ASSOCIATION BETWEEN URINARY BISPHENOL A CONCENTRATION AND OBESITY PREVALENCE IN CHILDREN AND ADOLESCENTSLeonardo Trasande, MD, MPPTeresa Attina, MD, PhD, MPHJan Blustein, MD, PhD
Bisphenol A (BPA)Used to manufacture polycarbonate resinFound in canned food, polycarbonate bottled liquids and other consumer productsBreakdown product of coatings intended to prevent metal corrosion in food and beverage containersRecently banned from baby bottles and sippy cups by US Food and Drug AdministrationComprehensive, cross-sectional study of dust, indoor and outdoor air, and solid and liquid food in preschool age children suggested that dietary sources constitute 99% of BPA exposureSchecter et al. Environ Sci Technol. 2010;44(24):9425-9430Wilson et al. Environ Res. Jan 2007;103(1):9-20.Tavernise S. New York Times, 17 July 2012 edition.
Discovered by Aleksandr Dianin, 1891
BPA in humansStahlhut et al. Environ Health Perspect. 2009;117(5):784-789.Volkel et al.Chem Res Toxicol. 2002;15(10):1281-1287.Fernandez et al. Reprod Toxicol. Aug-Sep 2007;24(2):259-264.
BPA and obesityLaboratory studies suggest that BPA disrupts multiple metabolic mechanisms, Occurs at exposure levels commonly seen in US populationUrinary BPA concentration has been associated with:Adult obesityAdult diabetes, cardiovascular diagnoses and abnormalities in liver functionIncreased frequency of later coronary artery disease in later lifeDifferences in heart rate variability and blood pressure in elderly
Masuno et al. J Lipid Res. 2002;43(5):676-684Sakurai K et al. Br J Pharmacol. 2004;141(2):209-214Carwile JL, Michels KB. Environ Res. 2011;111(6):825-830 Lang al. JAMA. 2008;300(11):1303-1310Melzer et al. PLoS One. 2010;5(1):e8673Melzer et al. Circulation. 2012;125(12):1482-1490Bae et al. Hypertension 2012;60:786-793
BPA and childhood obesity?Children are known to be uniquely vulnerable to environmental chemicalsYet no studies to date connecting environmental chemical exposures to obesityWe examined associations of urinary BPA concentration with body mass in 6-19 year olds in NHANES 2003-8.NHANES is a federal survey of the nations health, conducted nationally through mobile testing sites.Sample was 2838 US children, representative of the US
Quantifying BPA and body massBPAUrinary concentrations from Centers for Disease Control and Prevention (CDC)s laboratoriesWe transformed the concentrations in two ways:Divided the sample into fourths based on BPA concentration (lowest to highest)Also looked at linear BPA concentration (expressed as the logarithm to normalize the distribution)Body mass Height and weight measured by CDCs trained staffWe transformed these in two waysStandardized BMI (weight in kilograms divided by height in meters squared) for age and gender into Z-scoresClassified overweight as at/above 85th percentile for age and gender (obese at/above 95th percentile)
Other factors that were consideredSimultaneously examined other factors associated with obesityAge group (6-11 and 12-19 years)GenderRacial/ethnic groupSocioeconomic statusCaregiver educationSerum cotinine level (tobacco smoke exposure)Television watchingCaloric intakeUrinary dilution (creatinine)
Key characteristics of the sampleMedian BPA: 2.8 ng/mL
Caloric intake and television watching not associated with BPA, but BPA was associated with overweight and obesity34.1% overweight17.8% obese
- Main (multivariable) results*p
Specificity of associationWe also examined chemically similar environmental phenols used in sunscreens and soapsUrinary concentrations of these similar phenols were not associated with obesity
Race-specific effectsAssociations of BPA concentration with obesity (but not BMI Z-score) were isolated to whites, and were absent in Hispanics and Blacks.If obese whites have unique dietary behaviors that predispose them to increases in urinary BPA, then this could explain our results, though there is no evidence to support this.A difference in genetic or other predisposition is another plausible explanation.
CaveatsReverse causation is possibleObese children ingest more foods that contain BPAUrinary BPA represents more recent exposure, rather than the chronic exposure that is more likely to lead to obesityBPA may disrupt metabolism earlier in life than in the childhood and adolescent years we studied
Nonlinear associationConsistent with biological activity of many hormones Duplicated in many studiesDr. Linda Birnbaum (NIEHS Director) has emphasized that regulatory policymakers should include information about non-linear associations, when they deliberate.Vandenberg LN et al. Endocr Rev. Jun 2012;33(3):378-455.Birnbaum Environ Health Perspect. Apr 2012;120(4):A143-144.
SummaryFirst report of an association of an environmental chemical exposure with childhood obesity in a nationally representative sampleAssociation evident when exposure and outcome are modeled in a number of different waysAdjusted prevalence of obesity of 22.3% (among children in the highest uBPA quartile, compared with a 10.3% prevalence among those in the lowest uBPA quartile.
Available at www.jama.com
L Trasande and coauthorsAssociation Between Urinary Bisphenol A Concentration and Obesity Prevalence in Children and Adolescents