Critical windows of fluoride neurotoxicity in Canadian children.
Environ Res
; 200: 111315, 2021 09.
Article
em En
| MEDLINE
| ID: mdl-34051202
ABSTRACT
BACKGROUND:
Fluoride has been associated with IQ deficits during early brain development, but the period in which children are most sensitive is unknown.OBJECTIVE:
We assessed effects of fluoride on IQ scores across prenatal and postnatal exposure windows.METHODS:
We used repeated exposures from 596 mother-child pairs in the Maternal-Infant Research on Environmental Chemicals pregnancy and birth cohort. Fluoride was measured in urine (mg/L) collected from women during pregnancy and in their children between 1.9 and 4.4 years; urinary fluoride was adjusted for specific gravity. We estimated infant fluoride exposure (mg/day) using water fluoride concentration and duration of formula-feeding over the first year of life. Intelligence was assessed at 3-4 years using the Wechsler Preschool and Primary Scale of Intelligence-III. We used generalized estimating equations to examine the associations between fluoride exposures and IQ, adjusting for covariates. We report results based on standardized exposures given their varying units of measurement.RESULTS:
The association between fluoride and performance IQ (PIQ) significantly differed across prenatal, infancy, and childhood exposure windows collapsing across child sex (p = .001). The strongest association between fluoride and PIQ was during the prenatal window, B = -2.36, 95% CI -3.63, -1.08; the association was also significant during infancy, B = -2.11, 95% CI -3.45, -0.76, but weaker in childhood, B = -1.51, 95% CI -2.90, -0.12. Within sex, the association between fluoride and PIQ significantly differed across the three exposure windows (boys p = .01; girls p = .01); among boys, the strongest association was during the prenatal window, B = -3.01, 95% CI -4.60, -1.42, whereas among girls, the strongest association was during infancy, B = -2.71, 95% CI -4.59, -0.83. Full-scale IQ estimates were weaker than PIQ estimates for every window. Fluoride was not significantly associated with Verbal IQ across any exposure window.CONCLUSION:
Associations between fluoride exposure and PIQ differed based on timing of exposure. The prenatal window may be critical for boys, whereas infancy may be a critical window for girls.Palavras-chave
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Efeitos Tardios da Exposição Pré-Natal
/
Fluoretos
Limite:
Child, preschool
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Female
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Humans
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Infant
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Male
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Pregnancy
País como assunto:
America do norte
Idioma:
En
Ano de publicação:
2021
Tipo de documento:
Article