Maternal occupational exposure to chemicals and child cognitive function.

BACKGROUND: Limited data exist regarding child neurodevelopment in relation to maternal occupational exposure to endocrine-disrupting chemicals (EDCs). METHODS: We included 1058 mother-child pairs from the INfancia y Medio Ambiente (INMA) project (2003-2008). Using a job-exposure matrix, exposure probability scores for ten EDC groups were assigned to each mother based on her longest held job during pregnancy. At the child's 5-year visit, the McCarthy Scales of Children's Abilities was administered, yielding the general cognitive index and scales for specific cognitive domains. We analyzed region-specific associations between EDC exposures and each outcome separately using adjusted linear regression and combined region-specific effect estimates using random-effects meta-analyses. RESULTS: Approximately 24% of women were exposed to at least one EDC group, but exposure to most individual EDC groups was low (<5%). Maternal organic solvent exposure was associated with lower quantitative scores among children (-5.8 points, 95% confidence interval: -11.0, -0.5). Though statistically non-significant, exposures to polycyclic aromatic hydrocarbons, phthalates, alkylphenolic compounds, and miscellaneous chemicals were associated with poorer offspring performance for most or all cognitive domains. CONCLUSIONS: This study found limited evidence for a role of maternal occupational EDC exposures on child cognition. Further research is needed to better characterize exposures among pregnant workers. IMPACT: Using data from a prospective birth cohort, we help fill an important research gap regarding the potential consequences of work-related exposure to endocrine-disrupting chemicals (EDCs) among pregnant women on child neurodevelopment. We expand on existing literature-largely limited to pesticide and organic solvent exposures-by using a job-exposure matrix to estimate exposure to several EDC groups. We found limited evidence of an association between maternal occupational EDC exposure and children's overall cognition. We did observe specific associations between exposure to organic solvents and lower quantitative reasoning scores.

Maternal Iodine Status During Pregnancy Is Not Consistently Associated with Attention-Deficit Hyperactivity Disorder or Autistic Traits in Children.

BACKGROUND: Severe iodine deficiency during pregnancy can cause intellectual disability, presumably through inadequate placental transfer of maternal thyroid hormone to the fetus. The association between mild-to-moderate iodine deficiency and child neurodevelopmental problems is not well understood. OBJECTIVES: We investigated the association of maternal iodine status during pregnancy with child attention-deficit hyperactivity disorder (ADHD) and autistic traits. METHODS: This was a collaborative study of 3 population-based birth cohorts: Generation R (n = 1634), INfancia y Medio Ambiente (n = 1293), and the Avon Longitudinal Study of Parents and Children (n = 2619). Exclusion criteria were multiple fetuses, fertility treatment, thyroid-interfering medication use, and pre-existing thyroid disease. The mean age of assessment in the cohorts was between 4.4 and 7.7 y for ADHD symptoms and 4.5 and 7.6 y for autistic traits. We studied the association of the urinary iodine-to-creatinine ratio (UI/Creat) <150 µg/g-in all mother-child pairs, and in those with a urinary-iodine measurement at ≤18 weeks and ≤14 weeks of gestation-with the risk of ADHD or a high autistic-trait score (≥93rd percentile cutoff), using logistic regression. The cohort-specific effect estimates were combined by random-effects meta-analyses. We also investigated whether UI/Creat modified the associations of maternal free thyroxine (FT4) or thyroid-stimulating hormone concentrations with ADHD or autistic traits. RESULTS: UI/Creat <150 µg/g was not associated with ADHD (OR: 1.2; 95% CI: 0.7, 2.2; P = 0.56) or with a high autistic-trait score (OR: 0.8; 95% CI: 0.6, 1.1; P = 0.22). UI/Creat <150 µg/g in early pregnancy (i.e., ≤18 weeks or ≤14 weeks of gestation) was not associated with a higher risk of behavioral problems. The association between a higher FT4 and a greater risk of ADHD (OR: 1.3; 95% CI: 1.0, 1.6; P = 0.017) was not modified by iodine status. CONCLUSIONS: There is no consistent evidence to support an association of mild-to-moderate iodine deficiency during pregnancy with child ADHD or autistic traits.

Causal Effects of Prenatal Exposure to PM2.5 on Child Development and the Role of Unobserved Confounding.

