Sun protection factor persistence during a day with physical activity and bathing

Background/purpose: The persistence of sunscreens during a day with physical activity and bathing is often debated. We wished to examine the durability of the protection achieved by one sunscreen application. Methods: Seven areas were marked on the back of 24 volunteers. One area was phototested to determine UV sensitivity. Six areas were treated with either an organic or an inorganic sunscreen (2 mg/cm²). The participants performed physical activities, were exposed to a hot environment and bathing during 8 h and were phototested with ultraviolet‐B (UVB) radiation 30 min, 4 and 8 h after sunscreen application. The minimal erythema dose (MED) was determined 24 h after irradiation. The sun protection factor (SPF) was calculated, as MED on protected skin/MED on unprotected skin. Results: The SPFs of the inorganic and organic sunscreen, respectively, were reduced by 38% and 41% after 4 h and by 55% and 58% after 8 h. Conclusion: One application of either an inorganic or an organic sunscreen reduced the erythema caused by UVB during a day with physical activity and bathing. After 8 h the sunscreens still provided approximately 43% of the initial protective effect. This might simulate what happens during a day at the beach.     

Do ‘cinnamon‐sensitive’ patients react to cinnamate UV filters?

Background:  Use of sunscreens has increased dramatically worldwide, and some sunscreen chemicals may be allergens. Ultraviolet (UV) filters are added to various cosmetic products. Cinnamate UV filters are structurally related to cinnamon-related fragrances.
Objective:  The purpose of this study was to determine if 'cinnamon-sensitive' patients show positive photopatch tests to cinnamate UV filters and, therefore, should avoid these UV filters.
Method:  We photopatch tested cinnamon-sensitive patients ( n  = 18) with cinnamon, cinnamon-related fragrances, Myroxylon pereirae , and two cinnamate UV filters.
Results:  No positive photopatch test to cinnamate UV filters was found (95% confidence interval 0–13%).
Discussion:  The risk of developing unwanted allergic contact dermatitis because of cinnamate UV filters in cinnamon-sensitive patients seems to be low, but our study population was small. Therefore, we recommend cinnamon-sensitive patients to perform a use test, for example the repeated open application test, before using cosmetic products containing cinnamate UV filters. In addition, physicians and patients should be aware that many sunscreens contain (cinnamon-related) fragrances and could, therefore, elicit allergic contact dermatitis in cinnamon-sensitive patients, independently from other potential sensitizing components of the sunscreen.     

Sunscreens--the ultimate cosmetic

One decade ago, a sun protection factor (SPF) of 15 was considered a complete blocker of ultraviolet radiation (UV). The logic behind that cutoff point was that sunscreens with this SPF number would always prevent erythema and that preventing erythema would prevent all the ill effects of UV exposure. Today, we know that both of these assumptions were wrong and we tend to recommend higher SPF. Consumers apply only about one-quarter to one-half thickness of the layer of sunscreen material used to measure the SPF in the laboratory. That means that less than 50% of the SPF number claimed on the label is spread on the consumer's skin, meaning that a sunscreen with an SPF 30 will give the real protection of an SPF of 15. Therefore, recommend 60 when you want a real protection of 30! Significant injury, DNA damage, mutations, and carcinogenesis can and do occur also with cumulative suberythemal UV exposure. Thus, erythema induction, a criterion that defines SPF, is not a good indicator of UV damage. We also need higher SPF values to prevent the damage caused by suberythemal doses of UV. The value of the SPF claimed on the label is diminished by environmental factors that are not taken into account during SPF measurements in the laboratory, such as sweating, water immersion, rubbing off, and photodegradation. There are some misunderstandings and confusion about the mode of action of physical sunscreens. It was originally considered that, in contrast to organic sunscreens, the inorganic metal oxides (zinc oxide and titanium dioxide) acted as scatterers or reflectors of UV light, as a mirror. This is not the case with modern micronized forms of metal oxides. It has been shown that both zinc oxide and titanium dioxide mobilize electrons within their atomic structure while absorbing UV radiation. Thus, although metallic oxides are not inert per se, in their coated form they are stable, non-toxic, and safe and they act as highly efficient UV attenuators. Therefore, we recommend our patients to use this type of sunscreens. We should exert all our influence upon our patients not to expose themselves to excessive sunlight, to routinely use generous layers of sunscreen agents, and to wear protective clothing. To wait for the dust to settle around the issue of the effectiveness of sunscreens in preventing melanoma, while the ideal sunscreens--topical, systemic, whatever--are at our disposal, is a luxury we cannot afford.     

