Public primary and secondary skin cancer prevention, perceptions and knowledge: an international cross-sectional survey.

BACKGROUND: The incidence of melanoma and non-melanoma skin cancer is continuing to increase worldwide, with sun exposure serving as the primary external aetiologic force in its development. Despite noticeable public health efforts, there continue to be gaps in public awareness and primary and secondary prevention mechanisms. This survey study sought to investigate preventative behaviours regarding sun exposure and skin cancer detection at an international scale. METHODS: A questionnaire was submitted, both online and by telephone, to a representative sample (based on official demographic statistics on gender, age and region) of people aged from 15 to 65 originating from 23 countries. Questions dealt with demographics, sun exposure and protection, risk knowledge, self-examination, medical advice seeking. Data were then gathered and analysed at different levels. RESULTS: A total of 19 569 respondents were recruited. Overall, sunscreen and sunglasses were the most used measures for sun protection. There were however difference between countries and geographical areas. Some high-risk countries in terms of sun exposure (according to their location to Equator) exhibited higher rates of primary preventative behaviours, in particular Australia, Chile and Greece. There were also discrepancies between countries regarding secondary prevention through self-examination and medical advice seeking. Young people, men, individuals belonging to a lower socio-economic class or having a lower education level were all least likely to know or follow primary and secondary preventive measures. CONCLUSION: We found imperfections and geographical inequality both regarding primary and secondary prevention of skin cancer. Our study provides insights that could help to target populations more effectively through information campaigns embedded into the global needed endeavour aiming to reduce mid- and long-term development of skin cancer.

Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies.

A review of the oxidization of squalene, a specific human compound produced by the sebaceous gland, is proposed. Such chemical transformation induces important consequences at various levels. Squalene by-products, mostly under peroxidized forms, lead to comedogenesis, contribute to the development of inflammatory acne and possibly modify the skin relief (wrinkling). Experimental conditions of oxidation and/or photo-oxidation mechanisms are exposed, suggesting that they could possibly be bio-markers of atmospheric pollution upon skin. Ozone, long UVA rays, cigarette smoke… are shown powerful oxidizing agents of squalene. Some in vitro, ex vivo and in vivo testings are proposed as examples, aiming at studying ingredients or products capable of boosting or counteracting such chemical changes that, globally, bring adverse effects to various cutaneous compartments.

The revised COLIPA in vitro UVA method.

A multicentred study derived from the COLIPA in vitro UVA method was performed to assess the influence of test conditions on UVA protection factor (UVAPF) values in terms of amplitude, reproducibility between laboratories and correlation with in vivo UVA results. Eight products with a range of in vivo UVAPF from three to 29 were used. Two different types of plates, namely high-roughness (5 µm) and low-roughness (2 µm) plates, were used with a different application rate for each (1.3 mg cm(-2) and 0.75 mg cm(-2) respectively). The UVR dose applied to both plate types followed the same principle as the original test (1.2 J. cm(-2)  × UVAPF0). Strong, significant correlations between in vitro and in vivo UVAPF values were observed for both plate types (Pearson correlation > 0.9, P ≤ 0.01). The correlation and slope obtained with the low-roughness plates confirmed the previous results obtained by COLIPA. Across all laboratories, higher UVAPF values were obtained on the high-roughness plates (P < 0.01). Reproducibility of UVAPF values between laboratories was comparable between the two plate roughness values (low roughness, COV = 8%; high roughness, COV = 12%). Considering the in vitro/in vivo comparisons, a regression slope of 0.83 was observed for the low-roughness plates, in comparison with a value of 1.05 for the high-roughness plates. The accuracy of the method was improved, therefore, with the use of the high-roughness plates. With a constraint to recommend the use of only one plate type in the COLIPA UVA in vitro Test, the high-roughness plate was selected on an on-going basis to limit variability of results and to provide better accuracy with in vivo data.

UVA filters in sun-protection products: regulatory and biological aspects.

