High Spf Sunscreen Not Linked with Longer Exposure

NEW YORK (Reuters Health) - Adults who use sunscreens with a high sun protection factor (SPF) do not necessarily spend more time in the sun than those who use sunscreens with a lower SPF, new study findings suggest.

Sun exposure is the single most important environmental factor that can increase a person's risk of skin cancer. While daily sunscreen use has been shown to protect against skin cancer, some research also suggests that it may put sunbathers at risk of the condition.

Such research shows that sunbathers who use sunscreens with a higher value SPF may get a false sense of security from the increased protection against harmful UV rays and consequently spend even more time in the sun.

Yet, the current study did not find this to be true.

"In this population, our findings do not support the hypothesis that a higher SPF induces a higher exposure by delaying the alarm signs or the hypothesis that mentioning 'high protection' on the label may induce longer exposure by giving an impression of safety," write Dr. Alain Dupuy, of the Hôpital Saint-Louis in Paris and colleagues.

"In addition," they write, "this study logically confirms that the use of higher-SPF sunscreens does reduce the number of sunburns in real life."

Dupuy and colleagues investigated sun-exposure behavior among 367 healthy adults, mostly women, 39 years old on average, at four French seaside resorts during the summer of 2001.

The adults were offered free sunscreens and randomly divided into groups based on whether they were given SPF 40 sunscreens, labeled as "high protection," SPF 40 sunscreens labeled as "basic protection" or SPF 12 sunscreens labeled as "basic protection." The subjects were not told the actual SPF value of the sunscreen they received.

Neither the sunscreen label nor the SPF value, however, appeared to influence the amount of time the study participants spent in the sun, Dupuy and colleagues report in this month's issue of the Archives of Dermatology.

Adults given "high protection" SPF 40 sunscreens spent an average 14.2 hours a week sunbathing, those given "basic protection" SPF 40 sunscreens spent 12.9 hours sunbathing and those given "basic protection" SPF 12 spent 14.6 weekly hours sunbathing. Sixty-three adults experienced sunburn, including six who had severe sunburns that caused pain for more than two days or blistering.

The "high protection" or "low protection" labels did not seem to have an effect on the study participants' sunscreen use or whether they experienced any sunburns, however, the report indicates.

Overall, adults who used the higher value SPF 40 sunscreens did get fewer sunburns and used less sunscreen than those who used the SPF 12 sunscreen, the investigators report.

"While further data are awaited," the researchers conclude, "public health recommendations should stress wearing clothing and hats and limiting midday exposures, but should not be reluctant to promote high-SPF rather than low-SPF sunscreens."

However, Dupuy and colleagues' findings may not be able to be generalized to the population at large, according to an editorial published in the same issue of the journal. Dr. Mark Naylor, of the Oklahoma Medical Research Foundation, and Dr. June K. Robinson caution that the study group largely consisted of middle-aged white women, who may be "less inclined to high-risk sun exposure than younger women or younger men" who may be more interested in tanning.

They recommend sun-protection strategies that should be adopted by individuals, including setting a date to stop deliberate tanning and making a pact with others to use sun protection and remind each other to use it.

"It is time that physicians, public health officials, and the public commit to a long-term national strategy that will begin to change public opinion and reverse the current trend of increasing cancer prevalence," Naylor and Robinson write.

Grants from Société Française de Dermatologie and Pierre Fabre Dermo-Cosmétique, which provided the sunscreens, supported Dupuy's study.

SOURCE: Archives of Dermatology, August 2005.