Challenges in Sun Protection.

Since time immemorial, people protected themselves from solar radiation. Limiting time in the sun by seeking shade or wearing clothing was a matter of course. In the early 20th century, tanned skin - a result of exposure to sunlight - was associated with good health. At the same time, however, one also had to protect oneself against the potential of excessive exposure to avoid sunburns. Around 1945, the first sunscreen products for protection against solar radiation became available. In the years to follow and up to the recent past, a vast number of different sunscreen filters were developed and incorporated into a wide variety of product formats. Frameworks regulating filter substances and preparations and methods to characterize sunscreen products' performance parameters were developed. Over the past 50-70 years, the perception regarding the tasks of sunscreen products changed several times. It was initially promoted as a lifestyle product and had the task of preventing sun-related erythema (tan without burn). Later, the prevention of skin cancer was added. Only in recent times, sunscreen products have been increasingly advertised and perceived as beauty and lifestyle products again. Also, the use of sunscreen products for antiaging purposes is now commonplace. The different intended purposes (averting harm and prevention) and the widespread use of topical sunscreen products have promoted many investigations and generated a vast and ongoing need for consumer and patient information and education. In the following review, we analyze and discuss current topics from conflicting areas, such as sun protection products (e.g., ideal sun protection products, sun protection metrics), product safety (e.g., nanoparticulate sunscreen filters, regulatory issues), application in everyday life (e.g., wish to tan, vulnerable cohorts), as well as controversies and future challenges (e.g., risks and benefits of UV radiation).

Spectral Homeostasis - The Fundamental Requirement for an Ideal Sunscreen.

Sunscreen application to UV-exposed skin is promoted to prevent skin cancer and sun damage, within a comprehensive photoprotection strategy that also includes sun avoidance and wearing UV protective clothing. The benefits of sunscreen are verified in preventing sunburn but appear to be largely presumptive in skin cancer prevention. Contemporary science establishes UVA as a primary driver of melanoma and photoaging. Consequentially, the traditional UVB-skewed protection of sunscreens provides an intellectual and logical explanation for rising skin cancer rates and, in particular, their failure to protect against melanoma. Better protection could be achieved with more balanced UVB/UVA sunscreens, toward spectral homeostasis protection. Greater balanced protection has another advantage of attenuating fewer UVB rays, which aid synthesis of vitamin D and nitric oxide. Percutaneous absorption of Soluble Organic UV Filters leads to systemic exposure, which becomes the relevant safety consideration. It is minimized by selecting Insoluble UV Filters with low absorption potential from a molecular weight above 500 Da. The filters must also be very hydrophilic, very lipophilic, or consist of particles. The risk-benefit ratio is a medical imperative, more so for cosmetics or sunscreens, since in principle there should be no risk from their use. The production of ideal sunscreens that mimic the effective, balanced UVB/UVA attenuation of textiles and shade is now possible, while maintaining an acceptable therapeutic margin of safety in humans and a favorable ecologic profile. Sunscreens with a favorable risk-benefit ratio and good esthetic properties or other consumer-friendly attributes will improve compliance and may achieve substantial clinical benefits.

Challenges in Formulating Sunscreen Products.

Developing efficient sunscreen products with an acceptable sensory feel after application on skin, that meet current regulatory market and consumer requirements, is a major challenge, exacerbated by new restrictions limiting the use of certain ingredients previously considered crucial. This paper outlines a development strategy for -formulating sunscreens along a generic professional development pathway. Each galenic system will be different and must be customized. Development starts with benchmarking, followed by UVA/UVB filter platform selection and in silico calculation/optimization of photoprotection performance for the desired SPF, UVA-PF, and other requested endpoints. Next comes the selection of the emulsifier system and other key formulation ingredients, such as oil components, triplet quenchers, and antioxidants, with sensory, rheological, and film formation functions. Preliminary cost estimation is then performed to -complete the conceptual process before the start of the practical galenic development. The successful development of modern sunscreen products is based on -comprehensive expertise in chemistry, galenic methodology, regulation, and patenting, as well as specific -market and consumer requirements. The selection of the UV filters is the first key decision and constrains later choices. Other properties, such as water resistance and preservation or active ingredients, may need to be considered. The 4 basic requirements of efficacy, safety, registration, and patent freedom become checklist items to ensure that after development, a sunscreen product has a chance of success.