This review of published in vitro and in vivo studies concerning the biological effects of ultraviolet A (UVA; 320-400 nm) radiation illustrates the evidence for combining UVA and UVB filters in sun-protection products. These data have led to the development of new sunscreens as well as methods to evaluate their efficacy. After listing the UVA filters available and briefly noting the requirements for a high SPF, broad-spectrum sunscreen, the methods for evaluating the level of UVA protection will be described. This article also summarizes several studies looking at the prevention of erythema, pigmentation, DNA damage, photoimmunosuppression, photoaging and photodermatoses. These data demonstrate in vitro and in vivo that only well-balanced UVA-UVB sunscreens, absorbing over the entire UV spectrum are able to prevent or significantly reduce the associated biological damage.

Photodamage to human skin by suberythemal exposure to solar ultraviolet radiation can be attenuated by sunscreens: a review.

The effects of acute or repeated suberythemal solar ultraviolet radiation (UVR) exposure on human skin have been insufficiently investigated. Such exposure almost certainly has important long-term consequences that include skin ageing and skin cancer. This review summarizes the published data on the biological effects of suberythemal exposure using a wide range of clinical, cellular and molecular endpoints, some of which may be considered as biomarkers for skin cancer and photoageing. We also include some recent unpublished results from our laboratories. The effects of UVA (320-400 nm), UVB (290-320 nm) and total solar UVR (290-400 nm) are compared. We demonstrate that avoiding sunburn does not prevent many indicators of cutaneous biological damage and that use of low sun protection factor (SPF) sunscreen can inhibit much of the damages induced by suberythemal exposure to UVR. However, even when applied correctly, sunscreen use will result in suberythemal exposure. The degree and spectral quality of such exposure will depend on the SPF and absorption spectrum of the sunscreen, but nonetheless it may contribute to cumulative photodamage. This review may help to determine the level of photoprotection required in sunscreens and daily use products, as well as the ideal ratio of UVB/UVA protection, to improve long-term photoprotection outcomes.

The COLIPA in vitro UVA method: a standard and reproducible measure of sunscreen UVA protection.

There is a continuing need to measure and communicate reliably the UVA protection offered by commercial sunscreens. To that end, the COLIPA (European Cosmetics Trade Association) 'In Vitro Sun Protection Methods' group has developed a new in vitro method for measuring UVA protection in a standardized, reproducible manner. The method is based on in vitro UV substrate spectrophotometry and convolution of resulting absorbance data with the action spectrum for the in vivo Persistent Pigment Darkening (PPD) endpoint to provide an in vitro UVA protection factor (UVAPF) which is correlated with an in vivo measure. This method has been published as a COLIPA guideline, used currently in European geographies for testing and labelling sunscreen products. This article summarizes two 'ring' studies, involving eight separate testing laboratories, which both defined critical parameters for the method and validated it. In Ring Study 1, eight laboratories tested the in vitro UV transmission of a total of 24 sunscreens and, from the data, a unit dose of UVA (D(0) of 1.2 J cm(-2)) was defined to provide a single irradiation step which, by taking into account potential sunscreen photo-instability, gave the closest agreement with in vivo UVAPF values. In Ring Study 2, eight laboratories tested the in vitro UV transmission of a total of 13 sunscreens using this single irradiation step and established a very good correlation (r(2) = 0.83; slope = 0.84, P < 0.0001) between resulting in vitro UVAPF values and corresponding values derived from the in vivo PPD method. This new method, therefore, can be used to provide a reliable in vitro metric to describe and label UVA efficacy in sunscreen products, in line with the EU Commission recommendation 2006/247/EC.

Importance of sunscreen products spreading protocol and substrate roughness for in vitro sun protection factor assessment.

