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Background Monitoring iodine status during pregnancy is essential to prevent iodine-related disorders. The objectives of this study are to estimate iodine intake and excretion, to assess their association and to evaluate the compliance of the recommendations in a multicentre cohort of pregnant women. Methods Cross-sectional data on maternal iodine nutritional status, compiled between weeks 8 and 22 of gestation in three Spanish areas (Valencia, Gipuzkoa and Sabadell), were analysed. Information on iodine intake from diet, salt and supplements was estimated through questionnaires. Spot urine samples were analysed for urinary iodine concentration (UIC). Tobit regression analysis was used to assess the association between iodine intake and UIC. Results 1522 women were included in the study. Median UIC was 134 (IQR 80-218) mu g/l in Valencia, 168 (IQR 108-272) mu g/l in Gipuzkoa and 94 (IQR 57-151) mu g/l in Sabadell. 48.9% of Valencian women consumed iodine supplements, 93.3% in Gipuzkoa and 11.0% in Sabadell. Prevalence of iodised salt consumption was 50.5% in the whole sample. UIC was associated with intake of supplements, iodised salt, dietary iodine and water. UIC levels were lower than expected according to the estimated iodine intake. Conclusion Median UIC reflected iodine deficiency according to WHO reference levels, except in Gipuzkoa where supplements are widely consumed. It is necessary to strengthen iodised salt consumption since it is already far from the objective proposed of coverage of 90% of households. More data would be valuable to assess the correspondence between iodine intake and excretion during pregnancy.

Background: An adequate iodine intake during pregnancy is essential for the synthesis of maternal thyroid hormones and normal brain development in the fetus. Scant evidence is available on the effects and safety of iodine supplementation during pregnancy in areas with adequate or mildly deficient iodine intake. We examined the association of maternal iodine intake and supplementation with thyroid function before 24 weeks of gestation in population-based samples from 3 different areas in Spain. Methods: A cross-sectional study of 1844 pregnant women (gestational age range 8-23 weeks) was carried out in 3 areas in Spain (Guipúzcoa, Sabadell, Valencia), during the period 2004-2008. We measured levels of free thyroxine and thyroid-stimulating hormone (TSH) in serum, iodine in a spot urine sample, and questionnaire estimates of iodine intake from diet, iodized salt and supplements. Adjusted associations were assessed by multiple linear regression and logistic regression analyses. Results: There was an increased risk of TSH above 3 μU/mL in women who consumed 200 μg or more of iodine supplements daily compared with those who consumed less than 100 μg/day (adjusted odds ratio = 2.5 [95% confidence interval = 1.2 to 5.4]). We observed no association between urinary iodine and TSH levels. Pregnant women from the area with the highest median urinary iodine (168 μg/L) and highest supplement coverage (93%) showed the lowest values of serum free thyroxine. (geometric mean = 10.09 pmol/L [9.98 to 10.19]). Conclusions: Iodine supplement intake in the first half of pregnancy may lead to maternal thyroid dysfunction in iodine-sufficient or mildly iodine-deficient populations. © 2009 by Lippincott Williams & Wilkins., Supported by grants from Instituto de Salud Carlos III (Red INMA G03/176 and CB06/02/0041), the Spanish Ministry of Health (FIS 03/1615, FIS 04/1509, FIS 04/1436, FIS 05/1079, FIS 06/1213, FIS06/0867), Ministerio Educacion y Ciencia (SAF2002-03508), the Generalitat de Catalunya-CIRIT 1999SGR 00241, Departamento de Sanidad-Gobiemo Vasco 2005111093, and Diputacion Foral de Gipuzkoa 06/004.

The effect of organochlorine compounds (OCs) on thyroid function, as well as the potential confounding effect of iodine intake, was studied in a large sample of pregnant women from two population-based cohort studies in Sabadell (n = 520) and Gipuzkoa (n = 570), Spain. Thyroid hormones (free T4 and total T3), thyrotropin, and polychlorinated biphenyls (PCB congeners 118, 138, 153, and 180), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (beta-HCH), dichlorodiphenyl dichloroethylene (p'p'-DDE) and dichlorodiphenyl richloroethane (p'p-DDT) were measured in serum samples collected at first trimester of pregnancy. Urinary iodine concentration (UIC) was measured and iodine intake from diet, iodized salt, and supplements were estimated from a food frequency questionnaire. Levels of HCB and PCBs congeners 180, 153, and 138 were related to lowe rtotal T3 levels (adjusted coefficient (SE): -4.0(1.1), -6.1(1.6), -5.5(1.6), and 3.8(1.4), respectively) and higher free T4 levels (adjusted coefficient (SE): 0.013(0.05), 0.017(0.007), 0.016(0.007), and 0.007(0.006), respectively). These associations were homogeneous in both cohorts, especially for PCBs and total T3 (p-value forthe interaction between cohorts >0.8). Iodine intake and UIC did not affect the association between OCs and thyroid hormones. Our results indicate that exposure to OCs during pregnancy can alter TH levels.

