u C .E C a 100 80 60 !} 40 Q,) #- 20 TiO 2 :Mn IN SUNSCREENS 0 ------------- - 1% Loading C:=:J 2%Loading - 3%Loading 393 Figure 5. Retention of vitamin C in Type III W/0/W emulsion in the absence of inorganic UV absorbers and in conjunction with nanopartide Ti0 2 and Ti0 2 :Mn over two hours of solar exposure. CONCLUSIONS The addition of manganese to sunscreen grade TiO 2 results in an almost (97%) total elimination of photogenerated ROS due to electron/hole de-excitation via the manganese dopant ion and an ROS scavenging effect from manganese associated with the surface region of the particle. These properties result in photostabilization of organic sunscreen and cosmetics additives such as BMDM, OMC, vitamin E, and vitamin C. Significantly enhanced retention of active organics during solar exposure has been demonstrated. It has also been shown that photogenerated ROS from TiO2 acts to degrade anti-oxidant cosmetic components during topical use and that this degradation rate is directly related to TiO2 concentration. Only partial protection of UV-absorbing components is shown by TiO2 in comparison with TiO2:Mn. The beneficial effects on emulsion ROS load from incorporation of TiO2:Mn have been demonstrated during solar exposure, but it seems reasonable to postulate that any mechanism of ROS generation in emulsions, e.g., thermal generation, will also exhibit organic active stabilization effects in conjunction with TiO2:Mn. REFERENCES (1) B. L. Diffey, Sources and measurement of UV radiation, Methods, 28, 4--13 (2002). (2) W. A. Bruls, H. van Weelden, and J.C. van der Leun, Transmission of UV radiation through human

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