The Contribution of Diet to Total Bisphenol a Body Burden in Humans: Results of a 48 Hour Fasting Study
Human biomonitoring studies measuring BPA in urine have shown widespread exposure in the general population. Diet is thought to be a major route of exposure. We studied urinary BPA patterns in five individuals over a 48-hr period of fasting (bottled water only). Personal activity patterns were recorded with a diary to investigate non-dietary routes of exposure. All urine void events during the fast were collected, as well as events before and after the fast. The pattern of BPA concentrations was similar for all participants: they rose near the beginning of the fast (after the pre-fast meal), declined over the next 24 hours, fluctuated at lower levels during the second day, and then rose after the post-fast meal. Concentrations (~2 µg/g creatine) and calculated BPA intakes (~0.03 µg/kg-day) in these individuals during the first 24 hours were consistent with general population exposures. For the second 24 hours, concentrations and intakes declined by about two-thirds. One of the individuals had an extraordinary pre-fast exposure event with concentrations rising as high as 98 µg/g creatine but declining to < 5 µg/g creatine by day 2. Given patterns found in day 1 and the subsequent decline to lower levels in day 2, we hypothesize that BPA exposures in these individuals were diet-driven. No events in the diary (use of personal care products, e.g.) appear associated with exposures. On day 2, non-dietary sources may still be present, such as from dust. Another hypothesis is that small reservoirs of BPA from past exposures are released from storage (lipid reservoirs, e.g.) and excreted.