Aug. 15, 2005 - Sun worshipers who routinely use a high-protection sunscreen are not necessarily more likely to spend longer periods of time in the sun than those favoring sunscreens that offer only basic protection.
That's the conclusion of researchers who conducted a weeklong study tracking the sun exposure of vacationing sunbathers who used sunscreen with higher and lower levels of sun protection factor (SPF).
Their findings appeared in the August issue of Archives of Dermatology.
Nearly Half of All Cancers in the U.S.
Sun exposure has been shown to be the single most important environmental factor in the development of skin cancer. Behaviors that increase sun exposure may be a risk factor.
Cancer of the skin is the most common of all cancers. It accounts for almost half of all cancers in the U.S. Most of the 1 million cases of nonmelanoma skin cancer diagnosed every year are sun related, according to the American Cancer Society (ACS).
One of the best ways to lower the risk of developing nonmelanoma skin cancer is to avoid prolonged exposure to direct sunlight. Daily sunscreen use has been shown to decrease the risk of nonmelanoma skin cancer.
According to the ACS, while the cause of melanoma skin cancer is not known, there are several risk factors, including too much exposure to UV radiation. The main source of UV radiation is sunlight. Tanning lamps and booths are also sources.
Findings Contradict Previous Studies
"Some studies have suggested that sunscreen use might be a risk factor for melanoma," write the researchers. And it's been suggested that higher protection by more potent sunscreen may induce longer sun exposure by postponing warning signs such as sunburns or by providing a false impression of safety in the sun, they add.
In this study, 367 vacationers from four French seaside resorts were given one of three sunscreens:
- SPF 40, labeled "high protection"
- SPF 40, labeled "basic protection"
- SPF 12, labeled "basic protection"
Participants were asked to complete questionnaires detailing their sun exposure and protection at half-hour intervals throughout the day.
Eighty percent of the participants were women. The average age was 39.
Neither SPF nor labeling was associated with differences in durations of sunbathing during the week, the researchers write. Average weekly sun exposure time was 14.2 hours in the high SPF- 40 group, 12.9 hours in the basic SPF-40 group, and 14.6 hours in the SPF 12 group.
The percentage of those experiencing sunburn during the week was higher (24%) in the low-SPF group than the high-SPF group with the same "basic protection" label (14%).
"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," says researcher Alain Dupuy, of the Hopital Saint Louis, Paris, in a news release.