Penetration of aflatoxins through isolated human epidermis

The purpose of this study was to determine if aflatoxin B1 (AFB1) could penetrate through isolated human epidermis (stratum corneum plus viable epidermis). [14C]AFB1 (7.5-9.3 micrograms) was applied to the stratum corneum of epidermal disks mounted in Teflon diffusion cells. [14C]AFB1 penetrated chemically unaltered through the isolated epidermis. Chloroform-extractable radioactivity accounted for 82.5 +/- 3.7% of the total penetrating radioactivity in the receptor fluid of the diffusion cells. The rate of penetration was very slow when experiments were conducted under nonoccluded conditions, but was approximately 40 times greater under conditions of occlusion. The maximum velocity of penetration was 0.63 +/- 0.71 and 27.31 +/- 10.15 pmol/h under conditions of exposure to ambient conditions and occlusion, respectively. Penetration after 46 h was less than 0.05% and 3.41% of the applied dose under nonoccluded and occluded conditions, respectively. Total recovery expressed as a percentage of the applied radioactivity was 98.6 +/- 6.4%.