Mechanisms of sunscreen failure

Sunscreen enhancement of UV-induced reactive oxygen species in the skin

The number of UV-induced (20 mJ cm(-2)) reactive oxygen species (ROS) generated in nucleated epidermis is dependent upon the length of time the UV filter octocrylene, octylmethoxycinnamate, or benzophenone-3 remains on the skin surface. Two-photon fluorescence images acquired immediately after application of each formulation (2 mg cm(-2)) to the skin surface show that the number of ROS produced is dramatically reduced relative to the skin-UV filter control. After each UV filter remains on the skin surface for t=20 min, the number of ROS generated increases, although it remains below the number generated in the control. By t=60 min, the filters generate ROS above the control. The data show that when all three of the UV filters penetrate into the nucleated layers, the level of ROS increases above that produced naturally by epidermal chromophores under UV illumination.

Children and sun exposure in the northeast of Italy

Excessive, incorrect exposure to the sun at a young age can be a risk factor for skin cancer at a later age. In this study we have investigated the exposure and protection habits of a group of children to see whether there are behavioral errors that should and possibly could be corrected. We handed out a multiple-choice questionnaire to 310 subjects, 212 boys and 98 girls between the ages of 6 and 14, all residents in the province of Udine in the northeastern part of Italy. Of these children, 24% had sunburn on several occasions; boys were four times more at risk than girls (OR = 0.4) and the frequency reduced by 30% for each skin phototype class higher. In children between 11 and 14 years of age, exposure was prolonged (43% for 2-4 hours, 38% for 4-8 hours) and 30% preferred peak hours. Eighty percent of the children, mostly girls, younger children (6-10), and the lower skin phototypes used sunscreens, but only 38% used them on a regular basis, whereas 20% applied them after sunbathing and 42% used a single daily application. Two percent of the children used sunglasses and 5% wore a T-shirt regularly. The dermatologist and pediatrician play an important role in advising parents that the sun is good for children, but appropriate measures must be taken to reduce any risks, both immediately and in the long term.

Photoprotection

Many agents affect the transmission of ultraviolet light to human skin. These include naturally occurring photoprotective agents (ozone, pollutants, clouds, and fog), naturally occurring biologic agents (epidermal chromophores), physical photoprotective agents (clothing, hats, make-ups, sunglasses, and window glass), and ultraviolet light filters (sunscreen ingredients and sunless tanning agents). In addition, there are agents that can modulate the effects of ultraviolet light on the skin (antioxidants and others). All of the above are reviewed in this article.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be able to provide an overview of all aspects of photoprotection.

Determination of UV-filter residues in bathing waters by liquid chromatography UV-diode array and gas chromatography–mass spectrometry after micelle mediated extraction-solvent back extraction

A preconcentration methodology utilizing the cloud point phenomenon is described in this study for the determination of sunscreen agent residues in bathing waters by reversed phase liquid chromatography with UV detection and gas chromatography (GC) with mass spectrometric (MS) detection. The method employs the entrapment of the analytes in the micelles of the non-ionic surfactant TX-114, upon increase of the solution temperature to 60 degrees C. The analytes are either re-extracted or back extracted from the final micellar extract into appropriate organic solvents, a procedure that facilitates the direct application of the method not only with liquid chromatography but mostly importantly with gas chromatographic analysis. Ultrasonication was employed to assist the procedure and accelerate the extraction of the analytes into the solvent phase. Under the optimum experimental conditions, the method affords satisfactory recoveries in the range of 95-102% and relative standard deviation lower than 6% without interference from the presence of the surfactant. The method was successfully applied to the determination of UV filters in natural waters.

Interventional study in 1,232 young German children to prevent the development of melanocytic nevi failed to change sun exposure and sun protective behavior

Sunscreens have been proposed as protective measures to inhibit the development of melanocytic nevi in childhood and to decrease the long term risk for cutaneous melanoma development. Our present study investigates the influence of sunscreen use and education on the number of incident melanocytic nevi. A total of 1,812 children in 78 public nursery schools in 2 German cities were randomized to 3 study arms: (i) parents were informed on study purpose and sun protection measures only at an initial educational meeting; (ii) parents received educational material 3 times yearly; and (iii) education and 800 ml free broad spectrum sunscreens with sun protection factor 25 provided on a yearly basis. Final assessment after 3 years follow-up included 1,232 children (68%). Changes of sun protection habits including sunscreen use were sparse, without any differences attributable to the intervention efforts. As a consequence, there were no significant differences between the 3 study arms for the main outcome measure, the number of incident melanocytic nevi. Analysis of the sunscreen use in the entire cohort irrespective of our study arms did not show any impact on incident nevus numbers in bivariate or multivariate analysis. In conclusion, intervention with educational letters and free sunscreens seemingly had no additional effect on sun-protection for German children. High prevalence of sunscreen use at study commencement, social desirability, and inadequate application of sunscreens might have partially covered their effect.

