Metal powders of cobalt, nickel, and chromium were applied to excised human skin in Franz cells for 24 hours, with synthetic sweat at pH 4.5, and the receiving phase was measured by electrothermal atomic absorption spectrometry. Damaged skin passed far more cobalt and nickel than intact skin. Chromium did not show that difference. Intact and damaged skin are separate results.
Key numbers
Receiving-phase metal, ng/cm2, from the results table. Columns are median, 25th percentile, 75th percentile, minimum, and maximum.
| Metal | Skin | Median | 25th | 75th | Min | Max |
|---|---|---|---|---|---|---|
| Co | Intact | 8.4 | 4.9 | 13.4 | 0.9 | 30.6 |
| Co | Damaged | 3566 | 2296 | 4977 | 100 | 6288 |
| Ni | Intact | 31.0 | 19.4 | 41.9 | 16.1 | 54.6 |
| Ni | Damaged | 2631 | 1369 | 4961 | 1110 | 10180 |
| Cr | Intact | 5.0 | 4.5 | 5.5 | 3.5 | 5.5 |
| Cr | Damaged | 4.6 | 4.3 | 9.4 | 4.2 | 11.2 |
The abstract and the table print intact cobalt as 8.4 ng/cm2. One results sentence prints 38.4 ng/cm2 in the same comparison. The table value 8.4 is the headline. Both tokens are retained in the ledger.
Detection limits are printed with the glyph lg, read as µg but not rewritten: Co 0.4 lg/L, Cr 0.2 lg/L, Ni 0.2 lg/L.
Methods (brief)
Franz cells, 24 h, synthetic sweat pH 4.5, ETAAS. Powders are elemental metals, not finished sunscreens or pigments in a cream. Skin content is discussed by the authors and is not given as a second full table on this page.
Evidence fitness
The table supports an in vitro permeation contrast for three metals and two skin conditions. It does not support a product occurrence rate.
Limitations
The 8.4 versus 38.4 conflict is unresolved. The unit glyph lg is flagged. Blank-cell medians are in the same table and are not the exposed-skin results.
Related evidence
Update history
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