The purpose of this study was to evaluate the impact of substrate roughness and of product spreading method on in vitro sun protection factor (SPF) measurement and to define the experimental conditions most appropriate to reach the best level of correlation to in vivo SPF. In vitro SPF assessment was carried out on 13 products (including different formulation types with SPF from 20 to 75) using various in vitro SPF protocols and comparing related predictive potential regarding in vivo SPF. In the first part, two spreading methods were compared on two types of PMMA (Polymethyl methacrylate plate with different roughness. The impact of a second spreading step after product drying was also evaluated. From the various investigated parameters, it was shown that (i) a higher roughness (Ra = 4, 5 microm) was preferred for O/W formulations (ii) using a defined sequence of light linear and circular strokes was more adequate than monitoring product spreading in terms of time and pressure (iii) both correlation to in vivo SPF and results variability were improved when a second spreading step was added. The altered protocol showed a good predictive potential regarding in vivo SPF values for O/W formulations (correlation coefficient 0.92, correlation curve slope 0.98) and coefficient of variation of in vitro results (14% of the mean SPF value) close to what is usually obtained in vivo. The repeatability of the protocol was also demonstrated. In the second part, we evaluated the impact of PMMA plate pre-treatment with paraffinum liquidum before spreading the product to get a better correlation between in vivo and in vitro SPF values for W/O formulations. This allowed us to define a protocol suitable for both O/W and W/O formulations.

In vivo persistent pigment darkening method: proposal of a new standard product for UVA protection factor determination.

The European Commission (EC) has recommended assessing the level of ultraviolet A (UVA) protection afforded by sunscreen products using the in vivo persistent pigment darkening (PPD) method or other methods giving equivalent results. In this context, the reproducibility of the in vivo PPD method is of importance. To check the validity of the UVA protection factor (UVAPF) tests, the Japanese Cosmetic Industry Association (JCIA) recommends using a standard product (JCIA standard) with an expected UVAPF 3.75 (SD 1.01). However, considering the increase in UVA efficacy of the new sunscreen products available in the market, with UVAPF up to 30, it seemed useful to develop a new standard product to be used when testing products with expected UVAPF > or =10. The PPD method was used in six centres to determine the UVAPF of the two products. Reproducibility of results was also studied by testing two batches of the new product at two different times. There was no statistical difference between the six centres with regard to the JCIA standard. The ring study showed that the mean value of UVAPF (4.3) was higher than that given by JCIA (3.75). These data enable the proposal of a new acceptance range for the JCIA standard product (3.4-5.2) derived from actual results from European laboratories. Whereas this range is different from that proposed by JCIA (2.74-4.76), there is an overlapping of the values. Data on the new standard product show that reproducibility is not influenced by the batches of this product. The mean UVAPF value obtained is 12.1. An acceptance range (9.6-14.6) is proposed for the new standard. Data presented here demonstrate that if an identical protocol is used, reproducible results can be expected and that the PPD method is reproducible and reliable.

Protection of skin biological targets by different types of sunscreens.

In vitro and in vivo studies provide a body of evidence that adequate protection of the skin against ultraviolet (UV)-induced damage requires photostable broad-spectrum sunscreens with a proper level of UVA protection. UVA alone and UV solar simulated radiation (SSR) induce DNA lesions in keratinocytes and melanocytes as reflected by the comet assay and p53 accumulation. UVA and SSR impair the immune system as shown by significant alteration of Langerhans cells and inhibition of contact hypersensitivity response to chemical allergens and delayed-type hypersensitivity response to recall antigens. Any of these detrimental effects is more efficiently prevented by sunscreens with a higher level of protection in the UVA range. The involvement of UVA (fibroblast alteration, increased metalloproteinase expression) and the pivotal need for well-balanced UVA/UVB sunscreens were further demonstrated using reconstructed three-dimensional skin models.

Non-invasive in vivo determination of UVA efficacy of sunscreens using diffuse reflectance spectroscopy.