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.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.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.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.

Background: Mental health has been reported to be associated with allergy, but only a few cohort studies have assessed if neurodevelopment predicts atopy. Objective: To investigate if neurobehavioral status of healthy 4-year-old children was associated with specific immunoglobulin E (IgE) at the same age and skin prick test results 2 years later. Methods: A population-based birth cohort enrolled 482 children, 422 of them (87%) provided neurobehavioral data, 341 (71%) had specific IgE measured at the age of 4 years; and 395 (82%) had skin prick tests completed at the age of 6 years. Atopy was defined as IgE levels higher than 0.35 kU/l to any of the three tested allergens at the age of 4 or as a positive skin prick test to any of the six tested allergens at the age of 6. McCarthy Scales of Child Abilities and California Preschool Social Competence Scale were the psychometric instruments used. Results: Twelve percent of children at the age of 4 and 17% at the age of 6 were atopic. Neurobehavioral scores were negatively associated with 6-year-old atopy after adjustment for socio-demographic and allergic factors, A relative risk of 3.06 (95% CI: 1.30–7.24) was associated with the lowest tertile (scorings ≤90 points) of the general cognitive scale. Similar results were found for verbal abilities, executive functions, and social competence. Asthma, wheezing, rhinitis, and eczema at the age of 6, but not at the age of 4, were associated with neurodevelopment at the age of 4. Conclusions: Neuropsychologic functioning and later atopy are negatively associated in preschool age children.

Background: There is growing evidence that traffic-related air pollution reduces birth weight. Improving exposure assessment is a key issue to advance in this research area./nObjective: We investigated the effect of prenatal exposure to traffic-related air pollution via geographic information system (GIS) models on birth weight in 570 newborns from the INMA (Environment and Childhood) Sabadell cohort./nMethods: We estimated pregnancy and trimester-specific exposures to nitrogen dioxide and aromatic hydrocarbons [benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX)] by using temporally adjusted land-use regression (LUR) models. We built models for NO2 and BTEX using four and three 1-week measurement campaigns, respectively, at 57 locations. We assessed the relationship between prenatal air pollution exposure and birth weight with linear regression models. We performed sensitivity analyses considering time spent at home and time spent in nonresidential outdoor environments during pregnancy./nResults: In the overall cohort, neither NO2 nor BTEX exposure was significantly associated with birth weight in any of the exposure periods. When considering only women who spent < 2 hr/day in nonresidential outdoor environments, the estimated reductions in birth weight associated with an interquartile range increase in BTEX exposure levels were 77 g [95% confidence interval (CI), 7–146 g] and 102 g (95% CI, 28–176 g) for exposures during the whole pregnancy and the second trimester, respectively. The effects of NO2 exposure were less clear in this subset./nConclusions: The association of BTEX with reduced birth weight underscores the negative role of vehicle exhaust pollutants in reproductive health. Time–activity patterns during pregnancy complement GIS-based models in exposure assessment.

IntroductionThe fetus is most vulnerable to severe iodine deficiency and hypothyroidism during pregnancy. The effects of mild iodine deficiency and subclinical hypothyroidism are poorly known. The present study assesses the association between thyroid hormones (TH)s and urinary iodine concentration (UIC) in healthy pregnant women and the birth weight of their children.MethodsAbout 657 pregnant women were recruited in Sabadell and followed until delivery. The association between THs during the first trimester, UIC during the first and third trimesters, and birth weight was studied in 557, 251, and 528 mother–newborn pairs respectively, using linear and logistic regression models adjusted for potential confounders. Only 239 women had all the data available (thyroid function and UIC at the first and third trimesters). Six percent of newborns were classified as small for gestational age (SGA).ResultsThe median UIC was 95 and 104 μg/l during the first and third trimesters respectively. Women with the third trimester UICs between 100 and 149 μg/l had lower risk of having an SGA newborn than women with UICs below 50 μg/l (adjusted OR (95%CI): 0.15 (0.03–0.76). There was no significant reduction in SGA among mothers with higher UICs. Lower free thyroxine and higher TSH levels during the first trimester were not associated with birth weight or SGA. Nevertheless, the analyses were repeated including only those women with all the data available, and high TSH levels became statistically significantly associated with lower birth weight and higher risk of SGA.ConclusionsThe present study suggests that iodine status during pregnancy may be related to prenatal growth in healthy women.