Prenatal exposure to airborne particles is a potential risk factor for infant neuropsychological development. This issue is usually explored by regression analysis under the implicit assumption that all relevant confounders are accounted for. Our aim is to estimate the causal effect of prenatal exposure to high concentrations of airborne particles with a diameter < 2.5 µm (PM2.5) on children's psychomotor and mental scores in a birth cohort from Gipuzkoa (Spain), and investigate the robustness of the results to possible unobserved confounding. We adopted the propensity score matching approach and performed sensitivity analyses comparing the actual effect estimates with those obtained after adjusting for unobserved confounders simulated to have different strengths. On average, mental and psychomotor scores decreased of -2.47 (90% CI: -7.22; 2.28) and -3.18 (90% CI: -7.61; 1.25) points when the prenatal exposure was ≥17 µg/m3 (median). These estimates were robust to the presence of unmeasured confounders having strength similar to that of the observed ones. The plausibility of having omitted a confounder strong enough to drive the estimates to zero was poor. The sensitivity analyses conferred solidity to our findings, despite the large sampling variability. This kind of sensitivity analysis should be routinely implemented in observational studies, especially in exploring new relationships.

Association of Maternal Iodine Status With Child IQ: A Meta-Analysis of Individual Participant Data.

CONTEXT: Although the consequences of severe iodine deficiency are beyond doubt, the effects of mild to moderate iodine deficiency in pregnancy on child neurodevelopment are less well established. OBJECTIVE: To study the association between maternal iodine status during pregnancy and child IQ and identify vulnerable time windows of exposure to suboptimal iodine availability. DESIGN: Meta-analysis of individual participant data from three prospective population-based birth cohorts: Generation R (Netherlands), INMA (Spain), and ALSPAC (United Kingdom); pregnant women were enrolled between 2002 and 2006, 2003 and 2008, and 1990 and 1992, respectively. SETTING: General community. PARTICIPANTS: 6180 mother-child pairs with measures of urinary iodine and creatinine concentrations in pregnancy and child IQ. Exclusion criteria were multiple pregnancies, fertility treatment, medication affecting the thyroid, and preexisting thyroid disease. MAIN OUTCOME MEASURE: Child nonverbal and verbal IQ assessed at 1.5 to 8 years of age. RESULTS: There was a positive curvilinear association of urinary iodine/creatinine ratio (UI/Creat) with mean verbal IQ only. UI/Creat <150 µg/g was not associated with lower nonverbal IQ (-0.6 point; 95% CI: -1.7 to 0.4 points; P = 0.246) or lower verbal IQ (-0.6 point; 95% CI: -1.3 to 0.1 points; P = 0.082). Stratified analyses showed that the association of UI/Creat with verbal IQ was only present up to 14 weeks of gestation. CONCLUSIONS: Fetal brain development is vulnerable to mild to moderate iodine deficiency, particularly in the first trimester. Our results show that potential randomized controlled trials investigating the effect of iodine supplementation in women with mild to moderate iodine deficiency on child neurodevelopment should begin supplementation not later than the first trimester.

Thyroid Function in Early Pregnancy, Child IQ, and Autistic Traits: A Meta-Analysis of Individual Participant Data.

Context: Low maternal free T4 (FT4) has been associated with poor child neurodevelopment in some single-center studies. Evidence remains scarce for the potential adverse effects of high FT4 and whether associations differ in countries with different iodine status. Objective: To assess the association of maternal thyroid function in early pregnancy with child neurodevelopment in countries with a different iodine status. Design, Setting, and Participants: Meta-analysis of individual participant data from 9036 mother-child pairs from three prospective population-based birth cohorts: INMA [Infancia y Medio Ambiente (Environment and Childhood project) (Spain)], Generation R (Netherlands), and ALSPAC (Avon Longitudinal Study of Parents and Children, United Kingdom). The exclusion criteria were multiple pregnancies, fertility treatments, thyroid-interfering medication usage, and known thyroid disease. Main Outcomes: Child nonverbal IQ at 5 to 8 years of age, verbal IQ at 1.5 to 8 years of age, and autistic traits within the clinical range at 5 to 8 years of age. Results: FT4 <2.5th percentile was associated with a 3.9-point (95% CI, -5.7 to -2.2) lower nonverbal IQ and a 2.1-point (95% CI, -4.0 to -0.1) lower verbal IQ. A suggestive association of hypothyroxinemia with a greater risk of autistic traits was observed. FT4 >97.5th percentile was associated with a 1.9-fold (95% CI, 1.0 to 3.4) greater risk of autistic traits. No independent associations were found with TSH. Conclusions: Low maternal FT4 was consistently associated with a lower IQ across the cohorts. Further studies are needed to replicate the findings of autistic traits and investigate the potential modifying role of maternal iodine status. FT4 seems a reliable marker of fetal thyroid state in early pregnancy, regardless of the type of immunoassay.

Time trends in serum organochlorine pesticides and polychlorinated biphenyls in the general population of Biscay, Spain.