Aqueous photolysis of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid. Formation of disinfection byproducts in chlorinated swimming pool water

The photochemical behavior of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid (ODPABA) was studied in different aqueous solutions and under different conditions. ODPABA photolysis was performed under laboratory conditions using a xenon light source and under natural sunlight conditions in sea, swimming pool as well as in distilled water. The influence of dissolved organic matter (DOM) on the degradation kinetics was also studied in the presence of various concentrations of humic acids (HA). The phototransformation was shown to proceed via pseudo-first-order reaction in all cases and the reaction rates followed the order: distilled water > swimming pool water > seawater, depending mainly on the presence of dissolved organic matter that retarded the photolysis reaction. Kinetic experiments were monitored with HPLC/UV-DAD and the half-lives (t 1/2) varied between 1.6 and 39 h in simulated solar irradiation and between 27 and 39 h in natural sunlight conditions. The product distribution during illumination was strongly dependent on the constitution of the irradiated media. Irradiation of the aqueous ODPABA solutions gave rise to several transformation products that were isolated by means of solid-phase extraction (SPE) and identified using GC-MS techniques. These were formed mainly through dealkylation and hydroxylation reactions and were detected in all aqueous solutions investigated. In the case of swimming pool water some additional byproducts were isolated and were tentatively identified as chlorinated intermediates, formed by the subsequent chlorination of the parent molecule as well as other intermediates.

Sun Protection Attitudes and Behaviors of Solid-Organ Transplant Recipients

BACKGROUND

Solid-organ transplant recipients (OTRs) with sun-sensitive skin, a history of sun exposure, and clinical signs of photoaging have an increased risk of developing squamous cell carcinoma.

OBJECTIVE

The objective of this study was to compare the sun protection attitudes and behaviors of OTRs with those of the general public.

METHODS

In spring 2003, a telephone survey of 200 OTRs and a random sample of 1091 U.S. residents were performed with standardized questions previously used in population surveys.

RESULTS

Seventy-nine percent of OTRs and 69% of the U.S. public believe that the appearance of a tan is attractive. The attitude was expressed more often by men than by women and is not related to the education of the person. A greater proportion of OTRs believed that people looked "healthier" with a tan and 88% of OTRs were not aware of their increased risk of developing skin cancer. Thirty-five percent of OTRs reported regularly using sunscreen, which is the principal form of sun protection used. Women report more regular use of sunscreen than men. OTRs wear less protective clothing and seek less shade when outdoors than the public. Sunburning was reported by 35% of OTRs, which is similar to the rate reported by the public.

CONCLUSION

OTRs' attitude that people look "better, healthier" with a tan inhibits effective sun protection. Although physicians who care for OTRs provide patient education in the hope that it increases their awareness of their risk of developing skin cancer and will promote change in their sun protection behaviors, the OTRs' perception of risk is influenced by many concerns. Interpersonal motives, particularly for OTRs, the self-presentational ones related to appearance and the social image or prototype of a tanned person being healthy, mitigate risk perception of the health problem. Risk perception does not always inhibit risk behavior; therefore, unprotected sun exposure occurs in OTRs.

Avaliação dos hábitos de exposição ao sol e de fotoproteção dos universitários da Região Metropolitana de Porto Alegre, RS

FUNDAMENTOS: Sabe-se que a mudança de hábito da população mundial com relação à exposição ao sol provocou aumento da incidência de câncer da pele nas últimas décadas. Tais informações são especialmente relevantes na Região Sul, na qual há maior prevalência da população branca, mais propensa aos danos solares, em comparação ao restante do Brasil. OBJETIVOS: Avaliar os hábitos de exposição ao sol e de fotoproteção dos universitários da Região Metropolitana de Porto Alegre no período de julho a setembro de 2001. MÉTODOS: Foram respondidos 1.030 questionários por universitários residentes na Região Metropolitana de Porto Alegre. RESULTADOS: Nos finais de semana, 38,4% dos estudantes permanecem ao sol entre duas e seis horas diárias. Durante o verão, 43,7% deles se expõem ao sol entre as 10 e as 15h; 85% dos estudantes afirmam usar filtro solar, mas 65% não o usam ao praticar esportes ao ar livre. CONCLUSÕES: Os autores observaram que a maioria dos universitários se expõe excessivamente ao sol, em horários impróprios e sem efetiva proteção solar.

Determination of residues of UV filters in natural waters by solid-phase extraction coupled to liquid chromatography–photodiode array detection and gas chromatography–mass spectrometry

This study describes a procedure for the enrichment, separation and quantification of four major UV filters in natural waters. Solid-phase extraction combined with liquid chromatography and photodiode array detection (LC-UV-DAD), and gas chromatography with mass spectroscopy (GC-MS) were employed for the analyses. LC of the four compounds with surfactant-modified hydro-organic eluents gave satisfactory resolution of overlapping peaks. In GC, a significant improvement of the detection limits was attained, but only three compounds could be detected. The method was validated for, and applied to, various water samples prone to UV filter accumulation due to recreational activities. Recoveries from real samples were 86-99% with LOQs as low as 0.5 ng/l depending on the sample volume and the analytical procedure.