BACKGROUND: Evaluation of sunscreen efficacy is most relevant when measured on the surface it is meant to protect, namely on human skin in vivo. Application of any material to the surface of the skin alters its optical properties. Diffuse reflectance spectroscopy (DRS) is a non-invasive technique to measure changes in the optical properties of the skin decoupled from its biological responses following sunscreen application. METHODS: This study compared measurements of UVA efficacy of oxybenzone and avobenzone at different concentrations (0-5%) using DRS, human phototest and an in vitro technique. Twenty subjects were enrolled for each product measured by DRS and 10 different subjects were enrolled for each product measured by human phototest. Six areas 5 cm x 10 cm were outlined on each subject's back. DRS measurements were performed on four subsites within each area before and 20 min after sunscreen application. UVA efficacy for each concentration of product was calculated from the measured transmission spectrum of a given product convoluted with the spectrum of a Xenon light source adequately filtered to obtain the UVA spectrum from 320 to 400 nm and the erythema action spectrum. Phototesting was performed using the same light source and persistent pigment darkening as the biological endpoint. Measurements were made with sunscreen coverage of 2 mg/cm2. In vitro measurements were performed using an Optometrics instrument. RESULTS: All three techniques showed a linear response between calculated UVA efficacy and product concentration. CONCLUSIONS: This study showed that DRS is a rapid and reproducible method to calculate UVA efficacy of sunscreen materials and that its results correlate closely with those obtained by human phototesting.

Efficacy of broad-spectrum sunscreens against the suppression of elicitation of delayed-type hypersensitivity responses in humans depends on the level of ultraviolet A protection.

Sunscreens have been designed to protect against sunburn and their efficacy has, therefore, been labeled by the so-called sun protection factor (SPF). Although this value is well determined using a standardized protocol and it affords a good evaluation of the protection against erythema it may be inadequate to provide a relevant measurement of efficacy against other biologic damages. This is particularly true when action spectra and threshold dose are different from those of erythema. In the case of ultraviolet (UV)-induced immune suppression, the action spectrum is not known, so it cannot be asserted that SPF may accurately predict the level of protection against this endpoint. We addressed this issue by measuring in human volunteers the ability of two broad-spectrum SPF 15 sunscreens with different ultraviolet A (UVA) protection levels, to prevent the alteration of the efferent phase of the local delayed-type hypersensitivity (DTH) response to recall antigens (Multitest Pasteur/Mérieux, Lyon, France) after acute solar-simulated UV exposure. We first determined the ultraviolet radiation (UVR) dose needed to induce a significant DTH inhibition in several groups of 15 volunteers. Two minimal erythemal doses (2 MED) were found to be the minimal immunosuppressive dose (MISD). As a result, the immune DTH response is reduced in average by 36%. The lower doses tested (0.5 and 1 MED) were ineffective. Sunscreen-treated groups were exposed to either 1 or 2 MED x SPF doses. As expected, no alteration in DTH response was observed in the groups exposed to 1 MED x SPF whatever the sunscreen applied. In contrast, after exposure to 2 MED x SPF, the DTH response remained unaltered in the group pretreated with the sunscreen product with the higher protection in the UVA range but was significantly suppressed by 55.7% in the group pretreated with sunscreen with a much lower protection in the UVA range. These data suggest that SPF may not be sufficient to predict the ability of sunscreens to protect from UV-induced immune suppression. Determining the level of UVA protection is particularly needed, as UVA seems to have a relatively low contribution to erythema but is highly involved in immunosuppression.

Alterations in human epidermal Langerhans cells by ultraviolet radiation: quantitative and morphological study.

BACKGROUND: Ultraviolet (UV) exposure of human skin induces local and systemic immune suppression. This phenomenon has been well documented when UVB radiation (290-320 nm) is used. The mechanism is thought to involve Langerhans cells (LCs), the epidermal dendritic cells that play a crucial role in antigen presentation. A variety of studies have clearly demonstrated that UVB radiation decreases LC density and alters their morphology and immunological function, but little is known about the effects of the entire UV spectrum (ultraviolet solar simulated radiation, UV-SSR or UVB + UVA) or UVA (320-400 nm) radiation alone. OBJECTIVES: The purpose of this study was to analyse and compare the effects of a single exposure of human volunteers to UV-SSR, total UVA or UVA1 (340-400 nm) in the human epidermal LC density and morphology. METHODS: Immunohistochemistry on epidermal sheets with various antibodies and transmission electron microscopy (TEM) were used. RESULTS: Immunostaining for class II antigen revealed that a single UV-SSR exposure, corresponding to twice the minimal erythemal dose (MED), induced a significant reduction in LC density with only slight morphological alterations of remaining cells. After a single UVA exposure, LC density showed a dose-dependent reduction with a significant effect at 60 J cm(-2) (well above the MED). Moreover, the reduction of LC dendricity was also dose-dependent and significant for doses exceeding 30 J cm(-2). UVA1 radiation was as effective as total UVA for the later endpoint. As demonstrated by TEM, the location of Birbeck granules containing epidermal cells was modified in UVA-exposed areas. They were located in the spinous rather than in the suprabasal layer. In addition, the morphology of these cells was altered. We observed a rounding up of the cell body with a reduction of dendricity. Alterations of mitochondrial membrane and ridges were also seen. CONCLUSIONS: A single exposure of human skin in vivo to UV-SSR, UVA or UVA1 radiation results in different alterations of density and/or morphology of LCs. All these alterations may impair the antigen-presenting function of LCs leading to an alteration of immune response.

