Sunscreens: The Good, the Bad, and the Questionable

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Even though the arrival of summer has been a bit slow here in the south it is definitely important to be thinking about sun protection.  We are all aware of New Zealand’s astronomical skin cancer rates and want to avoid this. 

While burning is bad, some regular sun exposure on the skin is still very important.  Vitamin D is produced in this way, and most of us in NZ are low in this vital nutrient.  Also, research shows that it is high dose, irregular sun exposure that increases our risk of melanoma, the most dangerous kind of skin cancer.  Studies in people who are regularly exposed to sun in low doses, such as people who work outdoors, show a correlation with lower risk of melanoma.

So while the evidence around sunscreen and the risk of skin cancer is mixed, it is still important to reduce the risk of sunburn, which we know is dangerous.

In the past ten years or so, much attention has been given to the ingredients in sunscreens.  People want to know that they are not only protecting us from the sun, but that they are non-toxic to our bodies.

The good:
Zinc oxide

The best type of broad spectrum sunscreen you can use is zinc oxide.  Zinc is a mineral sunscreen which sits on top of the skin rather than being absorbed.  It is more of a sun “block” as it is widely believed that it reflects and scatters the sun’s rays rather than chemically “screening” the sun out.  This is why zinc oxide sunscreens often leave a whiteish hue on your skin.
While most sunscreens protect well against UVB rays, the ones that cause sunburn, not as many protect well against UVA rays, which can still damage skin and lead to skin cancer but without the tell-tale burn. While zinc may not have the highest SPF, it does provide a good balance between UVA and UVB protection.

Zinc oxide is also a highly stable molecule.  In the last few years, reports have come out that the chemicals in sunscreens may themselves be carcinogenic.   This is because some of the chemicals in sunscreen can break down when exposed to UV light, causing free radical damage.  Zinc’s stability means that it does not break down, and is safer than many other chemical sunscreens.

While studies show that the actual zinc is not absorbed into the living layers of skin tissue and into the body, zinc is an essential mineral for humans.  This is in direct contrast with any of the chemical sunscreens, none of which belong in our bodies. 

The bad:
Oxybenzone

This chemical rates highest for being a health concern.  It is a known endocrine-disruptor and allergen.  It has been found in the urine, blood, and breast milk of large samples of the population, meaning that it sticks around in the body, where it can potentially wreak havoc.  I recommend that you avoid it.

Avobenzone
While one of the best broad spectrum chemicals for both UVA and UVB protection (next to zinc), avobenzone is one of those chemicals which can break down in the presence of UV light, creating damaging free radicals.  Zinc works at least as well, and is much safer.

The questionable:
Nano particles

One of the ways in which manufacturers of zinc oxide sunscreens have tried to make them more appealing to the general public is through the use of nanoparticles.  This makes the appearance of the zinc sunscreen less white and chalky.  Nanoparticles are simply very small particles- so instead of using a normal, relatively large molecule of zinc oxide, they are using tiny zinc oxide molecules. 

Concerns have arisen about the safety of nanoparticles- are they absorbed into the body because they are so small?  Can they cause damage?

Essentially, the jury is still out.  The Environmental Working Group, a US-based organisation that keeps a close eye on such matters, states that at this stage, the research indicates that nanoparticles in sunscreen don’t penetrate the skin, and that the smaller particles actually work better as a sunscreen.  They also state that given the broad definition of the term nanoparticle, companies which state they are using “non-nano” zinc or titanium dioxide may not be telling the truth.

If ingested or inhaled, these nanoparticles could be damaging to the body. For that purpose, I would recommend attempting to avoid nanoparticles, and especially avoiding spray or aerosol sunscreens containing them.  (In general I think these kinds of sunscreens increase the risk of taking in chemicals which were never meant to be eaten!).
 
At the end of the day, sunscreen should be your last resort- not your main source of protection.  Get some measured, unprotected sun exposure every day if possible, and then be sun smart the rest of the time.  Wear clothes, spend some time in the shade, keep your eyes protected, and regularly apply sunscreen when needed.
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Enjoy your summer safely!