Prenatal, concurrent, and sex-specific associations between blood lead concentrations and IQ in preschool Canadian children

Background: Lead exposure predicts altered neurodevelopment and lower intelligence quotient (IQ) in children, but few studies have examined this association in children who have relatively low blood lead concentrations. Objectives: To test the associations between blood lead concentrations and cognitive function in Canadian preschoolers, with a possible moderation by sex. Methods: The data were gathered from 609 mother-child pairs from the Maternal–Infant Research on Environmental Chemicals (MIREC) Study. Lead was measured in umbilical and maternal blood, and in children's venous blood at age 3–4 years. Cognitive function was measured with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) at 3–4 years. We tested the relationship between WPPSI-III scores and blood lead concentrations with multiple linear regression, adding child sex as a moderator. Results: Median blood lead concentrations for the mother at 1st trimester and 3rd trimester of pregnancy, and for cord and child blood were 0.60 μg/dL, 0.58 μg/dL, 0.79 μg/dL and 0.67 μg/dL, respectively. We found no association between cord blood lead concentrations and WPPSI-III scores in multivariable analyses. However, cord blood lead concentrations showed a negative association with Performance IQ in boys but not in girls (B = 3.44; SE = 1.62; 95% CI: 0.82, 5.98). No associations were found between WPPSI-III scores and prenatal maternal blood or concurrent child blood lead concentrations. Conclusions: Prenatal blood lead concentrations below 5 μg/dL were still associated with a decline in cognitive function in this Canadian cohort, but only for boys

Impacts d'une exposition prénatale et postnatale au plomb sur le quotient intellectuel de jeunes enfants canadiens

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2017-2018.L’établissement d’un seuil d’exposition sécuritaire au plomb (Pb) pour les jeunes enfants nécessite davantage d’évidences scientifiques. Pendant que certains pays utilisent un seuil d’intervention aussi bas que 5 µg/dl, le seuil d’identification canadien est encore situé à 10 µg/dl. Il n’existe présentement aucunes données nationales sur les plombémies d’enfants âgés de moins de 6 ans. Cette lacune est importante en raison des plus grands risques neuro-développementaux chez les jeunes enfants. L’objectif principal de ce mémoire est de regarder l’association entre les plombémies des jeunes enfants canadiens et leurs fonctions intellectuelles pour contribuer à l’identification d’un seuil d’intervention sécuritaire. Les analyses sont réalisées sur 397 dyades mère-enfant de l’étude « Maternal–Infant Research on Environmental Chemicals ». L’exposition au Pb a été mesuré dans le sang du cordon ombilical ainsi que chez les enfants à l’âge de 3 ans. Le « Wechsler Preschool and Primary Scale of Intelligence » (WPPSI-III) permet d’évaluer les fonctions cognitives vers l’âge de 3 ans. Des régressions linéaires multiples vérifient la relation entre les scores du WPPSI-III et les plombémies observées au niveau prénatal et postnatal. Des modèles additifs généralisés (GAM) vérifient la présence de relations non linéaires. Aucune association significative n’a été trouvé (p > 0,05) entre les plombémies à 3 ans et le quotient intellectuel (QI). Une diminution marginalement significative sur le QI global a été observée avec les plombémies prénatales (β = –0,097; 95% IC: –0,199, 0,006 Les analyses GAM entre les plombémies prénatales et postnatales et les scores au WPPSI-III n’ont montré aucune relation non-linéaire significative. Ces résultats montrent que les jeunes enfants issus d’une population générale canadienne sont faiblement exposés au Pb. Une attention particulière devrait être porté sur les sous-groupes de population à risque, comme les enfants de famille avec un faible statut socioéconomique.The establishment of acceptable thresholds of lead (Pb) exposure still requires empirical evidence. While the French government has set an intervention threshold at 5 µg/dL and a vigilance threshold at 2.5 µg/dL, and the American government uses a threshold of 5 µg/dL to identify children with high exposure, the Canadian intervention threshold is still at 10 µg/dL. There is no national-level blood Pb data for Canadian children under 6 years of age, a critical gap since this population runs higher neurodevelopmental risk. The main objective was to assess the blood Pb levels in Canadian children under 4 years of age and their association with cognitive function, which could contribute to the identification of an intervention level for Pb exposure. The analysis focused on 397 mother-child dyads from the Maternal–Infant Research on Environmental Chemicals study. A sample cord blood and venous obtained from each child at the time of testing was used to assess prenatal and concurrent child Pb exposure respectively. Cognitive function was assessed using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) at around age 3. Linear multivariate regressions were done to assess the relationship between WPPSI-III scores and both child and cord blood levels. Generalized additive models (GAM) were used to look at non-linear relationship. No significant association was found (p < 0.05) for concurrent child Pb levels and cognitive functioning. A marginally significant decrease on the Full-scale IQ was found with cord blood Pb (β = –0.097; 95% CI: –0.199, 0.006). The GAM analyses between Pb concentrations and WPPSI-III scores showed no significant non-linear associations. Even though no significant results have been found, more investigations should be done to ensure that the impact of Pb exposure is not higher in low socio economic status Canadian family, as a result of higher exposure and of interactions with other predictors of lower IQ

