There’s been a lot of alarm recently over a few ingredients in some types of sunscreen. From the chatter on the internet, you might get the impression wearing sunscreen is a bad idea. Not at all. Its just important to choose the right sunscreen.

The worry is that three particular chemicals in certain sunscreens might actually contribute to skin cancer. But the evidence for them is inconclusive at the moment. The evidence for UV causing skin cancer is conclusive, so it shouldn’t stop you protecting yourself.

So which sunscreens are thought to be dangerous? There are two main types, classified according to the way they work.

‘Physical’ sunscreens, or sunblocks, sit on the surface of the skin and create an actual barrier against the sun. They contain titanium dioxide and zinc oxide which are harmless and non-allergenic.

‘Chemical’ sunscreens are absorbed into the skin and react with or scatter the sun’s rays. These contain a range of chemicals, including oxybenzone and avobenzone, two chemicals which have been under scrutiny recently by a group called the Environmental Working Group (EWG).

Their main concern about oxybenzone is that it is similar to the hormone oestrogen and so might disrupt the endocrine system. But the levels used are argued to be too low to have a significant effect.

The EWG also claim that avobenzone, which is unstable in UV light, could cause damage that might lead to skin cancer. Most products, however, use a stabilised form of the chemical and avoid this problem. Avobenzone protects against the full range of both UVA and UVB, which as we mentioned in our last post, is very important.

Why don’t people just use the physical ones? The sunscreens containing zinc oxide and titanium dioxide are very effective but they leave a white residue which many people don’t like. They also need to be reapplied more frequently as they tend to rub off. If you don’t mind looking white, these are the best bet.

The EWG also raised concerns over zinc and titanium nano-particles in some sunscreens. Nano-particles are small particles of the chemical, and make a smooth, clear sunscreen rather than a sticky white one. The nanoparticles are absorbed into the skin and act as chemical sunscreens, absorbing the UV rays. The worry is that they may heat up when they absorb the rays, causing damage or the release of free radicals.

Many dermatologists, however, criticise the claims of the EWG as lacking in scientific rigour. One study in particular sought to counter the fear-mongering. Current sunscreen controversies: a critical review looked at the claims and found no evidence for adverse effects from the use of sunscreen.

Whats the best thing to do? Stay out of the sun in the first place. Wear a hat and long sleeves. While the evidence against chemical sunscreen isn’t conclusive, the zinc oxide and titanium dioxide sunblocks (non nano-particles) are known to be safe and protect against both UVA and UVB rays.

And, as ever, check your moles, even in places that are not normally exposed to sunlight. Map any new ones using a digital camera, ask your doctor, or use our service. Even a small change can be the start of a melanoma so it’s important to be on the lookout.