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| NIOSH Home > Safety and Health Topics >Skin Exposures and Effects >Occupational & Environmental Exposures of Skin to Chemicals- 2005> Abstracts |
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Investigation of the penetration of aromatic amines through the human skin in vitro
L. Lueersen, T. Wellner, J. Angerer, H. Drexler, G. Korinth* Background
Aromatic amines (AA) are used as intermediates in the chemical industry. They serve for the preparation of dyes, pharmaceuticals, pesticides and plastics. Some AA have been classified as carcinogenic and are referred to penetrate intact human skin. The dermal penetration of AA can be examined in animal experiments or in vitro studies. The aim of our study is to investigate the dermal penetration of different AA in vitro close to the real workplace exposure conditions. Methods
The four tested AA are o-toluidine (oT), 2-naphthylamine (BNA), 4,4´-methylenedianiline (MDA) and N-phenyl-2-naphthylamine (PBN). Their dermal penetration was examined by means of the static diffusion cell using excised split-thickness human skin of the upper arm and thigh. The skin was exposed for 24 h under occlusion. The exposure was a finite dose in order to mimic occupationally relevant situations according to OECD guidelines. The test compounds oT and BNA (c=30 mg/L) are dissolved in phosphate buffer with 5% ethanol, MDA (c=5 g/L) in NaCl-solution with 50% ethanol and PBN in phosphate buffer with 5% ethanol (c=5 mg/L) and with 20% acetone (c=25 mg/L). A physiological NaCl-solution was used in the receptor compartment of the diffusion cells. Inter- (3 donors) and intra-individual variability between the skin donors was considered. The receptor fluid samples were collected at 1, 2, 4, 7, 16 and 24 h and analyzed with an expressly developed GC/MS-method. Results
BNA and oT penetrated remarkably fast (after 1 h 0.7 vs. 0.9% of the total exposed quantity). After 7 h, which represents approximately the cumulative exposure of a shift at the workplace, ca. 15% of the exposed quantity of BNA and oT penetrated into the receptor fluid. BNA and oT penetrated the skin barrier after 24 h at ca. 45% of the exposed dose. MDA penetrated in significant lower quantities. PBN does not penetrate into the physiological receptor fluid under the experimental conditions of our study. Conclusions
The dermal penetration of AA varied extensively between BNA, oT, MDA and PBN. In particular oT and BNA penetrated in high rates under conditions relevant to the workplace exposure. In vitro studies provide relevant data of dermal absorption of potential carcinogenic compounds by the interpretation of dermal absorption data as well as the evaluation of skin notations by regulatory authorities. Therefore in vitro studies are a useful tool to complete the data from human biomonitoring.
Content last modified: 18 May 2005 |