BACKGROUND: In elderly individuals, hypertension is a main risk factor for cardiovascular disease and oxidative damage is increased. Our aim was to assess the relationship between the degree of in vivo low-density lipoprotein (oxLDL) oxidation and the hypertensive status in a elderly population at high cardiovascular risk. METHODS: Cross-sectional study with baseline data from the PREDIMED (PREvención con DIeta MEDiterránea) trial, an intervention study directed at testing the efficacy of the Mediterranean diet on the primary prevention of cardiovascular disease. Participants were 1,130 subjects at high cardiovascular risk aged 55-80. At baseline, in vivo circulating oxLDL was measured, and stages of hypertension determined according to the USA Joint National Committee guidelines. RESULTS: A positive relationship between in vivo oxLDL and systolic and diastolic blood pressure (DBP) was observed after adjusting for confounding factors (P < 0.05). OxLDL concentrations increased in a linear manner from low to high hypertensive stages (P < 0.05). CONCLUSIONS: Elderly individuals at high cardiovascular risk showed higher levels of circulating oxLDL when their hypertensive status increased. This fact identifies the hypertensive elderly population as a target for antioxidant preventive measures., This study was funded by the Spanish Ministry of Health (Networks G03/140, RD06/0045 and research grants PI040233, PI070240, and CP06/00100 of the Instituto de Salud Carlos III). The CIBER Fisiopatología de la Obesidad y Nutrition and the CIBER Epidemiología y Salud Pública are an initiative of the Instituto de Salud Carlos III. We thank the Fundación Patrimonio Comunal Olivarero and Hojiblanca SA, California Walnut Commission, Borges SA, and Morella Nuts SA for donating the olive oil, walnuts, almonds, and hazelnuts, respectively.

Two particular polymorphisms, namely PON1-192 and PON2-311, in the genes encoding the antioxidant enzymes paraoxonase-1 (PON1) and paraoxonase-2 (PON2) have been associated with an increased risk of acute myocardial infarction (AMI). However, previous findings have been contradictory. The aim of this study was to investigate the association between the PON1-192 and PON2-311 polymorphisms and their interaction on AMI risk.This case-control study involved 746 consecutive AMI patients and 1796 control subjects without cardiovascular disease, who were randomly selected from the same population from which the patients came. All participants were recruited between 1999 and 2000 from four Spanish autonomous regions. All were assessed for the presence of PON1-192 and PON2-311 and for classical cardiovascular risk factors. Multivariate analysis was carried out using logistic regression modeling.The odds ratios (OR) of AMI for patients with the PON1-192 QQ and PON2-311 SS genotypes (who comprised 50% and 66% of the population, respectively) were 1.26 (95% confidence interval [CI], 1.02-1.55) and 1.25 (95% CI, 1.04-1.50), respectively, compared with R and C allele carriers. Moreover, in patients with both QQ and SS genotypes, the adjusted OR of AMI increased to 1.41 (95% CI, 1.13-1.76).Our results indicate that the PON1-192 and PON2-311 polymorphisms were independent risk factors of AMI in our population.

To compare the utility of two multivariate analytic methods, case-control (CC) analysis and nested case-control (NCC) analysis in a cohort, to identify the factors associated with the onset of cannabis use.A longitudinal cohort study of a sample of secondary school students (n = 1,056) in the first year of secondary school was carried out. Participating students were followed-up annually until the fourth year of secondary school. In the CC analysis, students in the fourth year who reported having consumed cannabis at some time were considered cases and those who had never consumed cannabis were considered controls. Logistic regression (LR) models were estimated. In the NCC analysis, cases in each year of follow-up were compared with a random sample of controls at risk in the same year and conditional LR models were estimated.In the CC analysis, 6 variables in boys and 9 variables in girls in bivariate models and 3 variables in boys and 4variables in girls in multivariate models were identified. In the NCC analysis, 17 variables in univariate models and 4 in multivariate models were obtained in both boys and girls. The estimators of the CC analysis showed an average of 1.2-fold more variability.A higher number of factors associated with cannabis use were identified in the NCC analysis and the estimators were more precise. NCC could be a more efficient option than CC analysis.

