Wednesday, June 25, 2014

Blast from the past: Suncreens - What does SPF mean? What exactly is sunscreen? Why shouldn't we make our own?

WHAT DOES SPF MEAN? (Originally found here...)

What is sun protection factor or SPF? How is it defined? SPF is defined as...
the dose of UV radiation required to produce 1 minimal erythema dose (MED) on protected skin after the application of 2 mg/cm2 of produce divided by the UV radiation to produce 1 MED on unprotected skin.
In other words, it's how much of this stuff you need to use to protect your skin from a dose of radiation that would affect unprotected skin. The higher the number, the more protection you should get. (Sort of...see the post below on sunscreens!) 

"Water resistant" sun screen must maintain its SPF after immersion in water for 40 minutes. "Very water resistant" sunscreen must maintain its SPF after immersion in water for 80 minutes.

Broad spectrum or full coverage sunscreen will protect against both UVB and UVA rays.

How does SPF work? It's all about you! Let's say you burn after 10 minutes in the sun. SPF 15 will get you 150 minutes in the sun. SPF 30 will get you 300 minutes in the sun. But you have to re-apply after about 2 hours with a non-water resistant sunscreen anyway, so what's the point if you take 20 minutes to burn and you have to re-apply it after about 120 minutes? Because SPF 15 will block out about 93% of the UV rays, and SPF 30 will block out about 97%. For very fair skinned people, going from SPF 30 to 50 might get them another 1% coverage. Might not be a big deal for someone who has dark skin, but if you're like my husband (more below), that 1% could mean the difference between a slight reddening of his skin and a burn.

WHAT EXACTLY IS SUNSCREEN? (Original found here)

Yep, it's that time of year again (at least in the Northern Hemisphere)! It's time to buy buckets of sunscreen and make sure Mr. Sun doesn't make us all red and unhappy! We definitely need to be wearing sunscreen!

There are two types of sunscreen ingredients - physical blockers and chemical blockers. The physical blockers are titanium dioxide and zinc oxide, both of which work by preventing the sun's rays from reaching our skin by reflecting and dispersing them. The chemical sunscreens work by absorbing ultra-violet rays and keep them from penetrating the skin. They are great at blocking about 95% of the UVB rays, but very little UVA. The degree of absorption depends on the type and concentration of chemical sunscreen. Ideally, you'd have a combination of the two in your sunscreen.

To get maximum sunscreen-age, apply it about 15 to 30 minutes before going into the sun so it can penetrate the keratinous layer of your skin. Re-apply it regularly every 2 to 4 hours, and especially if you've been swimming or sweating a lot.

The physical sunscreens are unlikely to cause a reaction on our skin - any reaction you might have is thanks to the other ingredients in the sunscreen - so if you have sensitive skin, stick with zinc oxide and titanium dioxide and be okay with looking a little ghostly (I like this on my face, not so much on my legs!) These sunscreens might feel a little draggy, but it's a small price to pay to avoid sunburns!

If you're out in the sun - meaning, if you ever go outside - don't forget to protect your nose and lips. Your nose gets the most sun exposure, so sunscreen it well. And our lips can be protected with as little as your lipstick on a cloudy day, or with a water resistant sunscreen or lip balm during a sunny day.

Don't forget to get a good pair of UV blocking sunglasses. They'll protect your retinas and they'll make you squint less - and less squinting means fewer wrinkles, so you're looking good as well as feeling good!

So how do we make our own? We don't.

As you may or may not know, my husband has vitiligo, a condition that leaves him without melanin in big patches in his skin and hair. (This is what they say Michael Jackson had, the condition that was making him white. As Raymond is already quite fair skinned, you don't notice it much.) We buy sunscreen by the bucketload in the summer to ensure he isn't at risk for burning, which can happen in a few minutes for him. If I could make sunscreen that I could guarantee would work for him, I'd make it. But there are so many factors that go into ensuring a sunscreen works, I don't feel confident that it will prevent him from agonizing pain today and skin cancer in the future.

