What you need to know about sunscreens

What to consider when buying and using sunscreens, which are now regulated in NZ

While summer in New Zealand is prone to false starts, it’s quite likely to arrive soon, and experts are warning about UV radiation levels already averaging higher than last year. It is time to stock up on sunscreens, but how much sunscreen do you need and what sun protection factor (SPF) should you choose?

The good news is earlier this year, Parliament passed the Sunscreen (Product Safety Standard) Bill, which means sunscreens are now regulated under the Fair Trading Act. And about time too. Six months later, the Australian skincare company Ego Pharmaceuticals pleaded guilty to two charges of making unsubstantiated claims on two sunscreens that failed to provide the very high protection claimed on the products.

Consumer NZ has done several surveys over the years that found sunscreens failing to meet SPF claims – primarily those not measuring up to SPF 50 claims. But will an SPF 50 sunscreen protect us better than, say, an SPF30 sunscreen?

It’s not so much what you use, but how you use it

Higher SPF sunscreens provide a safety margin, but an SPF 15 sunscreen would protect from sunburn all day if it’s applied thickly and every two hours and after bathing. Unfortunately, surveys have shown the average Kiwi applies a fifth as much sunscreen as the recommended amount.

Higher SPF sunscreens provide better protection against UVA radiation, the longer and more deeply penetrating wavelengths that contribute to ageing and skin cancer. Your skin doesn’t have to go red for the sun to have damaged it. UVA suppresses the immune protective cells in the skin, so those whose skin has already been sun damaged and who apply sunscreen for protection will grow fewer cancers than those with similar damage that cover up.

The sun damages our skin by burning it, causing premature ageing, and leading to an increased risk of melanoma and non-melanoma skin cancers such as basal cell carcinoma (BCC), the most common form of skin cancer in New Zealand, and squamous cell carcinoma (SCC).

Untreated non-melanoma skin cancers grow larger and destroy normal skin and underlying tissues if left unchecked. BCCs rarely metastasise so they won’t kill you, but some SCCs can. Older patients may have many BCCs and SCCs, sometimes hundreds, which can cause pain and require multiple surgeries, which come at a cost to the patient, insurers and Te Whatu Ora Health New Zealand.

Sunscreens can only go so far in protecting us from ageing signs and skin cancers, though. They need to be applied thickly and frequently all year round. Even then, they are a filter, not a complete block. Avoiding the sun (staying indoors) and wearing fully covering clothing are much more effective at protecting us from the harms of the sun.

What should we look for in a sunscreen?

There are lots of choices, and you may have to try a few to work out what suits you. Thick products may be more protective but take longer to apply, sand sticks to them, and they may provoke acne. You’ll likely want a different product for your face than elsewhere, and you may choose one for the beach, another for when you play sports, and a third for everyday use.

Sunscreens do have expiry dates – three years after manufacturer or the date at which they have been tested to meet their advertised SPF if stored in cool conditions. It’s best not to rely on out-of-date sunscreens if you’re going to be in the sun for a long period. And watch out for mould, discolouration or the separation of their ingredients. Chemical ingredients are not photostable and if exposed to light may lose their protective properties

How thickly, and how often, and when?

Follow the instructions on the bottle. A little sunscreen applied once might be fine if you’re mostly indoors and not sweating. If you are at the beach for the day, apply generously every two hours and after bathing. Ideally, apply before you leave home and reapply 15 minutes later to fill the crevices and spots you missed the first time.

But we need some sun, don’t we, for vitamin D?

Most people need exposure to ultraviolet radiation between October and April to make vitamin D in the skin, as we don’t usually get enough in our diet. Vitamin D production doesn’t require much UV though, so those often outdoors in shorts and a shirt for 15 or 30 minutes a day don’t need to worry. If you’re mostly indoors, especially if you already have sun damage or wear covering clothing, I’d recommend Vitamin D supplements.

Naturally dark skin (skin of colour) is protective against the effects of the sun and we rarely diagnose skin cancers in Indian, African and dark-skinned Māori or Pasifika people. White skin is protected much less well, and even those who tan are at risk of skin cancers if they spend much time outdoors. If you don’t like having a pasty white look? Apply artificial tanning cream but remember, this won’t protect you at all from sun damage.