Sunscreen protection against cis-urocanic acid production in human skin

Commercial sunscreens may offer some protection from immunosuppression induced by ultraviolet (UV) radiation, but agreement concerning the degree of protection is lacking. Cis-urocanic acid, formed by the photoisomerization of transurocanic acid is considered an important mediator of the cutaneous immunomodulation resulting from exposure to UV radiation. We investigated the effect of sunscreens on the isomerization of urocanic acid in 17 human subjects. Two sunscreens containing chemical filters, sun protection factor (SPF) 4 and SPF 10, and a SPF 10 sunscreen with a physical filter were applied at a thickness of 2 mg/cm2. The effect of a thin layer (0.5 mg/cm2) of the chemical SPF 10 sunscreen was also evaluated, as the amount of sunscreen applied in practice may be considerably less than recommended. All areas were irradiated with a single UV dose of 3.6 SED (standard erythema doses). In irradiated unprotected skin the median net production of cis-urocanic acid was 52% (relative amount). In the sites treated with the chemical sunscreens, the production of cis-urocanic acid was 7.4% (SPF 4) and 3.5% (SPF 10), and isomerization was thus reduced more efficiently at a higher SPF (p<0.01). The physical sunscreen reduced the formation of cis-UCA to 15%, and was significantly less effective than both the chemical SPF 10 sunscreen (p<0.01) and the SPF 4 sunscreen (p<0.01). The production of cis-urocanic acid in the area treated with the thin layer of the chemical SPF 10 sunscreen was 22%. The protection against the production of cis-urocanic acid was therefore reduced significantly (p<0.01) when the sunscreen was applied in an amount lower than recommended.     

Update on photoprotection

ABSTRACT:  Photoprotection is an effective method for preventing damaging effects from ultraviolet radiation (UVR). Photoprotection is accomplished through the use of sunscreens, protective clothing, and safe sun practices. Sunscreens are composed of various UV filters, including inorganic/physical blockers and organic/chemical sunscreen agents. New technologies are emerging in sunscreen development and may soon be available to U.S. consumers. General guidelines for sunscreen use should be reinforced to improve patient compliance and sunscreen efficacy. Habitual use of sunscreen is recommended with UV exposure, and concerns for vitamin D deficiency with sunscreen use should not supersede proper photoprotective behavior.     

Effect of daily versus intermittent sunscreen application on solar simulated UV radiation-induced skin response in humans

BACKGROUND: Acute and chronic skin damage occurs as a consequence of solar UV radiation exposure. To diminish such skin damage, the dermatologic community advocates the daily use of sunscreens as part of a sun avoidance strategy. OBJECTIVE: We determined the effectiveness of a sunscreen product with a sunscreen protection factor (SPF) of 15 applied daily in preventing UV-induced histologic damage in human skin compared with the protection afforded by sunscreens with equal or higher SPF applied intermittently. METHODS: Twenty-four subjects were exposed to 2 minimal erythema doses of solar-simulated UV on 4 consecutive days. Three sunscreen products were applied to the buttock of each subject. One SPF 15 product was applied daily before exposure to UV and, to simulate intermittent product use, an SPF 15 or SPF 29 product was applied on 3 of 4 days, with one missed application on days 2, 3, or 4. Skin biopsy specimens were taken and processed for routine and immunohistochemical staining. Changes in number of sunburn cells and Langerhans cells as well as degree of inflammatory infiltrate and lysozyme immunostaining were determined. RESULTS: There was a statistically significant increase in the number of sunburn cells, degree of inflammation, and intensity of lysozyme staining, and there was a decrease in the number of Langerhans cells at sites where sunscreen application was missed as compared with unirradiated control and daily SPF 15 sunscreen-treated sites. CONCLUSION: Our data suggest that daily use of a sunscreen reduces the skin damage produced by UV exposure compared with intermittent use of equal or higher SPF products. The daily application of sunscreens in appropriate quantities reduces the harmful effects of solar UV radiation on skin. Compliance is essential for maximal benefit of sunscreens.     

