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Stenberg C & Larko O. Sunscreen application and its importance for the sun protection factor. Arch Dermatol121: 1400-1402
Abstract
To achieve a good sun protection, a layer thickness of 2 mg/sq cm is often recommended. Fifty individuals were asked to apply five different sunscreens ad libitum. Ten percent dihydroxyacetone was added to the sunscreens in order to make them fluoresce when irradiated with Wood's light. The layer thickness was calculated by dividing the amount applied by the area. The thicknesses of the sunscreen layers varied little between different parts of the body and different brands; in general it was close to 1 mg/sq cm. The corresponding protection factor was measured for two sunscreens on 20 persons. The results indicate that the sun protection factor under ad libitum conditions is only 50% of what would be achieved using a layer thickness of 2 mg/sq cm.
... In a sample of 50 individuals, ad libitum sunscreen application was ∼1 mg cm −2 (Stenberg & Larko, 1985), thus providing only 50% of the protection that would be afforded with proper application. Therefore, it is important that those who are exposed to repeated and/or prolonged sun exposure practise proper application of sunscreen to prevent the deleterious effects of UVR. ...
Acute exposure to ultraviolet (UV)‐B light elicits an inflammatory response in the skin, resulting in erythema (reddening) and increased skin blood flow over the following 24 hours. However, the time course of, and relation between, these responses is unclear. Likewise, it is unknown whether these responses differ following exposure to broad spectrum (UV‐AB) vs. UV‐B light, as well as how application of sunscreen on the skin impacts these two responses.
Purpose
To examine (1) the time course of erythema and skin blood flow responses over 8 h following acute UV‐B and UV‐AB exposure, and (2) the impact of sunscreen application on those responses. We hypothesized that (1) the erythema and blood flow responses would track each other, (2) both responses would be higher following UV‐AB compared to UV‐B exposure, and (3) sunscreen would attenuate responses to both UV‐AB and UV‐B.
Methods
The ventral aspect of both forearms of 10 healthy young adults (25±4 yrs; 6M/4F) were exposed to either UV‐AB (10 mJ/cm ² ; 6 mJ/cm ² UVA + 4 mJ/cm ² UV‐B) or UV‐B (4 mJ/cm ² ). Two 2‐cm ² sites on each arm were randomly chosen for acute UV exposure with or without pre‐treatment with topical SPF‐50 sunscreen. Erythema index (EI; reflectance spectrometry) and red cell flux (laser‐Doppler flowmetry) were measured at each site before, immediately after, and 2, 4, 6, and 8 h post‐exposure. Cutaneous vascular conductance was calculated (CVC=flux/MAP) at each time point and both EI and CVC were expressed as change from baseline.
Results
EI increased linearly after exposure to UV‐B (p<0.01 at 4, 6, and 8 h post‐exposure) and UV‐AB (p=0.02 at 6 h, p<0.01 at 8 h). Unlike the immediate increase in EI, no increase was seen for CVC until 4 h post‐UV‐B (p<0.01) and UV‐AB (p=0.06). Sunscreen effectively blocked the EI response to both UV‐B and UV‐AB exposures (p>0.05) and prevented, the CVC responses to UV‐B (p<0.01 at 6 and 8 hours) and UV‐AB (p=0.03 at 8 h).
Conclusion
Exposure to UV‐B or UV‐AB induced an immediate and linear increase in EI, but a delayed (by 4 h) increase in CVC. Sunscreen prevented the EI response and blunted the rise in CVC. These data suggest that the inflammatory response to acute UV exposure is characterized by an immediate erythema response and a delayed blood flow response in the cutaneous microvasculature and that sunscreen may protect against both responses.
Support or Funding Information
ACSM Foundation Doctoral Student Research Grant
This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
... In a sample of 50 individuals, ad libitum sunscreen application was ∼1 mg cm −2 (Stenberg & Larko, 1985), thus providing only 50% of the protection that would be afforded with proper application. Therefore, it is important that those who are exposed to repeated and/or prolonged sun exposure practise proper application of sunscreen to prevent the deleterious effects of UVR. ...
New findings:
What is the central question of this study? Are ultraviolet radiation (UVR)-induced increases in skin blood flow independent of skin erythema? Does broad-spectrum UVR exposure attenuate NO-mediated cutaneous vasodilatation, and does sunscreen or sweat modulate this response? What are the main findings and their importance? Erythema and vascular responses to UVR are temporally distinct, and sunscreen prevents both responses. Exposure to UVR attenuates NO-mediated vasodilatation in the cutaneous microvasculature; sunscreen or simulated sweat on the skin attenuates this response. Sun over-exposure may elicit deleterious effects on human skin that are separate from sunburn, and sunscreen or sweat on the skin may provide protection.
Abstract:
Exposure to ultraviolet radiation (UVR) may result in cutaneous vascular dysfunction independent of erythema (skin reddening). Two studies were designed to differentiate changes in erythema from skin vasodilatation throughout the 8 h after acute broad-spectrum UVR exposure with (+SS) or without SPF-50 sunscreen (study 1) and to examine NO-mediated cutaneous vasodilatation after acute broad-spectrum UVR exposure with or without +SS or simulated sweat (+SW) on the skin (study 2). In both studies, laser-Doppler flowmetry was used to measure red cell flux, and cutaneous vascular conductance (CVC) was calculated (CVC = flux/mean arterial pressure). In study 1, in 14 healthy adults (24 ± 4 years old; seven men and seven women), the skin erythema index and CVC were measured over two forearm sites (UVR only and UVR+SS) before, immediately after and every 2 h for 8 h post-exposure (750 mJ cm-2 ). The erythema index began to increase immediately post-UVR (P < 0.05 at 4, 6 and 8 h), but CVC did not increase above baseline for the first 4-6 h (P ≤ 0.01 at 6 and 8 h); +SS prevented both responses. In study 2, in 13 healthy adults (24 ± 4 years old; six men and seven women), three intradermal microdialysis fibres were placed in the ventral skin of the forearm [randomly assigned to UVR (450 mJ cm-2 ), UVR+SS or UVR+SW], and one fibre (non-exposed control; CON) was placed in the contralateral forearm. After UVR, a standardized local heating (42°C) protocol quantified the percentage of NO-mediated vasodilatation (%NO). The UVR attenuated %NO compared with CON (P = 0.01). The diminished %NO was prevented by +SS (P < 0.01) and +SW (P < 0.01). Acute broad-spectrum UVR attenuates NO-dependent dilatation in the cutaneous microvasculature, independent of erythema. Sunscreen protects against both inflammatory and heating-induced endothelial dysfunction, and sweat might prevent UVR-induced reductions in NO-dependent dilatation.