Despite the measures adopted, levels of organochlorine compounds (OCs) are still being detected in the human body. This study aimed to explore factors related to changes in the concentrations of polychlorinated biphenyls (PCBs) and pesticide OCs in blood samples obtained from a general population cohort. Two cross-sectional samples were taken from 162 adults (2-75 years of age), with a gap of 2 years, from four areas in Biscay (Spain). More than 75 % had quantifiable levels of hexachlorobenzene (HCB), beta-hexachlorocyclohexane (ß-HCH), dichlorodiphenyldichloroethylene, and PCBs 138 153 and 180. During this time, significant changes were observed: PCB 180 and HCB levels increased, and PCB 138 and ß-HCH levels decreased. Regarding age, this study shows a decrease suggesting a cohort effect. The period was not related to the decrease of levels in all age intervals, but a statistically significant increase of PCBs in older people was found. High body mass index was associated with lower PCB 180 levels and greater HCH levels. Inversely, greater levels of HCB and ß-HCH were in those who had lost weight before the study. Levels of HCB and ß-HCH were also greater in women who had had children, although they were lower in those who breastfed. Levels of these same OCs were greater in fish consumers, whereas those of PCBs 138 and 153 were greater in those who consumed local produce; all of these trends were close to significance. Efforts should continue to decrease exposure to these pollutants and to assess their influence on general population.

Plaguicidas organoclorados en población general adulta de Bizkaia / Organochlorine pesticides in the general adult population of Biscay (Spain)

ObjetivoDeterminar y analizar las concentraciones de siete plaguicidas organoclorados; hexaclorobenceno (HCB), beta-hexaclorociclohexano (β-HCH), gamma-hexaclorociclohexano (γ-HCH), heptacloro epóxido, beta-endosulfán, diclorodifenildicloroetileno (p,p′-DDE) y diclorodifeniltricloroetano (p,p′-DDT) en suero de adultos de cuatro zonas de Bizkaia no expuestos a fuentes conocidas de plaguicidas.MétodoSe analizaron 283 muestras individuales de voluntarios captados a partir del censo. Se les entrevistó utilizando un cuestionario con variables sociodemográficas y de consumo. Se analizaron los datos utilizando la ji al cuadrado para variables discretas, y el análisis de varianza y un modelo de regresión lineal múltiple para las variables continuas.ResultadosEl p,p′-DDE fue detectado en el 100% de los individuos (media: 191,43ng/g lípido), mientras que el 31% mostró valores detectables de p,p′-DDT (media: 18,9ng/g lípido). Un 96,5% de los individuos presentaban valores detectables de HCB (media: 78,56ng/g lípido); el 90,4% β-HCH (media: 42,78ng/g lípido) y un 3,5% γ-HCH. No se detectó heptacloro epóxido ni beta-endosulfán. En el modelo de regresión, el incremento de la edad aumentaba los valores de todos los plaguicidas (p<0,05). No se observaron diferencias significativas por zona de residencia, excepto para el HCB y el p,p′-DDE. Las mujeres presentaron valores significativamente más altos de HCB y de β-HCH (p<0,001). El índice de masa corporal mostró un gradiente positivo significativo con el HCB y el β-HCH (p<0,05). No se observó asociación entre los plaguicidas y otras variables, lactancia, ocupación o clase social.ConclusionesLos resultados indican que la población general adulta de Bizkaia ha estado y está expuesta a plaguicidas organoclorados. Sin embargo, sus valores se encuentran dentro del intervalo observado por otros autores (AU)

ObjectiveTo identify and analyze levels of seven organochlorine pesticides [hexachlorobenzene (HCB), beta-hexachlorocyclohexane (β-HCH), gamma-hexachlorocyclohexane (γ-HCH), heptachlor epoxide, beta-endosulfan, dichlorodiphenyldichloroethylene (p,p′-DDE) and dichlorodiphenyltrichloroethane (p,p′-DDT)] in the serum of adults of four areas of Biscay (Spain) not exposed to known sources of pesticides.MethodWe analyzed 283 individual samples from volunteers recruited from the census. The volunteers were interviewed using a questionnaire with items on demographic variables and consumption. Data were analyzed using the chi-square test for discrete variables and analysis of variance and multiple linear regression models for continuous variables.ResultsWe detected p,p′-DDE in 100% of the volunteers (mean: 191.43ng/g lipid), while 31% had detectable levels of p,p′-DDT (mean: 18.9ng/g lipid). Detectable levels of HCB were found in 96.5% of the volunteers (mean: 78.56ng/g lipid), β-HCH in 90.4% (mean: 42.78ng/g lipid) and γ-HCH in 3.5%. Heptachlor epoxide and beta-endosulfan were not detected. In the regression model higher levels of all pesticides were found with increasing age (p<0.05). There were no significant differences by area of residence, except for HCB and p,p′-DDE. Women had significantly higher levels of HCB and β-HCH (p<0.001). Body mass index showed a significant positive gradient in HCB and β-HCH (p<0.05). There was no association between pesticides and other variables, breast feeding, occupation or social class.ConclusionsThese results indicate that the general adult population of Biscay has been and is exposed to organochlorine pesticides. However, their levels are within the range observed by other authors (AU)

[Organochlorine pesticides in the general adult population of Biscay (Spain)]. / Plaguicidas organoclorados en población general adulta de Bizkaia.

