Titanium dioxide nanoparticles in synthetic sweat were applied to intact and needle-abraded human skin in Franz cells for 24 hours. No titanium reached the receiving solution for either skin condition. Titanium was found in the epidermis of intact skin (0.47 ± 0.33 µg/cm2) and was below the detection limit in the dermis. Damaged skin as a whole held a similar amount (0.53 ± 0.26 µg/cm2).
Key numbers
- Receiving solution, 24 h: below the 5 µg/L detection limit, intact and damaged skin (PDF p. 9).
- Intact skin: epidermis 0.47 ± 0.33 µg/cm2; dermis below detection limit (PDF p. 9-10, Figure 3).
- Damaged skin, whole: 0.53 ± 0.26 µg/cm2 (PDF p. 10).
- Donor phase: 2.5 mL of a 1.0 g/L suspension, printed as 606 µg/cm2 (PDF p. 6).
- HaCaT EC50 after seven days: 8.8 × 10^-4 M (MTT), 3.8 × 10^-5 M (AlamarBlue), 7.6 × 10^-4 M (propidium iodide) (PDF p. 2).
The micro sign and exponent signs are missing from the text layer and were read from the page image.
Methods (brief)
Franz diffusion cells, mean exposed area 3.29 cm2; titanium by ETAAS (detection limit 5 µg/L) and ICP-AES for the donor; six cells per condition. Corresponding author: larese@units.it.
Evidence fitness
Supports the observation that titanium dioxide nanoparticles remain in the upper skin layers even when the barrier is mechanically damaged, in a sweat vehicle. It is not a sunscreen test and does not address impurity metals.
Limitations
Synthetic-sweat vehicle, adult abdominal skin, 24 h only. The printed donor dose does not match 2.5 mL of 1.0 g/L over 3.29 cm2 (about 760 µg/cm2).
Related evidence
- Opinion on Titanium Dioxide (nano form), COLIPA S 75 (SCCS/1516/13)
- Dermal Absorption of Nanomaterials Titanium Dioxide and Zinc Oxide Based Sunscreen: Role of Size and Surface Coating
- Titanium
Update history
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