... It is used in risk assessment, but is not meant as a recommended amount to be applied by the consumer (SCCNFP/0321/02). Under laboratory controlled conditions or under realistic conditions of tanning on the beach using own sun products (lotions, alcoholic solutions, gels, creams) applied on the whole body surface, values for use of products between 0.5 -1.3 mg/cm² are reported (Stenberg et al., 1985;Bech-Thomsen et al., 1993;Diffey, 1996, Gottlieb et al., 1997Autier et al., 2001 and. The values are depending on the study protocol used, the location on the body measured and several other factors. ...
The SCCS Notes of Guidance are regularly updated according to the scientific and technological progress. Meanwhile an updated version has been issued end of 2018, the 10th revision, SCCS/1602/18. This new version is available on the webseite of the SCCS: https://ec.europa.eu/health/sites/health/files/scientific_committees/consumer_safety/docs/sccs_o_224.pdf.
Cannabidiol (CBD) is a promising natural agent for treating psoriasis. CBD activity is attributed to inhibition of NF-kB, IL-1β, IL-6, and IL-17A. The present study evaluated the anti-psoriatic effect of cannabidiol in lipid-stabilized nanoparticles (LSNs) using an imiquimod (IMQ)-induced psoriasis model in mice. CBD-loaded LSNs were stabilized with three types of lipids, Cetyl alcohol (CA), Lauric acid (LA), and stearic-lauric acids (SALA), and were examined in-vitro using rat skin and in-vivo using the IMQ-model. LSNs loaded with coumarin-6 showed a localized penetration depth of about 100 µm into rat skin. The LSNs were assessed by the IMQ model accompanied by visual (psoriasis area severity index; PASI), histological, and pro-psoriatic IL-17A evaluations. Groups treated with CBD-loaded LSNs were compared to groups treated with CBD-containing emulsion, unloaded LSNs, and clobetasol propionate, and to an untreated group. CBD-loaded LSNs significantly reduced PASI scoring compared to the CBD emulsion, the unloaded LSNs, and the untreated group (negative controls). In addition, SALA- and CA-containing nanoparticles significantly inhibited IL-17A release, showing a differential response: SALA > CA > LA. The data confirms the effectiveness of CBD in psoriasis therapy and underscores LSNs as a promising platform for delivering CBD to the skin.
Human skin exposure to ultraviolet radiation (UVR) from sunlight can cause many adverse effects. UVB rays are mainly responsible for the most severe damage being acute such as erythema, and long‐term skin cancer included, and they can act by directly impacting deoxyribonucleic acid (DNA) and proteins. Sunscreen filters must be carefully combined to achieve esthetically pleasant products with photo‐stability and well‐balanced UVB(290‐320nm)–UVA (320‐400nm) photoprotection. Sunscreen products can be classified in terms of regulatory status. In order to protect against both UVB and UVA, the sunscreen product contain a combination of approved UV filters within a complex vehicle matrix. The quality and amount of sunscreen applied to skin have a profound impact on the actual sun protection factor of product, and better consumer compliancy can be achieved when the formula has appealing esthetics. It is important that a minimal proportionality between UVA and UVB protection be ensured to avoid high UVB protection with low UVA protection.
When conducting risk assessments of cosmetic ingredients, it is important that reliable exposure information is obtained for cosmetic products. As cosmetics are becoming more diverse, continuous effort must be made to obtain exposure data that reflect their growth and usage trends. The usage pattern of cosmetics, such as the application area and amount used, may differ by product type and also by country. We conducted a survey to compare the amount of sun spray and sun cream used in a usage environment in South Korea. The study was conducted on Haeundae Beach, one of the most popular beaches in South Korea. A total of 1,255 beachgoers participated in this study; 604 and 651 participants used the sun spray and sun cream, respectively, while sunbathing and enjoying water activities on the beach for one day. Exposure was analyzed following a probabilistic method. On comparing all subjects, it was found that the group that used sun spray (mean: 44.52 g/day) used significantly more product (p = 0.000) than those who used sun cream (mean: 20.51 g/day). By analyzing the daily exposure of sun spray and sun cream per unit body weight according to age and gender, the exposure amount of sun spray and sun cream was found to be highest among 2~9 year-old girls (mean for sun spray: 2.51 g/kg/day, p95: 5.50 g/kg/day, mean for sun cream: 0.79 g/kg/day, p95: 1.79 g/kg/day). The amount of sun spray used is approximately twice that of sun cream. Among both the sun spray and sun cream groups, the exposure amount per unit body weight was highest in girls younger than 10. These factors should be considered when conducting risk assessments of sun spray and sun cream.
Nur ein geringer Anteil (etwa 3%) der Globalstrahlung des Sonnenlichtes besteht aus ultravioletter Strahlung. Dennoch ist diese Strahlung für die meisten durch Sonnenlicht hervorgerufenen Hautschäden verantwortlich. Abgesehen von der therapeutischen Wirkung bei einzelnen Dermatosen, ist der einzige bekannte günstige Effekt der ultravioletten Strahlung die Photokonversion von Pro-Vitamin D3 in der Epidermis durch UVB. Alle anderen Reaktionen führen zu akuten und chronischen Schäden. Die akuten Schäden bestehen aus Sonnenbrand und Pigmentveränderungen. Die chronischen Schäden, die durch kumulative Wirkung der ultravioletten Strahlung verursacht werden, sind Hautatrophie, Elastose, Ausbildung von Pigmentflecken und Teleangiek tasien — Veränderungen, die als „Lichtalterung“der Haut bezeichnet werden und nichts mit dem physiologischen Alterungsprozeß zu tun haben — und als übelste Folge die Ausbildung von Hauttumoren.
