Estimating dermal exposure to jet fuel (naphthalene) using adhesive tape strip samples

A simple, non-invasive dermal sampling technique was developed and tested on 22 human volunteers under laboratory conditions to estimate acute dermal exposure to jet fuel (JP-8). Two sites on the ventral surface of each forearm were exposed to 25 micro l of JP-8 and the non-viable epidermis (stratum corneum) was sequentially tape-stripped using an adhesive tape. Samples were extracted with acetone and analyzed by gas chromatography/mass spectrometry. Analysis of the first tape strips indicated that JP-8 was rapidly removed from the stratum corneum over the 20 min study period. On average, after 5 min of exposure the first two tape strips removed 69.8% of the applied dose. The amount recovered with two tape strips decreased over time to a recovery of 0.9% 20 min after exposure. By fitting a mixed-effects linear regression model to the tape strip data, we were able to estimate accurately the amount of JP-8 initially applied. This study indicates that naphthalene has a short retention time in the human stratum corneum and that the tape stripping method, if used within 20 min of the initial exposure, can be used to measure reliably the amount of naphthalene initially in the stratum corneum due to a single exposure to jet fuel. We are currently investigating the applicability of the developed mixed-effects linear regression model to estimate acute JP-8 exposure levels based upon naphthalene measurements from tape strips collected from occupationally exposed workers.