Rendez-vous de l'internationalisation de la formation. Partie 01: le nouveau BUT français : incidences et perspectives dans la collaboration pédagogique cégeps – IUT

Rendez-vous de l'internationalisation de la formation : Direction des affaires internationales de la fédération des cégep

Visuospatial processing and fine motor function among 7-years old Guadeloupe children pre- and postnatally exposed to the organochlorine pesticide chlordecone

International audienceBACKGROUND: Chlordecone is an organochlorine that was largely used as an insecticide to control a species of root borers, the Banana weevil (Cosmopolites sordidus), in the French West Indies, Guadeloupe and Martinique. Its molecules have been shown to be very persistent in the environment as pollution in soils leading to contamination of water sources and foodstuff will last for several decades. Our team previously reported associations between prenatal chlordecone exposure and poorer fine motor development at two points in time during infancy. OBJECTIVE: To document whether effects of prenatal exposure to chlordecone previously reported persists until middle-childhood, and whether deleterious effects are observed in domain of visual processing. Associations with postnatal exposure and sex-specific vulnerabilities were also investigated. METHODS: We examined 410 children from the TIMOUN mother-child cohort in Guadeloupe at 7 years of age. Concentrations of chlordecone and other environmental contaminants were measured in cord- and children’s blood at age 7 years. Fine motor function was assessed using the Bruininks Oseretsky Test of Motor Proficiency Second Edition (BOT-2). The Computerized Adaptive Testing System (CATSYS) was used to evaluated postural hand tremor, while non-verbal visuospatial processing was measured using the Stanford Binet copying (S-B copying) test. We used adjusted multiple linear regressions to test the relationship between children’s scores and both continuous and categorical blood chlordecone concentrations, adding child sex as a moderator in continuous models. RESULTS: Cord chlordecone concentrations are associated with a regular frequency pattern of subtle hand tremors in both hands, and not related to visual processing and fine motor precision. Chlordecone concentrations in blood sample collected at testing time are associated with poorer visual processing when copying geometric figures, but not significantly related to poorer fine movement precision in tasks requiring pencil, scissors and paper. No sex-specific vulnerability was reported in any of the outcomes. CONCLUSIONS: These results at school aged expand those previously reported in the same cohort during infancy at age 7- and 18 months, and corroborate the negative effects of chlordecone exposure on fine motor function in absence of intoxication. Our results support the need to continue public health efforts aimed at reducing exposure especially among women of child bearing age and young children

Prenatal and childhood exposure to chlordecone and sex-typed toy preference of 7-year-old Guadeloupean children

International audienceChlordecone was used intensively as an insecticide in the French West Indies. Because of its high persistence, the resulting contamination of food and water has led to chronic exposure of the general population as evidenced by its presence in the blood of people of Guadeloupe, in particular in pregnant women and newborns, and in maternal breast milk. Chlordecone is recognized as a reproductive and developmental toxicant, is neurotoxic and carcinogenic in rodents, and is considered as an endocrine-disrupting compound with well-established estrogenic and progestogenic properties both in vitro and in vivo. The question arises of its potential consequences on child neurodevelopment following prenatal and childhood exposure, in particular on behavioral sexual dimorphism in childhood. We followed 116 children from the TIMOUN mother–child cohort study in Guadeloupe, who were examined at age 7. These children were invited to participate in a 7-min structured play session in which they could choose between different toys considered as feminine, masculine, or neutral. The play session was video recorded, and the percentage of the time spent playing with feminine or masculine toys was calculated. We estimated associations between playtime and prenatal exposure to chlordecone (assessed by concentration in cord blood) or childhood exposure (determined from concentrations in child blood obtained at the 7-year follow-up), taking into account confounders and co-exposures to other environmental chemicals. We used a two-group regression model to take into account sex differences in play behavior. Our results do not indicate any modification in sex-typed toy preference among 7-year-old children in relation with either prenatal or childhood exposure to chlordecone