The high energy content of alcohol makes its consumption a potential contributor to the obesity epidemic.To determine whether alcohol consumption is a risk factor for abdominal obesity, taking into account energy underreporting.The subjects were Spanish men (n = 1491) and women (n = 1563) aged 25-74 years who were examined in 1999-2000, in a population-based cross-sectional survey in northeastern Spain (Girona). Dietary intake, including alcohol consumption, was assessed using a food frequency questionnaire. Anthropometric variables were measured.The mean consumption of alcohol was 18.1 +/- 20.7 g/d in men and 5.3 +/- 10.4 g/d in women. 19.3% of men and 2.3% of women reported alcohol consumption of more than 3 drinks per day. The consumption of alcohol was directly associated with total energy intake in men (P0.001) and women (P = 0.001). The proportion of energy underreporting significantly (P0.001) decreased with higher amounts of alcohol drinking in both genders. Multiple logistic regression analysis, controlled for energy underreporting, smoking, educational level, leisure-time physical activity, energy, and diet quality, revealed that consuming more than 3 drinks of alcohol (30 g ethanol) was significantly associated with the risk of abdominal obesity (Odds ratio 1.80; 1.05, 3.09) and exceeding recommended energy consumption (Odds ratio 1.97; 1.32, 2.93) in men. A very small number (2.13%) of women in this population reported high levels of alcohol consumption.Alcohol consumption in elevated amounts was associated with risk of abdominal obesity in men, independent of energy underreporting.

Objetivo: Determinar los factores asociados al inicio del consumo de cannabis a partir de una revision sistematica de estudios de cohortes. Metodos: Se realizo una busqueda bibliografica informatizada utilizando diversas palabras clave y sus combinaciones. Entre los estudios identificados se seleccionaron los estudios originales de diseno longitudinal que utilizaran como variable dependiente el inicio de consumo de cannabis, asi como los estudios de revision, publicados entre enero de 1980 y mayo de 2004. Se evaluo la calidad metodologica de los estudios mediante 2 revisores, de manera independiente y a partir de unos criterios prestablecidos, clasificando los articulos en 3 categorias: alta, intermedia o baja calidad. Se midio el nivel de concordancia de los revisores a partir del coeficiente kappa. Resultados: Se identificaron 32 estudios que cumplian los criterios de seleccion, de los cuales 13 fueron determinados de alta calidad. Las causas de exclusion fueron el sesgo de seleccion, por la inclusion de consumidores al inicio de la cohorte estudiada, y la falta de ajuste por los potenciales confusores. Los factores que se relacionaron con una mayor evidencia con el inicio del consumo de cannabis fueron el sexo masculino, el consumo de tabaco y alcohol, tener una relacion problematica con los padres y el consumo de cannabis por parte de los amigos. Conclusiones: Los resultados senalan la importancia de diversos factores individuales, familiares y del entorno en el inicio del consumo de cannabis, que deberian considerarse de forma conjunta en el abordaje preventivo entre los adolescentes.

Background Despite the richness in antioxidants of the Mediterranean diet, to our knowledge, no randomized controlled trials have assessed its effect on in vivo lipoprotein oxidation. Methods A total of 372 subjects at high cardiovascular risk (210 women and 162 men; age range, 55-80 years), who were recruited into a large, multicenter, randomized, controlled, parallel-group clinical trial (the Prevención con Dieta Mediterránea [PREDIMED] Study) directed at testing the efficacy of the traditional Mediterranean diet (TMD) on the primary prevention of coronary heart disease, were assigned to a low-fat diet (n = 121) or one of 2 TMDs (TMD + virgin olive oil or TMD + nuts). The TMD participants received nutritional education and either free virgin olive oil for all the family (1 L/wk) or free nuts (30 g/d). Diets were ad libitum. Changes in oxidative stress markers were evaluated at 3 months. Results After the 3-month interventions, mean (95% confidence intervals) oxidized low-density lipoprotein (LDL) levels decreased in the TMD + virgin olive oil (−10.6 U/L [−14.2 to −6.1]) and TMD + nuts (−7.3 U/L [−11.2 to −3.3]) groups, without changes in the low-fat diet group (−2.9 U/L [−7.3 to 1.5]). Change in oxidized LDL levels in the TMD + virgin olive oil group reached significance vs that of the low-fat group (P = .02). Malondialdehyde changes in mononuclear cells paralleled those of oxidized LDL. No changes in serum glutathione peroxidase activity were observed. Conclusions Individuals at high cardiovascular risk who improved their diet toward a TMD pattern showed significant reductions in cellular lipid levels and LDL oxidation. Results provide further evidence to recommend the TMD as a useful tool against risk factors for CHD., This study was funded by the Spanish Ministry of Health (Networks G03/140 and RD06/0045).

