Sunscreen Chemicals Explained

Written By Bernitta Robinson

As the weather improves, many of us spend more time outdoors. Whether you're walking the dog, watching children's sports, gardening or heading off on holiday, sunscreen becomes part of the daily routine.

Over the past few years there's also been growing interest in what actually goes into sunscreen. More people are reading ingredient lists and trying to understand what they're putting on their skin, particularly when reports suggest that some sunscreen ingredients can be absorbed into the bloodstream.

Like many areas of health, the headlines don't always tell the full story.

Both mineral and chemical sunscreens are effective at protecting the skin from harmful ultraviolet (UV) radiation, but they work in very different ways. Understanding those differences makes choosing the right product much easier.

How sunscreen protects your skin

Ultraviolet radiation damages our skin in two main ways.

UVB rays are responsible for sunburn and direct damage to skin cells.

UVA rays penetrate much deeper into the skin, contributing to wrinkles, pigmentation, loss of elasticity and increasing the risk of skin cancer.

A good sunscreen should protect against both, which is why looking for Broad Spectrum protection is far more important than focusing on marketing claims on the front of the bottle.

Mineral sunscreen

Mineral sunscreens contain zinc oxide, titanium dioxide, or a combination of both.

These ingredients remain on the surface of the skin, forming a protective barrier that reflects and scatters much of the UV radiation before it reaches the deeper layers of the skin.

Because they stay on the skin's surface, they have the lowest level of absorption into the body. Current research shows that even nano-sized zinc oxide and titanium dioxide particles do not penetrate beyond the outer layer of healthy skin.

Historically, mineral sunscreens developed a reputation for leaving a white film over the skin. Modern formulations have improved considerably, with tinted versions and finer particles making them much easier to wear every day.

Chemical sunscreen

Chemical sunscreens work in a completely different way.

Ingredients including avobenzone, octocrylene, octisalate, homosalate and oxybenzone absorb ultraviolet radiation before converting that energy into heat, which is then released from the skin.

Because these ingredients interact with the skin in this way, some are absorbed into the bloodstream.

FDA research demonstrated that several common sunscreen ingredients could be detected in the blood after regular application, with some remaining measurable for more than two weeks after sunscreen use had stopped.

Absorption alone does not mean these ingredients are harmful, but it has prompted further research into their long-term safety.

Current research

Oxybenzone has received the greatest attention. Laboratory research has suggested it may have hormone-disrupting effects, while studies have shown it can be detected in blood, urine and breast milk following repeated use.

Homosalate has also come under increasing scrutiny, with European regulators limiting its concentration because of concerns about potential endocrine-disrupting effects.

At present, however, there is no convincing evidence that using approved chemical sunscreens causes disease in humans.

The established health risks of excessive UV exposure remain far greater than the theoretical risks currently being investigated.

Choosing the right sunscreen

For patients who prefer to minimise ingredient absorption, a mineral sunscreen provides an excellent alternative without compromising protection.

When choosing one, check the active ingredients rather than relying on the wording on the front of the bottle.

Look for:

  • Zinc oxide and/or titanium dioxide as the only active ingredients.

  • Broad Spectrum protection.

  • SPF 30 for everyday use or SPF 50 if spending prolonged periods outdoors.

  • Creams or lotions rather than sprays.

Some products described as "mineral" still contain chemical UV filters, so it's always worth reading the ingredient list.

Sun protection goes beyond sunscreen

No sunscreen provides complete protection on its own.

The strongest UV radiation occurs between 10 am and 4 pm, making this the time when seeking shade, wearing sunglasses, a wide-brimmed hat and covering exposed skin becomes particularly important.

Sunscreen should always form part of a wider approach to protecting your skin rather than being the only line of defence.

My advice

When patients ask which sunscreen I recommend, my advice is always based on the evidence.

If you're happy using a chemical sunscreen, continue to do so. The protection it provides against sun damage and skin cancer is well established.

If you would rather avoid ingredients that are absorbed into the bloodstream while research continues, mineral sunscreens containing zinc oxide or titanium dioxide offer excellent protection with minimal absorption.

Whichever product you choose, applying enough, reapplying regularly and protecting yourself during the middle of the day will make far more difference than the name on the bottle.

Sources

Bernitta Robinson
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