Ratios between apparent permeability coefficients (<i>K</i>_<i>p</i>) for neat solvent obtained in the present study and those previously reported plotted over the log octanol:Water partition coefficient (log P estimated using US EPA [73]).

Data were available for 20 chemicals, of which 9 had been tested on humans in vivo (13 ratios) and 18 on animal or human skin in vitro (47 ratios). Notes: 1: toluene, styrene and ethylbenzene [37–39]; 2: cyclohexanone [46]; 3: ethanol and methanol [55,62]; 4: ethylbenzene, n-hexane, toluene [52, 54].