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Oulhote, Youssef

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Oulhote

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Youssef

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Oulhote, Youssef

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2016 - 20177

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Author's Publications: search.filters.isAuthorOfPublication.afa68ed8-95d9-4b73-9526-c4f9b8bd19bc

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Now showing 1 - 7 of 7
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    Associations of Prenatal Urinary Bisphenol A Concentrations with Child Behaviors and Cognitive Abilities
    (Environmental Health Perspectives, 2017) Braun, Joseph M.; Muckle, Gina; Arbuckle, Tye; Bouchard, Maryse F.; Fraser, William D.; Ouellet, Emmanuel; Séguin, Jean R.; Oulhote, Youssef; Webster, Glenys M.; Lanphear, Bruce P.
    Background: Prenatal bisphenol A (BPA) exposure has been associated with adverse neurodevelopment in epidemiological studies. However, prior studies had limited statistical power to examine sex-specific effects, and few examined child cognition. Objectives: We estimated the association between prenatal BPA exposure and child neurobehavior at 3 y of age in a prospective cohort of 812 mothers and their children. Methods: We measured BPA concentration in urine samples collected at ∼12 wk gestation among women enrolled in a 10-city Canadian cohort study. At approximately 3 y of age, we assessed children’s cognitive abilities with the Wechsler Primary and Preschool Scale of Intelligence™–III (WPPSI-III) and two scales of the Behavior Rating Inventory of Executive Function–Preschool (BRIEF-P). Parents reported children’s behavior using the Behavior Assessment System for Children–2 (BASC-2) and the Social Responsiveness Scale™ – 2. (SRS-2). We estimated covariate-adjusted differences in neurobehavioral outcomes with a doubling in BPA concentration and sex-specific associations. Results: BPA was not associated with WPPSI-III scores; child sex did not modify these associations. The association between BPA and BRIEF-P scores was modified by child sex (BPA×sex p-values≤0.03). For example, a doubling of BPA concentration was associated with 1-point (95% CI: 0.3, 1.7) poorer working memory in boys and 0.5-point (95% CI: −1.1, 0.1) better scores in girls. BPA was not associated with most BASC-2 scales; however, it was associated with more internalizing and somatizing behaviors in boys, but not in girls (BPA×sex p-values≤0.08). A doubling of BPA concentration was associated with poorer SRS-2 scores [β=0.3 ( 95% CI: 0, 0.7)]; this association was not modified by sex. Conclusion: Prenatal urinary BPA concentration was associated with some aspects of child behavior in this cohort, and some associations were stronger among boys. https://doi.org/10.1289/EHP984
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    Aerobic Fitness and Neurocognitive Function Scores in Young Faroese Adults and Potential Modification by Prenatal Methylmercury Exposure
    (National Institute of Environmental Health Sciences, 2016) Oulhote, Youssef; Debes, Frodi; Vestergaard, Sonja; Weihe, Pal; Grandjean, Philippe
    Background: Exposure to methylmercury was shown to decrease neural stem cell populations, whereas aerobic fitness has beneficial effects on the adult brain that relies on improved neurogenesis in the hippocampus. Objectives: We examined the association between aerobic fitness and neurocognitive outcomes at young adult age, along with the potential moderating effect of prenatal exposure to methylmercury. Methods: At age 22 years, 262 members of a Faroese birth cohort, established in 1986–1987, underwent a graded exercise test of aerobic fitness to measure maximal oxygen uptake (VO2Max). Their prenatal methylmercury exposure had been assessed from the mercury concentration in cord blood. We estimated cross-sectional associations between VO2Max and multiple measures of neurocognitive function. In addition, we compared groups with low and high prenatal methylmercury exposure. Results: A 1 standard deviation (SD) increase in VO2Max was associated with better scores on short-term memory and cognitive processing speed by 0.21 SD (95% CI: –0.04, 0.46) and 0.28 SD (95% CI: 0.02, 0.54), respectively. In the group with lower prenatal methylmercury exposure, a 1 SD increase in VO2Max was associated with increased scores on cognitive processing speed by 0.45 SD (95% CI: 0.08, 0.81) and with a slightly lesser benefit in short-term memory. No such association was observed in the group with high prenatal methylmercury exposure. Conclusions: Higher aerobic capacity was associated with better performance in short-term memory and processing speed. However, prenatal methylmercury exposure seemed to attenuate these positive associations. Citation: Oulhote Y, Debes F, Vestergaard S, Weihe P, Grandjean P. 2017. Aerobic fitness and neurocognitive function scores in young Faroese adults and potential modification by prenatal methylmercury exposure. Environ Health Perspect 125:677–683; http://dx.doi.org/10.1289/EHP274
