Chemical uptake into human stratum corneum in vivo from volatile and non-volatile solvents.
OBJECTIVE
Simple, safe and quick in vivo methods for estimating chemical uptake into the stratum corneum (SC) from volatile and non-volatile solvents are invaluable to health risk assessors. This study compares the human in vivo SC uptake of a model compound (4-cyanophenol) from water and acetone using quantitative attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy.


METHODS
Small areas on the ventral forearms of human volunteers were treated with 4-cyanophenol (CP) dissolved either in water or acetone. After the skin was cleansed of remaining surface CP, SC samples were taken by a standard tape-stripping method. CP concentration profiles across the SC were quantitated by direct measurement of the permeant on the individual tape-strips using ATR-FTIR.


RESULTS
Increasing the duration of exposure to CP aqueous solutions resulted in increasing CP uptake into the SC; the kinetics of uptake correlated well with predictive diffusion equations. Increasing the 'dose' of CP in acetone also resulted in increasing uptake into the SC, but uptake eventually plateaued at a maximum level. The amount of CP taken up into the SC from acetone was 2 to 8-fold greater than that from water following similar short-time exposures.


CONCLUSIONS
These safe, simple experimental methods provide practical and predictive assessments of chemical uptake into human SC in vivo.
Stinchcomb
A L
AL
Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, University of California-San Francisco, 94143-0446, USA. stinchca@panther.acp.edu
Pirot
F
F
Touraille
G D
GD
Bunge
A L
AL
Guy
R H
RH
D000328:Adult; D004817:Epidermis / Q000378:metabolism*; D005542:Forearm / Q000502:physiology; D006801:Humans; D008996:Monoamine Oxidase Inhibitors / Q000493:pharmacokinetics*; D010636:Phenols / Q000493:pharmacokinetics*; D012869:Skin Absorption; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014835:Volatilization
D008996:Monoamine Oxidase Inhibitors; D010636:Phenols; D012997:Solvents; C007178:4-cyanophenol