katie lee , the university of queensland and monika janda , the university of queensland
many australians are reluctant to use sunscreen , even though it’s an important element in preventing the skin cancers that affect about two in three of us at some time in our lives.
the cancer council says myths about sunscreens contribute to this reluctance.
many australians are concerned using sunscreen might lead to vitamin d deficiency . the idea is that sunscreen would block the uv light the skin needs to make vitamin d, critical for bone health.
however, you need far less uv than you think to make the vitamin d you need: only one-third of the uv that causes a sunburn, and less than you need to tan.
tests on humans going about their daily business generally show
no vitamin d differences
between people who use sunscreen and those who don’t.
if you google “toxic sunscreen”, you get more than eight million results . so people are clearly worried if it’s safe.
however, there’s little evidence of harm compared to the large benefits of sunscreens, which are highly regulated in australia .
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there is evidence large amounts of some sunscreen components can act as hormone disruptors . but the amounts needed far outstrip the amount sunscreen users are actually exposed to.
some people have also been alarmed by the us food and drug administration (fda) announcing further testing of the sunscreen ingredients avobenzone, oxybenzone, octocrylene and ecamsule. this was after a study showed their concentrations could reach over 0.5 nanograms/ml in the blood.
the fda recommends people continue using sunscreen . if you still feel uneasy, you can stick to zinc oxide and titanium dioxide sunscreens, which the fda says are “ generally recognised as safe and effective ”.
that leads us to another common concern: nano-sized zinc oxide or titanium dioxide in sunscreens. nanoparticle forms of these uv filters are designed to make them invisible on the skin while still keeping uv rays out.
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human studies show they either do not penetrate or minimally penetrate the stratum corneum. this is the upper-most layer of the skin, where the cells are already dead and tightly packed together to protect the living cells below. this suggests absorption and movement through the body, hence toxicity, is highly unlikely.
genetics and family history do play a role in many melanomas in australia. for instance, mutations in genes such as cdkn2a substantially increase a person’s melanoma risk .
it’s true that sunburns in childhood seem to have a disproportionate effect on the risk of melanomas and basal cell carcinomas . but squamous cell carcinomas are more affected by sun exposure over the years.
ongoing sunscreen use also reduces the number new actinic keratoses, a pre-cancerous skin lesion, and reduces the number of existing keratoses in australians over 40 years old .
regular sunscreen use also puts the brakes on skin ageing , helping to reduce skin thinness, easy bruising and poor healing that older skin can be prone to. and of course, getting burnt feels terrible at any age.
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this one’s only half a myth. many people say they have an allergic reaction to sunscreen but only about 3% really do.
often, people are just sunburned. they thought they were well-protected but simply stayed out in the sun too long, or didn’t reapply sunscreen often enough.
your sunscreen might also be out of date . sunscreen eventually breaks down and loses its effectiveness, faster if you store it somewhere very hot, like a car.
alternatively, you may have polymorphic light eruption , a condition where uv light alters a skin compound, resulting in a rash. this can be itchy or burning, small pink or red bumps, flat, dry red patches, blisters, or even itchy patches with no visible signs.
if none of those causes fit the bill, you may indeed have an allergy to some component of your sunscreen ( allergic contact dermatitis ), which a dermatologist can confirm.
this article is republished from the conversation under a creative commons license. read the original article .