Exposure to toxic agents alters organic elemental composition in human fingernails Original Research Article

Subjects and methods: Participants were 71 occupationally exposed workers (49 hairdressers, 22 painters) and 49 unexposed controls. Aspects of exposure were assessed by questionnaire. Nail clippings of index and little fingers were analyzed for sulfur (S), nitrogen (N), carbon (C), and hydrogen (H) contents, using an automatic elemental analyzer (Vario EL III, Elementar Analysensysteme, Hanau, Germany). C/N, N/S, and C/S ratios were calculated. Reliability of elemental measurements was tested in a subset. Results: Reliability analysis of elemental measurements showed a very good agreement. Both painters and hairdressers displayed in their fingernails significantly lower percentages of sulfur, but higher percentages of carbon than unexposed controls. A trend was observed in that sulfur content was lowest in those hairdressers who reported structural changes in their fingernails. As a consequence, the C/S and N/S ratios were significantly increased in both exposed groups. Conclusion: The occupational use of harmful substances leads to decreased sulfur levels in the exposed persons, probably due to diminution of sulfur-rich proteins in the nails, resulting from destruction of disulfide-bonds by alkaline and acid groups. Thus, the C/S ratio seems to be a useful indicator for the amount of damage of nail protein by harmful agents.