How to pick the right sunscreen

If you’re like most people, the thing you pay attention to when buying a sunscreen is Sunscreen Sun Protection Factor-SPF

In theory, sunscreen with super high SPF should give you the best protection against damaging UV radiation, right? SPF of 100 sounds like you will get twice as much protection from SPF 50? A no-brainer! 

Wrong!

In reality, higher-SPF products are only marginally better at shielding you from UVB and have nothing to do with UVA-ironically.

SPF is actually the measurement of how well a sunscreen protects skin from UVB rays and it is not meant to help you determine duration of exposure. Say it took 300 seconds for skin to burn with sunscreen, and 10 seconds to burn without it. 300 is divided by 10, which is 30. The SPF is 30.

Each minute wearing SPF 30 sunscreen lotion, you get a 1/30th, or 3.33%, of UV exposure that you would get without the lotion. Subtracting that 3.33 percentage points from 100, you're protected from 97% of UVB rays with SPF 30 sunscreen.

Buying SPF 80 improves on SPF 30, but not by much. The stronger product blocks another 1.75 percentage points of UVB radiation. Upgrading again to SPF 100 blocks 99 percent of UVB rays, but compared to SPF 80, it's really only a quarter of a percentage point better.

As you can see SPF scale is not linear: So, one way of looking at this is that SPF 30 sunscreen only gives you 4% more protection than SPF 15 sunscreen.
 

  • SPF 15 (93% protection) allows 7 out of 100 photons through
  • SPF 30 blocks 96.7% of UVB rays allows 3 out of 100 photons through
  • SPF 50 blocks 98% of UVB rays allows 2 out of 100 photons through
  • SPF 100 blocks 99%
     

So, while you may not be doubling your level of protection, an SPF 30 will block half the radiation that an SPF 15 would let through to your skin.

But the concern with sun exposure is deeper than burn. You want a protection for both UVB and UVA, especially UVA actually! Think of UVA as the bad guy that ranks A in creating damage that goes down deeper and breaks down collagen, elastin and hyaluronic acid.

For best protection, experts recommend

  • Using a minimum SPF sunscreen of 15
  • Applying the proper amount (2mg/cm2of skin) and
  • Reapplying every 2 hours.

Most people under-apply sunscreens and use ¼ to ½ the amount required. Using half the required amount of sunscreen only provides the square root of the SPF. So, a half application of an SPF 30 sunscreen only provides an effective SPF of 5ish. I know it’s a bit confusing.

That’s why the regulatory bodies say Sunscreens with a very high SPF of 75 or more offer little extra protection but often lead people into having a false sense of protection.

That’s the front of your sunscreen bottle taken care of. . .

what else should you be looking for if not that big font SPF number?

Let’s continue.

I’ll make this as succinct and simple as possible. Stay with me. . .

If you turn to the back of your sunscreen bottle or box, you will see active ingredients listed. UV sun protection filter actives have been described by two classifications

  1. organic or chemical ingredients, that are typically either in liquid form, or readily dissolved into a liquid oil‐ or water‐based medium, and
  2. Inorganic or mineral ingredients that are sometimes called physical sunscreens. These are insoluble metal oxide particulates.

Depending on where in the world you live and the regulation in the country, the availability of these ingredients differs. For example, There are 33 active sunscreen ingredients that have been approved by the Australian Therapeutics Goods Administration.

If you live in the US, the FDA regulates sunscreen as an over-the-counter medication and Currently, 16 UV filters are listed on the monograph: 14 organic filters, and two inorganic.

Looking at mineral or physical sunscreen ingredients closer:

Until recently, it’s been believed that inorganic particulates disperse and reflect UV radiation to block UVA and UVB rays. And organic or chemical ingredients absorbed UV to convert it to heat before it gets down the skin layers.

Zincoxide  and titanium dioxide  are physical sun-screen ingredients. Studies show these filters act primarily as UV‐absorbing materials contrary to long-held beliefs, and not as UV‐scattering or UV‐reflecting materials.

The average range of reflection for zinc oxide and titanium dioxide throughout the UV range was only 4–5% (less than SPF 2), providing minimal UV protection via this mechanism.

I personally use mineral based sunscreens. Sunscreens that have Zinc-oxide should have strong absorption against both UVA and UVB. Evidence suggests that few if any zinc or titanium particles penetrate the skin to reach living tissues. I never use sunscreen sprays either. Or hair spray unless at the hair salon where I can’t avoid it because they insist on it. We could inhale ingredients in sprays and I’d not assume that to be safe.  

On the other hand, in recent FDA testing, all non-mineral sunscreen chemicals have shown to be absorbed into the body and could be measured in blood after just a single use.  They also have noticed many sunscreen ingredients have been detected in breast milk and urine samples. FDA has indicated that the agency does not have enough information to determine whether the chemicals are causing harm. But I personally don’t even want to go  there because there is no need and I’m perfectly happy even with my white residue sunscreens.