Natural and Simulated Solar Radiation.

The extra-terrestrial solar spectrum corresponds approximately to a black body of temperature about 5,800 K, with the ultraviolet region accounting for almost 8% of the total solar energy. Terrestrial solar spectral irradiance peaks at around 500 nm in the blue-green region, whereas the diffuse component peaks in the UVAI-blue region of the spectrum, with the infrared component comprising almost entirely direct radiation. Several factors impact on the magnitude and spectral profile of terrestrial solar spectral irradiance, and these include solar elevation, reflection from land and sea, air pollution, altitude above sea level and cloud cover. Measurements of erythemal UV from a number of ground-based networks around the world indicate an approximate 4-fold difference in ambient annual exposure between Australia and countries in northern Europe. In the absence of measured data, models to compute solar UV irradiance are a useful tool for studying the impact of variables on the UV climate. Simulated sources of sunlight based on a xenon arc lamp can be configured to give a close match to the spectral output of natural sunlight at wavelengths less than about 350 nm, and these are invaluable in the laboratory determination of sunscreen performance, notably the Sun Protection Factor (SPF). However, the divergence -between natural and simulated solar spectra at longer wavelengths may explain why SPFs measured in natural sunlight are less than those determined in the laboratory.

Sunscreen Secondary Claims: Market Differentiation or Market Confusion?

This chapter is focused on those products that are sold primarily as sun protection products and considers the additional claims made for these that are intended to differentiate and imply additional benefits. It is essentially an overview, as each claim would require an individual chapter to deal with in detail. We do not consider products with another intended primary use, such as moisturizer or colour comments, which are, in themselves "secondary sunscreens," defined specifically in Australia [AS/NZS 2604:2012 Sunscreen products - Evaluation and classification] or Canada. Primarily, the chapter serves as a reference guide. An argument is presented for the potential negative impact on the credibility of the whole product category brought about by the marketing strategy of attempting to segment on the basis of either criticism of competitor products and/or targeting niche groups of consumers. The European Union (EU) Regulation 655/2013 [Commission Regulation (EU) No 655/2013 laying down common criteria for the justification of claims used in relation to cosmetic products] states 6 criteria for representation of products. These are Legal Compliance, Truthfulness, Evidential Support, Honesty, Fairness and Informed Decision Making. More specifically to sunscreens, the EU Synthesis Document makes recommendation on efficacy and related claims [European Union Synthesis Document - Commission recommendation on the efficacy of sunscreen products and claims related thereto]. This chapter does not consider or test these criteria but does include a table of claims and suggested ways to substantiate these.

Environmental Effects of Ultraviolet (UV) Filters.

Organic and inorganic ultraviolet (UV) filters are used in topical sunscreens and other applications to prevent or limit damage following exposure to UV light. Increasing use of UV filters has contributed to a growing number of investigations examining potential effects on human health and the environment. Worldwide environmental monitoring data demonstrate that UV filters reach aquatic environments through two main input sources - direct (i.e., washoff from swimmers/bathers) and indirect (i.e., incomplete wastewater treatment removal) - and can be taken up by various algal, plant, and animal species and sediments. In areas where industrial wastewater sources or significant recreational activities result in a greater input load, levels may be elevated and could impart an increased risk on native species health. In vitro, at higher levels typically not measured in the environment, effects on growth and reproduction are observed in different species, including fish, coral reef, and plants. Despite this, predicted no-effect concentrations for UV filters are generally above measured environmental concentrations. Recent legislative activity banning the use of certain UV filters has heightened awareness of their environmental ubiquity and precipitated a need for a thorough examination of evidence linking their ecological presence with adverse outcomes. In order to gauge the true potential risk to native ecosystems associated with UV filters, future studies should consider factors inherent both to finished sunscreen products (e.g., metabolic fate/transport and effect of inactive ingredients) and to the sampled environment (e.g., species sensitivity, presence of other contaminants, water flow, and photodegradation).

