BPA Plastics Linked to ADHD in Boys

July 21, 2016
Dee Rapposelli

Have these researchers found a smoking gun?

RESEARCH UPDATE

Is bisphenol A (BPA) a smoking gun in ADHD?

Data from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) suggest that exposure to BPA-a plastic commonly used in baby bottles, water bottles, and food storage containers-may be at least be a contributing factor. The data also confirm that boys are more susceptible than girls.1

[[{"type":"media","view_mode":"media_crop","fid":"50347","attributes":{"alt":"ADHD","class":"media-image media-image-right","id":"media_crop_6728454801896","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"6137","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right; width: 200px; height: 134px;","title":"©SuzanneTucker/Shutterstock","typeof":"foaf:Image"}}]]These findings are in keeping with related animal studies and add clarity to a handful of human studies, which have been equivocal in regard to the association between BPA and sex-specific risks of ADHD. The NHANES-derived study, conducted by a multicenter US and Canadian research team, looked at a national sample of US children age 8 to 15 years.

The goal was to examine, via multivariable logistic regression, the correlation between urinary concentrations of BPA (limit of detection, 0.36 μg/L) and a current diagnosis of ADHD (primary outcome) or a past history of ADHD (secondary outcome). Data on both urinary BPA concentration and ADHD diagnosis were available for 460 of 1771 NHANES participants in the specified age group.

 Researchers found an association between higher urinary BPA concentrations and ADHD in American children.

Bivariate analyses revealed a higher prevalence of ADHD among children with urinary BPA concentrations above the median, which was 3.9 μg/L (11.2% vs 2.9%; P = .01). A similar pattern was seen for the secondary outcome.

Multivariable analyses, adjusted for potential confounders, revealed that children with urinary BPA concentrations at or above the median were more than 5 times more likely to have an ADHD diagnosis than children with levels below the median (adjusted odds ratio [OR], 5.68; 95% confidence interval [CI], 1.63-19.83).

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Boys more vulnerable than girls

Sex-stratified analyses of the data showed that boys with urinary BPA concentrations at or above the median were much more vulnerable to ADHD than were girls or were boys with concentrations below the median.

Boys with concentrations above the median were nearly 11 times more likely to have an ADHD diagnosis than their below-the-median counterparts (adjusted OR, 10.93; 95% CI, 1.39-86.0). The odds of having an ADHD diagnosis among girls with urinary BPA concentrations above the median were not that much higher than for their below-the-median counterparts (adjusted OR, 2.8; 95% CI, 0.37-21.29).

In all, the researchers confirmed animal and human studies that showed an association between higher urinary BPA concentrations and ADHD in American children.

Although existing human studies, most of which have been regional and conducted in young children (< 8 years), have been equivocal regarding sex-specific vulnerability, the current study showed that the association in older, school-age children was stronger in boys.

The team called for studies to determine whether reducing exposure to BPA translates into a relevant means of ADHD prevention.

Also see:

Infographic: Men With Versus Men Without ADHD in Childhood

References:

1. Tewar S, Auinger P, Braun JM, et al. Association of bisphenol A exposure and attention-deficit/hyperactivity disorder in a national sample of U.S. children. Environ Res. 2016;150:112-118.