Effect of a traditional Mediterranean diet on lipoprotein oxidation: a randomized controlled trial. BACKGROUND: Despite the richness in antioxidants of the Mediterranean diet, to our knowledge, no randomized controlled trials have assessed its effect on in vivo lipoprotein oxidation. METHODS: A total of 372 subjects at high cardiovascular risk (210 women and 162 men; age range, 55-80 years), who were recruited into a large, multicenter, randomized, controlled, parallel-group clinical trial (the Prevención con Dieta Mediterránea [PREDIMED] Study) directed at testing the efficacy of the traditional Mediterranean diet (TMD) on the primary prevention of coronary heart disease, were assigned to a low-fat diet (n = 121) or one of 2 TMDs (TMD + virgin olive oil or TMD + nuts). The TMD participants received nutritional education and either free virgin olive oil for all the family (1 L/wk) or free nuts (30 g/d). Diets were ad libitum. Changes in oxidative stress markers were evaluated at 3 months. RESULTS: After the 3-month interventions, mean (95% confidence intervals) oxidized low-density lipoprotein (LDL) levels decreased in the TMD + virgin olive oil (-10.6 U/L [-14.2 to -6.1]) and TMD + nuts (-7.3 U/L [-11.2 to -3.3]) groups, without changes in the low-fat diet group (-2.9 U/L [-7.3 to 1.5]). Change in oxidized LDL levels in the TMD + virgin olive oil group reached significance vs that of the low-fat group (P = .02). Malondialdehyde changes in mononuclear cells paralleled those of oxidized LDL. No changes in serum glutathione peroxidase activity were observed. CONCLUSIONS: Individuals at high cardiovascular risk who improved their diet toward a TMD pattern showed significant reductions in cellular lipid levels and LDL oxidation. Results provide further evidence to recommend the TMD as a useful tool against risk factors for CHD.

Objectives To evaluate the association between occupational exposure to extremely low frequency magnetic fields (ELF-MF) or electric shocks and brain cancer, haemopoietic and lymphatic malignancies, and breast cancer incidence in the Nordic Occupational Cancer cohort. Method The cohort was set up by linking occupational information from national censuses held in 1960, 1970, 1980–1, and/or 1990 to national cancer registry data in Finland, Iceland, Norway, and Sweden. All subjects aged 30–64 years who participated in a census were followed-up for cancer incidence until 2003–2005. Occupational exposure to ELF-MF or electric shocks (low, medium, high) was assigned to each subject based on census reported jobs using job-exposure matrices. For each case, five controls were randomly selected by matching for country, age, and sex. Conditional logistic regression models were performed adjusting for social class and occupational exposure to solvents. Results A total of 68 770 brain cancer cases, 65 609 non-hodgkin lymphoma cases, 83 088 leukaemia cases, 33 791 multiple myeloma cases, 1827 male breast cancer cases, and 297,283 female breast cancer cases were included. Thirty-five percent of the total population was ever exposed to medium levels of ELF-MF and 7% to high levels, whereas 19% was ever exposed to a medium risk of electric shocks and 13% to a high risk. No associations were found between occupational exposure to ELF-MF or electric shocks and any of the cancer outcomes. Conclusions In this very large census cohort we found no evidence of increased risk of several cancers in relation with occupational exposure to ELF-MF or electric shocks.