Regular sunscreen use is widely promoted by government health agencies as well as non-profit organizations concerned with child health and cancer prevention. Indeed, more than half of the British public has bought or used sunscreens in the past 3 years (McGregor 1996). Despite the recommended use of sunscreens, the role that they should ideally play in sun protection remains poorly defined.
Background: Originally developed to protect against sunburn, sunscreen has been assumed to prevent skin cancer. However, conflicting reports include claims that sunscreen increases risk for melanoma. Objective: To examine the strength and consistency of associations between melanoma and sunscreen use in the published literature. Data Sources: A comprehensive MEDLINE search of articles published from 1966 to 2003 that reported information on sunscreen use and melanoma in humans. Study Selection: Analytic studies reporting data on sunscreen use before diagnosis of melanoma. Data Extraction: Two independent reviewers extracted data. Inconsistencies were rereviewed until agreement was achieved. When necessary, a third party resolved discrepancies. Data Synthesis: Odds ratios were pooled across studies by using standard meta-analytic techniques. Pooled odds ratios for ever use among 18 heterogeneous studies did not support an association between melanoma and sunscreen use. Variation among odds ratios was explained by studies that did not adjust for confounding effects of sun sensitivity. The lack of a dose-response effect with frequency of use (never, sometimes, or always) or years of use provided further evidence of a null association. Conclusions: No association was seen between melanoma and sunscreen use. Failure to control for confounding factors may explain previous reports of positive associations linking melanoma to sunscreen use. In addition, it may take decades to detect a protective association between melanoma and use of the newer formulations of sunscreens.
The incidence of skin tumors including squamous cell carcinoma (SCC), and its biological precursor, the actinic keratosis, and basal cell carcinoma (BCC) often named together non melanoma skin cancer (NMSC) is growing all over the world in people of caucasian ancestry. A plenty of clinical and epidemiological studies have demonstrated the causal relationship with high cumulative solar dosages and number of sunburns, although the hazard may be different for different tumors according to the modalities of ultraviolet (UV) exposure. BCC is much more strongly related to measures of intermittent ultraviolet exposure (particularly those of childhood or adolescence) than to measures of cumulative exposure. In contrast, SCC is more strongly related to constant or cumulative sun exposure. Photobiological studies have clarified that sunlight and UVB radiation are complete carcinogens for AK and SCC although the relationship with UVA exposure is much less known. Also the likelihood of BCC has been related to either sunburns and high lifetime solar, UVA and UVB cumulative doses but the pathogenetic pathways of both UVB and UVA radiation for BCC development need to be clarified so far. The lack of a complete knowledge of the photocarcinogenic pathways of keratinocytes has contributed to the limited results of solar photoprotection strategies, beside the limitations of the available sunscreens and present EU regulations.
This chapter traces changes in the perception of tanning and tanning behavior primarily within the United States (U.S.) from the later part of the nineteenth century to the early part of the twenty-first century. Originally seen as a hallmark of the working class/disadvantaged groups and associated with disease and ill health, societal perceptions of the tan evolved over time to reflect the opposite: wealth, health and beauty. These core beliefs regarding the value of tanning and ultraviolet (UV) radiation exposure have proven extremely difficult to modify despite substantial efforts by the public health community to do so. In an attempt to understand why millions of Americans continue to engage in high-risk, intentional UV exposure such as use of indoor tanning facilities, the beliefs and behaviors related to tanning are considered within the context of the historical medical and societal factors, especially the role of fashion and advertising, which helped to shape current opinion.
Sunscreen is used to help provide some protection from the harmful effects of the sun. Each sunscreen identifies its sun protection factor (SPF) which indicates the degree of protection offered by the product. However, the SPF is dependent upon an internationally agreed amount of 2 mg/cm 2 being applied. Studies have shown that people rarely use sufficient sunscreen to offer protection from the sun. A simple photographic technique is described which demonstrates the uniformity of sunscreen applied by users. By employing an ultraviolet fluorescence photographic technique with a sunscreen known to exhibit fluorescent characteristics, it can be shown that in many instances sunscreen is not applied in an even layer. The SPF for the product may therefore not be achieved over the entire area of skin which was intended to be protected by the user. This photographic method could be used in a clinical setting to demonstrate application techniques of skin preparations where uniformity of product on the skin is of u...
Background/PurposeStudies have shown that individuals apply less than the 2 mg/cm2 lotion sunscreen needed to achieve the labeled SPF. However, there is little information regarding the application of spray and stick sunscreens. The objectives of this study were to measure the amount of sunscreen applied to skin by different application methods, to examine the relationship between application and demographic factors, and to evaluate the potential for sensitization from the preservative methylisothiazolinone (MI) in lotion sunscreens.Methods
Fifty-two participants applied lotion, spray, and stick sunscreen and answered a questionnaire. Lotion sunscreens were tested for MI content, and a margin of safety for the induction of skin sensitization was calculated.ResultsThe geometric means for the application thickness of lotion, spray, and stick sunscreens were 1.1, 1.6, and 0.35 mg/cm2, respectively. Several factors influenced sunscreen application thickness, including age and skin type. The MI concentration in tested sunscreen lotions ranged from <1 to 5.6 ppm, and likely MI exposures were below the threshold for induction of allergy (margin of safety > 8.1).Conclusions
In this study, sunscreen users applied different amounts of sunscreen depending on the application method, affording different levels of sun protection. Typical use of the sunscreens is not likely to result in MI sensitization.This article is protected by copyright. All rights reserved.
PurposePhotoaging is frequently encountered in a dermatologic practice. This systematic literature review aims to explore the etiology of photoaging and address the evidence behind its current management.MethodsA comprehensive search of MEDLINE, EMBASE, UpToDate and the Cochrane Library was conducted. Articles were limited to those relating to photoaging.ResultsThere are two major approaches in the current management of photoageing. This includes strategies to prevent against UV damage (e.g sunscreen) and medications that attempt to reverse existing skin damage (topical retinoids and 5-fluorouracil).Conclusion
There has been a large growth in the variety of treatment options in recent years. While it is important for such growth to continue, prevention via sensible photoprotection methods still remains the best current management option.
