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Environ Res. 2019 Sep;176:108505. doi: 10.1016/j.envres.2019.05.036. Epub 2019 May 24.

Prenatal air pollution and childhood IQ: Preliminary evidence of effect modification by folate.

Author information

1
Department of Environmental and Occupational Health Sciences, 4225 Roosevelt Way NE, University of Washington (UW), Seattle, WA, 95105, USA. Electronic address: cloftus@uw.edu.
2
Department of Epidemiology, 1959 NE Pacific Street, Box 357236, UW, Seattle, WA, 98195, USA.
3
Department of Biostatistics, UW, Box 357232, Seattle, WA, 98195, USA.
4
Department of Biostatistics and Epidemiology, 462 Doctors Office Building, 66 N Pauline St, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
5
Department of Psychiatry, University of California (UC) 401 Parnassus Ave, San Francisco, CA, 94143, USA; Department of Pediatrics, 550 16th Street, Box 0110 UC, San Francisco, CA, 94143, USA.
6
Department of Environmental and Occupational Health Sciences, 4225 Roosevelt Way NE, University of Washington (UW), Seattle, WA, 95105, USA; Seattle Children's Research Institute, 1900 9th Ave, Seattle, WA, 98101, USA; Department of Pediatrics, 1959 NE Pacific St, UW, Seattle, WA, 98195, USA.
7
Division of General Pediatrics, 2200 Children's Way, Vanderbilt University Medical Center, Nashville, TN, 27232, USA.
8
Department of Environmental and Occupational Health Sciences, 4225 Roosevelt Way NE, University of Washington (UW), Seattle, WA, 95105, USA; Department of Epidemiology, 1959 NE Pacific Street, Box 357236, UW, Seattle, WA, 98195, USA; Department of Pediatrics, 1959 NE Pacific St, UW, Seattle, WA, 98195, USA.
9
Department of Psychiatry, University of California (UC) 401 Parnassus Ave, San Francisco, CA, 94143, USA.

Abstract

OBJECTIVES:

Animal studies suggest that air pollution is neurotoxic to a developing fetus, but evidence in humans is limited. We tested the hypothesis that higher air pollution is associated with lower child IQ and that effects vary by maternal and child characteristics, including prenatal nutrition.

METHODS:

We used prospective data collected from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood study. Outdoor pollutant exposure during pregnancy was predicted at geocoded home addresses using a validated national universal kriging model that combines ground-based monitoring data with an extensive database of land-use covariates. Distance to nearest major roadway was also used as a proxy for traffic-related pollution. Our primary outcome was full-scale IQ measured at age 4-6. In regression models, we adjusted for multiple determinants of child neurodevelopment and assessed interactions between air pollutants and child sex, race, socioeconomic status, reported nutrition, and maternal plasma folate in second trimester.

RESULTS:

In our analytic sample (N = 1005) full-scale IQ averaged 2.5 points (95% CI: 0.1, 4.8) lower per 5 μg/m3 higher prenatal PM10, while no associations with nitrogen dioxide or road proximity were observed. Associations between PM10 and IQ were modified by maternal plasma folate (pinteraction = 0.07). In the lowest folate quartile, IQ decreased 6.8 points (95% CI: 1.4, 12.3) per 5-unit increase in PM10; no associations were observed in higher quartiles.

CONCLUSIONS:

Our findings strengthen evidence that air pollution impairs fetal neurodevelopment and suggest a potentially important role of maternal folate in modifying these effects.

KEYWORDS:

Air pollution; Neurodevelopment; Particulate matter; Pediatric health; Prenatal folate

PMID:
31229778
PMCID:
PMC6710141
[Available on 2020-09-01]
DOI:
10.1016/j.envres.2019.05.036

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