Prolonged Exposure to Bisphenol A from Single Dermal Contact Events

Bisphenol
A (BPA) is an endocrine disruptor frequently detected
in human biofluids. Dermal absorption of BPA from thermal paper receipts
occurs but BPA pharmacokinetics following dermal exposure is not understood.
To compare the pharmacokinetics of dermal and dietary BPA exposure,
six male participants handled simulated receipts containing relevant
levels of BPA (isotope-labeled BPA-d16) for 5 min, followed by hand-washing 2 h later. Urine (0–48
h) and serum (0–7.5 h) were monitored for free and total BPA-d16. One week later, participants returned for
a dietary administration with monitoring as above. One participant
repeated the dermal administration with extended monitoring of urine
(9 days) and serum (2 days). After dietary exposure, urine total BPA-d16 peaked within 5 h and quickly cleared within
24 h. After dermal exposure, cumulative excretion increased linearly
for 2 days, and half the participants still had detectable urinary
total BPA-d16 after 1 week. The participant
repeating the dermal exposure had detectable BPA-d16 in urine for 9 days, showed linear cumulative excretion
over 5 days, and had detectable free BPA-d16 in serum. Proportions of free BPA-d16 in urine following dermal exposure (0.71%–8.3% of total BPA-d16) were generally higher than following the
dietary exposure (0.29%–1.4%).
Compared to dietary BPA exposure, dermal absorption of BPA leads to
prolonged exposure and may lead to higher proportions of unconjugated
BPA in systemic circulation.