El envejecimiento prematuro causado por la radiación es responsable del 90% de los cambios que sufre la piel. La radiación UVA con longitudes de onda 320-400 nm, son las de menor energía, penetran la epidermis y la dermis de la piel y pueden dañar algunos componentes estructurales, tal como la matriz de elastina y colágeno, daño conocido como foto envejecimiento -UV inducido. Estos procesos son acumulativos y contribuyen a la aparición de líneas de expresión, arrugas y otros signos de la edad. Los protectores solares son clasificados como productos que tienen ingredientes activos que pueden absorber la radiación ultravioleta para proteger la piel de los daños ocasionados por el sol. Esto a su vez están compuestos por los filtros ultravioletas que son sustancias que pueden absorber o hacer reflexión de la radiación UV gracias a su estructura química, encontrado filtros químicos, filtros físicos, filtros naturales y protectores solares biológicos; estos últimos contribuyen a proteger la piel sin ser filtros solares. Para seleccionar el protector solar adecuado se debe tener en cuenta la tipología cutánea, el tiempo de exposición al sol y la cantidad de radiación que existe en un lugar.
Background A great number of journeys to sunny destinations are sold to the Danish population every year. We suspect that this travel considerably increases personal annual ultraviolet-radiation (UVR) exposure doses. This is important because such exposure is the main cause of skin cancer, and studies have shown a correlation between intermittent solar UVR exposure and malignant melanoma.
Objectives To prospectively monitor the behaviour of a group of sun seekers during a winter sun holiday and to study the impact of behaviour on personal UVR exposure doses.
Methods In this observational study 25 Danish sun seekers were closely monitored by on-site investigators for 6 days during a winter sun holiday in the Canary Islands, thus avoiding the possible recall bias of retrospective studies with questionnaires. The volunteers recorded their location, clothing and sunscreen use in diaries, and their UVR doses were measured by personal UVR dosimeters worn on the wrist. This resulted in 3450 half-hour registrations during 150 participation days.
Results On average, each volunteer received a total UVR dose of 57 standard erythema doses over 6 days, which is 43% of the annual UVR dose of a Danish indoor worker. Their exposed body area, sunscreen use and percentage of body with sunscreen application were positively correlated with their personal UVR doses, and there was also a strong relationship between location and UVR doses received.
Conclusions The behaviour of the volunteers had a major impact on their personal UVR doses. Our results emphasize the importance of changing the behaviour of sun seekers with protanning attitudes to reduce their personal annual UVR exposure doses, and possibly their risk of skin cancer.
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.
We present research on sunscreen use with possible pitfalls and discuss theory versus reality.
A literature review in PubMed was conducted using the terms 'sunscreen application', 'sunscreen use', and 'sun protection factor'.
The sun protection factor of sunscreens are tested using a thickness of 2 mg/cm(2) , but investigations show that sunscreen under natural conditions is applied insufficiently with amounts about 0.39 to 1.0 mg/cm(2) , which decreases the protection factor considerably. It has been shown that early reapplication or use of very high SPF (70-100) may partly compensate for the discrepancy between the amounts of sunscreen applied during testing and in reality, and that sunscreen application can be improved by education of consumers. Missing areas and UVR exposure before sunscreen application are other pitfalls that reduce the protective effect of sunscreens considerably.
Current sunscreen labelling overrates the protective effect of a given sunscreen when the reality of sunscreen use is taken into account. This may possibly mislead consumers to feel it is safe to extend sun exposure. Alternatively to educating people to use large amounts of sunscreen, we suggest a simple teaching strategy: 1. Apply before sun exposure 2. Reapply once within one hour.
› UV absorbing chemicals act mainly by conversion of absorbed photonic energy to heat and transfer to surrounding molecules and cells.
› Physical sunblocking agents protect mainly by reflection and scattering.
› Broad-spectrum sunscreens contain both UV-absorbing chemicals and physical sunblocking agents.
› The efficacy of a sunscreen preparation is measured by its sun protection factor (SPF).
› Photostability is important for the efficacy of UVA filters.
› Micropigment-containing sunscreen preparations are transparent when applied to the skin.
› Self-tanning lotions contain ingredients that chemically change skin color.
› Topical application of liposomal-incorporated DNA repair enzymes is a novel approach in photoprotection.
› Oral beta-carotene ameliorates photosensitivity in erythropoietic protoporphyria.
› Photoprotection by fabrics depends on nature of the textile, structure of the fabric, and type of weave.
› Sunscreens protect against p53 mutations and likely against nonmelanoma skin cancers.
› Effective UVA photoprotection is needed in photodermatoses and photosensitive diseases.
Zu hohe Sonnen- bzw. UV-Belastung führt zu akuten und chronischen Lichtschäden der Haut. Auf molekularer Ebene entstehen durch die UV-Strahlung Veränderungen an der DNA, vor allem sog. Zyklobutanpyrimidindimere und 6-4-Photoprodukte [3]. Unter der Einwirkung von UV-Strahlung entstehen in der Haut auch freie Radikale wie der Singulettsauerstoff (1O2), das Hydroxylradikal (HO*), das Superoxidanion (02-) und Peroxiradikale (ROO*) [14]. Diese Radikale schädigen die Zellmembranen und auch die Zellkern-DNA. Die durch die UV-Strahlung verursachten DNA-Schäden führen zur Freisetzung löslicher Faktoren - Zytokine wie Interleukin-10 und Tumornekrosefaktor -, die zur akuten Sonnenbrandreaktion und immunsuppressiven Wirkung der UV-Strahlung beitragen [15]. Bei mangelhafter Wiederherstellung durch endogene Reparaturmechanismen entstehen aus DNA-Schäden spezifische, für die UV-Strahlung typische Mutationen (C→T, CC→TT Transitionen), u.a. am p-53-Tumor-supressorgen [2]. Die UV-Strahlung des Sonnenspektrums ist ein vollstaändiges karzinogen, das als Tumorinitiator und -promotor workt. Die kausale Rolle hoher kumulativer UV-Dosen bei der Enstehung von Basaliomen und Plattenepithelkarzinomen der Haut ist durch epidemiologische Studien eindeutig belegt [21]. Die durch die UV-Strahlung verursachte Immunsuppression, die sowohl lokaler als auch systemischer Natur sein kann, sowie die Schädigung immunkompetenter Langerhans-Zellen in der Haut tragen zur UV-Karzinogenese bei.
