Background: The efficacy of sunscreens is assessed on the basis that 15-20 g/m(2) (1.5-2 mg/cm(2)) is applied. However, expecting people to apply such large amounts is perhaps unrealistic.
Aim: To evaluate the application of sunscreen usage by young people.
Materials and methods: Forty-nine subjects (24 females and 25 males) in the age range 18-32 years (mean 23.1 years) were included in the study. They were asked to apply sun protection factor (SPF) to the whole of their own skin surface in just the same way that they would customarily do it during/prior to sun exposure. Two agents were applied: emulsion with SPF30 and a fatty cream with SPF > 60. The amount of preparation used/m(2) was calculated. Statistical analysis was performed using the Student's t-test.
Results: The average amount of both preparations used was about half that expected to achieve correct sun protection (p < 0.00001). The mean applied amount of the fatty cream was 9.6 +/- 5.3 g/m(2) (50.7% of the ideal value) and the emulsion 9.2 +/- 5.5 g/m(2) (48.6% of the ideal value). Neither gender (male/female) nor type of agent (emulsion/fatty cream) affected the amount used.
Conclusions: Young people customarily apply less than 10 g of SPF/m(2). It is therefore unrealistic and possibly even misleading of manufacturers to assess SPF ratings as if people applied 15-20 g of SPF/m(2). Perhaps it is for manufacture's to increase the efficacy of their products rather than for consumers to be asked to apply twice as much?