Noninvasive in vivo human multiphoton microscopy: a key method in proving nanoparticulate zinc oxide sunscreen safety.
Level 5 - mechanism / opinion, no new human data
Narrative review/retrospective summarizing the authors' past imaging studies without systematic review methodology
PubMed 31939224 · doi:10.1117/1.JBO.25.1.014509
What was done
The authors summarized findings from ten years of their research using noninvasive in vivo multiphoton microscopy (MPM) with a CE-certified tomograph (DermaInspect) to evaluate the transdermal penetration of nanoparticulate zinc oxide (ZnO) in sunscreens. The research incorporated spectral imaging, fluorescence lifetime imaging, second harmonic generation, and phosphorescence microscopy across various skin types and topical application methods, alongside assessments of epidermal morphology and redox state.
What was found
The abstract reports no numerical data, effect estimates, or sample sizes. The authors qualitatively report that nanoparticulate zinc oxide particles do not penetrate human skin across tested application methods and skin types, with preserved viable epidermal morphology and redox state.
Why it matters
This work synthesizes in vivo optical imaging evidence supporting the barrier safety of physical nanoparticle-based sunscreens, supporting regulatory frameworks classifying zinc oxide as generally recognized as safe and effective.
Limits
The abstract provides a high-level narrative summary of the authors' own previous studies rather than a systematic review or primary trial. No quantitative metrics, participant counts, formulation concentrations, or detailed experimental controls are reported in the text.
Cited by
- supports Chemical-based sunscreens contain endocrine disruptors, whereas mineral sunscreens using zinc oxide only do not.