Link Love Month, here’s how it works: we answer questions from other bloggers. After reading our answer you go visit their site.  The bloggers get readers, you get to read more blogs. Now go practice with Nicole from Bagful of Notions!  

Nicole needs to know…Is there a really big difference between using SPF 15 and SPF 30 facial moisturizer? If so, why? I was told to wear 30 in order to prevent rosacea flare ups.

The Left Brain’s loquacious reply: 

Skin exposure to UV rays is almost never good for the skin. It causes sun burn, wrinkles, dryness, and as you’ve implied, rosacea flare ups. This is why the most important thing you can do for your skin is to wear a sunscreen or stay out of the sun. But what kind of sunscreen should you use?

SPF

Before answering this, we should first tell you what the SPF number means. SPF stands for sun protection factor and it essentially is a rating of how much UV light will be blocked. In general, a higher SPF number offers more protection from UV exposure than a lower number. How effective it is depends on many factors but the number one factor is your skin type. SPF 15 means that if you would normally burn after being in the sun for 20 minutes, you will be able to stay in the sun for 15 times as long or 5 hours. But it is important to note that the SPF scale is not a linear one. An SPF 2 will block 50% of the UV light while an SPF 15 will block 92% of all the UV light that reaches your skin and an SPF 34 blocks 97% of the UV light.

SPF effectiveness

Although skin type is the number one factor is determining the effectiveness of a sunscreen, it is not the only factor. The intensity of the sun and the amount that you apply is also important. It’s this second factor that is most relevant to your question.

SPF 15, 30 or more

For cosmetic chemists, creating a great sunscreen is a balance between making a product that is effective and making one that feels good on the skin. If it were just a matter of effectiveness, everyone would create SPF 50 products or higher. But the problem with creating a higher SPF product is that for each number you go up, you increase the greasy, nasty feel on your skin. An SPF 15 feels much better than an SPF 30. And an SPF 100 is, well, gross.

Of course, the point of a sunscreen is to protect you from UV damage so you need to use an SPF sunblock with a high enough number to give you good protection.

SPF experts

Experts at the FDA have suggested that an sPF 15 is the minium that you should be using to protect your skin from UV damage. In testing these sunscreens have been shown to provide adequate protection when combined with limiting your time in the sun, wearing sun protective clothes. And an SPF 15 also can be made so it doesn’t feel excessively greasy.

SPF 15 is not enough

While the experts say SPF 15 scores high enough in testing to give protection, that is only true if you are applying the right amount. In testing, scientists use 2 mg/cm2 of skin. So, do people apply this much?

In a word…no. It is well known that people typically apply much less than the amount tested by sunscreen manufacturers.

Think about how much you use. If you were applying 2 mg/cm2 of sunscreen, your skin should feel greasy, slippery, and some of the sunscreen will be running off your skin. For an average sized person, you would need to apply about 30 mL of sunscreen per application. One bottle wouldn’t even be enough for a week at the beach.

1/3 effective

So, while technically an SPF 15 will work (and it’s certainly better than nothing), it requires much more than you apply now. A good rule of thumb is that your sunscreen will be 1/3 as effective as the number based on the way people typically apply the product. That means an SPF 15 will protect you like a lab tested SPF 5. An SPF 30 will give SPF 10 protection in real life application.

Therefore, unless you going to glop on a lot more SPF sunblock than you are using now, you should stick with an SPF 30 or higher. This will give you the best chance at preventing sunburns and UV induced rosacea flare ups.

For more information on sunscreen effectiveness see the following resources
1. Melanoma foundation facts about sunscreens.
2. FDA Sunscreen guide
3. National Institute of Health and Clinical Excellence Skin cancer prevention report
4. Dr. Steven Wang – Sunscreen Guide

Image credit: Flickr.com
If you need to purchase sunscreen, please shop using the link below and you’ll be supporting the Beauty Brains.

LisePunch asks...Why is Octocrylene being targeted as being dangerous? I am hearing all kinds of conflicting info about chemical sunblocks.

The Left Brain responds:

After this question on Octocrylene came up in our Forum I decided to dig a little deeper to find out if this controversy is really fact or just another beauty myth. Here’s what I found…

Crying over Octocrylene

To begin, it’s helpful to understand why we need Octocrylene in the first place. Does it do anything different from all the other sunscreens we have? The answer is yes: it provides improved sun protection. Although by itself Octocrylene isn’t a very good sunscreen, it can protect other UV absorbers from breaking down and it can even boost their performance. It also helps them coat the skin better.  So Octocrylene is a great tool for boosting sunscreen efficacy.

As with all sunscreens it has been thoroughly tested before it was approved. In the US, Octocrylene has been evaluated by the FDA and is considered safe for use up to 10% in the formula.  Similarly, the EU allows its use up to 10% in a formula while Health Canada allows a maximum use level of 12%. With three independent approvals this looks pretty safe, so why the controversy? There are two reasons.

Potential irritant

There are a number of reports in the literature about Octocrylene causing irritation. Octocrylene had 2 reported cases of irritation in 2003 but according to an article published in the Contact Dermatitis journal, reports of positive patch testing have been increasing. Here’s some additional information from Medscape about sunscreen allergies. The Archives of Dermatology and the Dermatology Journal Online also discuss allergic responses Octocrylene.