Mineral sunscreens are less likely to cause irritation than chemical sunscreens as well.

The downside to these mineral sunscreens is the white residue that is just not aesthetically appealing, especially if you have darker skin. But considering the alternative, I don’t mind waiting a little longer for the mineral white residue to blend with my skin. Also, there are tinted sunscreens that you can find that might very well match your skin color and save you this trouble anyway.

Manufacturers are using ultrafine, nanoparticles of these minerals also. These are transparent rather than white. So, you might have no issue at all. I will make another video to recommend some brands that seem to work for me.

Organic sunscreens are often called Chemical sunscreens. You know how I feel about this chemical word if you’ve watched my other video. Everything is made of chemicals and I don’t understand how some things get the label and others don’t.

Anyway, their mechanism of action is based on their chemical structure involving an aromatic compound conjugated with a carbonyl group. This structure allows for high energy UV rays to be absorbed, causing the molecule to be in an excited state. As the molecule returns to the ground state, it will release the lower energy of longer wavelengths. The specific range of wavelength a sunscreen absorbs will vary. Chemical sunscreens consist of UVA and UVB blockers. 

Ingredients include: oxybenzone, avobenzone, octisalate and Tinosorb.

According to studies all “chemical” ingredients get systemically absorbed into the body after a single use.

The FDA also concluded that the risks of using aminobenzoic acid, or PABA (Para-aminobenzoic acid) and trolamine salicylate outweigh their benefits, and has classified  them as unsafe. As I mentioned above, the FDA recognizes zinc oxide and titanium dioxide to be considered. To be fair and balanced, There isn't enough information to decide whether the remaining 12 are safe and effective at this time. The FDA is currently asking the industry for additional data.

Last but certainly not least: You get to decide whether you like mineral or organic “chemical” sunscreens. Just make sure it says Broad-spectrum. Some products might have PA which is short for “Protection Grade of UVA.”

This is an important distinction because as we’ve beat it to death, SPF measures only UVB protection while the PA rating measures UVA protection. If you see the PA protection on the labels, make sure you go for the highest you can get your hands on.

PA+ = Some UVA protection
PA++ = Moderate UVA protection
PA+++ = High UVA protection
PA++++ = Extremely High UVA protection

Don’t forget to reapply the sunscreen every two hours, as it can come off through sweat or by being rubbed off by clothing. Finally, be sure to check the ‘use by’ or ‘expiry’ date of any sunscreen before you use it. If it’s out of date, some of the active ingredients may have broken down and the sunscreen won’t work as well. And don't forget to shake it before applying if it's not a thick cream.

REFERENCES

Agin, Patricia Poh. "Measuring ultraviolet A protection in sunscreen products." Journal of the American Academy of Dermatology 77.3 (2017): e81. 

Brenner, Michaela, and Vincent J. Hearing. "The protective role of melanin against UV damage in human skin." Photochemistry and photobiology 84.3 (2008): 539-549.

Cole, Curtis, Thomas Shyr, and Hao Ou‐Yang. "Metal oxide sunscreens protect skin by absorption, not by reflection or scattering." Photodermatology, photoimmunology & photomedicine 32.1 (2016): 5-10.

Crowther, J. M. "Understanding sunscreen SPF performance using cross‐polarized UVA reflectance photography." International journal of cosmetic science 40.2 (2020): 136-145.

Diffey, Brian L. "Sources and measurement of ultraviolet radiation." Methods 28.1 (2002): 4-13.

Gabros, Sarah, Trevor A. Nessel, and Patrick M. Zito. "Sunscreens and photoprotection." StatPearls [Internet] (2020).

Latha, M. S., et al. "Sunscreening agents: a review." The Journal of clinical and aesthetic dermatology 6.1 (2013): 16. 

Linden, Kenneth G. "Commentary: Sunscreen sun protection factor (SPF): Is higher better?." Journal of the American Academy of Dermatology 78.5 (2018): 911-912.

Silva, Elizabet Saes da, and Samuel Carvalho Dumith. "Non-use of sunscreen among adults and the elderly in southern Brazil." Anais brasileiros de dermatologia 94.5 (2019): 567-573.

Trivedi, Megha, and Jenny Murase. "Titanium dioxide in sunscreen." Application of Titanium Dioxide. IntechOpen, 2017.

https://www.aad.org/media/stats-skin-cancer

https://www.who.int/news-room/q-a-detail/radiation-ultraviolet-(uv)#:~:text=Altitude%E2%80%94at%20higher%20altitudes%2C%20a,otherwise%20reach%20the%20Earth's%20surface.

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