Every Sunscreen Question You've Ever Had, Answered
Facts are facts, Australia—we have one of the highest rates of melanoma in the world. The third most common cancer diagnosed in Australian women, it kills more young people in our country than any other single cancer. Worryingly, though survival has improved, rates of diagnosis are rising.
As members of a generation who grew up hearing ‘80s sun safety icon Sid the Seagull preach a message that captured the changing zeitgeist of the time—Slip, Slop, Slap—we’re committed to ending this deadly disease. Our goal is to encourage you to take the steps necessary to help prevent the 95% of melanomas caused by the sun. We’re talking: Daily application and reapplication of broad-spectrum sunscreen, wearing hats, sunglasses and cover-ups, finding shade during peak sun intensity hours, having regular specialist skin checks, and knowing how to stay alert to changes in your body.
It’s estimated that one person dies every five hours from melanoma in Australia, and that’s not okay. The moment to #CallTimeOnMelanoma has arrived, and we’re blowing the end of game whistle.
Wearing sunscreen every single day is one of the most important things you can do to prevent both sun-related cancers and some signs of ageing (like hyperpigmentation). But studies suggest most of us aren't wearing a broad-spectrum sunscreen daily, and according to Cancer Council research that's at least partly because we're "increasingly misinformed". Here at Byrdie Australia, we feel that this is a massive problem. It's not hard to see how inadequate sun protection can and does play a significant part in Australian melanoma and skin cancer rates being amongst the highest in the world.
As part of our #CallTimeOnMelanoma campaign, we are doing our part to address some of the most frequently asked sunscreen questions in the hope we can add clarity. Questions like: How much product do you need to apply for adequate sun protection? Is a higher SPF always better? And what is the difference between chemical and mineral sunscreens? We believe that by providing fact-based information about sunscreen and sun protection we can help spread the message that wearing a broad-spectrum sunscreen every day is an important health precaution we should all be taking.
To cut through the noise, we enlisted the expertise of Michelle from Lab Muffin Beauty Science. If you're not already a fan of hers on Instagram, you soon will be. Michelle is a science educator with a PhD in chemistry and a passion for cosmetics and skincare. She specialises in setting facts straight and dispelling sometimes damaging beauty myths. Below Michelle answers everything we've ever wanted to know about sunscreen and then some. (But if you still have questions, feel free to hit us up on social media.)
Keep scrolling for the full Q&A.
What is the difference between physical/mineral, and chemical sunscreen?
First up, let's clarify the language. So-called "chemical" sunscreens are organic (carbon-based) substances, while physical/mineral sunscreens are inorganic (non-carbon-based). "Chemical" is a bit of a confusing name since physical/mineral sunscreens are definitely chemicals as well! The only inorganic sunscreens currently used are zinc oxide and titanium dioxide.
In terms of function, they work in a very similar way. It's a common myth that physical/mineral sunscreens mostly reflect and scatter UV. Both "chemical" and physical/mineral sunscreen ingredients mostly absorb UV and convert it into heat, although some sunscreen ingredients will also reflect and scatter a small amount of UV (zinc oxide and titanium dioxide reflect and scatter about 5% of incoming UV, while the organic sunscreen Tinosorb M, also know as methylene bis-benzotriazolyl tetramethylbutylphenol, does the same thing).
What are your thoughts on the efficacy of natural formulas versus the chemicals in chemical sunscreen?
There actually isn't any such thing as a natural sunscreen. While the physical/mineral sunscreen ingredients zinc oxide and titanium dioxide are thought of as natural, they're actually synthetic. Zinc oxide is found naturally, but the natural forms aren't suitable for use in cosmetics. Titanium dioxide is made either by treating a mineral called ilmenite with concentrated sulfuric acid then heating it to almost 1000 degrees Celcius, or by turning naturally occurring titanium dioxide into titanium, then reacting it to synthesise pure titanium dioxide again.