Background Maternal psychological distress during pregnancy might affect fetal lung development and subsequently predispose children to childhood asthma. Objective We sought to assess the associations of maternal psychological distress during pregnancy with early childhood wheezing. Methods We performed a population-based prospective cohort study among 4848 children. We assessed maternal and paternal psychological distress at the second trimester of gestation and 3 years after delivery and maternal psychological distress at 2 and 6 months after delivery by using the Brief Symptom Inventory questionnaire. Wheezing in the children was annually examined by using questionnaires from 1 to 4 years. Physician-diagnosed ever asthma was reported at 6 years. Results Mothers with psychological distress during pregnancy had increased odds of wheezing in their children from 1 to 4 years of life (overall distress: odds ratio [OR], 1.60 [95% CI, 1.32-1.93]; depression: OR, 1.46 [95% CI, 1.20-1.77]; and anxiety: OR, 1.39 [95% CI, 1.15-1.67]). We observed similar positive associations with the number of wheezing episodes, wheezing patterns, and physician-diagnosed asthma at 6 years. Paternal distress during pregnancy and maternal and paternal distress after delivery did not affect these results and were not associated with childhood wheezing. Conclusion Maternal psychological distress during pregnancy is associated with increased odds of wheezing in their children during the first 6 years of life independent of paternal psychological distress during pregnancy and maternal and paternal psychological distress after delivery. These results suggest a possible intrauterine programming effect of maternal psychological distress leading to respiratory morbidity.

We thank Sudan et al 1for their reflections on our work. We appreciate that they reanalysed their data and provided a table of estimates restricting to prenatal cell phone, making their results comparable with that of ours. We acknowledge that, since our study was smaller compared with their study, we obtained less precise risk estimates, but do not agree that our study is uninformative.2 We showed in our paper a consistent non-association between maternal cell phone use and cordless phone use on behavioural problems in children. Even though exposure from cell phones is not identical to that of cordless phones, we would like to highlight that if a biological effect of the exposure to radiofrequency–electromagnetic fields (RF–EMFs) exists, we would expect to observe some similarities regarding the health effects related to cell phones and cordless phones. The fact that we do not …

Objective: To determine whether the amount, type, and patterns of television viewing predict the onset or the persistence of externalizing problems in preschool children. Design: Longitudinal study of a prospective population-based cohort in the Netherlands. Setting: Parents reported time of television exposure and type of programs watched by children. Externalizing problems were assessed using the Child Behavior Checklist at 18 and 36 months. Participants: A population-based sample of 3913 children. Main Exposure: Television viewing time, content, and patterns of exposure (at 24 and 36 months) in children with and without preexisting problems to assess the incidence and persistence of externalizing problems. Main Outcome Measures: Externalizing problems at 36 months. Results: Program content and time of television exposure assessed at 24 months did not predict the incidence of externalizing problems at 36 months (odds ratio, 2.24; 95% CI, 0.97-5.18). However, the patterns of exposure over time reflecting high levels of television viewing were associated with the incidence of externalizing problems (odds ratio, 2.00; 95% CI, 1.07-3.75) and the persistence of the preexisting externalizing problems (2.59; 1.03-6.55). Conclusions: Our study showed that high television exposure increases the risk of the incidence and the persistence of externalizing problems in preschool children. Arch Pediatr Adolesc Med. 2012;166(10):919-925. Published online August 6, 2012. doi:10.1001/archpediatrics.2012.653

Objective We assessed whether maternal C-reactive protein (CRP) levels during pregnancy and CRP gene variations are associated with wheezing and lower respiratory tract infections (LRTIs) in offspring. Study Design Information on wheezing and LRTIs in the offspring at 6 and 14 months of age, and maternal CRP levels and genotype was obtained from a population-based birth cohort. Results A total of 63 children (12.5%) experienced recurrent wheezing and 61 (12.4%) a recurrent diagnosis of LRTIs. Children in the highest tertile of maternal CRP levels had a higher risk of experiencing recurrent wheezing (adjusted odds ratio, 2.87; 95% confidence interval, 1.23–6.71) and being diagnosed with recurrent LRTIs (odds ratio, 2.37; 95% confidence interval, 1.01–5.55), as compared with children in the lowest tertile. The rs1205 polymorphism influenced maternal serum CRP levels but not the risk of the offspring outcomes. Conclusion Higher CRP levels in pregnancy are associated with wheezing and LRTIs in offspring. However, genetic variation in CRP influencing maternal levels is not related to these phenotypes.

