Chemistry World Blog

We’re not using our sunscreen properly, according to researchers in Denmark. Bibi Petersen and colleagues at Bispebjerg Hospital in Copenhagen observed 20 sun seekers on a week’s holiday in Hurghada, Egypt, to monitor how often, and when, they applied their sunscreen. ‘Our results led us to suspect that the protective effect of sunscreen use against DNA damage, and thereby skin cancer, is minimal the way sunscreen is used under real sun holiday conditions,’ said the researchers. It’s all to do with the time the sunscreen is applied and how thickly it’s applied.

The team gave the volunteers a skin examination each morning and weighed their sunscreen bottles each evening. What the team saw was that people wearing sunscreen exposed their skin to the sun for longer than those without. And, even before they applied sunscreen, they had already developed skin redness. The team also found that while the volunteers thought they were protecting themselves with a sunscreen with a sun protection factor (SPF) of 15, the thickness of sunscreen they applied (on average 0.79mg/cm²) actually corresponds to an SPF of 3.

‘The volunteers who intended to stay in the sun for a prolonged period attempted to protect themselves from sunburn by using sunscreen, but the improper use of sunscreen according to time of application and application thickness was ineffective in preventing sunburn and could not compensate for the risk of prolonged UV exposure and high UV exposure doses,’  the team said.

Elinor Hughes