Pump found to be best sunscreen dispenser but application still proving to be inefficient
Some sunscreen dispensers facilitate thicker application than others, and this was the driver behind a study published in the Archives of Dermatology.
Researchers composed a crossover quasi experimental study (an empirical study used to estimate the causal impact of an intervention on its target population) in order to compare three sunscreen dispenser types: 500ml pump; 125ml squeeze bottle; and 50ml roll-on.
The research team also measured the thickness at which primary school children apply sunscreen and compared it with the thickness at which sunscreen is tested during product development, as well as to investigate how application thickness was influenced by age of the child.
Efficacy dependent on application
The use of topical sunscreens is considered to be an important intervention to reduce skin damage induced by ultraviolet radiation from sunlight.
The sun protection factor (SPF) of a sunscreen is based on a uniform application thickness of 2 mg/cm2. However, there is no known linear relationship between an effective SPF and the amount of sunscreen applied, meaning the efficacy is therefore highly dependent upon its correct application.
The amount of sunscreen that most people apply usually never exceeds more than 60 percent of the quantity needed to achieve the SPF on the label product.
The scientists collected data from 87 children selected randomly from enrolment lists of seven different primary schools in Queensland, Australia, gathering three observations from each child.
And the winner is…
The children then applied sunscreen during 3 consecutive school weeks (Monday through Friday) using a different dispenser each week.
The dispensers were weighed before and after use to calculate the weight of sunscreen applied. This was divided by the coverage area of application (in square centimeters), which was calculated by multiplying the children's body surface area by the percentage of the body covered with sunscreen.
The study found that children applied their sunscreen at a median thickness of 0.48 mg/cm2. Children applied significantly more sunscreen when using the pump (0.75 mg/cm2) and the squeeze bottle (0.57 mg/cm2) compared with the roll-on (0.22 mg/cm2).