The Australian experience in sun protection and screening for melanoma

Australia has the world's highest incidence of skin cancer. Despite excellent prevention and early diagnosis education programs and an increasing percentage of the population with darker and more UV tolerant skins, skin cancer remains a major and expensive community medical problem. However, primary and secondary prevention programs are now showing positive outcomes, especially in melanoma incidence and survival. Primary and secondary prevention programs are conducted by a variety of non-government organizations such as the Australian Cancer Council, which is comprised of state anticancer groups, with some assistance from State and Federal health agencies. Current and future campaigns are becoming focused on specific community groups, noticeably teenagers and the older population. The role of sunscreens as the primary preventative approach has been superceded by sunlight avoidance campaigns. In light of an increasing rate of early diagnosis, a low and falling morbidity of melanoma, improving general practitioner competence in skin cancer diagnosis and proliferation of skin cancer clinics throughout Australia, it is unlikely a national skin cancer screening program will be implemented. Ozone depletion, a sunlight overloaded environment, increased leisure time and an outdoor lifestyle necessitate continued efforts to minimise the cost and morbidity of skin cancer in Australia.

Double exposure: natural and artificial ultraviolet radiation exposure in beachgoers

BACKGROUND

Although the beach is a high-risk environment for ultraviolet light exposure and subsequent skin damage, little is known about beachgoer tanning habits outside the beach setting. Our purpose was to evaluate indoor tanning and additional, nonbeach sunlight exposure in a beachgoing population.

METHODS

We conducted an epidemiologic survey.

RESULTS

There was more use of indoor tanning salons among sunbathing beachgoers who applied little or no skin protection from the sun (50.8% [31 of 61 respondents]) compared with nonsunbathing beachgoers (22.7% [5 of 22 respondents]). In addition to increased use of tanning salons, we observed that poorly protected sunbathers tanned at locations other than the beach on a regular basis (50.8% [31 of 61 respondents]) more than nonsunbathers did (9.1% [2 of 22 respondents]).

CONCLUSION

Beachgoing sunbathers often used both natural sunlight and tanning beds, subjecting themselves to two forms of ultraviolet radiation exposure.

Effects of a multicomponent intervention on motivation and sun protection behaviors among midwestern beachgoers

Skin cancer is the most prevalent of all cancers in the United States. Although avoiding sun exposure and using sun protection reduces skin cancer risk, rates of such behaviors are moderate at best. The present study examined the impact of a multicomponent intervention that aimed to increase the saliency of skin cancer risk while promoting the use of sun protection. Midwestern beachgoers (n = 100) participated in an intervention or questionnaire-only control group. Sun protection, stage of change, and sun exposure were measured at baseline and 2-month follow-up. The intervention group significantly improved in sun protection use and stage of change, but not sun exposure, compared with the control group. Personalizing the risks of unprotected sun exposure combined with providing education about sun protection facilitated healthy changes in behavior and motivation.

Gas chromatographic determination of 2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid sunscreen agents in swimming pool and bathing waters by solid-phase microextraction

A method has been developed for the trace determination of two sunscreen constituents (2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid) in water samples, which are commonly used in commercial formulations. The method employs solid-phase microextraction (SPME) and gas chromatography with flame ionization and mass spectrometric detection. The technique was developed with headspace and direct sampling in order to demonstrate the applicability of these SPME extraction modes for the identification of these two UV absorbing compounds in waters. The main parameters affecting the SPME process, such as desorption time, extraction time profile, salt additives, pH, and temperature, were investigated. The poly(dimethylsiloxane) 100-microm and polyacrylate 85-microm fiber coatings were found to be the most efficient for the extraction of these compounds from aqueous matrices. Linear calibration curves in the wide range of 10-500 microg/l were obtained for both compounds yielding typical RSD values of 5-9% for both extraction modes. The recoveries were relatively high, 82-98%, with quantitation limits below 1 microg/l. A comparison between the proposed methods and the conventional multiresidue solid-phase extraction revealed that the proposed technique(s) can be reliably used for sunscreen residue measurement in water samples with satisfactory results.

Sunscreen use and melanoma: a case of evidence-based prevention?

BACKGROUND

A preventive effect of sunscreens on melanoma development is still subject of intense discussion. The practical consequences for changes in public health campaigns are neglected in this debate.

METHODS

An extensive literature search for studies on the association between sunscreen use and melanoma occurrence was performed. The principles of evidence-based medicine (EBM) are applied to the issue to derive at recommendations for an evidence-based prevention of melanoma.

RESULTS

We identified 17 case-control studies providing risk estimates for the relationship under study. These risk estimates are too heterogeneous to allow a reasonable conclusion by summarizing the evidence. The application of the EBM approach yields therefore an inconclusive result: the melanoma protective potential of sunscreens cannot be proven using the existing evidence. The information necessary to fully assess the effect of sunscreen use on melanoma development is not currently available.

CONCLUSION

Based on the current evidence the focus of recommendations for melanoma prevention in public awareness campaigns has to be changed. It should be much more emphasized to minimize exposure to ultraviolet (UV) radiation during peak hours, wear protective clothing, hats and UV-opaque sunglasses, seek shade and protect infants and children against too much UV radiation exposure at all than to use sunscreens.