Pigs with a moderate UVB sunburn were treated with four sunscreens: 10% coated titanium dioxide in oil/water, 10% coated titanium dioxide in water/oil, 5% coated zinc oxide in oil/water, and 5% uncoated zinc oxide in oil/water. Skin was examined by microscopy and mass-spectrometric mapping. Perfusate from in vitro cells was analysed for titanium and zinc. Titanium in perfusate stayed below the printed detection threshold. Zinc in perfusate matched untreated controls.
Key numbers
Figures below are copied as printed. Units are not converted. Species are not merged.
| Analyte | What was reported | Value | Unit | Basis | Where |
|---|---|---|---|---|---|
| Ti | Titanium (lg/ml) None 6 h <0.1 | <0.1 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Ti | Titanium (lg/ml) CM 630 6 h <0.1 | <0.1 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Ti | Titanium (lg/ml) CM 634 6 h <0.1 | <0.1 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Ti | Ti was below detectable limits (< 0.1% of applied dose) in all samples tested | <0.1 | % of applied dose | fraction of applied dose in perfusate | ICP-MS of In Vitro Perfusate Samples, p. 10 |
| TiO2 | CM 630 (10% TiO2 [named product] in o/w formulation) | 10 | % | as formulated | Methods, p. 2 |
| TiO2 | CM 634 (10% TiO2 [named product] in w/o formulation) | 10 | % | as formulated | Methods, p. 2 |
| ZnO | CM 643 (5% ZnO [named product] in o/w formulation) | 5 | % | as formulated | Methods, p. 2 |
| ZnO | CM 644 (5% ZnO [named product] in o/w formulation) | 5 | % | as formulated | Methods, p. 2 |
| TiO2 | dosed with 50 µl of the four sunscreen formulations | 50 | µl | topical dose on 0.64 cm2 cell area | In vitro flow-through diffusion cells, p. 3 |
| TiO2 | treated with 250 µl of each formulation; 200 µl was loaded onto the pad of the Hill Top chamber (1.0 cm2 area) and | 250 | µl | occluded topical dose | In vivo treatment, p. 3 |
| Zn | Zinc (lg/ml) None 6 h 0.5 | 0.5 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Zn | Zinc (lg/ml) None 20 h 0.4 | 0.4 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Zn | Zinc (lg/ml) None 24 h 0.3 | 0.3 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
| Zn | Zinc (lg/ml) CM 643 6 h 0.5 | 0.5 | lg/ml | receptor fluid, not skin content | Table 1, p. 15 |
The structured evidence record for this source holds 42 copied values. The table above is the short set.
Methods (brief)
In vitro skin (400 µm) was dosed with 50 µl on 0.64 cm2 for 24 h. In vivo sites received 250 µl under a 1.0 cm2 chamber for 48 h, with a redose at 24 h. Titanium dioxide primary particles were 10 by 50 nm with mean agglomerates of 200 nm. Zinc oxide mean size was 140 nm. UVB doses that produced a +2 erythema were 100 to 120 mJ/cm2.
Evidence fitness
These data support ICP-MS detected no Ti above the printed detection threshold in 24-hour perfusate from UVB-exposed skin treated with 10% TiO2 sunscreens (<0.1 lg/ml; <0.1% of applied dose); Zn in the same perfusates was 0.3 to 0.5 lg/ml and was also present in untreated controls, which the authors call background; TEM found TiO2 particles inside stratum corneum, deeper in some UVB-damaged sites than in normal skin, and ZnO particles shallower than TiO2.
They do not support Does not support transdermal absorption of Ti or Zn into perfusate; Does not report organ Ti or Zn concentrations; Does not report infant or human skin concentrations; Layer counts are not concentrations of Ti or Zn in tissue.
Limitations
Perfusate zinc is explicitly background. TOF-SIMS maps show titanium and zinc in epidermis but the authors give no numeric tissue concentrations from those maps. Stated stratum corneum depths differ between the abstract (zinc oxide in the upper one to two layers) and the results (up to 10 layers, and one site at 16). The animal model is weanling pig skin, not infant human skin.
Related evidence
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