). Smoking limited to the first month of pregnancy was also associated with child overweight. Neither paternal smoking nor maternal smoking before or after pregnancy was associated with child overweight. Significant interactions with breastfeeding duration indicated that first-trimester smoking was associated with overweight only among children breastfed for <6 mo, suggesting prolonged breastfeeding may help to counter adverse effects of smoking in early pregnancy., Conclusions: These data suggest maternal smoking very early in pregnancy may increase risk of later overweight in children and provide further support for promoting smoking cessation before rather than during early pregnancy. Further studies are needed to confirm these results.

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. The most comprehensive studies are the National Reports on Human Exposure to Environmental Chemicals (USA), the German Environmental Survey, and the Arctic Monitoring and Assessment Programme. Population-wide studies exist as well in New Zealand, Australia, Japan, Flanders (Belgium) and the Canary Islands (Spain). Most such studies are linked with health surveys, which is a highly-relevant additional strength. Only the German and Flemish studies analyzed POPs by educational level, while studies in the USA offer results by ethnic group. The full distribution of POPs concentrations is unknown in many countries. Knowledge gaps include also the interplay of age, gender, period and cohort effects on the prevalence of exposures observed by cross-sectional surveys. Local and global efforts to minimize POPs contamination, like the Stockholm convention, warrant nationwide monitoring of concentrations of POPs in representative samples of the general population. Results of this review show how such studies may be developed and used.

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., Methods: In the context of a multi-center project (INMA project), a prospective birth cohort was set up in Valencia, Spain, from 2005 to 2006. A total of 253 newborns were included in this study. We compared cord blood T-Hg concentration by levels of fish intake assessed by a food frequency questionnaire completed at 28-32 weeks of gestation. Maternal covariates were obtained through a questionnaire., Results: The geometric mean of T-Hg at birth was 9.9 microg/L (95% CI: 9.0, 10.8). Seventy five percent of cord blood samples were above the estimated level assumed to be without appreciable harm (5.8 microg/L). Women who consumed a portion of large oily fish, lean fish, or mixed fried fish two or more times per week had mean cord blood levels 1.6, 1.4 and 1.3 times higher, respectively, than those who rarely or never consumed fish. Other factors such as the mother's age, country of origin, smoking and season of delivery were also significantly and independently associated with cord blood T-Hg concentrations., Conclusions: Newborns from a Mediterranean area presented elevated levels of T-Hg in cord blood. Higher concentrations of T-Hg were related to maternal fish intake, particularly in the case of large oily fish species.

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. Two birth cohorts in Spain (Ribera d'Ebre and Menorca) were recruited between 1997 and 1999 (n = 391). Infants were assessed at age 4 years using the McCarthy Scales of Children's Abilities. Levels of organochlorine compounds were measured in umbilical cord serum. Information on type and duration of breastfeeding was obtained by questionnaire when the children were 1 year of age. Children who were breastfed for more than 20 weeks had better cognitive performance regardless of their in utero exposure to DDT. A linear dose response between breastfeeding and cognition was observed in all DDT groups (for children highly exposed to DDT, adjusted beta = 0.30 (standard error, 0.12) per week breastfed). Despite the possibility of harm from environmental contaminants in breast milk, breastfeeding for long periods should still be recommended as the best infant feeding method.

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. Interviewer-administered questionnaires were completed by mothers during the third trimester of pregnancy and then every year up to age 4 years of their child. A standardized version of the McCarthy Scales of Children's Abilities (MCSA) was used to evaluate the child's motor and cognitive capabilities. Multivariable regressions were used with MCSA's assessed outcomes adjusting for: home location, maternal alcohol consumption, mother's social class and level of education during pregnancy, parity, marital status, father's education level, child's gender, birth weight and height, breastfeeding duration, passive smoking, school season, age during test administration and evaluator (psychologist)., Results: A high global consistency in maternal smoking habits was found (total agreement = 88.7%). Maternal social class and education level were inversely associated with maternal smoking behaviour. Maternal smoking during pregnancy (in cig./day) was associated with a decrease (in points) of children's global cognitive score [beta = -0.60, (95% CI: -1.10; -0.09)]; as well as global cognitive sub-areas like verbal score [beta = -0.59, (95% CI: -1.11; -0.07)]; quantitative score [beta = -0.57, (95% CI: -1.08; -0.06)]; executive function score [beta = -0.71, (95% CI: -1.23; -0.20)]; and working memory score [beta = -0.46, (95% CI: -0.92; -0.01)]., Conclusion: Our findings suggest an association with maternal smoking during pregnancy and lowered cognitive development in children at age 4 years.

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). Children were assessed by three psychologists and their respective teachers for neuropsychological functions (McCarthy test), attention-hyperactivity behaviours (Attention-Deficit Hyperactivity Disorder Criteria of DSM-IV) and social behaviour (California Preschool Social Competence Scale)., Results: Long-term breast-feeding was associated with executive function scores (an increase of 4.9 points after breast-feeding >20 weeks), and the improvement of social competence scores (relative risk for being in the poorest 20%, RR = 0.57; 0.52-0.66, after >12 weeks) and attention-deficit hyperactivity symptom scores (RR = 0.56; 0.37-0.85, after >12 weeks). All three outcomes remained significant when included as covariates in the regression models., Conclusion: Long-term breast-feeding was found to be associated with fewer attention and hyperactivity symptoms and an improvement in related behavioural areas (neuropsychological and socio-behavioural outcomes).