Belinda Carli
Institute of Personal Care Science (IPCS), Australia

Abstract

The sun does more to age our skin daily than just about any other element we may come in contact with on a daily basis. Consumers in countries where sun exposure is high not only tend to show their age more, but the accrued sun damage over time has other impacts, such as skin cancer. Conversely, now that we know the damage the sun has, consumers are protecting themselves, and their children, more conscientiously than ever before. There is also an increasing number of claims made on the internet about skin irritation from the use of UV filters and the biggest surprise of this century – an increase in prescribed cases of rickets from too little sun exposure! So how do you get it right, and what should you be considering when formulating sunscreens for various age groups? This article will take a look at some of the ‘burning’ issues of sunscreen development.

PROVIDING ENOUGH PROTECTION?

There have been some news reports of badly burnt consumers after a day at the beach with their ‘supposed’ SPF50+. Just why are consumers still getting burnt when using an SPF50+ product? The biggest issue is the thickness of the product film applied, which is unfortunately quite different to that which is used during testing to determine the SPF rating. 

To determine the sun protection factor (SPF) of a sunscreen product, visible reddening of the skin is compared when using product compared to skin that is exposed without product. The minimum time to produce the slightest reddening of the skin is called the ‘minimum erythemal dose’ (MED) and is tested over at least 10 subjects with pale, easy-to-burn skin. It’s important to note that 1 MED = the minimum time for visible reddening. So, if you are very pale and burn easily, 1 MED may be as little as 5 minutes in full sun (unprotected); while with an SPF30+ product, this means that you could instead be protected from receiving 1 MED (unit of visible reddening) for 150 minutes – but at that point, you will have 1 unit of perceptible reddening. Anothe ...