A quantitative minimally invasive assay for the detection of metals in thestratum corneum

A quantitative, minimally invasive tape-stripping assay for the detection o f metals on and in skin that also has application to the detection of metal lic elements on dry surfaces (where human contact could occur) has been dev eloped. This development included construction, using commercial products, of an approximately 25 mu m thick, low-metal content tape suitable both for tape-stripping and elemental analysis. Individual tapes were sequentially applied to the skin surface and then removed, taking with them a sample of the dead outer layer of the skin (stratum corneum). Analysis of such tape s trip samples by particle induced X-ray emission (PIXE) - a well-characteriz ed, sensitive, analytical technique based on X-ray spectrometry - identifie d and accurately quantified the metals in the sample. The assay had element al sensitivities of approximately 1 ng/cm(2) for many metals and analysis o f elemental contents could be performed in as little as 5 min. The feasibil ity of the assay for measuring metals in the stratum corneum was demonstrat ed on the forearms of healthy human volunteers. Samples from approximately half the subjects were found to contain zirconium, possibly arising from th e use of roll-on antiperspirants. The assay has potential as a tool: (1) fo r risk assessment, (2) to identify exposure levels following possible conta ct with a hazardous metal, and (3) to determine the effectiveness of cleanu p or removal measures. (C) 2000 Elsevier Science B.V. All rights reserved.