Promoting sunscreen use is an integral part of prevention programmes aimed at reducing ultraviolet (UV) radiation-induced skin damage and skin cancers. Protection against both UVB and UVA radiation is advocated. Most sunscreens combine chemical UV absorbing sunscreens and physical inorganic sunscreens, which reflect UV, to provide broad-spectrum protection. Newer triazole and camphor-derivative based sunscreens, also provide broad-spectrum protection and are more cosmetically acceptable than many traditional agents. Currently licensed sunscreen ingredients in common use rarely cause allergic or photoallergic reactions. Vitamin D levels are not significantly affected by regular use of a sunscreen. Sunscreen use reduces both the development of precancerous solar keratosis and the recurrence of squamous cell carcinomas. Sunscreen use early in life may be important in prevention of basal cell carcinomas. Increased melanoma risk is influenced by the behaviour patterns of regular sunscreen users, as opposed to any direct effect of sunscreens. Sun protection factor (SPF) is affected by application density, water resistance and other factors. An adequate SPF for an individual should be balanced to skin phenotype and exposure habits. The correct use of sunscreens should be combined with the avoidance of midday sun and the wearing of protective clothing and glasses, as part of an overall sun protection regimen.
Sunscreens are in common use, with more than half of the public buying or using sunscreens within a 3-year period.32 Sun avoidance and regular sunscreen use are widely promoted by organizations and individuals interested in cancer prevention; however, 70% of those who participated in a beach survey were on the beach to get or maintain a suntan.57 Although they stayed on the beach for an average of 4 hours, only half were using sunscreen.
There appears to be some confusion in the public health sunscreen message or in the public's interpretation of that message. Some use sunscreens to prevent sunburn, whereas others use sunscreens to improve sun tanning. Some wish to avoid the wrinkling associated with sun exposure, whereas others believe that sunscreens prevent all types of skin cancer. Others seem to believe sunscreens should be used to prolong their time in the sun.
Despite, or conceivably because of, the confusing message, sunscreen use remains sporadic. The majority of male college students in North Carolina “rarely, if ever, use sunscreens.”50 Fewer than 10% of the students used sunscreens in each instance of intentional sun exposure exceeding 30 minutes. In a study of more than 10,000 subjects, fewer than one third were very likely to use sunscreen, wear protective clothing, or seek shade.21 Despite past sunburn experience, skiers often do not use sunscreens. A springtime survey in of skiers in Alberta showed that only two thirds were using sunscreen, and of those using a sunscreen, one third were sunburned at the time of survey.28 Even in situations of high sunburn risk, sunscreen use is less than ideal.
Sunscreen use is perhaps most prevalent in Australia where three fourths of adult patients visiting a family physician reported using a sunscreen.31 Indeed, sunscreen use was more popular than seeking shade, altering the time of day of exposure, or wearing covering clothing. The reverse priority sequence is commonly recommended by public health authorities.
Childhood exposure to the sun continues to be significant. Past experience of sunburn is a more significant determinant of childhood sunscreen use than other concerns.56 Despite this fact, only one third of U.K. parents regularly protect their children from the midday sun, and approximately half of their children burn at least once a year.7 Early childhood exposure continues to be significant, with estimates that children aged 9 to 10 years sustain even more exposure than adolescents aged 14 to 15 years.11
This study explores sun protection attitudes, preferences, and behaviors among young adult males participating in an open-field activity with extreme ultraviolet radiation exposure. Male drum corps members (n = 137) responded to survey questions regarding their behavior and willingness to engage in sun protection and barriers to sunscreen usage. A subset of members (n = 31) participated in cognitive interviews exploring various sunscreen products and intervention techniques. Participants were knowledgeable about health risks and protection benefits regarding sun exposure. Generally, males had positive attitudes and normative beliefs about using sunscreen. A barrier to sunscreen re-application was lack of adequate time to reapply sunscreen during the open field activity. Males preferred a towelette application method, but were unfamiliar with its efficacy and proper use. Thus, they were more likely to use the more familiar sunscreen spray. To increase sun protection behaviors and lower skin cancer risk for males participating in open-field activities, breaks must be allotted every 2 h and have sufficient time to allow sunscreen application. Future development and research into delivery systems that rapidly and evenly apply sunscreen may help lower exposure in this population.
It is well recognized that exposure to solar radiation is a major risk factor for the development of skin cancer, photoaged skin, and immune system alterations. However, major questions remain regarding the specific wavelengths and type of exposure that incur risk. The purpose of this article is to critically examine, on the basis of current knowledge, the impact of stratospheric ozone depletions, tanning bed skin cancer risk, the safety of sunscreens as an important element of our solar protection strategies, the wavelengths of solar radiation responsible for melanoma, and the incidence of melanoma. Recommendations are made on prevention stategies and public health messages. (J Am Acad Dermatol 1999;41:81-99.)
Sunburn is a common feature in sunscreen users. The purpose of this paper is to estimate the expected frequency and magnitude of sunburn resulting from typical use of sunscreens labelled SPF15 and SPF30 by people spending long periods outdoors in strong summer sunshine.
By combining the probability distribution of the measured sun protection factor (SPF) in vivo with those for the average application thickness and the uniformity of application over the skin surface, a simulation model was developed to estimate the variation in delivered protection over the exposed skin surface from consumer use of sunscreens.
While either sunscreen, if delivering the nominal SPF over the entire exposed skin, would be sufficient to prevent any erythema, the simulation indicates that the combination of the average quantity applied with the variability in thickness over the skin surface will lead to erythema, especially in SPF15 sunscreen users.