Objetivo: Determinar los factores asociados al inicio del consumo de cannabis a partir de una revisión sistemática de estudios de cohortes. Métodos: Se realizó una búsqueda bibliográfica informatizada utilizando diversas palabras clave y sus combinaciones. Entre los estudios identificados se seleccionaron los estudios originales de diseño longitudinal que utilizaran como variable dependiente el inicio de consumo de cannabis, así como los estudios de revisión, publicados entre enero de 1980 y mayo de 2004. Se evaluó la calidad metodológica de los estudios mediante 2 revisores, de manera independiente y a partir de unos criterios prestablecidos, clasificando los artículos en 3 categorías: alta, intermedia o baja calidad. Se midió el nivel de concordancia de los revisores a partir del coeficiente kappa. Resultados: Se identificaron 32 estudios que cumplían los criterios de selección, de los cuales 13 fueron determinados de alta calidad. Las causas de exclusión fueron el sesgo de selección, por la inclusión de consumidores al inicio de la cohorte estudiada, y la falta de ajuste por los potenciales confusores. Los factores que se relacionaron con una mayor evidencia con el inicio del consumo de cannabis fueron el sexo masculino, el consumo de tabaco y alcohol, tener una relación problemática con los padres y el consumo de cannabis por parte de los amigos. Conclusiones: Los resultados señalan la importancia de diversos factores individuales, familiares y del entorno en el inicio del consumo de cannabis, que deberían considerarse de forma conjunta en el abordaje preventivo entre los adolescentes. Objective: To determine the factors associated with the onset of cannabis use through a systematic review of cohort studies. Methods: An internet-based search was performed using several keywords and their combinations. Original studies with longitudinal design and the onset of cannabis use as dependent variable, as well as review studies were included, published between January 1980 and May 2004. Methodology quality of the studies was assessed independently by two reviewers, according to pre-established criteria, in order to classify studies in high, mid or low quality. Agreement between reviewers was assessed through kappa coefficient. Results: A total of 32 relevant studies were identified, of which 13 were of higher quality. Selection bias for the inclusion of consumers at the baseline measurement and lack or insufficient adjustment for confounders were the causes of exclusion. The factors of great evidence related to the onset of cannabis use were masculine sex, consumption of tobacco or alcohol, having a problematic relationship with parents, and cannabis consumption by friends. Conclusion: Results highlight the importance of different individual, family and environmental factors on the onset of cannabis use. These must be considered to properly arrange intervention programs focusing on primary prevention among teenagers.

ResumenObjetivoComparar la utilidad de 2 métodos analíticos multivariados, el análisis como casos y controles (CC) y como casos y controles anidados (CCa) en una cohorte, para identificar los factores asociados al inicio del consumo de cannabis.MétodosEstudio longitudinal con una muestra de 1.056 alumnos de primer curso de Educación Secundaria Obligatoria (ESO), seguidos anualmente hasta cuarto de ESO. En el análisis como CC se consideraron casos los que declararon, en el cuarto año, haber consumido cannabis y controles los que no habían consumido nunca, estimando modelos de regresión logística (RL). En el análisis como CCa, se compararon los casos de cada año de seguimiento con una muestra aleatoria de controles de riesgo en ese mismo año, estimando modelos de RL condicional.ResultadosEn el análisis como CC, se identificaron 6 variables en los chicos y 9 en las chicas en los modelos bivariados, y 3 en los chicos y 4 en las chicas en los multivariados. En el análisis como CCa se obtuvieron 17 variables en los modelos bivariados y 4 en los multivariados, tanto en los chicos como en las chicas. Los estimadores del análisis como CC tenían 1,2 veces más variabilidad.ConclusionesEl análisis como CCa permitió identificar un mayor número de factores asociados al consumo de cannabis y los estimadores fueron más precisos. El CCa puede ser una alternativa más eficiente frente al análisis como CC.AbstractObjectiveTo compare the utility of two multivariate analytic methods, case-control (CC) analysis and nested case-control (NCC) analysis in a cohort, to identify the factors associated with the onset of cannabis use.MethodsA longitudinal cohort study of a sample of secondary school students (n = 1,056) in the first year of secondary school was carried out. Participating students were followed-up annually until the fourth year of secondary school. In the CC analysis, students in the fourth year who reported having consumed cannabis at some time were considered cases and those who had never consumed cannabis were considered controls. Logistic regression (LR) models were estimated. In the NCC analysis, cases in each year of follow-up were compared with a random sample of controls at risk in the same year and conditional LR models were estimated. IResultsIn the CC analysis, 6 variables in boys and 9 variables in girls in bivariate models and 3 variables in boys and 4 variables in girls in multivariate models were identified. In the NCC analysis, 17 variables in univariate models and 4 in multivariate models were obtained in both boys and girls. The estimators of the CC analysis showed an average of 1.2-fold more variability.ConclusionsA higher number of factors associated with cannabis use were identified in the NCC analysis and the estimators were more precise. NCC could be a more efficient option than CC analysis.