Association between early lead exposure and externalizing behaviors in adolescence: A developmental cascade

International audienceBACKGROUND:Lead (Pb) exposure is associated with adverse neurological development. Most notably, it has been observed through externalizing behavior symptoms, as observed among Inuit children from northern Québec. Evidence for a persistent neurological impact of early Pb exposure later in life is however scarce. Pb exposure may initiate a developmental cascade that increases the risk of long-term behavior problems.OBJECTIVES:Testing for direct associations between childhood Pb concentrations and adolescent externalizing symptoms and substance use, as well as indirect associations through childhood behavior assessments.METHODS:The study sample is a longitudinal cohort of Inuit children (n = 212) followed since birth. Blood Pb concentrations were measured during childhood (median age = 11.4 years) and adolescence (median age = 18.5 years). Externalizing/inattentive behavior were teacher-assessed through the Teacher Report Form and the Disruptive Behavior Disorders Rating Scale for children. At the adolescence follow-up, behavior problems were self-reported by filling Achenbach's Youth Self-Report, the Barkley Adult ADHD-IV Rating Scale, and the Diagnostics Interview Schedule for Children. Adolescent substance use was also self-assessed through the DEP-ADO. Direct and indirect associations of child Pb concentrations with adolescent outcomes were tested through mediation models.RESULTS:Child blood Pb concentrations were not directly associated with any adolescent outcomes. On the contrary, childhood Pb exposure was indirectly associated, through childhood externalizing behavior assessments, with adolescent externalizing behaviors, binge drinking, and cannabis use. These indirect associations held after controlling for adolescents' concurrent Pb blood concentrations.DISCUSSION:Our results highlight the indirect but lasting effects of child Pb exposure on adolescent behavior problems, and the importance of childhood externalizing behavior in this relationship. Adverse early-life environment put children on a riskier developmental trajectory, increasing their likelihood of lifelong psychological, social and health problems

Effects of polychlorinated biphenyls exposure on physical growth from birth to childhood and adolescence A prospective cohort study

International audienceBackground/aims: Given that their traditional lifestyle and diet still relies on fish and other marine species for sustenance, the Inuit are highly exposed to polychlorinated biphenyls (PCBs) and PCBs are increasingly linked to obesity. However, evidence is not consistent regarding which periods of exposure are most relevant. In this study, we examine whether in utero, childhood, and adolescent exposure to PCBs are related to physical growth at adolescence.Method: Inuit adolescents from Canada (N=212) enrolled in a prospective longitudinal cohort study since birth were assessed for height, weight, body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI) at 18 years of age. PCB 153 concentrations were quantified in blood samples obtained at birth (umbilical cord), 11, and 18 years of age. Maternal anthropometrics were measured and those for the newborns collected from medical records. Data on biological mothers and participants' sociodemographic characteristics and food security were collected using interviews. Multiple linear regression analyses were used to test associations between PCB 153 concentrations and adolescent anthropometric measures.Results: Cord PCB 153 was not related to height or FFMI at adolescence. By contrast, analyses showed that cord PCB 153 was related to higher BMI, FMI and marginally to weight in girls but not boys. Child PCB 153 was not related to height, weight or FFMI in adolescence. Child PCB 153 was related to lower BMI and FMI at adolescence in both sexes, particularly among those considered overweight or obese during childhood. Adolescent PCB 153 was not associated with any outcome.Conclusion: This study suggests that prenatal exposure to PCBs may have a long-term effect on growth in early adulthood among girls and identifies the peri-pubertal period as another window of sensitivity for the action of PCBs. Our findings also suggest that exposure to PCBs and body size be documented in multiple time periods from infancy to adulthood