People who intend spending long periods outside in strong sunshine would be better advised to use SPF30 labelled sunscreens than SPF15 sunscreens, and to apply the product carefully over exposed skin if they wish to minimize their risk of sunburn and, by implication, skin cancer.
Sun exposure of the skin triggers several inflammatory pathways via a multitude of photochemical and photobiological effects. Furthermore, local and systemic immune suppression develops. The main clinical effects of UV exposure can be classified schematically into immediate, including sunburn, tanning, vitamin D production and exacerbation of inherited and acquired photosensitive skin disorders and long-term, including solar ageing and skin cancer. The protection against solar radiation is afforded by a healthy behavior of reasonable sun avoidance and the use of topical sunscreens as well as topical and oral antioxidants. However, users of sunscreen products should be able to choose correctly the most convenient product according to their needs. In Europe, the sun protection factor (SPF) and the UVA-protection factor (UVA-PF) are labeled to indicate the degree of protection against UVB and UVA, respectively. However, dermatologists must be aware that the present knowledge of UV effects on human skin needs to be clarified and several regulatory issues of photo-protection remain to be clarified and standardized. Finally, much work is needed to improve water resistance, spreadability, transparency and homogeneity of the sunscreen agents.
A number of mechanisms have been developed during evolution to protect human skin from excessive UV radiation. To classify the susceptibility of human subjects to develop erythema following UV exposure, Fitzpatrick's system differentiates six sun reactive skin phototypes (SPT) [9] (Table 3.10.1). In this system, the capacity to tan is equally important to help to categorise individuals of any colour or ethnic background. Using this method, the physician can estimate the relative risk of developing acute and chronic changes related to UV exposure. A study by Carrettero-Mangolis and Lim confirms that there is a correlation between minimal erythema dose (MED) and SPT, that is, the higher the SPT, the higher the MED [6].
Skin cancer is the most common cancer in the United States. Exposure to ultraviolet radiation is a known risk factor for skin cancer but is also the principal means by which the body obtains vitamin D. Several studies have suggested that vitamin D plays a protective role in a variety of internal malignancies. With regard to skin cancer, epidemiologic and laboratory studies suggest that vitamin D and its metabolites may have a similar protective effect. These noncalcemic actions of vitamin D have called into question whether the current recommended intake of vitamin D is too low for optimal health and cancer prevention. Part I will review the role of vitamin D in the epidermis; part II will review the role of vitamin D in keratinocyte-derived tumors to help frame the discussion on the possible role of vitamin D in the prevention of skin cancer.
Background:
High-performance sunscreen protects both healthy consumers and photosensitive patients from strong ultraviolet (UV) exposure. The sun-protection factor (SPF), which indicates the efficacy of UV protection, is determined using a prescribed sunscreen application thickness of 2.0 mg/cm(2). Therefore, users should apply at least 2.0 mg/cm(2) of sunscreen to obtain the level of UV protection expected from a product. In most cases, however, users apply insufficient amounts of sunscreen.
Aim:
To determine the amount of sunscreen applied under specific conditions, and the relationship between application thickness and SPF value in high-performance sunscreen.
Methods:
The amount of applied sunscreen was calculated under practical conditions and conditions that directed a double application. The SPF values of high-performance sunscreen applied at three thicknesses (2.0, 1.0 and 0.5 mg/cm(2)) were determined according to the international SPF testing method. RESULTS. The relationship between SPF value and application thickness correlated in a logarithmic curve. The mean application thickness under practical conditions was approximately 1 mg/cm(2), and directing subjects to use a double application increased the application thickness to nearly 2 mg/cm(2).
Conclusion:
Encouraging a double application of sunscreen will help users apply products at a thickness sufficient to achieve expected SPF efficacy. We recommend that guidance on double application of sunscreen should be posted in public locations where sunscreen is likely to be in use.
With this observation study we aimed to determine how and when sunscreen was used. 20 sun seekers were observed during a one-week sun holiday in Hurghada, Egypt. The sunscreen application thickness was related to part of body, time outdoors, exposure to ultraviolet radiation and to sunburning. Skin sites with sunscreen were exposed to UVR significantly longer and received significantly higher UVR doses than skin sites without sunscreen. They received an average of 0.62 SED [0.0-9.3 SED] (13% of their MED) before the first sunscreen application of the day. The average sunscreen used was SPF15 and the sunscreen application thickness was in average 0.79 mg cm(-)2 giving an approximated effect of SPF3. For different body parts either the total UVR exposure dose or the UVR exposure time and UVR exposure dose before the first sunscreen application were higher for sunburned than non-sunburned skin sites. In the final model gender, skin type and UVR to skin (adjusted for SPF and sunscreen application thickness) were significant predictors of sunburning. The sunscreen application thickness of 0.79 mg cm(-)2 was less than the 2 mg cm(-2) used for testing SPF. The late start of sunscreen use and improper application thickness was ineffective in preventing sunburn, and therefore could not compensate for the risk of prolonged UVR exposure and high UVR doses. Our results lead us to suspect that the protective effect of sunscreen use against DNA-damage, and thereby skin cancer, is minimal the way sunscreen is used under real sun holiday conditions.
Objective There is accumulating evidence that in spite of the large campaigns against excessive solar exposure undertaken by dermatologists worldwide, children and adolescents are still spending long periods in the sun, and do not follow the recommended sun protection guidelines.
The purpose of the present study was to evaluate sun exposure in a group of young Israeli adults and to compare it to their knowledge and application of the various sun protection methods.
Methods 202 Caucasian volunteers, (mean age 21.4 ± 2.6), filled out detailed questionnaires on their sun exposure and sun protection habits.
Results More than 80% of our study participants are regularly sun exposed for longer than 2 h per day whereas sunscreens are utilized only by 64.9%. Sunscreen use was significantly more prevalent in females than males (81.3% vs. 46.5%). The majority of sunscreen users and nonusers believed that sunscreen could prevent skin cancer (94.3% and 82.0%, respectively) and that these compounds can slow skin aging (90.8% and 76.4% respectively). The understanding of the meaning of the “SPF” was significantly higher in the sunscreen users (85%) than in the nonusers (62.0%). The majority of sunscreen users utilized less than 150 ml of the compound per year which is probably an inadequate amount for a year for full body protection. The two most common reasons for not using sunscreens regularly, were that the application is time consuming, and that sunscreens prevent tanning.