Environment International 131, 104927 (2019)

Environment International 131, 104927 (2019)

Background: Studies investigating the relationship between exposure to air pollution and brain development using magnetic resonance images are emerging. However, most studies have focused only on prenatal exposures, and have included a limited selection of pollutants. Here, we aim to expand the current knowledge by studying pregnancy and childhood exposure to a wide selection of pollutants, and brain morphology in preadolescents. Methods: We used data from 3133 preadolescents from a birth cohort from Rotterdam, the Netherlands (enrollment: 2002–2006). Concentrations of nitrogen oxides, coarse, fine, and ultrafine particles, and composition of fine particles were estimated for participant's home addresses in pregnancy and childhood, using land use regression models. Structural brain images were obtained at age 9–12 years. We assessed the relationships of air pollution exposure, with brain volumes, and surface-based morphometric data, adjusting for socioeconomic and life-style characteristics, using single as well as multi-pollutant approach. Results: No associations were observed between air pollution exposures and global volumes of total brain, and cortical and subcortical grey matter. However, we found associations between higher pregnancy and childhood air pollution exposures with smaller corpus callosum, smaller hippocampus, larger amygdala, smaller nucleus accumbens, and larger cerebellum (e.g. -69.2mm3 hippocampal volume [95%CI -129.1 to -9.3] per 1ng/m3 increase in pregnancy exposure to polycyclic aromatic hydrocarbons). Higher pregnancy exposure to air pollution was associated with smaller cortical thickness while higher childhood exposure was associated with predominantly larger cortical surface area. Conclusion: Higher pregnancy or childhood exposure to several air pollutants was associated with altered volume of several brain structures, as well as with cortical thickness and surface area. Associations showed some similarity to delayed maturation and effects of early-life stress.

Graphical abstract, Highlights • A wide range of pre- and postnatal environmental exposures affects child behavior. • The exposome includes outdoor, indoor, chemical, lifestyle and social exposures. • Maternal tobacco smoke and car traffic increased behavioural problems in children. • Child sleep, healthy diet and higher family social capital reduced symptoms. • Child exposure to lead, copper, indoor air pollution, increased symptoms., Background Environmental exposures in early life influence the development of behavioral outcomes in children, but research has not considered multiple exposures. We therefore aimed to investigate the impact of a broad spectrum of pre- and postnatal environmental exposures on child behavior. Methods and findings We used data from the HELIX (Human Early Life Exposome) project, which was based on six longitudinal population-based birth cohorts in Europe. At 6–11 years, children underwent a follow-up to characterize their exposures and assess behavioral problems. We measured 88 prenatal and 123 childhood environmental factors, including outdoor, indoor, chemical, lifestyle and social exposures. Parent-reported behavioral problems included (1) internalizing, (2) externalizing scores, using the child behavior checklist (CBCL), and (3) the Conner’s Attention Deficit Hyperactivity Disorder (ADHD) index, all outcomes being discrete raw counts. We applied LASSO penalized negative binomial regression models to identify which exposures were associated with the outcomes, while adjusting for co-exposures. In the 1287 children (mean age 8.0 years), 7.3% had a neuropsychiatric medical diagnosis according to parent’s reports. During pregnancy, smoking and car traffic showing the strongest associations (e.g. smoking with ADHD index, aMR:1.31 [1.09; 1.59]) among the 13 exposures selected by LASSO, for at least one of the outcomes. During childhood, longer sleep duration, healthy diet and higher family social capital were associated with reduced scores whereas higher exposure to lead, copper, indoor air pollution, unhealthy diet were associated with increased scores. Unexpected decreases in behavioral scores were found with polychlorinated biphenyls (PCBs) and organophosphate (OP) pesticides. Conclusions Our systematic exposome approach identified several environmental contaminants and healthy lifestyle habits that may influence behavioral problems in children. Modifying environmental exposures early in life may limit lifetime mental health risk.