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    Early-life exposures to persistent organic pollutants in relation to overweight in preschool children
    (Elsevier BV, 2017) Karlsen, Martina; Grandjean, Philippe; Weihe, Pal; Steuerwald, Ulrike; Oulhote, Youssef; Valvi, Damaskini
    Current knowledge on obesogenic effects of persistent organic pollutants (POPs) is equivocal. We therefore evaluated the associations between early-life POP exposures and body mass index (BMI) in 444 Faroese children born in 2007-2009. POPs were measured in maternal 2-week postpartum serum and child age-5 serum. Linear regression and generalised linear models assessed the associations with continuous and dichotomous BMI z-scores, respectively, at ages 18 months and/or 5 years. Maternal serum concentrations of HCB, PFOS and PFOA were associated with increased BMI z-scores and/or overweight risk (i.e. BMI z-score≥ 85th WHO percentile). No clear association was found for maternal serum-PCBs, p,p’-DDE, PFHxS, PFNA and PFDA. In cross-sectional analyses, we observed a pattern of inverse associations between child serum- POPs and BMI z-scores at age 5, perhaps due to reverse causation that requires attention in future prospective analyses. Findings in this recent cohort support a role of maternal exposure to endocrine disruptors in the childhood obesity epidemic.
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    Association Between Child Poverty and Academic Achievement
    (American Medical Association (AMA), 2016) Oulhote, Youssef; Grandjean, Philippe
    Hair et al1 reported in the September 2015 issue of JAMA Pediatrics on the association between child poverty, brain development, and academic achievement. This study provided evidence that as much as 20% of poverty-associated achievement deficits may be a result of a maturation lag in the frontal lobe, the temporal lobe, and the hippocampus. The authors suggested that the results might underestimate the true effect of poverty on child development because they examined a relatively healthy sample of US children who, for the most part, differ only in terms of family income.
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    Behavioral difficulties in 7-year old children in relation to developmental exposure to perfluorinated alkyl substances
    (Elsevier BV, 2016) Oulhote, Youssef; Steuerwald, Ulrike; Debes, Frodi; Weihe, Pal; Grandjean, Philippe
    Background: Perfluorinated alkyl substances (PFAS) are suspected endocrine disruptors that are highly persistent and neurotoxic in animals. Human epidemiological studies of exposure-related deviations of children’s behaviors are sparse. We assessed the associations between prenatal, 5- and 7- year PFAS exposures and behavioral problem scores in 7-year Faroese children. Methods: Concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonic acid (PFHxS) were measured in maternal serum and in serum from children at ages 5 and 7 years (n=539, 508, and 491, respectively). We used multivariable regressions and structural equations models to estimate the covariate-adjusted associations between serum-PFAS concentrations and behavioral difficulties, as assessed by the strengths and difficulties questionnaire (SDQ) at age 7. Results: Serum-PFOS and PFHxS concentrations declined over time, whereas PFOA, PFNA, and PFDA tended to increase. No associations were observed between prenatal PFAS concentrations and SDQ scores. However, a two-fold increase in 5-year serum-PFOA, PFNA, and PFDA concentrations was associated with increases in total SDQ scores by 1.03 (95% CI: 0.11, 1.95), 0.72 (95% CI: 0.07, 1.38) and 0.78 points (95% CI: 0.01, 1.55), respectively. For SDQ subscales, significant associations were found in regard to hyperactivity, peer relationship, and conduct problems, as well as internalizing and externalizing problems and autism screening composite scores. Cross-sectional analyses at age 7 years showed possible sex-dimorphic associations between PFAS concentrations and SDQ scores, where girls had consistently positive associations with SDQ scores whereas boys exhibited a pattern of negative or null associations. Conclusions: Higher serum PFAS concentrations at ages 5- and 7- years, but not prenatally, were associated with parent-reported behavioral problems at age 7.
