Development, validation and testing of a skin sampling method for assessment of metal exposure.

BACKGROUND: Nickel, cobalt and chromium are frequent skin sensitizers. Skin exposure results in eczema in sensitized individuals, the risk being related to the skin dose.

OBJECTIVES: To develop a self-sampling method for quantification of skin exposure to metals, to validate the method, and to assess its feasibility.

METHODS: Defined metal doses (0.01-5 µg) were applied to the fingers of 5 participants. Skin areas (2 cm2 ) were sampled with 1% HNO3 , either as 0.1 ml on a swab, or as 0.5 ml on a wipe. Furthermore, 17 participants performed self-sampling by swab after 2 h of leisure activity. Samples were extracted in 1% HNO3 and analysed by inductively coupled plasma mass spectrometry.

RESULTS: The sampling efficiency by swab was 46%, as compared with 93% for acid wipe sampling, for all tested doses. Most metal from the skin dose was detected in the first swab (33-43%). Despite lower sampling efficiency by swab, skin doses of metals following 2 h of leisure activity without hand washing were quantified in all participants, and ranged from 0.0016 to 0.15 µg/cm2 , from 0.00014 to -0.0020 µg/cm2 and from 0.00048 to -0.027 µg/cm2 for nickel, cobalt, and chromium, respectively.

CONCLUSIONS: The results indicate a future potential of skin sampling by swab to detect and monitor metals on skin by self-sampling. This will contribute to better knowledge of metal skin exposure among dermatitis patients, workers, and the general population.