Commentary on “Formula Feeding as a Risk Factor for Attention Deficiency Hyperactivity Disorder: Is Bisphenol A Exposure a Smoking Gun?”

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Bisphenol A (BPA) is an endocrine disruptor that has the potential to interfere with the endocrine system by mimicking naturally occurring hormones in the body, resulting in overstimulation and adverse developmental, reproductive, immune, and neurological effects, even at low doses. For more than 40 years, it has been used in the manufacturing of plastics, flame retardants, and food and beverage products to harden plastics and coat metal products.1 Its use has been so widespread that human exposure to BPA is nearly universal, with 95% of the US population having detectable levels of BPA.2 Exposure to BPA has been linked to an increased risk of cancer, diabetes, neurological, and developmental disorders, and there has been a growing movement to examine the effects of BPA on the prenatal and neonatal periods. Starting in 2008, many states and manufacturers began to phase out BPA from infant formula, infant formula packaging, and baby bottles. In recent years, several human studies have investigated the role of BPA exposure in child neurodevelopment with mixed results, ranging from reports of altered neurobehavior, such as hyperactivity, aggression, anxiety, depression, and attention problems3–5 to no association.
A handful of studies6,7 dating back to 2005 have found that breastfeeding may be a protective factor for attention deficiency hyperactivity disorder (ADHD). The current study8 is the first to find what it is in infant formula that could, in fact, explain such a difference, which may be of critical importance in explaining the mechanism underlying this association, thereby strengthening the evidence that the relationship between breastfeeding and ADHD may be causal in nature. The key finding is that from 2007 to 2011–2012, BPA exposure among formula-fed infants decreased, as did rates of ADHD, prompting the hypothesis that decreased ADHD rates among breastfed infants may be due to reduced exposure to BPA.
When considering the results in the current study, it is important to note that there are a myriad of other environmental exposures that may result in increased ADHD rates. ADHD is considered a genetic disorder, but many environmental risk factors have also been implicated, including prenatal substance use, heavy metal exposure, and nutritional factors.9 Both prenatal exposure to smoking and exposure to lead in childhood, which are some of the most significant and prevalent public health problems in the United States, have consistently been linked to ADHD and ADHD symptoms, as stated by the Centers for Disease Control and Prevention (CDC) and systematic reviews.5,10 The study, in this issue of the Journal of Behavioral and Developmental Pediatrics, included an assessment of secondhand smoke exposure but only compared it among ever breastfed versus never breastfed children and did not directly investigate secondhand smoke exposure and ADHD prevalence.
As noted by the authors, one of the limitations of the data set was that breastfeeding was presented as a dichotomous variable and did not include the length of breastfeeding, nor whether the breastfeeding was exclusive. In a similar vein, the CDC has stated that despite increasing breastfeeding rates, many mothers are not meeting the American Academy of Pediatrics' recommendations for continued and exclusive breastfeeding.11 There is still much work to be done to provide ongoing breastfeeding support for these mothers through their families, communities, health care providers, employers, and policymakers.
The phasing out of BPA has been a highly contentious public health issue since 2007. In 2008, the National Toxicology Program, headquartered at the National Institute of Environmental Health Sciences, released a statement on BPA concluding that there were adverse health effects on human reproduction and development.
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