Conclusion Our data reveals a discrepancy between a considerably good understanding of the need for sun protection and the still deficient application of these measures especially in young adult males.
Background:
Skin protection creams (PCs) are used in the occupational setting to prevent irritant hand dermatitis. However, so far, the actual amounts of PC applied and the resulting dose per area unit on hands at work have not been a matter of systematic investigation. The quantities used in experimental studies investigating the efficacy of PCs range between 4 and 25 mg/cm(2).
Objectives:
To develop a practical and accurate method to analyse the actual consumed quantities of PCs at workplaces in relation to hand surface area.
Methods:
Thirty-one hospital nurses without hand eczema were provided with a sample PC in special monitoring tubes with Medication Event Monitoring Systems (MEMS TrackCaps(®); Aardex Ltd, Zug, Switzerland), and used the product over 5 working days as usual. The consumption was calculated by weighing of the tubes and analysis of the application frequency, and related to the individual calculated hand surface area.
Results:
The mean PC dose applied was 0.97 ± 0.6 mg/cm(2).
Conclusions:
The amounts of PC applied by hospital nurses were significantly lower than the amounts that have been used in experimental studies. The method appears to be suitable for use in different in occupational settings. Further investigations are needed to gain realistic insights into consumers' attitudes regarding PCs.
Background:
There is mounting evidence that sun exposure is a cause of skin cancer. Therefore, the focus of skin cancer prevention is on sun protection. The present study investigated the use of sunscreens in a sample from the adult Central European population.
Methods:
As part of a case-control study of cutaneous melanoma, a total of 498 controls with classical dermatological disorders were selected from hospitals in Central Europe. All people underwent whole-body skin examinations and were interviewed using a standardized questionnaire.
Results:
Overall, 40.8% of the people never used sunscreen and of the 281 persons who used sunscreen, 41.5% applied it only once per sun bath. Persons who did not use sunscreen tended to be older (P<0.0001) and of male gender (P = 0.0004). Young people, women, and people who expressed a positive attitude to the sun spent more time in the sun and were more likely to apply sunscreens. People who worked almost always outdoors had a six times increased odds ratio of not using sunscreens (P<0.0001) compared to people who worked always indoors.
Conclusions:
Men, older people, and outdoor workers should be targeted in health education campaigns. On the other hand, people who apply sunscreen as a means of sun protection should be advised about adequate usage.
Interest in protection against solar ultraviolet radiation (UVR) among the general public in Australia has been increasing steadily as a result of the `SunSmart' campaigns run by the various state cancer councils. This increasing awareness is due in part to the requirements for occupational protection of outdoor workers and to provision of UVR protection for the recreational market. Behaviour outdoors can significantly affect exposure to solar UVR and use of items of personal protection can provide a substantial reduction in the UVR dose received. The protective properties of sunscreens, sunglasses, hats and clothing against UVR have been the subject of considerable research for some time, and over the last few years interest has extended to the provision of shade structures and the UVR protection provided by various commonly used materials. These materials include shadecloth, plastics, glass, windscreens and applicable tints. Australia has rigorous standards covering protection and UVR, in particular for sunscreens [Standards Australia/Standards New Zealand, Sunscreen products—evaluation and classification, Report No. AS 2604, Sydney/Wellington, 1993.], sunglasses [Standards Australia, Sunglasses and fashion spectacles—nonprescription types, Report No. AS 1067.1, Sydney, 1990.], protective eyewear [Standards Australia/Standards New Zealand, Eye protectors for industrial applications, Report No. AS/NZS 1337, Sydney/Wellington, 1992.] and shadecloth [Standards Australia, Synthetic shadecloth, Report No. AS 4174, Sydney, 1994.]. Compliance with the sunglass standard became mandatory in 1988 and UVR protection provided by sunglasses has increased substantially since then. In July 1996 a standard on `sun protective textiles' [Standards Australia/Standards New Zealand, Sun protective clothing—evaluation and classification, Report No. AS/NZS 4399, Sydney, 1996.] incorporating ultraviolet protection factors (UPFs) and a rating scheme with protection categories, was introduced; this was the first of its kind in the world. Australian Radiation Laboratory (ARL) UPF swing tags with UVR protection advice from the Australian Cancer Society on the reverse side are used to denote the amount of protection against solar UVR provided by clothing. To date in excess of 5 million ARL swing tags have been issued. Work on the various standards is continuing. The maximum allowed `sun protection factor' (SPF) limit for sunscreens may be increased to SPF 30+ in the near future, and additions to the sun protective textiles standard are also planned. This paper discusses measurement methods, results, the rationale used in formulating the Australian Standards and the current state of UVR protection in Australia.
Topical sunscreens act by absorbing or scattering UV radiation and are widely available for general public use as a consumer product. Market surveys carried out in the UK find that the majority of people report using sunscreens, with British people using sunscreens most often whilst sunbathing on holiday in sunny climates, and least often when outdoors (but not sunbathing) at home. Sunscreens applied at the thickness tested by manufacturers need only posses a SPF of 15 to prevent sunburn even for all day exposure in tropical sunshine. Yet behavioural studies show that high SPF (>15) sunscreens do not always prevent sunburn. That the protection achieved is often less than that expected depends upon a number of factors: application thickness and technique; type of sunscreen applied; resistance to water immersion and sand abrasion; and when, where and how often sunscreen is re-applied. These factors provide ample evidence that the numerical measure of protection indicated on the product pack is generally higher than achieved in practive. This mismatch between expectation and realisation may be one contributing factor why sunscreens have been reported to be a risk factor in melanoma.
Background:
Extensive print, radio, and television coverage about the dangers of sun exposure and benefits of sun protection occurred over the past decade. Illinois teen knowledge and attitudes about sun exposure/protection, sun-exposure/protection behavior, and information sources were determined by a summer telephone survey.
