The contribution of dermal exposure to the internal exposure of bisphenol A in man.

New findings on Bisphenol A (BPA) contents in thermal printing papers, and receipts, in g/kg concentrations and on its dermal uptake (up to 60%) prompted us to assess the risk arising from dermal exposure. Using physiologically based toxicokinetic modelling, we simulated concentrations in blood, in liver and kidney, the target organs exhibiting the lowest no observed adverse effect levels (NOAEL). By comparing organ concentrations at the dose level of the NOAEL divided by a safety factor of 100 (liver: 50μg/kg/day; kidney: 500μg/kg/day), with concentrations arising from the dermal dose of 0.97μg/kg/day (worst case assumption by Biedermann et al., 2010) this dermal exposure can be assumed safe. Additionally, based on the model simulations the high blood concentrations, reported earlier in the literature, are highly improbable because the related exposure levels are orders of magnitude higher than the currently estimated aggregate exposure levels.