Sunscreens in the United States: Current Status and Future Outlook.

Incidence rates of nonmelanoma skin cancer and melanoma have been on the rise in the USA for the past 25 years. UV radiation (UVR) exposure remains the most preventable environmental risk factor for these cancers. Aside from sun avoidance, sunscreens continue to provide the best alternative protection. UVR directly damages DNA and causes indirect cellular damage through the creation of reactive oxygen species, the sum of which leads to cutaneous immunosuppression and a tumorigenic milieu. The current generation of sunscreens protect from UVR through two main mechanisms: absorption and deflection. In the USA, the Food and Drug Association (FDA) regulates sunscreen products which are considered over-the-counter drugs. With the release of new FDA testing and labeling requirements in 2011 and the enactment of the Sunscreen Innovation Act in 2014, sunscreen manufacturers are now required to evaluate their products not only on the sun protection factor (SPF) but also on broad-spectrum UVA protection. The American Academy of Dermatology Association and the American Academy of Pediatrics have provided specific recommendations for proper sun protection and sunscreen usage with the continual goal of increasing public awareness and compliance with appropriate sun protective measures. Antioxidants, photolyases, and plant polyphenols remain an interesting avenue of research as additives to sunscreens or stand-alone topical or oral products that appear to modulate the immunosuppressive effects of UVR on the skin. Additionally, although UVR induces endogenous cutaneous production of vitamin D, its damaging effects overshadow this positive benefit, especially in light of the ease of achieving recommended amounts of vitamin D through diet and supplementation.

Photoprotection With Mineral-Based Sunscreens.

BACKGROUND: Although chemical sunscreens have traditionally been at the forefront of sun protection, safety concerns and increasing awareness of the environmental impact of personal-care products have led to greater interest in the use of mineral blockers as photoprotective agents. OBJECTIVE: To examine the safety and efficacy of mineral-based sunscreens to allow patients to make informed choices about ultraviolet (UV) protection. MATERIALS AND METHODS: A review of the literature was performed using the PubMed database. RESULTS: This article provides an overview of physical blockers and focuses on the efficacy of mineral sunscreens in offering broad-spectrum UV protection and safety concerns, including the controversy surrounding the use of nanoparticles. Practical tips for application are also reviewed. CONCLUSION: Mineral sunscreens are an attractive, efficacious option for consumers who prefer alternative choices in sun protection.

Sunscreen Application, Safety, and Sun Protection: The Evidence.

Recently in Canada, there has been an effort to create consistent messaging about sun safety as there is a lack of up-to-date evidence-based guidelines regarding sun-protection measures. This review aimed to provide updated, evidence-based recommendations on sunscreen application, safety, and sun protection regarding the following topics for which there is clinical uncertainty: physical barriers, sunscreen properties, sunscreen application, and risk-benefit analysis.

Quick and brief review: Comparison between different in vivo SPF determination methods.

BACKGROUND: The use of sunscreen products has grown considerably in the last few decades because sunscreen products considered as one of the most important ways of skin protection against UV rays by different mechanisms such as reflecting, absorbing, or scattering. Excess expose to UV causes sunburn, early skin aging, and skin cancers. OBJECTIVE: This review aimed to review and compare prominent in vivo sun protection factor (SPF) determination protocols and investigate their approach in test criteria. Finally, this can help skin care specialists to choose the comprehensive SPF determination protocol. METHODS: Four current SPF determination protocols including ISO 24444, AS/NZS 2604:2012, CEN 2006, and FDA 2011 were selected and compared to each other. RESULTS AND CONCLUSIONS: Despite the similarity of the test method among these protocols, there are some obvious differences in test criteria which results in a better performance in the individual steps of the test process for each of these methods.

Examine all available evidence before making decisions on sunscreen ingredient bans.

Coral bleaching is a worldwide problem and more needs to be done to determine causes and potential solutions. A myopic focus on sunscreen ingredients as the proximate cause of coral bleaching provides consumers a false belief that enacted bans of these ingredients will erase decades of coral reef decline. Instead, these bans will likely only lead to decreased sunscreen use and exposure to potentially harmful UV radiation. A closer examination of all available evidence on the causes of coral reef bleaching needs to be undertaken, including a more thorough appraisal of studies conducted under artificial conditions using higher concentrations of sunscreen ingredients.

