Experimental feature

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Experimental feature

Maths has never been my strong suit but lately I’ve found myself tied up in knots by the numbers game played by the sunscreen industry. You see, now I have a new logic problem, akin to those sorts of maths questions I could never answer at school: if Miriam wears SPF100 on Miami Beach, how many minutes will it take her to burn when she uses the same sunscreen in Mykonos? Answer: how can we possibly know?

Sunscreen used to work along similar lines to mortgages: multiply your salary (or in this case, the number of minutes it would normally take for you to burn without protection) by three (or the number on the bottle) and that was pretty much the length of time you could sunbathe, or thereabouts. With the emphasis on the “thereabouts” – because that formula never really stacked up, especially if you dived into the sea, used an out-of-date bottle or found yourself in Europe, where the sunscreen you bought in the US with an SPF100 is rebranded to 50 thanks to EU regulations.

Either way Miriam, whether in Miami or Mykonos, still needs to be careful – the efficaciousness of sunscreen beyond an SPF30 isn’t predictably incremental: her SPF50 doesn’t mean she can stay in the sun twice as long as an SPF25. But at least her intentions are good – below SPF25 and you’re all but in Baby Oil territory.

Add to this increasing scientific concern about our not getting enough vitamin D, chiefly available from sunlight, and thus risking rickets or worse. Some dermatologists maintain that using sunscreen halves our body’s ability to synthesise vitamin D. Others say we should just take the supplements and keep slapping it on, pointing out that sunscreen only halves vitamin D production if we apply it properly – which, typically, most of us don’t – in tests it’s slathered on until it’s thick and opaque. How much should you apply? If you aim to apply enough cream to fill a tequila shot glass every two hours or so (particularly after being in the sea or pool), then you’re doing well.

The problem is that with the best will in the world, it’s hard for sunscreen manufacturers to keep up with the science surrounding the sun and skin cancer, which is evolving rapidly, and subsequent regulations introduced to protect us. Over the past decade there have, for instance, been studies linking the common sunscreen ingredient oxybenzone with adverse effects from photoallergenic reactions to low birth weights.

Nonetheless, there have also been some interesting and positive developments.

I’m intrigued by new protection that works by prepping the skin before you’re exposed to the elements. For example, Imedeen’s Tan Optimizer (from £40.80) is a nutritional supplement that contains lutein, lycopene and beta-carotene. Imedeen claims that, if you use its product for a few weeks before going away, it will help protect you from prickly heat, or sunburn, and that testers reported finding themselves applying less sunscreen after a week or so in the sun than they might usually. You will still need to wear sunscreen, though, and I certainly wouldn’t advise skimping on it.

I also love the new sunscreen (£47) from Susanne Kaufmann, a plant-based, family-owned brand from Austria. Kaufmann worked on the formula for her SPF25 sunscreen with a chemist for three years. You might think an all-natural formulation would be simple – why add chemicals? – but the usual organic filters of zinc oxide and titanium dioxide can leave a white residue on the skin unless they’re reduced to nanoparticle size, and there is evidence that molecules this small can be absorbed by skin cells where they can react with the light, causing more harm than good. Kaufmann’s sunscreen – and another new favourite, La Roche-Posay’s Antihelios XL 50+ (£16.50), which is just the right size to pop into a handbag or purse – are both nanotechnology (and oxybenzone) free.

For all the confusion, there is one message that’s clear: while sunscreen is still important, its role in protecting us might not be as big as previously thought. The EU has recommended that terms such as “sunblock” are avoided as they imply we’re 100 per cent protected from the sun, when we’re not, and, instead, argues that a sunscreen is only as important as other sun-protection measures, such as hats, staying in the shade and sunglasses. Which sounds like a great excuse for a new purchase – have you seen Chloé’s new large, round wire-rimmed sunglasses? Not so much a fashion extravagance as an essential, I’d say.

Photograph by Getty