Sunscreens

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.     

Sun protection factors: world wide confusion

The Sun Protection Factor (SPF) is a very popular instrument in the marketing of sunscreens. Unfortunately it is often not understood how sunscreens work and where the limitations of the SPF are. A lot of aspects of the SPF are confusing, e.g. the race for higher and higher numbers, the effect on SPF when less sunscreen is applied and if sunscreen should be used at all because they may block the Vitamin D synthesis. All this has a negative impact on compliance by the consumer or patient which is the most important influence factor in sun protection. This paper explains how sunscreens work, how the SPF is determined and where the limitations of the current methods exist. The dynamic view of 'UV radiation applied' and the 'UV dose transmitted' through the sunscreen onto the skin as well as onto a substrate in vitro help in the understanding and are also promising approaches in the in vitro assessment. A variation of the in vitro assessment of a sunscreen is the in silico calculation based on the absorption spectrum of the UV filters and an assumption about the irregular sunscreen film on the skin. The sunscreen simulator program can be used to determine how the SPF is affected by applying smaller amounts of sunscreen. Besides the SPF, UVA protection is also discussed. The degree of UVA protection determines the quality of the overall UV protection, whereas the SPF is an indication of the quantity of protection. Furthermore other protection factors such as IPF, iSPF, RSF and p53, and the inhibition of the Vitamin D3 synthesis by sunscreens are also discussed. In conclusion it is shown that the accuracy and robustness of the SPF and other Protection Factors will improve significantly with the availability of true broad-spectrum sunscreens rather than conventional UVB-biased sunscreens, because uniform protection profiles lead to protection independent of the action spectrum of the endpoint and the UV-radiation source.     

防晒霜的应用和评价

局部应用防晒霜越来越被公众接受。大部分的防晒霜由物理防晒剂和化学防晒剂组成．可以有效地防止紫外线引起的皮肤红斑反应、免疫抑制、光老化以及皮肤癌的发生。防晒霜应有中波紫外线和长波紫外线的全面防护功能。评价防晒霜要从其吸收光谱，衰减系数，中波紫外线防护功能以及长波紫外线防护功能等方面进行考虑。     

The influence of the amount of sunscreen applied and its sun protection factor (SPF): evaluation of two sunscreens including the same ingredients at different concentrations

Background: To estimate labeled sun protection factor (SPF) for sunscreen, the amount of product applied on volunteers, according to food and drug administration (FDA) and International protocols, is 2 mg/cm². However, different studies have shown that consumers actually apply much less product when exposed to the sun. Previous studies have reported contradictory findings in an attempt to correlate the amount applied in relation to SPF. The objective of the present study was to estimate the influence of the quantity of sunscreen applied in the determination of SPF, according to the FDA methodology.
Subjects and methods: Forty volunteers were included in two groups (SPF 15 and 30). The selected sunscreen was then applied in four different quantities (2, 1.5, 1.0 and 0.5 mg/cm²). All areas were irradiated with a solar simulator. After 24 h, the minimal erythemal dose (MED) and SPF were determined.
Results: In both groups, we observed that the SPF decreased when the amount of sunscreen applied was decreased. The differences between the 2 mg/cm² area and the others were significant in both groups ( P <0.001). The correlation between specified SPF and applied amount grew exponentially.
Conclusion: The protection provided by sunscreen is related to the amount of product applied. It is essential to educate consumers to apply larger amounts of sunscreen for adequate photoprotection.     

