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Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

ABSTRACT: BACKGROUND:Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined. METHODS:Participants (mean corrected age?=?6.6?months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n?=?429) and the visual evoked potentials in a sub-group (n?=?63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses. RESULTS:We observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values

SUBMITTER: Polevoy C

PROVIDER: S-EPMC7006412 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

Polevoy C C Arbuckle T E TE Oulhote Y Y Lanphear B P BP Cockell K A KA Muckle G G Saint-Amour D D

Environmental health : a global access science source 20200207 1

<h4>Background</h4>Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of seleniu ...[more]

PMID: 32028962

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Project description:BackgroundAchieving optimal folate status during early gestation reduces the risk of neural tube defects (NTDs). While inadequate folate intake remains a concern, it is becoming increasingly common for individuals to consume higher than recommended doses of folic acid (FA) with minimal additional benefit.ObjectiveHere, we sought to investigate the determinants, including FA supplement dose and use, of plasma total and individual folate vitamer concentrations in the first and third trimesters of pregnancy.MethodsUsing data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a cohort exposed to mandatory FA fortification, we measured plasma total folate and individual folate vitamer [5-methyltetrahydrofolate (5-methylTHF), unmetabolized FA (UMFA), and non-methyl folates (sum of THF, 5-formylTHF, 5,10-methenyl-THF)] concentrations in the first and third trimesters (n = 1,893). Using linear mixed models, we estimated associations between plasma folate concentrations, total daily supplemental FA intake, plasma vitamin B-12 concentrations, and multiple demographic, maternal, and reproductive factors.ResultsAlmost 95% of MIREC study participants met or exceeded the recommended daily supplemental FA intake from supplements (≥400 μg/d), with approximately 25% consuming more than the Tolerable Upper Intake Level (>1000 μg/d). Over 99% of MIREC participants had a plasma total folate status indicative of maximal NTD risk reduction (25.5 nmol/L) regardless of FA supplement dose. UMFA was detected in almost all participants, with higher concentrations associated with higher FA doses. Determinants of adequate FA supplement intake and folate status associated with reduced NTD risk included indicators of higher socioeconomic position, higher maternal age, nulliparity, and lower prepregnancy BMI.ConclusionsIn the context of mandatory FA fortification, our data indicate that higher-than-recommended FA doses are unwarranted, with the exception of individuals at higher risk for NTDs. Ideally, prenatal supplements would contain 400 rather than 1000 µg FA, thereby enabling the consumption of optimal and safe FA doses.

Project description:BackgroundPolychlorinated biphenyls (PCBs), methylmercury (MeHg), and lead (Pb) are environmental contaminants known for their adverse effects on cognitive development.ObjectivesIn this study we examined the effects of prenatal exposure to PCBs, MeHg, and Pb on cognitive development in a sample of Inuit infants from Arctic Québec.MethodsMothers were recruited at local prenatal clinics. PCBs, mercury (Hg), Pb, and two seafood nutrients-docosahexaenoic acid (DHA) and selenium (Se)-were measured in umbilical cord blood. Infants (n = 94) were assessed at 6.5 and 11 months of age on the Fagan Test of Infant Intelligence (FTII), A-not-B test, and Bayley Scales of Infant Development-2nd Edition (BSID-II).ResultsMultiple regression analyses revealed that higher prenatal PCB exposure was associated with decreased FTII novelty preference, indicating impaired visual recognition memory. Prenatal Hg was associated with poorer performance on A-not-B, which depends on working memory and is believed to be a precursor of executive function. Prenatal Pb was related to longer FTII fixation durations, indicating slower speed of information processing.ConclusionsPCBs, MeHg, and Pb each showed specific and distinct patterns of adverse associations with the outcomes measured during infancy. By contrast, none of these exposures was associated with performance on the BSID-II, a global developmental measure. The more focused, narrow band measures of cognitive function that appeared to be sensitive to these exposures also provide early indications of long-term impairment in specific domains that would otherwise not likely be evident until school age.CitationBoucher O, Muckle G, Jacobson JL, Carter RC, Kaplan-Estrin M, Ayotte P, Dewailly É, Jacobson SW. 2014. Domain-specific effects of prenatal exposure to PCBs, mercury, and lead on infant cognition: results from the Environmental Contaminants and Child Development Study in Nunavik. Environ Health Perspect 122:310-316;?http://dx.doi.org/10.1289/ehp.1206323.

Dataset Information

Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

Publications

Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

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