MILAN, ITALY. There is growing evidence that the use of sunscreens tends to increase the time spent in the sun, thereby possibly increasing the risk of cutaneous melanoma. A team of researchers from the European Organization for Research and Treatment of Cancer now reports that people who use sunscreens with higher sun protection factors (SPFs) tend to spend more time in the sun than do people who use sunscreens with lower SPFs. The study that was conducted in June 1998 involved 58 participants aged 18 to 24 years who were on their summer vacation. Forty-four of the participants were instructed in the use of personal dosimeters that accurately measured their exposure to UVA and UVB solar radiation. All participants were instructed to keep a daily log of their sun exposure and were randomized to one of two groups. The first group was given a 30 SPF sunscreen to use during their vacation while the second group was given a 10 SPF sunscreen.
The researchers found that the group using the 30 SPF sunscreen spent 25 per cent more time in the sun than did the group using the 10 SPF sunscreen. This increase was paralleled by an increase in daily UVB exposure. Those using the 30 SPF sunscreen that did not experience sunburn spent the highest number of hours sunbathing out of all the participants. Experiencing sunburn markedly decreased time spent in the sun in both the 10 SPF and the 30 SPF groups. The researchers conclude that the use of a 30 SPF sunscreen tends to maximize UVB exposure and that the absence of sunburn encourages longer sunbathing sessions. In other words, high SPF sunscreens provide a false sense of security.
Autier, P., et al. Sunscreen use and intentional exposure to ultraviolet A and B radiation: a double blind randomized trial using personal dosimeters. British Journal of Cancer, Vol. 83, No. 9, November 2000, pp. 1243-48