Efficiency of opaque photoprotective agents in the visible light range

Effects of Visible Light on the Skin†

“…Adding another visible light absorber, iron oxide, substantially lowered transmittance below that predicted by the product of the transmittances for each component alone. The addition of pigments greatly enhances photoprotection and can produce a better match with the patient's skin color, which consequently increases cosmetic acceptability (70).…”

The impact of oral Polypodium leucotomos extract on ultraviolet B response: A human clinical study

“…4, 5 In addition, transparent organic and inorganic sunscreens do not prevent transmission of wavelengths in the visible spectrum. 6 Therefore, oral supplements with photoprotective properties may be helpful in reducing UV-induced injury when other photoprotective measures fail.…”

Sunblocks: Mechanisms of action

“…Regarding the amount of sunblock required to decrease the transmission of visible light and UV radiation, it might be expected that thickness of application would be directly proportional to transmission. Experiments show that particulate sunblocks do not obey Beer's law (11) and after a certain thickness of film, the sunblock fails to give increasing protection proportionate to the thickness. Thus, one should advocate application of the same amount of sunblock as would be used to determine the protection factor.…”

“…A rough estimate of their comparative efficacy may be gauged by a number of in vitro techniques. Perhaps the best is by means of a xenon arc source, integrating sphere and photomultiplier (11). Using this technique to compare visible light transmission, differences between a variety of sunblocks were explored, indicating that combinations of TiO 2 with Fe 2 O 3 gave best protection.…”

“…1). Combination of pigment particles gives broad spectrum protection (11). Increasing concentrations of TiO 2 give protection factors of 1.5-2 for every 1% of sunblock used.…”