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    Children’s white blood cell counts in relation to developmental exposures to methylmercury and persistent organic pollutants
    (Elsevier BV, 2017) Oulhote, Youssef; Shamim, Z.; Kielsen, K.; Weihe, Pal; Grandjean, Philippe; Ryder, L.P.; Heilmann, C.
    Background: To explore possible markers of developmental immunotoxicity, we prospectively examined 56 children to determine associations between exposures to mercury and persistent organic pollutants since birth and the comprehensive differential counts of white blood cells (WBC) at age 5 years. Materials and methods: Extended differential count included: neutrophils, eosinophils, basophils, lymphocytes (including T cells, NK cells, and B cells), and monocytes. Organochlorine compounds (OCs) including polychlorinated biphenyls (PCBs) and pesticides, five perfluoroalkyl substances (PFASs), and mercury (Hg) were measured in maternal (n=56) and children’s blood at 18 months (n=42) and 5 years (n=56). We constructed latent functions for exposures at three different ages using factor analyses and applied structural equations models adjusted for covariates. Results: Prenatal mercury exposure was associated with depleted total WBC, especially for lymphocytes, where a one standard deviation (SD) increase in the exposure was associated with a decrease by 23% SD (95% CI: -43, -4) in the cell count. Prenatal exposure to OCs was marginally associated with decreases in neutrophil counts. In contrast, the 5-year PFASs concentrations were associated with higher basophil counts (B= 46% SD, 95% CI: 13, 79). Significantly reduced subpopulations of lymphocytes such as B cells, CD4-positive T helper cells and CD4 positive recent thymic emigrants may suggest cellular immunity effects and dysregulation of T-cell mediated immunity. Conclusion: Thus prenatal exposure to mercury and PFASs appears to have differential impacts on WBC counts.
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    Gestational diabetes and offspring birth size at elevated environmental pollutant exposures
    (Elsevier BV, 2017) Valvi, Damaskini; Oulhote, Youssef; Weihe, Pal; Dalgård, Christine; Bjerve, Kristian S.; Steuerwald, Ulrike; Grandjean, Philippe
    BACKGROUND: Gestational diabetes mellitus (GDM) is associated with increased availability of glucose and macronutrients in fetal circulation and macrosomia. Therefore, the role of GDM in the association between metabolism-disrupting chemicals and birth size deserves attention. OBJECTIVE: We examined whether GDM may mediate or modify the associations between maternal environmental pollutant exposures and offspring birth size measures. METHODS: We analyzed 604 Faroese pregnant women and their offsprings born in 1997-2000. Maternal pregnancy serum concentrations of organochlorine compounds (OCs: polychlorinated biphenyl (PCB) congeners and dichlorodiphenyldichloroethylene (DDE)), and five perfluoroalkyl substances (PFASs), and hair and cord blood mercury concentrations were measured. We used regression (single-pollutants) and structural equation models (SEMs) (multiple-pollutant analyses using latent constructs of OCs, PFASs and mercury) to estimate the associations with GDM and birth size measures, accounting for mediation and/or effect modification by GDM. RESULTS: Serum-DDE and hair-mercury concentrations were associated with GDM (adjusted OR per concentration doubling: 1.29; 95% CI: 0.94, 1.77 for DDE, and 0.79; 95% CI: 0.62, 0.99 for mercury), but in multiple pollutant-adjusted SEMs only a positive association between OC exposure and GDM remained significant (change in GDM odds per OC doubling: 0.45; 95% CI: 0.05, 0.86). PCB and overall OC exposure were positively associated with head circumference (SEM; mean change per OC doubling: 0.13cm; 95% CI, 0.01. 0.25). Overall PFAS exposure was inversely associated with birth weight (SEM; mean change per PFAS doubling: -169g; 95% CI: -359, 21), and for many single-PFASs we found a pattern of inverse associations with birth weight and head circumference in boys, and positive or null associations in girls. None of the environmental pollutants was associated with offspring length. GDM neither modified nor mediated the associations with birth size measures. CONCLUSIONS: We found associations with GDM and offspring birth size to be specific to the environmental pollutant or pollutant group. Associations with birth size measures appear to be independent of GDM occurrence.