Accumulated p53 protein and UVA protection level of sunscreens

Nuclear p53 expression is a sensitive parameter for the detection of ultraviolet (UV)-induced skin damage, and it has been used as an endpoint to evaluate the effectiveness of sunscreens. In this study, we compared the protection provided by two sunscreens having identical sun protection factors (SPF) but different UVA protection factors (UVA-PF) measured by the persistent pigment darkening method (PPD). The SPF of the sunscreens was 7 and the UVA-PF were respectively 7 and 3. Nuclear p53 protein was quantified in human skin biopsies treated with sunscreens and exposed 8 times to 5 MED of solar simulated radiation (SSR). The results showed that both sunscreens offered only partial protection against the increased expression of nuclear p53 protein induced by repetitive SSR exposures. However, a significantly lower level of p53-positive cells was found in areas protected with the sunscreen having the higher UVA-PF compared to the other sunscreen protected areas. In order to verify whether the difference in efficacy of these products was due to the difference in UVA absorption capacity, we quantified epidermal p53 protein accumulation after 8 exposures to either UVA (320-400 nm) or UVA1 (340-400 nm). We showed that as with SSR, repetitive exposures to 12.5 and 25 J/cm2 of UVA or UVA1 induced a significant increase in p53-positive cells in the human epidermis. These results confirmed that SPF determined on the basis of an acute erythemal reaction does not predict the level of protection against cumulative damage. They also showed that the protection provided by two sunscreens with different UVA protection factors is different (based on nuclear p53 protein accumulation), and that the PPD method can distinguish varying levels of sunscreen efficacy against UVA-induced cell damage.     

Sunscreen ingredients and labelling: a survey of products available in the UK

BACKGROUND: In Europe, where sunscreens are classified as cosmetics, products may contain one or several of 27 permitted 'ultraviolet filters'. We were unable to find published data on the frequency of usage of individual ultraviolet (UV)-absorbing chemicals in currently available sunscreens. AIM: To record the active ingredients and labelling characteristics of sunscreens available in the UK. METHODS: In 2005, two dermatologists visited seven retail outlets, which stocked a large range of sunscreens. Manufacturers were also contacted. For each product, the names of UV-protective ingredients and the labelling information, including sun protection factor (SPF), UVA protection and age group for which the product was marketed were recorded. RESULTS: Data on 308 skin sunscreen products and 21 lip sunscreens were recorded. For skin products, the SPF ranged from 2 to 60. In total, 23 different UV-absorbing ingredients were found, 4 of which were found in > 25% of products. The child and baby skin sunscreens (n = 52) had a significantly higher median SPF of 40, compared with 15 for the remaining 256 adult products (P < 0.001). The number of UV-absorbing chemicals and the frequency of those commonly used did not differ substantially between child and adult products. Of skin sunscreens marketed for babies, 60% contained 2-6 UV-absorbing chemicals. Nearly half of the skin sunscreens contained at least one of nine UV-absorbing chemicals not available in patch testing formulations from commercial suppliers. CONCLUSIONS: The results of this survey indicate current sunscreen content and labelling, and are a benchmark from which new developments can be tracked. More standard sunscreen labelling, particularly separate listing of active ingredients, would be helpful. It was surprising to find UV-absorbing chemicals in products sold for use on babies.     

Application of sunscreen preparations: a need to change the regulations

Background/purpose: To achieve photoprotection indicated on the package of sunscreen products they should be used appropriately. As previously published data documented that people usually applied much less than the recommended dose, the current study was undertaken to assess whether a detailed instruction can improve the use of sunscreens.
Methods: A total of 105 volunteers were asked to apply sunscreen to the whole skin surface in the same way that they would do it before sun exposure. A subgroup of patients ( n =53) were precisely instructed about the proper usage of sunscreens and compared with uninstructed subjects ( n =52). Each tube containing the tested product was weighed before and after application to determine the quantity of the substance, that was used, and to compare it with the recommended dose.
Results: Instructed subjects used significantly more sunscreens (mean 8.6 ± 4.1 g/m²) compared with uninstructed controls (mean 6.8 ± 3.9 g/m², P =0.03). However, both groups used much less of sunscreens than was the recommended amount (i.e. 43.0% and 34.1% of the recommended dose, respectively).
Conclusion: Current regulations about the sunscreen use are inadequate when compared with clinical practice and better standards of photoprotection should be elaborated in the future.     