If you're considering making your own sunscreen, there is a lot of chemistry to know. (Check out this post from Zenitech!) You have to worry not only about the pH of a sunscreen but the emulsification of our lotion when making a sunscreen. As well, how do you know how effective your chosen sunscreen might be? Only by going into the sun and seeing if it works, and anecdotal evidence is not data - it might have been a cloudier than normal day, you might have been under a tree, you might have really sun resistant skin that doesn't burn for 30 minutes or more! If you have a fair skinned friend, she might burn in 10 minutes, and the product that works well for you might mean sunburn for her! 

There are so many scary things out there on the 'net about sunscreen, and I won't give them any validity by putting them into this post. The way I see it? Sunscreens block out the sun's rays. Sun makes me burn. Anything that prevents unnecessary pain today and wrinkling tomorrow works for me. (Click here for a post on pigmented skin through sun exposure and here for a post on photo-aging.)

Yes, I know anecdotes aren't data and this last paragraph is my opinion, but I really haven't found any valid studies showing that sunscreen causes more harm than good. 

If you're worried about sunscreens, then don't use them. Or choose sunscreens containing only certain ingredients, but not others. Just choose something...

There is no argument I haven't heard before about why you want to make your own sunscreen, so I'll ask you not to make one. There is absolutely nothing you can say that will make it okay for you to make something that could be quite dangerous to someone. Sunscreen makes my skin break out so badly and my skin is red all summer long because of the irritation, yet I still use it. I have the skill and knowledge to make something that might resemble sunscreen, yet I would not think of doing it, even though it would save my family a ton of money. You have so many products containing so many different types of physical and chemical sunscreens with so many different types of bases - anhydrous, fancy moisturizers, basic lotions - that there is something you will be able to use. You will have to invest some time and money to find a product that your skin likes - I've been searching for years - but you will find something.

If you want to try a zinc oxide cream - very nice if you've had a little too much fun in the sun - may I suggest this recipe I made recently for my husband? I've used it for soothing various problems and I like it! I did tweak mine to include 10% aloe vera - good for post sun exposure - and added 2% hydrolyzed protein to the heated water phase and 2% panthenol to the cool down phase. Feel free to switch the stearic acid for cetyl alcohol for a slightly less thick but more glide-y product. And switch the oils if you wish

Want to know more about the ingredients in sunscreen? Then click here for zinc oxide and click here for titanium dioxide. And click here for a post on micronized ingredients (it's kinda long with lots of studies and links, so I thought it wiser to link to it than copy it here!). 


Rachel said...

I am a skin cancer survivor and would NEVER leave the house without a sunblock applied to every inch of skin that may possibly be exposed to the sun. My specialist told me there is medical research to suggest physical blocks to be safer than chemical sunscreens. I also asked about people that make their own (I have a friend who does) and he didn't recommend doing this UNLESS you are prepared to have it laboratory tested and even then there is the danger of the formulation(and therefore the SPF factor) not being exactly the same for each batch. When sunblock is made commercially we can expect that the product will remain the same for each and every batch.

Alexis said...

I find Neutrogena's Clear Face sunscreen works well on my face, but I always put on my face spray and gel I make first.

I was badly sunburned when I was 21. Apparently SPF 30 sounded like SPF 3 to my friend, and the stupid beach we were at didn't have any venders that sold sunscreen! Weird, right?

15 years later I used a peel product that was packaged specifically for skin that had been sun damaged, and I had a horrible burn/allergic reaction to it even though I tested the product three times like the instructions said to do. The reaction occurred after the fourth use. >_>

I couldn't wear any lotion on my face for years, and sunscreen would burn so badly I had to wash it off. I tried just oil and that messed up my skin even more.

Making my own lotions really changed everything; although I really make gel-type products with pemulen tr-2 more than traditional emulsified lotions for my face. Key to me tolerating sunscreen has been to use a face spray and gel with loads of panthenol and sugar beet extract that dries before I put on the sunscreen.

Melanie said...

What about using a professional formula to make sunscreen? has a formula.If we followed that wouldnt it be pretty safe to say it would protect you?

Susan Barclay-Nichols said...

Hi Melanie. We cannot make sunscreen at home no matter where we find the recipe because we cannot test the efficacy of the recipe as a sunscreen. As I've said in the past, emulsifiers can inactivate the sunscreen ingredients, and we wouldn't know this was happening.