Broad-spectrum sunscreens provide better protection from the suppression of the elicitation phase of delayed-type hypersensitivity response in humans.

It is well established that ultraviolet radiation has immunomodulatory effects that may be involved in skin cancer. Recent studies have shown that ultraviolet A radiation (320-400 nm) as well as ultraviolet B (290-320 nm) is immunosuppressive. This means sunscreens that mainly absorb ultraviolet B (protection against erythema) may be less effective in preventing ultraviolet radiation-induced immunosuppression than broad-spectrum products. We have studied the effects of ultraviolet A exposure on the human delayed-type hypersensitivity response and compared the efficacy of sunscreens having different levels of ultraviolet A protection under both solar-simulated radiation and outdoor real-life solar exposure conditions. Delayed-type hypersensitivity was assessed using recall antigens. In a first study, two groups of volunteers were exposed to ultraviolet A (either full spectrum ultraviolet A or ultraviolet A1) without prior application of sunscreen and they were shown to exhibit significantly reduced delayed-type hypersensitivity responses. In order to compare the efficacy of sunscreens in preventing photoimmunosuppression, three groups of subjects received 10 cumulative exposures to solar-simulated radiation; one group was exposed unprotected and the other two were exposed after being applied either a ultraviolet B or a broad-spectrum sunscreen, each with the same sun protection factor 9, but with different ultraviolet A protection factors 9 and 2. Then, an outdoor study was conducted in which delayed-type hypersensitivity was assessed before and after six daily exposures. Two different groups of subjects were treated with one of two sunscreens having the same sun protection factor 25 but different ultraviolet A-protection factors. In unprotected volunteers, responses to delayed-type hypersensitivity tests were significantly reduced irrespective of ultraviolet exposure conditions (full spectrum ultraviolet A, ultraviolet A1, solar-simulated radiation). The ultraviolet B sunscreen failed to protect from solar- simulated radiation-induced immunosuppression. In contrast, the broad-spectrum sunscreen having the same sun protection factor but providing high protection in the ultraviolet A range significantly reduced local ultraviolet-induced immunosuppression and prevented the distal effects. In the outdoor study, as compared with delayed-type hypersensitivity responses obtained before sun exposure, no alteration of immune response was detected when the skin was protected by broad-spectrum sunscreen sun protection factor 25 and ultraviolet A-protection factor 14. Conversely, a broad-spectrum sunscreen sun protection factor 25 ultraviolet A-protection factor 6 failed to protect against the sun-impaired response. The above studies clearly demonstrate the role of ultraviolet A in the induction of photoimmunosuppression together with the need for sunscreen products providing efficient photoprotection throughout the entire ultraviolet spectrum.

Ultraviolet AI exposure of human skin results in Langerhans cell depletion and reduction of epidermal antigen-presenting cell function: partial protection by a broad-spectrum sunscreen.

