Analysis of titanium dioxide and zinc oxide nanoparticles in cosmetics

There have been rapid increases in consumer products containing nanomaterials, raising concerns over the impact of nanoparticles (NPs) to humankind and the environment, but little information has been published about mineral filters in commercial sunscreens. It is urgent to develop methods to characterize the nanomaterials in products. Titanium dioxide (TiO₂) and zinc oxide (ZnO) NPs in unmodified commercial sunscreens were characterized by laser scanning confocal microscopy, atomic force microscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that laser scanning confocal microscopy evaluated primary particle aggregates and dispersions but could not size NPs because of the diffraction limited resolution of optical microscopy (200 nm). Atomic force microscopy measurements required a pretreatment of the sunscreens or further calibration in phase analysis, but could not provide their elemental composition of commercial sunscreens. While XRD gave particle size and crystal information without a pretreatment of sunscreen, TEM analysis required dilution and dispersion of the commercial sunscreens before imaging. When coupled with energy-dispersive X-ray spectroscopy, TEM afforded particle size information and compositional analysis. XRD characterization of six commercial sunscreens labeled as nanoparticles revealed that three samples contained TiO₂ NPs, among which two listed ZnO and TiO₂, and displayed average particle sizes of 15 nm, 21 nm, and 78 nm. However, no nanosized ZnO particles were found in any of the samples by XRD. In general, TEM can resolve nanomaterials that exhibit one or more dimensions between 1 nm and 100 nm, allowing the identification of ZnO and TiO₂ NPs in all six sunscreens and ZnO/TiO₂ mixtures in two of the samples. Overall, the combination of XRD and TEM was suitable for analyzing ZnO and TiO₂ NPs in commercial sunscreens.     

When to apply sunscreen: a consensus statement for Australia and New Zealand

Introduction : Cancers of the skin are the most common cancers in humans, with Australia and New Zealand having the world’s highest incidence. Primary prevention campaigns advise people to apply sunscreen to exposed body sites when outdoors. However, despite growing evidence that cumulative sub‐erythemal exposures cause mutational damage, and trial data demonstrating benefit from daily sunscreen use, current policies do not consider the hazards of incidental (everyday) sun exposure. Thus, a Sunscreen Summit was convened to review the evidence and update the policies for people living in Australia and New Zealand. Results : After reviewing the benefits and risks of sunscreen application, the policy group concluded that people living in Australia and New Zealand should be advised to apply sunscreen to the face/head/neck and all parts of the body not covered by clothing on all days when the ultraviolet index is forecast to reach three or greater, irrespective of their anticipated activities. For planned outdoors activities, sunscreen should be used alongside other sun protection measures. Conclusions : People living in Australia and New Zealand are now advised to apply sunscreen every day when the UV index is predicted to reach 3 or above. Implications for public health : Increased use of sunscreen as part of the daily routine to reduce incidental sun exposure will lead to decreased incidence of skin cancer in the future.     

Global state of sunscreens

The use of sunscreen is embedded in a hierarchy of sun protection strategies consisting primarily of sun avoidance by seeking shade and covering up with clothing. Sunscreens are, however, important means of protection; thus, understanding how they work and knowing their limitations are crucial. This review explains the role of ultraviolet (UV) filters, emollients, emulsifier systems and other components in a sunscreen, as well as trends in formulations in Europe, North America, Latin America, and Asia Pacific. Furthermore, it explains how sunscreen performance in terms of sun protection factor, UVA protection, and other metrics can be simulated. The role of sensory characteristics in assessing and improving compliance is also discussed. In the final chapter, Facts and Fiction, five of the most common myths about sun exposure and sun protection by sunscreen are debunked.     

Sunscreens – what is the ideal testing model?

Sunscreen protection assessment methodologies have been evolving in tandem with the innovation and evolution of sunscreen products themselves; from initial human testing in the Swiss Alps, to laboratory testing with high intensity solar simulators, to spectrophotometers with modern CCD array photocells and diffuse reflectance spectroscopy techniques. The progress in the science leads regulatory development of standard methods, and provides new and improved ways to assess sunscreen protection properties. This review scans much of the history of the development of these methods and highlights the latest development in non‐invasive sunscreen testing as an opportunity to improve accuracy while eliminating human UV exposures.     

Chemical characterization of sunscreens composition and its related potential adverse health effects

Although the sun is very beneficial and essential for life, exposing ourselves too much to sunlight might lead to detrimental health effects such as skin cancer. Eight percent of the total different electromagnetic radiation that regularly irradiates the earth is classified as ultraviolet (UV) radiation. The ozone layer absorbs the most energetic UV rays; consequently, UV‐A and UV‐B reach the earth surface. UV‐A rays heavily contribute to both premature skin aging and skin cancer, while UV‐B rays cause sunburn. Hence, the use of sunscreen is strongly encouraged by many healthcare practitioners in order to minimize or possibly eradicate the harmful effects of UV rays on our skin, keeping in mind, that about 90% of all skin cancers are associated with exposure to the sun's harmful radiation. Unfortunately, inaccurate information is currently roaming the media and the Internet regarding the safety, toxicity, and acute side effects of the active ingredients currently used in sunscreens, therefore discouraging people from using sunscreens. In this review article, it is concluded based on the scientific published literature that the sunscreen ingredients are safe and there are no related potential hazardous health risks associated with their use. In addition, at present, sunscreens are very useful in preventing sunburn and probably skin cancer and photoaging and their regular use can have a positive and a significant impact on public health as means or instruments implemented to reduce exposure to UV radiation.