Having said this, I'm honestly done with this battle. I've written all I want on the topic and if someone wants to make it at home, I can't stop them. I have offered all I can, and if that wasn't enough, then I guess it wasn't enough.

Gabriel said...

Thank you so much for posting on this topic Susan! I was debating trying to make my own (due to cost) and figured I would come here for a top quality recipe. I'm glad you explained your position on the subject and shared your personal reasoning. That really helped to shut down my interest before it began, and you are absolutely right - Sunscreen is highly tested and should be considered a drug.

One question for you:
What is the use of zinc oxide cream? I see it painted on peoples' noses in older films and occasionally at the beach, but isn't it just being used as a sunscreen there? I know that it scatters and reflects almost all of the light, and is a true sun "block," but I cannot think of a use for it to be honest.

Thanks, and keep up the good work!

(p.s. had to repost the comment so I could get the email for follow-up comments. Sorry to clutter the blog!)

Susan Barclay-Nichols said...

Hi Gabriel! It is being used as a sunscreen, and zinc oxide is a very effective sunscreen indeed! It is a physical blocker. Having said this, it isn't as easy as adding some to a balm or lotion and using it that way, as I point out in the post!

Gabriel said...

Oh I see now. It makes much more sense after I read the actual zinc oxide cream post ^_^

Marina said...

Thank you, Susan, for this important post. Thank you for reminding everyone that sunscreen is classified as a drug, and for a good reason. It requires special labeling, packaging, formulation, and testing. As much as this might anger people, I think this is an excellent opportunity to explain the *benefits* of a chemically engineered product made by a large corporation:

1. Extensive research, development, and formulation from a team of chemists, chemical engineers, and/or other types of scientists and engineers.
2. Extensive product testing (including efficacy testing, SPF testing, challenge (preservative) testing, and batch-to-batch consistency testing)
3. Strict compliance with FDA laws
4. Consistency between bottles and batches
5. Special packaging which helps prolong efficacy and shelf life.

Try to find all of that with someone selling sunscreen at a Farmer's Market. Some folks always assume that something engineered and made by a large corporation in a chemical process facility is bad. This is good example of when a highly engineered product can save your life.

Thank you, Susan! Marina

Yulia said...

I just bought a Thinksport sunscreen manufactured in USA and wondering .. they claim spf 50+. I contacted them and they said third party verified. Non nano zinc 20%, however I do not see suspenders or other ingredients that would be responsible for uniform suspension of zinc oxide in the lotion... could you look into ingredients and advise whether this is not really a good choice for my daughter

Ms.ABC said...

Hi Susan,

I'm youngish, black, and am having the most difficult time finding a sunscreen that doesn't leave me looking like Casper. I've read somewhere physical sunscreens are better than chemical ones but both seem to show the same on me. At $35 plus tax Supergoop has a body butter sunscreen that's ok but I can't stomach the price. I currently mix body oil with a cvs spf 50 product that's both chemical and physical. I was wondering if I'm ruining the efficacy of the product and if it's safe to apply to my face as well. Dont worry I'm not interested in formulating my own sunscreen :-) thanks.



Cvs brand ingredients:

Active Ingredients: Octocrylene (4.0%), Zinc Oxide (5.0%). Inactive Ingredients: Water, Ethylhexyl Stearate, Diisopropyl Adipate, Cetyl Dimethicone, Polyglyceryl-4 Isostearate, Cetyl PEG/PPG-10/1 Dimethicone, Hexyl Laurate, Beeswax, Isohexadecane, Sodium Chloride, Hydrogenated Castor Oil, Silica, Triethoxycaprylylsilane, Dimethicone, Tocopherol, Disodium EDTA, Aloe Barbadensis Leaf Juice Powder, Sodium Ascorbyl Phosphate, Phenoxyethanol, Methylparaben, Propylparaben.

Susan Barclay-Nichols said...

Hi Melissa. The short answer is yes, you are likely ruining the efficacy of the product. It's about how the sunscreen spreads on your skin, and you could be messing with how it does that and deposits it.
As a note, the physical suncreens are the ones that are making your skin chalky white.
Why not the chemical sunscreens? My husband has vitiligo, and we go for a combination of both to ensure he's protected.