BACKGROUND: Ultraviolet (UV) B-induced effects on the skin immune system have been extensively investigated, but little is known regarding the immunological changes induced by UVA exposure of human skin. Recent data assessing the protection afforded by sunscreens against photoimmunosuppression stress the need for broad-spectrum sunscreens with an adequate UVA protection. OBJECTIVES: The purpose of this study was first to determine the changes observed in epidermal Langerhans cells (ELC) density and epidermal antigen-presenting cell (APC) activity after exposure of human skin to UVAI (340-400 nm) radiation, and secondly to assess the immune protection afforded in vivo by a sunscreen formulation containing a long wavelength UVA filter with a low UVA protection factor (UVA-PF = 3). METHODS: Epidermal cell (EC) suspensions were prepared from skin biopsies 3 days after exposure to a single dose of UVAI (either 30 or 60 J cm(-2)). RESULTS: Flow-cytometric analysis of EC suspensions revealed that exposure to 60 J cm(-2) UVAI resulted in a decreased number of ELC without infiltration of CD36+ DR+ CD1a- antigen-presenting macrophages into the epidermis, and a significant reduction of HLA-DR expression on viable ELC. In vivo exposure to both 30 and 60 J cm(-2) resulted in a decreased allogeneic CD4+ T-cell proliferation induced by UVAI-irradiated ECs. The sunscreen application partially prevented (57 +/- 9%) the decrease in epidermal allogeneic APC activity induced by 60 J cm(-2) UVAI. CONCLUSIONS: In vivo UVAI exposure of human skin results in a decreased number of ELC and in a downregulation of epidermal APC activity. This last effect is partially prevented by prior application of a sunscreen with a low UVAI-PF value. These results indicate that increasing the absorption of UV filters for long UVA wavelengths may lead to an improved immune protection.

Comparison of UVA protection afforded by high sun protection factor sunscreens.

UVA protection afforded by 6 different sunscreens with a sun protection factor of 21 or more was compared by means of the persistent pigmentation darkening method. Colorimetric and visual assessment showed significant differences in UV radiation-induced pigmentation at 2 hours. The labeled sun protection factor of the tested sunscreens was not predictive of UVA protection level.

Determination of UVA protection factors using the persistent pigment darkening (PPD) as the end point. (Part 1). Calibration of the method.

BACKGROUND/AIMS: The accuracy and reliability of any method to assess the UVA protection effectiveness of sunscreens needs to be demonstrated. The aim of the present study was to calibrate the effectiveness of a biological end point (Persistent Pigment Darkening, PPD) to assess UVA photoprotection, METHODS: Persistent Pigment Darkening was selected as the end point because its action spectrum extends across the UVA. A broad UVA source was chosen to challenge all UVA wavelengths. Attenuation of UVA was performed with neutral density filters (equally absorbing at all wavelengths). Human subjects were tested with a series of UVA beams attenuated by the neutral density filters. The UVA protection effectiveness of a standard sunscreen was also tested with four panels of volunteers to assess the reproducibility of the method. RESULTS: The attenuation factors of the neutral density filters were found to correspond to the UVA protection factors arrived at with PPD as the end point. The repetitive tests showed a good internal consistency of the method. CONCLUSIONS: The calibration procedure proposed shows threshold PPD, used as an end point in a UVA-PF test method, to be a reliable endogenous dosimeter for UVA radiation that enters the skin.

UVA protection efficacy of sunscreens can be determined by the persistent pigment darkening (PPD) method. (Part 2).

BACKGROUND: The UVA-induced Persistent Pigment Darkening (PPD) in vivo has been proposed as an end point for the evaluation of UVA protection. AIMS: This study was designed to determine whether PPD can be used to correctly evaluate the in vivo effectiveness of UVA filters such as oxybenzone, avobenzone, ecamsule and zinc oxide concentrated and together with UVB filters. METHODS: The UVA protection effectiveness of a number of commercial sunscreen products with either SPF 15 or SPF 30 was determined. RESULTS: The UVA protection increased closely with the concentration of the UVA filters and was independent of UVB filters. The PPD method proved sensitive to all UVA filters irrespective of their range of absorbance within the UVA range. CONCLUSION: The results show PPD to be a stable end point inducible by all the UVA wavelengths, not affected by fluence rate, i.e. a reliable endogenous UVA dosimeter in the skin.