Current problems in the use of organic UV fi lters to protect skin from excessive sun exposure

Abstract: The evidences of the harmful effects of skin exposure to excessive UltraViolet (UV) radiation, primarily on the development of skin cancer, have increased over the last decade. Therefore, national and international health authorities have encouraged the public to take protective sunscreens, and respectively also everyday cosmetics containing UV fi lters. In these products, a mixture of the UV fi lters, including both inorganic and organic nature, has been shown to be more effective than the individual UV fi lter. However, currently there are concerns about the safety and actual effectiveness of some UV fi lters; especially about certain UV-absorbing compounds (organic UV fi lters). Three cardinal problems are the most questionable. First, that certain UV fi lters are absorbed through the skin resulting in systemic exposure with unknown consequences. Second, that certain UV fi lters show the potential to be adversely endocrine disruptors. Third, that certain UV fi lters are partially degraded by UV radiation, what making them photounstable and unable to fulfi l their basic protective function. The purpose of this article is to discuss these problems

Transdermal absorption of active substances from cosmetic vehicles

Background: Cosmetic products mean any substance or mixture intended to be placed in contact with the external parts of the human body (eg, epidermis, lips) and should not pass to the lower parts and penetrate to the skin. As a part of evaluation of cosmetic safety, the transdermal absorption of substances should be investigated. Materials and Methods: In vitro absorption was investigated with Franz diffusion cells on untreated porcine skin and specimens of the same treated with 15%wt. SLS. The integrity of the skin was discerned by gauging transdermal electrical conductivity (TEC), the concentration of caffeine absorbed by the samples of skin membrane by liquid chromatography, which took place by applying an emulsion and/or a gel containing active hydration agents (urea, sodium hyaluronate, and sericin). Results: The greatest extent of caffeine penetration was seen for pretreatment with just SLS; similar results were in skin treated with the base gel with 10%wt. urea. In the skin treated with the base emulsion only, the amount of caffeine absorbed was twofold less; this increased after adding the active hydration substances. The values measured for TEC corresponded with the amount of caffeine absorbed. Conclusion: The gel proved to be the more potent vehicle for the active ingredient, as it demonstrated greater transdermal caffeine penetration than the emulsions, correlating with the degree of damage to the skin as detected by TEC. © 2019 Wiley Periodicals, Inc