One theory is that Octocrylene appears to be a strong allergen leading to contact dermatitis in children and mostly photoallergic contact dermatitis in adults with an often-associated history of photoallergy from ketoprofen (a pain reliever). Patients with photoallergy from ketoprofen frequently have positive photopatch test reactions to octocrylene. These patients need to be informed of sunscreen products not containing octocrylene, benzophenone-3, or fragrances.

DNA damage?

The second part of the controversy is more serious because it involves potential DNA damage. Octocrylene is one of those ingredients that can be absorbed into the skin and some studies have shown that it may promote generation of potentially harmful free radicals when exposed to light. Since free radicals can damage DNA, there is concern that this ingredient might have contributed to an increased incidence of melanoma in sunscreen-users compared to non-users.  Researchers say further studies are warranted to determine the true health impact of this ingredient. (References: Smartskincare.com; ScienceDirect)

The Beauty Brains bottom line

This beauty myth does have a kernel of truth to it. It seems like there is some legitimate concern regarding irritation for and children & some adults (still a minority of the population) will want to avoid it.  And further research is warranted into the free radical damage that this ingredient could potentially cause.

If you’re concerned about this ingredient you may get some peace of mind by using an Octocrylene free sunscreen which you can buy one here.

OR

Not ready to buy sunscreen but want to learn more about busting beauty myths? Download our FREE guide!

We’ve blogged before about whether or not indoor tanning should be illegal and now, according to, The Dermatology Times, there is a new law under consideration by Congress that could limit how long you could stay in a tanning bed.

Tanning bed dread

The bill, called the Tanning Bed Cancer Control Act, was sponsored in the House of Representatives by Carolyn B. Maloney (D-N.Y.) and Charlie Dent (R-Pa.). It calls for the FDA to review the medical device classfication for tanning beds and to set standards for exposure that are based on the latest scienctific evidence linking UV exposure to cancer.

You can learn more about the proposed law by clicking the link above; you learn more about current regulations at FDA.gov.

Brittany asks…Ok, I feel kind of stupid asking this because everyone else probably already know this but what exactly does SPF mean? I mean I know it stands for Sun (Solar?) Protecting Factor but what does that mean?

The Right Brain responds:

As far as we’re concerned, Brittany, there are no stupid questions. In fact, you raise a very good question because we think that a lot of people are unclear of the real answer. So, in today’s post we’ll spell out exactly what SPF means.

The ABCs of SPF

First of all, you were close on the meaning of the acronym. SPF actually stands for Sun Protection Factor. This factor is a measure of how much  Ultraviolet, or UV, radiation it takes to burn your skin when it’s unprotected compared to how much it takes to burn it when it’s slathered in sunscreen. The higher the SPF value of your sunscreen, the more protection it offers from sunburn.

Now, here’s the tricky part. Many people think that SPF relates to how much time you can spend in the sun. In other words, if you can stay in the sun for 30 minutes before burning and you wear a sunscreen with an SPF of 10, you should be able to stay in the sun for 30 x 10 = 300 minutes or 5 hours before burning. Right? WRONG!

Why is it wrong? Because SPF doesn’t just relate to the duration of sun exposure – it relates to the amount of sun exposure. Time is one factor that contributes to the total exposure level but it’s not the ONLY factor.  The intensity of the UV radiation also impacts the amount. For example, one hour of sunlight at 9:00 in the morning is equivalent to 15 minutes of sunlight at 1:00 in the afternoon. So if you’re only looking at how long you’re out in the sun you might drastically under estimate how much sun exposure you’re really getting. Geography is another factor: sunlight is more intense the closer you are to the equator. And weather is yet another consideration: even though you can get a sunburn on cloudy days,  the effect of sunlight is generally more intense when the sky is clear.

The Beauty Brains bottom line

The SPF value of a product does NOT tell you how long you can stay out in the sun before you burn. It only tells you the relative difference between the level of protection provided by different products.

Source: FDA.gov

Do YOU have a favorite sunscreen? Leave a comment and share your thoughts with Brittany and the rest of the Beauty Brains community.

Cubelixa’s question…I’ve been wondering about this for quite a while now. What happens to my sunscreen if I apply it to my face in the morning and then go to work (I’m an office girl)? If I don’t do sport and sweat a lot, take a bath or rub my face with my hands, do I still have to re-apply it several times throughout the day or will it protect me just fine the entire day? What happens to it?

The Right Brain’s response:

It’s true that sunscreen needs to be replenished if it’s removed by washing or sweating or rubbing. But that’s not the only reason it needs to be reapplied. Chemical sunscreens actually “wear out” over time.

Sun damaged sunscreens

UV absorbers work by trapping high energy photons in their structure.  This process excites the absorbing molecule and causes it to re-emit the energy from the photon in a harmless form. But the sunscreen molecule can only go through so many “absorb and re-emit” cycles before it begins to deteriorate. This is more common in strong sunlight and it’s why you have to reapply more lotion to maintain your Sun Protection Factor. If you’re in the office as you describe, it’s less likely to be a problem for you. U

This WebMD article provides some general details on sunscreen application that may be helpful. And here’s another source that explains that although this photodegradation of of UV absorbers is not fully understood that it can be reduced by adding stabilizing components. For instance, there is some evidence that the addition Mexoryl SX can reduce the photodegradation of Parsol 1789. Sunscreen breakdown can also be slowed down with the addition of other ingredients such as iron chelators or vitamins C or E.

This also helps to explain why you shouldn’t mix sunscreens with other lotions, you may be inadvertently messing up a formula that has been balanced to protect the photo-stability of the active ingredient.