Use and misuse of sunscreens

Study of Sunbathing in Children: The Preliminary Evaluation of a Prevention Program

Aims and background

Sunburn during childhood is associated with an increased risk for developing melanoma in an adult age. The aim of the present study was to define the validity of our educational program in order to teach the positive effects and risks of sun exposure during childhood.

Patients and methods

We conducted a population-based, case-control study in primary schools of three towns in Northern Italy (Brescia, Bergamo and Trento) between 2001 and 2002. The study was carried out on 1945 pupils (aged 8-9 years) and included 1309 case children who received an educational program before the summer to increase awareness towards sun exposure and 636 control children who did not. Parents of case and control children were interviewed using a questionnaire about their children's skin characteristics, sun protective behavior and sunburns. The questionnaire was completed twice, before and after the summer, to verify the changes of sun exposure habits.

Results

A significant decrease in sunburns was demonstrated in the group of subjects who received the educational program, indicating the validity of our operative procedure (from 14.6% to 10%, P = 4 × 10−4).

Conclusions

Our educational melanoma program may be important to disseminate in a wider range of children a correct education on sun exposure during childhood.

Rationale, design, and baseline data of a cross-national randomized trial on the effect of built shade in public parks for sun protection

Environments can be structured to reduce solar ultraviolet radiation (UV) exposure to prevent skin cancer. A prospective randomized trial is being conducted to test whether introducing shade sails in passive recreation areas (PRAs) in public parks will increase use and decrease UV exposure in the shaded compared to unshaded PRAs. Shade effects will be compared between Melbourne, Australia and Denver, USA. The trial enrolled 145 public parks with PRAs suitable for shade construction and randomized parks to intervention or control in a 1:3 ratio. Use of PRAs and UV levels were recorded at each park by trained observers during 30-minute periods on four weekend days in each of two summers (pretest and posttest). Shade sails were constructed between the summers. Given low numbers of users at pretest, the outcome measure was modified to use of the PRA (use vs. no use) and unit of analysis to the individual observation. Observations (n=580) occurred on average 29days from the summer solstice and 55min from solar noon in warm weather (mean=26.2°C) with some cloud cover but only slight or no wind. Typically, PRAs had benches and picnic tables and were located near playgrounds. PRAs were in use during 13.3% of observations (mean=0.41 users). UV over 30-minutes at the PRA boundary (mean=3.2 standard erythemal dose [SED]) and center (mean=3.3 SED) was high. Shade for skin cancer prevention has been understudied. This study will address this gap by determining whether purpose-built shade structures promote greater use of shaded areas within public parks.

Benefit and risk of organic ultraviolet filters

Modern sunscreen products provide broad-spectrum UV protection and may contain one or several UV filters. A modern UV filter should be heat and photostable, water resistant, nontoxic, and easy to formulate. Identification of a substance that meets these criteria is as difficult as discovering a new drug; hundreds of new molecules are synthesized and screened before a lead candidate is identified. The most important aspect in the development of a new UV filter is its safety. In our laboratories, the safety of new ultraviolet filters is assessed by an initial in vitro screen including photostability, cytotoxicity, photocytotoxicity, genotoxicity, and photogenotoxicity tests. These tests are performed in mammalian, yeast, and bacterial cell systems. Skin penetration potential is measured in vitro using human skin or, when required by regulations, in vivo. Because modern sunscreens are selected on the basis of their retention on and in the stratum corneum and are formulated as poorly penetrating emulsions, they generally have very low to negligible penetration rates. The safety and efficacy of UV filters are regulated and approved by national and international health authorities. Safety standards in the European Union, United States, or Japan stipulate that new filters pass a stringent toxicological safety evaluation prior to approval. The safety dossier of a new UV filter resembles that of a new drug and includes acute toxicity, irritation, sensitization, phototoxicity, photosensitization, subchronic and chronic toxicity, reproductive toxicity, genotoxicity, photogenotoxicity, carcinogenicity, and, in the United States, photocarcinogenicity testing. The margin of safety of new UV filters for application to humans is estimated by comparing the potential human systemic exposure with the no-effect level from in vivo toxicity studies. Only substances with a safe toxicological profile and a margin of safety of at least 100-fold are approved for human use. Finally, prior to marketing, new UV filters undergo stringent human testing to confirm their efficacy as well as the absence of irritation, sensitization, photoirritation, and photosensitization potential in man. UV filters not only protect against acute skin injury, such as sunburn, but also against long-term and chronic skin damage, including cellular DNA damage, photoinduced immune suppression, and, by extension, skin cancer. The protection provided by modern sunscreens against UV-induced skin cancer was shown in animal photocarcinogenicity studies and confirmed by numerous in vitro, animal, and human investigations: UV filters protect the p53 tumor suppressor gene from damage and prevent UV-induced immune suppression. Recent studies suggest that sunscreens protect against precursor lesions of skin cancer, such as actinic keratoses. Additional benefits of ultraviolet filters include prevention of photodermatoses, such as polymorphic light eruption, and, possibly, photoaging. Modern sunscreens are safe for children and adults. Percutaneous penetration and irritation rates of topically applied substances in children and adults are similar. The principal protective measure is to keep children out of the sun and/or to cover them with protective clothes; however, sunscreens are a safe and effective and often the only feasible defense of children against UV radiation. In conclusion, sunscreens are safe protective devices that undergo stringent safety and efficacy evaluation.