In vitro Human Epidermal Penetration of 1-Bromopropane

Abstract

1-Bromopropane (1-BP; CAS number 106-94-5), also known as n-propyl bromide, is a halogenated short-chain alkane used as an organic solvent with numerous commercial and industrial applications, including garment dry cleaning and vapor degreasing of metals. The purpose of this study was to determine the dermal absorption characteristics and corrosivity of 1-BP. Heat-separated human epidermal membranes were mounted on static diffusion cells. Different exposure scenarios were studied (infinite dose, finite dose, and transient exposure) using neat 1-BP and saturated aqueous solution as donor. Steady-state fluxes for infinite-dose neat 1-BP exposure averaged 625 to 960 μg cm−2 h−1. The finite-dose (10 μl/cm2 = 13.5 mg/cm2) unoccluded donor resulted in penetration of <0.2% of the applied dose (22 μg/cm2). A 10-min transient exposure to infinite dose resulted in total penetration of 179 μg/cm2. Steady-state 1-BP fluxes from neat application of a commercial dry cleaning solvent were similar (441 to 722 μg cm−2 h−1). The permeability coefficient of 1-BP in water vehicle was 0.257 ± 0.141 cm/h. The absorption potential of 1-BP following dermal exposure is dependent upon the type and duration of exposure. Donor losses due to evaporation were approximately 500-fold greater than dermal absorption flux; evaporation flux was 420 mg cm−2 h−1. 1-BP is cytotoxic but not corrosive, based on results from a cultured reconstructed human epidermal model (EpiDerm Skin Corrosivity Test).