By virtue of its binding to steroid hormone receptors, bisphenol A (BPA, the 
unconjugated bioactive monomer) is hypothesized to be estrogenic when present in 
sufficient quantities in the body, raising concerns that widespread exposure to 
BPA may impact human health. To better understand the internal exposure of adult 
humans to BPA and the relationship between the serum and urinary 
pharmacokinetics of BPA, a clinical exposure study was conducted. Blood and 
urine samples were collected approximately hourly over a 24-h period from 20 
adult volunteers who ingested 100% of one of three specified meals comprising 
standard grocery store food items for breakfast, lunch, and dinner. The 
volunteers' average consumption of BPA, estimated from the urinary excretion of 
total BPA ((TOT)BPA = conjugated BPA + BPA), was 0.27 μg/kg body weight (range, 
0.03-0.86), 21% greater than the 95th percentile of aggregate exposure in the 
adult U.S. population. A serum time course of (TOT)BPA was observable only in 
individuals with exposures 1.3-3.9 times higher than the 95th percentile of 
aggregate U.S. exposure. The (TOT)BPA urine concentration T(max) was 2.75 h 
(range, 0.75-5.75 h) post-meal, lagging the serum concentration T(max) by ∼1 h. 
Serum (TOT)BPA area under the curve per unit BPA exposure was between 21.5 and 
79.0 nM•h•kg/μg BPA. Serum (TOT)BPA concentrations ranged from less than or 
equal to limit of detection (LOD, 1.3 nM) to 5.7 nM and were, on average, 42 
times lower than urine concentrations. During these high dietary exposures, 
(TOT)BPA concentrations in serum were undetectable in 83% of the 320 samples 
collected and BPA concentrations were determined to be less than or equal to LOD 
in all samples.