Randomized placebo-controlled trial of metronidazole 1% cream with sunscreen SPF 15 in treatment of rosacea

Background: Rosacea is a photoaggravated dermatosis responsive to treatment with topical and oral antibiotics. A formulation combining metronidazole 1% cream with sunscreen SPF 15 was developed for the treatment of rosacea. Objective: The objective of this study was to determine the safety and efficacy of a formulation combining metronidazole 1% cream with sunscreen SPF 15 in the treatment of moderate to severe rosacea. Methods: One hundred and twenty patients with moderate to severe rosacea were enrolled for a randomized, placebo-controlled (vehicle containing sunscreen with SPF 15), double-blind study. Study cream was applied twice daily to the entire face over a 12-week period. Results: Treatment with metronidazole 1% cream with sunscreen SPF 15 resulted in significant improvement (p <0.05) in inflammatory lesion count, erythema and telangiectasiae scores, and investigator and patient global assessment scores compared with baseline and placebo. Adverse reactions related to study medication were typically mild, occurred at the site of application, and were reversible. There was no difference between the safety profiles of metronidazole 1% cream with sunscreen SPF 15 and placebo. Conclusions: The combined topical formulation of metronidazole 1% cream with sunscreen SPF 15 was an effective, well-tolerated topical agent for the treatment of moderate to severe rosacea.     

In vivo measurement of the photostability of sunscreen products using diffuse reflectance spectroscopy

BACKGROUND/AIM: The issue of the photostability of sunscreens has been frequently raised because of the possible loss of photoprotection, mainly in the UVA range, during sun exposure. Up to now, in vitro techniques have been mainly proposed to evaluate photostability. These techniques have generated controversial debates concerning the predictive value of these in vitro observations in relation to the in vivo reality during sun exposure. METHODS: Diffuse reflectance spectroscopy (DRS) is a recently developed technique that allows measurement of the UVA efficacy of sunscreen products in vivo on human volunteers. The absorption spectrum of the product is obtained by measuring the change in reflection of the skin with and without product. From this absorption spectrum, the UVA protective efficacy of the test product can be calculated for an appropriate source and a given biological action spectrum. We have used the DRS technique in vivo to determine the photostability of sunscreen products by measuring reflection spectra in the UVA range (320-400 nm) before and after product application and before and after UV exposure of the test products. Comparison between these spectra or between the corresponding calculated UVA protection factors has made it possible to determine the remaining level of protection in the UVA range after exposure. This study was designed to compare in vivo the protective efficiency and the photostability of three marketed sunscreen products (SPF 23-30) after solar-simulated exposure for SPF testing or after actual sun exposure. These in vivo data were then compared to in vitro photoinstability results. RESULTS: According to the in vitro measurements, one sunscreen product was found photostable and two products photo-unstable. After UVe exposure for in vivo SPF determination, a decrease in UVA absorption and UVA-PF was observed for the two photo-unstable products, while the photostable product did not present any decrease in UVA absorption. These results were confirmed through exposure to actual sun. CONCLUSION: Our study confirms the prediction of the in vitro methods previously used to assess the photostability of sunscreen products. In addition, DRS provides a powerful new tool for the in vivo simultaneous evaluation of photostability and estimation of the UVA protection factor of sunscreen products performed during the test for SPF determination.     

Sunburn cell formation, dendritic cell migration, and immunomodulatory factor production after solar-simulated irradiation of sunscreen-treated human skin explants in vitro

Using human skin explants, we investigated the effects of two different sunscreen preparations containing a chemical UVB filter alone [sun protection factor (SPF) 5.2] or UVA+UVB filter [SPF 6.2] on sunburn cell formation, dendritic cell (DC) migration, CD86- and CD1a-positive cell number, and tumor necrosis factor alpha (TNFalpha) and interleukin (IL)-1, IL-10, and IL-12 production in the skin after irradiation with different doses of solar-simulated UV radiation. Sunscreen- or placebo-treated skin explants were irradiated with solar-simulated UV radiation at 0.5, 1, and 2 minimal erythematous dose equivalents (MEDE) (as determined in an in vivo human study) multiplied by the SPF of the placebo or sunscreens. After irradiation, skin explants were floated on RMPI medium for 48 h. Cells that had emigrated and the skin explants were histologically analyzed, and the soluble mediators were measured in the supernatants by ELISA. Exposure to UV radiation led to concentration-dependent increases in sunburn cell formation and TNFalpha production but a concentration-dependent decrease in DC migration and CD86- and CD1a-positive cell number in the epidermis. Both chemical sunscreens protected against those alterations. The immunoprotective capacity of the sunscreens correlated with their SPF but was independent of the sunscreens' UVA protection capacity, suggesting that UVA is not a major factor for immunosuppression under the conditions used in the model. UV irradiation did not significantly affect the vitality of emigrated DC; the expression of HLA, CD80, and lag on emigrated cells; the number of CD1a-positive cells in the dermis; or the production of IL-1, IL-10, and IL-12. We conclude that our model may be useful in determining the immunoprotective capacity of sunscreens.     

