Higher protection sunscreens do not encourage people to spend more time in the sun

Aug 16 2005

Sunbathers wearing sunscreen labeled as "high protection" did not spend more time in the sun during a week-long vacation compared to those wearing "basic protection" sunscreen, according to an article in the August issue of Archives of Dermatology.

"Sun exposure is the most important environmental factor involved in the development of skin cancer," according to background information in the article. Melanoma has had one of the greatest increases in incidence among solid tumors in the past three decades and accounts for the vast majority of skin cancer deaths. Although daily sunscreen use has been shown to prevent squamous cell skin carcinoma, several studies suggest that sunscreen use may be a risk factor instead of a protective one for melanoma. Some believe that higher protection by stronger sunscreens may encourage more time in the sun by delaying warning signs such as sunburn, giving one a false sense of safety.

Alain Dupuy, M.D., M.P.H., from the Hospital Saint Louis, Paris, and colleagues, conducted a week-long, randomized, controlled trial during the summer of 2001 to determine the effect of sunscreen protection on sun-exposure behavior. Three hundred sixty-seven vacationers from four French seaside resorts were given one of three sunscreens: SPF 40 labeled as "high protection," SPF 40 labeled as "basic protection," and SPF 12 labeled as "basic protection." No mention of actual SPF was made on the labels. Participants were given an initial questionnaire about general sun-exposure behavior and completed self-administered questionnaires each evening, detailing their sun exposure and protection for every half-hour period during the day. Eighty percent of the participants were women, with an average age of 39 years.

The researchers found that neither SPF nor labeling was associated with significantly different durations of sunbathing during the week. Average weekly sun-exposure time was 14.2 hours in the high/SPF 40 group, 12.9 hours in the basic/40 group, and 14.6 hours in the basic/12 group. Ninety-six percent (343) of the vacationers said they'd used the sunscreen at least once, with 77 percent (276) saying they used it exclusively. The proportion of those who experienced sunburn during the week was higher in the low-SPF group (24 percent) than the high-SPF group with the same label (14 percent). In total, 63 participants experienced sunburn, with six of them having severe sunburn.

"In this population, our findings do not support the hypothesis that a higher SPF induces a higher exposure by delaying the alarm signs nor the hypothesis that mentioning 'high protection' on the label may induce longer exposure by giving an impression of safety," the authors write. "In addition, this study logically confirms that the use of higher-SPF sunscreens does reduce the number of sunburns in real life. Finally, our results suggest that people tend to self-regulate their sun protection with sunscreens, by inversely adapting the amount of sunscreen to the SPF, at least when sunscreens are freely delivered."