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5434552 
Journal Article 
Prenatal, concurrent, and sex-specific associations between blood lead concentrations and IQ in preschool Canadian children 
Desrochers-Couture, M; Oulhote, Y; Arbuckle, TE; Fraser, WD; Séguin, JR; Ouellet, E; Forget-Dubois, N; Ayotte, P; Boivin, M; Lanphear, BP; Muckle, G 
2018 
1 
Environment International
ISSN: 0160-4120
EISSN: 1873-6750 
121 
Pt 2 
1235-1242 
English 
30392942 
WOS:000453083000024 
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. 
blood lead concentrations; sex differences; intelligence quotient; Canadian children