Bisphenol A (BPA) is utilized primarily in the manufacture of polycarbonate plastic and epoxy resins, which are widely used in the fabrication of baby bottles and food can linings. Consequently, human exposures to BPA are widespread. However, there is still uncertainty about the extent and nature of these exposures. This pharmacokinetic (PK) study is aimed at refining our understanding of the metabolism and excretion of BPA following two different routes of administration. This investigation is also intended to help resolve current controversies in BPA risk assessment. We will administer 100 microgram/kg body weight (bw) of deuterated BPA (d-BPA) orally and/or dermally (as an ethanol solution or a carboxymethylcellulose suspension), in up to 50 participants, with comparable numbers of men to women, and collect blood and urine for measurements of d-BPA and d-BPA conjugates at selected time points over a six day period post-dosing. The use of d-BPA will allow the detection of the administered BPA to be distinguished from background BPA. The primary endpoint of the study is detection of measurable d-BPA and d-BPA conjugates in blood and urine after administration of a single dose of 100 microgram/kg bw d-BPA applied orally and/or dermally (as an ethanol solution or a carboxymethylcellulose suspension). Participants will be given an option to complete either one or both phases of the study, the exposure visits separated by a period of at least 4 weeks. Dose selection was based on balancing the need for detectable levels of BPA in blood and urine to meet the objective and the need to minimize human subject risk. Data from the first 3 participants in the study, who received oral d-BPA, confirmed dosing during the oral pilot phase was sufficient in capturing measurable d-BPA in blood and urine and will continue at 100 microgram/kg bw of d-BPA for oral dosing. Dermal exposure will consist of a pilot phase for this route of administration comprising 4 participants to assess whether 100 microgram/kg bw of d-BPA applied to the skin is sufficient to obtain measurable d-BPA in blood and/or urine in order to establish PK parameters and to evaluate whether the time points are appropriate and necessary. If needed, the dermal pilot phase will be repeated using an ethanol solution rather than a carboxymethylcellulose suspension. The design includes sufficient sampling of blood and urine to define relevant PK parameters, including the rate of BPA absorption, plasma elimination rate, area under the curve (AUC) and apparent clearance, half-life, the urinary excretion rate, and the fractional metabolic clearance of the glucuronide and sulfate conjugates.