Cosmetic Versus Medicine: How Does Your Country Define Sunscreen?

Skin cancer (melanoma and non-melanoma) is the most commonly diagnosed cancer in the United States of America, and non-melanoma skin cancer is the most common cause of Australian hospitalisations with cancer as the principle diagnosis, having a huge cost to the country's health care system. Primary and secondary skin cancer prevention is globally inadequate, with only 3 in 10 American adults using sun protection routinely. Evidence suggests that regular sunscreen use in Australians prevents both melanoma and non-melanoma skin cancers, and American research has found that daily sunscreen use reduced the incidence of melanoma - the most skin cancer deaths - by half. Despite this, in many countries and regions around the world, a major ongoing divergence remains on the classification of sunscreen as either a cosmetic product or a form of medical therapy, which in turn affects the consumers' attitudes towards the use of sunscreen. This is also affected by the increasing use of the internet, which has made the purchasing of products internationally convenient and easy for consumers worldwide, including sunscreen products, which are frequently marketed online. There is variation between each country or region and their regulations of sunscreen affect the consequent labelling claims of sunscreen products. This affects the unsuspecting consumer's choices in purchasing sun protection, which may be misinformed. Australia, Canada, and the US are the only countries to classify sunscreen as a form of medical therapy. This paper explores the current classification of sunscreen products in countries and regions around the world and discusses the impact of these discrepancies and similarities on the attitudes of consumers towards sunscreen use. Finally, we make suggestions on changes that can be made to encourage sunscreen use and safe sunscreen purchasing. J Drugs Dermatol. 2018;17(8):899-904.

Relaxing School Suncreen Restrictions.

(1) Utah, Delaware, Vermont, Minnesota and Idaho have the highest skin cancer rates of all U.S. states, according to the Centers for Disease Control and Prevention. (2) Sunscreen is regulated by the U.S. Food and Drug Administration because it makes a "drug claim"--that it helps prevent sunburn and decreases the risks of skin cancer and early skin aging caused by the sun. (3) In Europe and some other countries, sunscreens are regulated as cosmetics, not as drugs.

Sunscreens: An Update.

Sunscreens have been widely used by the general public for their photoprotective properties, including prevention of photocarcinogenesis and photoaging and management of photodermatoses. It is important to emphasize to consumers the necessity of broad-spectrum protection, with coverage of both ultraviolet A (320-400 nm) and ultraviolet B (290-320 nm) radiation. This review discusses the benefits of sunscreen, different ultraviolet filters, sunscreen regulations and controversies, the importance of broad-spectrum protection, issues of photostability and formulation, and patient education and compliance.

Active sunscreen ingredients in Australia.

UV radiation exposure is the major contributor to photocarcinogenesis and photoageing. Reducing UV radiation exposure can be achieved by using adequate sunscreen preparations. The use of sunscreen can significantly reduce the incidence of squamous cell carcinoma, actinic keratoses and invasive melanoma. In the Australian market over 900 sunscreen products are available, each with their own brand, formulation and ingredients. It can be difficult for dermatologists and consumers to determine which are the most effective and appropriate products to use. We discuss the specific active ingredients found in sunscreen formulations available in Australia, their mode of protection, photostability, solubility, and side-effects and the methods used by the Therapeutic Goods Administration to determine the ratings and efficacy of each sunscreen.

Ultraviolet radiation and the skin: Photobiology and sunscreen photoprotection.

The efficacy of sunscreens can be measured by different methods, involving in vitro, ex vivo, or in vivo techniques. There is a need for a worldwide standardization of these methods to avoid misunderstanding and confusion among sunscreen users. The clinical benefits of sunscreens have been demonstrated in randomized controlled trials that established the role of sunscreens in the prevention of actinic keratoses, squamous cell carcinomas, nevi, and melanomas. Sunscreens also prevent photoimmunosuppression and signs of photoaging. Continued efforts in public education on the proper application of sunscreens and the practice of photoprotection in general are needed.