Joseph Stanfield

In vitro assessments of UVA protection by popular sunscreens available in the United States

BACKGROUND The importance of adequate ultraviolet A (UVA) protection has become apparent with improved understanding of the mechanism of UVA-induced damage to tissues. Currently in the United States, there is no regulation on testing and labeling of sunscreens for UVA protection. In August 2007, the Food and Drug Administration (FDA) addressed this issue in a proposed rule. OBJECTIVES We sought to assess in vitro the degree of UVA protection provided by 13 popular sunscreen products that are commercially available in the United States. METHOD Thirteen sunscreen products were purchased. UVA protection of each product was measured and assessed with 3 in vitro UVA labeling indices: (1) the FDA Proposed Amendment of Final Monograph, August 27, 2007; (2) European Commission Recommendation--the Colipa and critical wavelength methods; (3) and United Kingdoms Boots star rating system. RESULTS Based on the new FDA-proposed guidelines, 8 products achieved the medium protection category, and 5 products achieved high protection. The latter 5 products also fulfilled the UVA protection based on the Colipa guideline desired by the European Commission Recommendation. Nine products achieved the desired critical wavelength value of 370 or higher. Based on the United Kingdoms Boots star rating system, 6 products achieved a rating of 3 stars, and the remaining 7 products achieved no star rating. LIMITATIONS The study only evaluated a small number of sunscreen products, and only in vitro methods were used to assess the degree of UVA protection. CONCLUSIONS The majority of the tested sunscreens in this study offered a medium degree of UVA protection. Compared with the sunscreens in the past, this study shows that UVA protection of sunscreens has improved. Sunscreens with avobenzone and octocrylene provided a higher degree of UVA protection. Globally, there is no uniform standard on testing and labeling sunscreens for UVA protection. In the United States, the FDA has just started to create a much-needed standard. This effort is necessary to educate the public better on how to choose products with adequate UVA protection.

High-SPF sunscreens (SPF ≥ 70) may provide ultraviolet protection above minimal recommended levels by adequately compensating for lower sunscreen user application amounts

BACKGROUND The manner in which consumers apply sunscreens is often inadequate for ultraviolet protection according to the labeled sun protection factor (SPF). Although sunscreen SPFs are labeled by testing at an application density of 2 mg/cm(2), the actual protection received is often substantially less because of consumer application densities ranging from 0.5 to 1 mg/cm(2). High-SPF sunscreens may provide more adequate protection even when applied by consumers at inadequate amounts. OBJECTIVE We sought to measure the actual SPF values of various sunscreens (labeled SPF 30-100) applied in amounts typical of those used by consumers. METHODS Actual SPF values were measured on human volunteers for 6 sunscreen products with labeled SPF values ranging from 30 to 100, applied at 0.5, 1.0, 1.5, and 2.0 mg/cm(2). RESULTS There was a linear relationship between application density and the actual SPF; sunscreens with labeled SPF values of 70 and above provided significant protection, even at the low application densities typically applied by consumers. Sunscreens labeled SPF 70 and 100 applied at 0.5 mg/cm(2) provided an actual SPF value of, respectively, 19 and 27. LIMITATIONS The study was conducted in a laboratory setting under standardized conditions and results are extrapolated to actual in-use situations. CONCLUSION Sunscreens with SPF 70 and above add additional clinical benefits when applied by consumers at typically used amounts, by delivering an actual SPF that meets the minimum SPF levels recommended for skin cancer and photodamage prevention. In contrast, sunscreens with SPF 30 or 50 may not produce sufficient protection at actual consumer usage levels.

Ultraviolet A sunscreen evaluations in normal subjects

We have used a specially modified xenon arc solar simulator to examine ultraviolet A (UVA) protection of a research sunscreen formulation. UVA doses were given to sunscreen-protected and unprotected skin with the use of irradiance values of 50 mW/cm2 and 100 mW/cm2. Erythemal responses were evaluated 5.2 +/- 0.9 hours later and again 24.4 +/- 1.8 hours later. The overall mean unprotected UVA minimal erythema dose (MED) was 23.6 joules/cm2 (SD = 4.8) and the mean UVA protection factor (APF) was 3.2 (SD = 0.78). Neither irradiance nor evaluation time significantly affected MED or APF. These preliminary findings indicate that the modified solar simulator permits convenient determination of sunscreen APF. The APF of a sunscreen is analogous to SPF: APF refers to UVA protection, while SPF refers to protection from the entire solar spectrum, predominantly from the effects of UVB.

