Mathematical description of the uptake of hydrocarbons in jet fuel into the stratum corneum of human volunteers

Abstract

The objective of this research was to develop a mathematical description of uptake of aromatic and aliphatic hydrocarbons into the stratum corneum of human skin in vivo. A simple description based on Fick's laws of diffusion was used to predict the spatiotemporal variation of naphthalene, 1- and 2-methylnaphthalene, undecane, and dodecane in the stratum corneum of human volunteers. The estimated values of the diffusion coefficients for each chemical were comparable to values predicted using in vitro skin systems and biomonitoring studies. These results demonstrate the value of measuring dermal exposure using the tape-strip technique and the importance of quantifying of dermal uptake.

Figure 1

Schematic of the exposure system and tape-strip procedure.

Figure 2

Schematic of the stratum corneum and mathematical model used to describe the diffusion of jet fuel components during the tape-stripping procedure.

Figure 3

Spatial profile of naphthalene in the SC as a function of location along the diffusion path (A). Also shown is a comparison of model prediction and tape-strip data (B). The dots represent data points, and the line represents model predictions. In Figure 4B, the concentration in the tape-strip was normalized by the concentration at the interface between the surface and the SC. The time at which each tape-strip measurement was made is normalized by the experimental exposure time.

Figure 4

Comparison of model predictions and tape-strip measurements for (A) 1-methylnaphthalene, (B) 2-methylnaphthalene, (C) undecane, and (D) dodecane. The dots represent data points, and the line represents model predictions. The concentration in the tape-strips is normalized by the concentration at the interface between the surface and the stratum corneum. The time at which each tape-strip measurement was made is normalized by the experimental exposure time.