Sunscreens as a preventative measure in melanoma: an evidence-based approach or the precautionary principle?

Background  Meta-analyses of observational case-control studies have demonstrated no association between sunscreen use and the development of malignant melanoma.
Objectives  To postulate whether modern sunscreens are likely to be effective as a preventative agent in melanoma and, if so, how many cases might be avoided by their use.
Methods  The potential number of melanomas prevented by encouraging the use of modern, high SPF, broad spectrum sunscreens during recreational summer exposure was estimated by combining the prevalence of their use with the relative risk of melanoma in nonusers compared with those people who regularly use these products.
Results  Notwithstanding the inherent uncertainties and assumptions that this approach involves, it is shown that significant numbers of melanomas might be avoided by regular sunscreen use during recreational summer sun exposure, and with them appreciable financial, social and emotional costs, even for very modest estimates of the benefit of broad-spectrum sunscreens.
Conclusions  Despite the lack of evidence demonstrating the efficacy of modern sunscreens in preventing melanoma, it is argued that it would be irresponsible not to encourage their use, along with other sun protection strategies, as a means of combating the year-on-year rise in melanoma incidence.     

Application of sunscreen preparations among young Polish people

Background The efficacy of sunscreens is assessed on the basis that 15–20 g/m² (1.5–2 mg/cm²) is applied. However, expecting people to apply such large amounts is perhaps unrealistic. Aim To evaluate the application of sunscreen usage by young people. Materials and methods Forty‐nine subjects (24 females and 25 males) in the age range 18–32 years (mean 23.1 years) were included in the study. They were asked to apply sun protection factor (SPF) to the whole of their own skin surface in just the same way that they would customarily do it during/prior to sun exposure. Two agents were applied: emulsion with SPF30 and a fatty cream with SPF > 60. The amount of preparation used/m² was calculated. Statistical analysis was performed using the Student's t‐test. Results The average amount of both preparations used was about half that expected to achieve correct sun protection (p < 0.00001). The mean applied amount of the fatty cream was 9.6 ± 5.3 g/m² (50.7% of the ideal value) and the emulsion 9.2 ± 5.5 g/m² (48.6% of the ideal value). Neither gender (male/female) nor type of agent (emulsion/fatty cream) affected the amount used. Conclusions Young people customarily apply less than 10 g of SPF/m². It is therefore unrealistic and possibly even misleading of manufacturers to assess SPF ratings as if people applied 15–20 g of SPF/m². Perhaps it is for manufacture's to increase the efficacy of their products rather than for consumers to be asked to apply twice as much?     

UV-induced immune suppression and sunscreen

Sun protection factor (SPF) that measures sunscreen protection against erythema and edema may not be enough to measure a sunscreen's activity against many other biologic reactions induced by ultraviolet radiation (UV). It may be better to evaluate sunscreen efficacy using various tools including immune protection factor (IPF), mutation protection factor (MPF) and protection against photocarcinogenesis. In terms of immune protection, sunscreens protected against UV-induced immune suppression significantly. But protection in some cases was partial and often the IPF of sunscreens were less than the SPF. IPF may differ with various immunological endpoints, and it may be better to use a couple of different assays to measure sunscreen protection more objectively. Sunscreen use protects against most UV-induced non-melanoma skin cancers and actinic keratoses but its activity against melanoma is not clear. More studies with broad-spectrum stable sunscreens and better models for the investigation of malignant melanoma are required.