Methods:
Telephone interviews with 658 teenagers between ages 11 and 19 included African-American, Asian, Hispanic, Native American, and white teenagers.
Results:
Teens knew that too much sun was harmful as it caused skin cancer and sunburn. Sunburn was mentioned more often by those with skin types that burned easily and tanned poorly (I,II) (P < 0.001), was better known to girls than to boys (P < 0.001), and was recognized more by those with higher socioeconomic status (P < 0.001) but was not associated with age. Widely held sun exposure attitudes were socializing with friends and feeling better when outdoors. On weekdays, boys averaged 5.3 hr (SD, 1.65 hr) outside compared with 3.9 hr (SD, 0.75 hr) for girls (P < 0.001). Teenage boys were more likely to obtain occupational sun exposure, and girls sunbathed. Subjects with skin types I and II reported an average of 3.3 sunburns in the past year. During unprotected sun exposure, extensive numbers of teens with moderate-risk skin type experienced at least 1 sunburn per year. Indoor tanning use was more prevalent among older girls and those with skin types I and II. Sunscreen use was associated with water recreational activities (swimming, water sports, and going to the beach) by girls slightly more than by boys (P < 0.001). Hat-wearing was more common among boys than among girls.
Conclusions:
Teen knowledge that excessive sun exposure causes skin cancer and sunburns and that wearing sunscreens and hats were sun-protective methods did not enable sun protection that prevented burning. This is particularly troublesome because severe sunburns in youth are associated with an increased risk of melanoma. Existing teen sunscreen use could be broadened by educating teens to use adequate quantities of sunscreen prior to daily sun exposure to prevent painful burns. Messages to teens that emphasize the short-term consequence of painful sunburns because of inadequate protection during outdoor occupational and non-water-related recreational exposure would increase the relevance of the message and may enable behavioral change. Parents and physicians need to be included in messages that are directed to teens and to become part of their education. Parents could ensure an adequate sunscreen supply for daily use by the family, encourage teens not to deliberately tan, and serve as role models for the use of protective clothing.
Protection from solar ultraviolet radiation is discussed. Methods of protection include avoiding outdoor activities during times of greatest ultraviolet radiation insolation, seeking shade while outdoors, and wearing appropriate clothing. Sunscreens are reviewed, including newer compounds that may also offer photoprotection.
To measure the thickness at which primary schoolchildren apply sunscreen on school day mornings and to compare it with the thickness (2.00 mg/cm(2)) at which sunscreen is tested during product development, as well as to investigate how application thickness was influenced by age of the child (school grades 1-7) and by dispenser type (500-mL pump, 125-mL squeeze bottle, or 50-mL roll-on).
A crossover quasiexperimental study design comparing 3 sunscreen dispenser types.
Children aged 5 to 12 years from public primary schools (grades 1-7) in Queensland, Australia.
Children (n=87) and their parents randomly recruited from the enrollment lists of 7 primary schools. Each child provided up to 3 observations (n=258).
Children applied sunscreen during 3 consecutive school weeks (Monday through Friday) for the first application of the day using a different dispenser each week.
Thickness of sunscreen application (in milligrams per square centimeter). The dispensers were weighed before and after use to calculate the weight of sunscreen applied. This was divided by the coverage area of application (in square centimeters), which was calculated by multiplying the children's body surface area by the percentage of the body covered with sunscreen.
Children applied their sunscreen at a median thickness of 0.48 mg/cm(2). Children applied significantly more sunscreen when using the pump (0.75 mg/cm(2)) and the squeeze bottle (0.57 mg/cm(2)) compared with the roll-on (0.22 mg/cm(2)) (P<.001 for both).
Regardless of age, primary schoolchildren apply sunscreen at substantially less than 1.00 mg/cm(2), similar to what has been observed among adults. Some sunscreen dispensers seem to facilitate thicker application than others.
Widely used polymethylmethacrylate substrates for in vitro sun protection factor (SPF) testing of sunscreens do not mimic the rough surface structure of skin, and in addition, sample loading is less than that used in in vivo SPF testing (2.00 mg cm(-2)). We have developed a skin-mimicking substrate (SMS), which has furrows and ridges on its surface, like human skin. A comparison of the photodegradation profiles of sunscreens on commercially available substrates (including SMS) at the recommended application amounts, and on SMS at various application amounts showed that the photodegradation rate of photounstable sunscreen was dependent on the application amount being higher at lower application amounts. SMS at the recommended application amount of 2.00 mg cm(-2) provided in vitro SPF values that were comparable with in vivo SPF values. Our results confirm that, in order to develop a reliable in vitro SPF method, which is consistent with in vivo SPF determination, it is important to use the same application amount of sample as in the in vivo method, in order to take proper account of sunscreen photostability.
The Sun Protection Factor (SPF) is the most important data to quantify the effectiveness of a sunscreen, being universally accepted. The method is based on determining the minimum erythematous dose (MED), defined as the smallest amount of energy required for triggering the erythema, in areas of protected and unprotected skin. The SPF value is then calculated as the ratio between the MED of protected and unprotected skin. The first publication of a method for determining the SPF was presented in 1978 by the U.S. FDA agency, followed by other publications of FDA and other international regulatory agencies. Although considered the reference method for quantification of sunscreen efficacy of topical products, there are controversies in literature about the method for determining the SPF and the implications of the real conditions of use in the protection achieved in practice by users.
Previous studies have shown that people often apply less sunscreen than the recommended amount of 2 mg/cm2. Our purpose in this study was to determine objectively how photoprotection varies with application thickness. The protection provided by differing quantities of sunscreens containing varying amounts of titanium dioxide was measured in vitro using excised human epidermis as the substrate. It was found that application thickness had a significant effect on the sun protection factor (SPF), with most users probably achieving a mean SPF of between 20-50% of that expected from the product label. Underprotection due to inadequate application, coupled with overexposure to the sun, might partially explain why sunscreen use has been reported to be a risk factor in melanoma.
The UV protection factors of twenty commonly used textiles were determined. Protection factors varied between 1.3 and 1700, which shows the importance of giving careful advice to light-sensitive and psoralensensitized patients, regarding suitable clothes.