In terms of efficacy, the main issue with physical/mineral sunscreens is that you need quite a lot of them in a sunscreen to provide protection, but they're also white! So in general, physical/mineral sunscreens can't be formulated into sunscreens with the highest UVB and UVA protection. Some organic sunscreens will decompose after absorbing too much UV light, but newer organic sunscreens don't have this issue.
In terms of safety, there's been a lot of fuss made about the potential hormonal effects of organic sunscreens by organisations like the Environmental Working Group, based on misinterpretations of scientific studies that were mostly performed on animals that ate large doses of sunscreen ingredients. Humans aren't animals, and putting something on your skin isn't the same as eating it. Based on our current knowledge, dermatologists have estimated that the most hormonally active sunscreen, oxybenzone, would only have noticeable effects if you applied it all over your body every day for over 200 years.
The other safety issue is if you have an allergy to a particular sunscreen ingredient. In general, organic sunscreens do cause more allergic reactions than physical/mineral ones, so if you fall into this category then a physical/mineral sunscreen might be a safer option. But newer organic sunscreen particles are designed so they're larger and don't absorb into the skin much, meaning they are far less likely to cause allergic reactions than older ingredients (plus they're really unlikely to have any hormonal effects at all).
Which type do you personally prefer to use, and why?
I personally use organic (chemical) sunscreens, especially the newer ones like Tinosorb S. My skin is dark enough that when I use an adequate amount of a physical/mineral sunscreen, I usually look ghostly white! I'm also really hyperpigmentation-prone, so I need high UVA protection to prevent sunspots, which means organic sunscreens are a safer bet.
What sunscreen brands do you trust?
I think most sunscreen brands are good! I personally prefer sunscreens that have high SPF ratings and broad spectrum protection. I don't really trust brands that make scaremongering claims, or call their sunscreens "all-natural" because it makes me feel like they don't actually understand their own product. My favourite brands at the moment are SunSense, Ultraceuticals and La Roche-Posay. I also like Asian brands for their newer filters and lighter textures, but a lot of the time they don't seem to be well-suited to a warmer climate so I only use them on days I'm not going to sweat.
What does SPF actually mean? And is SPF 50+ always better than SPF 30+?
It is! It's a common misconception that SPF 30 blocks 96.7% of UV so a higher SPF can only give marginal benefits. It makes more sense to look at how much UV gets to your skin—where SPF 30 lets 3.3% UV into your skin, SPF 50 would let in 2%, so SPF 50 is actually 1.65 times more effective. SPF 30 also only blocks 96.7% of UV if you apply the full amount, which is 2 milligrams per square centimetre of skin, but most people apply less than half of this, which means you only get about half the protection. A study found that an SPF 100+ sunscreen prevented burning more effectively than SPF 50+ sunscreen in practice, so higher SPF product will always be better, provided you would apply the same amount of both.
How often should you reapply if you’re outdoors, or at the beach?
Sunscreen should be reapplied every two hours.
How much do you need to cover your entire body adequately?
1/2 teaspoon (3 mL) of sunscreen on each arm, face and neck including the ears, and 1 teaspoon (6 mL) of sunscreen for each leg, and the front and back of your body.
At what point in your skincare routine should you apply sunscreen on your face?
At the end of your skincare routine, before makeup. There's no difference between organic and physical/mineral sunscreens in this regard.
Does makeup with an SPF factor provide enough protection for an average work day spent mostly in the office?
It really depends on your routine and the climate. The main problem with SPF-rated makeup is that you're very unlikely to use enough to get anywhere near the labelled protection or to form a continuous layer, which means both lowered and patchy protection. I would also say that most SPF-rated makeup products (especially powders) are giving you almost no sun protection, aside from foundation. It's better than nothing, but a dedicated sunscreen is much more effective!
How often do you get your skin checked personally?
I personally get it checked only once every two years even though I should do it more often! In my defence, I hardly ever go into the sun, have very few moles and no family history of skin cancer. But do as I say and not as I do! A yearly checkup is recommended.