Double-blind bilateral paired comparison of 0.05% halobetasol propionate cream and its vehicle in patients with chronic atopic dermatitis and other eczematous dermatoses

Six investigators evaluated 0.05% halobetasol propionate cream and its vehicle in 111 patients with chronic atopic dermatitis and several other eczematous dermatoses. Patients applied treatment twice daily to bilateral lesions for 14 days. Investigators graded pruritus, erythema, scaling, papulation, and lichenification using 4-point severity scales on days 0, 7, and 14. On day 14 patients provided an assessment of efficacy for both treatments. Statistically significant differences favoring halobetasol propionate over the vehicle were seen for all signs and symptoms (p less than 0.001). Substantial improvements were achieved by the active treatment by day 7 (p less than 0.001). Patients assessments of efficacy were significantly higher for halobetasol cream than for vehicle (p less than 0.001). No instances of systemic effects or skin atrophy were reported and adverse experiences were limited to burning or stinging and other minor, nonspecific complaints distributed uniformly between active treatment and vehicle. These results demonstrate that 0.05% halobetasol propionate cream is highly effective in the treatment of atopic dermatitis and other eczematous dermatoses.

Comparison of ultraviolet A light protection standards in the United States and European Union through in vitro measurements of commercially available sunscreens

Background The importance of adequate ultraviolet A light (UVA) protection has become apparent in recent years. The United States and Europe have different standards for assessing UVA protection in sunscreen products. Objective We sought to measure the in vitro critical wavelength (CW) and UVA protection factor (PF) of commercially available US sunscreen products and see if they meet standards set by the United States and the European Union. Methods Twenty sunscreen products with sun protection factors ranging from 15 to 100+ were analyzed. Two in vitro UVA protection tests were conducted in accordance with the 2011 US Food and Drug Administration final rule and the 2012 International Organization for Standardization method for sunscreen effectiveness testing. Results The CW of the tested sunscreens ranged from 367 to 382 nm, and the UVA PF of the products ranged from 6.1 to 32. Nineteen of 20 sunscreens (95%) met the US requirement of CW >370 nm. Eleven of 20 sunscreens (55%) met the EU desired ratio of UVA PF/SPF > 1:3. Limitations The study only evaluated a small number of sunscreen products. Conclusion The majority of tested sunscreens offered adequate UVA protection according to US Food and Drug Administration guidelines for broad‐spectrum status, but almost half of the sunscreens tested did not pass standards set in the European Union.

Improving compliance of daily sunscreen application by changing accessibility.

Sunscreens are effective in preventing sunburn, skin cancers and signs of photoaging (1). Over the past decades, a sustained effort to educate the public on the benefit of sunscreen use and proper application techniques has been carried out by dermatologists, academia, industry and nonprofit organizations (2). Although the public understands the benefits of sunscreen use (3, 4), the vast majority do not use sunscreen on a routine basis due to a variety of reasons (5). The aim of this study was to investigate whether sunscreen compliance can be improved by changing accessibility and storage location. The study took place from February 2016 to May 2016. All eligible participants were randomized into two groups: group A (sunscreen only) and group B (sunscreen + toothpaste/storage unit). On the initial visit, all participants were educated regarding the benefits of daily sunscreen application and received a 2-month supply of broad-spectrum, SPF-30 sunscreen (Neutrogena Ultra-Sheer Dry-Touch Lotion – 3 fl oz) with instructions to apply it each morning to their face, neck, and hands. In addition, participants in group B received a storage unit and were instructed to place the sunscreen with their current toothpaste in the same storage unit in their bathroom. Participants also completed baseline questionnaires regarding demographics and skin characteristics. After 6 weeks, participants returned for followup, and the weight of each participant’s sunscreen was measured before and after the study. Descriptive statistics and graphical methods were used to describe the study population and intervention results. The outcome measure was the difference in weight of sunscreen preminus postintervention for each participant. Least squares regression was used to assess differences between intervention group, while controlling for participant age and skin type. All analyses were performed with Stata v.14.1, Stata Corporation, College Station, TX, USA. A total of 62 Caucasian women took part in the study. Overall mean age of the participants was 38.1 years (SD = 10.7), and no difference in age was observed between the groups. Of the participants, 16% (n = 10) were skin type I, 32% (n = 20) were skin type II, and 52% (n = 32) were skin type III. No appreciable difference in skin types was observed between intervention groups. The mean preweight of sunscreens was 112.2 g for all study participants. Overall sunscreen usage was 40.7 g (SD = 17.8), reflecting a 36.2% change from baseline, P < 0.001. Participants with skin type I used significantly more sunscreen (53.4 g, SD = 13.0) than type II (40.7 g, SD = 15.9) and type III (36.4 g, SD = 18.8) participants, P-values 0.05 and 0.009, respectively.