Biomarkers of Bisphenol A Exposure and Metabolism in a Population of Neonates in Baltimore, Maryland

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Date
2013-10-30
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Johns Hopkins University
Abstract
Bisphenol A (BPA) exposure is widespread in the general population in countries around the world. Human health concerns arise from its estrogenic properties which may confer a range of health effects across the life span. Following ingestion, the main route of exposure, BPA undergoes first pass metabolism to BPA glucuronide, a rendering it biologically inactive. In newborns and young infants, glucuronidation capacity is low compared to that of adults and older children. The purpose of this research was to determine whether BPA glucuronidation capacity is limited in newborns and young infants. First, a review of the literature on metabolism of BPA in newborns and infants was conducted. Human studies, animal studies and PBPK models were included in the review. Both free BPA and BPA glucuronide were detected frequently in the urine of premature infants in a NICU but less frequently in populations of infants age 1 month and older. BPA glucuronidation was less complete in orally dosed neonatal rats and mice compared with adults, but this effect was not observed in primates. PBPK models predicted elevated serum free BPA concentrations in human infants age 0-3 months due to poor glucuronidation. Second, free BPA and BPA glucuronide were measured in the urine of 12 healthy, full-term neonates and young infants age at age 7-44 days using a laboratory method that greatly reduces contamination of samples with BPA from background sources. BPA exposure was confirmed in all 12 subjects, but free BPA was detected in only a single sample for which the replicate was negative. Lastly, free BPA and BPA glucuronide were measured in urine from 44 neonates collected at two separate time points before and after the first week of life. BPA exposure was confirmed in 71% of the study population, but free BPA was not detected in any urine sample collected from neonates in either age group. These data are the first human BPA biomarker measurements ever recorded for healthy full term neonates and fundamentally challenge our prior assumptions of the toxicology of BPA.
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Keywords
bisphenol A, neonate, exposure, environment, biomarker
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