OBJECTIVE: To identify and analyze levels of seven organochlorine pesticides [hexachlorobenzene (HCB), beta-hexachlorocyclohexane (ß-HCH), gamma-hexachlorocyclohexane (γ-HCH), heptachlor epoxide, beta-endosulfan, dichlorodiphenyldichloroethylene (p,p'-DDE) and dichlorodiphenyltrichloroethane (p,p'-DDT)] in the serum of adults of four areas of Biscay (Spain) not exposed to known sources of pesticides. METHOD: We analyzed 283 individual samples from volunteers recruited from the census. The volunteers were interviewed using a questionnaire with items on demographic variables and consumption. Data were analyzed using the chi-square test for discrete variables and analysis of variance and multiple linear regression models for continuous variables. RESULTS: We detected p,p'-DDE in 100% of the volunteers (mean: 191.43ng/g lipid), while 31% had detectable levels of p,p'-DDT (mean: 18.9ng/g lipid). Detectable levels of HCB were found in 96.5% of the volunteers (mean: 78.56ng/g lipid), ß-HCH in 90.4% (mean: 42.78ng/g lipid) and γ-HCH in 3.5%. Heptachlor epoxide and beta-endosulfan were not detected. In the regression model higher levels of all pesticides were found with increasing age (p<0.05). There were no significant differences by area of residence, except for HCB and p,p'-DDE. Women had significantly higher levels of HCB and ß-HCH (p<0.001). Body mass index showed a significant positive gradient in HCB and ß-HCH (p<0.05). There was no association between pesticides and other variables, breast feeding, occupation or social class. CONCLUSIONS: These results indicate that the general adult population of Biscay has been and is exposed to organochlorine pesticides. However, their levels are within the range observed by other authors.

Somatic coliphages and bacterial indicators of bathing water quality in the beaches of Gipuzkoa, Spain.

Monitoring the quality of the bathing waters of Gipuzkoa (the Basque Country, Spain) makes it possible to assess the suitability of its 15 beaches for bathing throughout each season. In 1998, the parameters E. coli, somatic coliphages (SOMCPH) and F-specific RNA bacteriophages (FRNAPH) were incorporated into the bathing water quality monitoring system. This enabled the study of the link between bacterial and viral indicators as well as the analysis of the ratios between both types of indicators in waters with different levels of pollution. Although bacterial indicators (total coliforms (TC) and faecal coliforms (FC)) and enterococci showed a strong correlation between them, the correlations between the viral indicators and between the viral and bacterial indicators were weaker, though significant in all cases. The ratio between SOMCPH and E. coli indicates that at low levels of bacterial pollution (E coli <100 MPN/100 ml) SOMCPH outnumber E coli. In contrast, at higher levels of pollution (E coli >100 MPN/100 ml), SOMCPH numbers are lower than those of E-coli. The data reveal the presence of viral indicators in waters classified as suitable for bathing by the European Directive and alert us to their suitability.

Analysis of population characteristics related to the total effective xenoestrogen burden: a biomarker of xenoestrogen exposure in breast cancer.

To analyse the link between breast cancer and the combined effect of environmental xenoestrogens, we developed, standardised and applied a biomarker of exposure to assess the total effective xenoestrogen burden (TEXB) in human adipose tissue in a case-control study. Environmental oestrogens (TEXB-alpha) are separated from endogenous oestrogens (TEXB-beta), and the combined oestrogenic effect is determined from its proliferative effect (E-Screen assay). The aim of the study was to identify potential confounders, effect modifiers or other covariates associated with higher TEXB levels. In cases, age, family history of breast cancer, lactation experience and smoking were associated with TEXB-alpha. In controls, only age was associated with TEXB-alpha levels. In cases, age, educational level, age at menarche, menopausal status, marital status, lactation experience and smoking were associated with TEXB-beta. In controls, only menopausal status was significantly associated with TEXB-beta levels. In conclusion, TEXB, as a biomarker of exposure, takes account of environmental, dietary, lifestyle, genetic and reproductive factors, which are not usually systematically measured across studies.