Sunscreens and the Athlete
Stan Reents, PharmD
07/20/2019 09:00 AM
Last Revision: 01/07/2020 03:00 PM
While cancer is a major cause of death in the US, skin cancer is way down the list. However, malignant melanoma is one of the deadliest of all cancers. If it spreads into lymph nodes and beyond, without treatment some patients may have less than a year to live!
The 3 most common types of skin cancer are:
- basal cell carcinoma
- squamous cell carcinoma
...and excessive sun exposure increases the risk of all 3 (Gandini S, et al. 2005) (Preston DS, et al. 1992).
Some athletes spend a lot of time in the sun:
- baseball and softball players
- beach volleyball players
- soccer players
- tennis players
- triathletes (especially Ironman triathletes!!)
Beach volleyball players may be most at risk for skin cancer due to:
- a large percentage of body surface area is exposed
- spending many continuous hours in the sun
- matches are commonly held in areas nearer the equator
But even if you just walk outdoors every day, you could be getting too much sun.
Fortunately, the risk of developing skin cancer can be reduced by doing 2 simple things:
1) Limit your exposure to sunlight: One rule of thumb is to spend 15 minutes in the shade for every hour you're outdoors. This strategy can reduce the risk of a severe sunburn by 31%. But don't count on a beach umbrella: Researchers in Spain found that a canvas umbrella only blocks 66% of UV radiation. This is probably because the sun's rays are reflected off of the surface of the ocean and lakes and can reach you from the side.
2) When you are out in the sun, wear hats, long-sleeve shirts, and sunscreen.
In 2019, two significant publications appeared regarding sunscreen safety and efficacy. In this article, I'll explain them and review sunscreen ingredients and provide recommendations on the best way to use these products.
SUNSCREEN TYPES: INORGANIC or ORGANIC
There are only 16 unique sunscreens approved for use in the US. However, thousands and thousands of commercial products based on these ingredients are available (see below). This makes the task of identifying the best sunscreen products extremely difficult.
Sunscreen ingredients used to be categorized as "physical" and "chemical". The terms "Inorganic" and "Organic" are now preferred.
How Sunscreens Work
• Inorganic sunscreens are titanium dioxide and zinc oxide. These are also referred to as "mineral" sunscreens. In the past, they were called "physical" sunscreens because it was originally thought that they worked by simply "coating" the skin to prevent UV rays from reaching the skin surface in the same manner that wearing a long-sleeve shirt does. Now, it is known that this is a very minor explanation for how they work. The major action of titanium dioxide and zinc oxide is due to their ability to absorb UV rays in the same manner as "chemical" type (aka: "organic") sunscreens do (Jansen R, et al. 2013) (More BD. 2007).
• Organic sunscreens interact with UV rays to absorb their energy. In the process of doing so, they break down and become less effective. Because there is an actual chemical reaction with light energy, they were called "chemical" sunscreens.
WHAT DOES "BROAD-SPECTRUM" MEAN?
Ultraviolet rays can be categorized as follows:
|200 - 290 nm ||UV-C ||mostly filtered out|
by the atmosphere
|290 - 320 nm ||UV-B ||sunburn spectrum;|
clearly linked to skin cancer
and immune suppression
|320 - 400 nm ||UV-A ||previously thought to only cause|
wrinkling and skin darkening;
now known to also contribute to
skin cancer and
Think of the "B" in UV-B as standing for "burn", as in sunburn. Sunburn is caused by UV-B rays. So, because sunburns increase the risk of skin cancer (Gandini S, et al. 2005), blocking UV-B rays is very important.
Decades ago, it was known that UV-A rays accelerated skin aging (wrinkling) but it was believed that they did not contribute to skin cancer. It's since been confirmed that UV-A rays can also increase the risk of melanoma (Garland CF, et al. 2003) (Planta MB. 2011).
And researchers at French cosmetics manufacturer L'Oreal have shown that UV-A rays can also suppress the normal immune response (Fourtanier A, et al. 2008) (Moyal DD, et al. 2003) (Moyal DD, et al. 2008). Previously, it was thought that immune suppression was only caused by UV-B rays.
"Broad spectrum" means that the sunscreen protects against both UV-A and UV-B rays...to some degree. Zinc oxide protects against UV-B very well and protects against almost the entire UV-A band. Thus, it can be called "broad-spectrum."
Few organic sunscreens currently available in the US protect against UV-A as well as they absorb UV-B rays (Planta MB. 2011). This is probably because for a long time, the target was only UV-B rays. Oxybenzone is effective against UV-B but only partially effective against UV-A. Avobenzone possesses strong activity in the UV-A range, but only part of it, and it doesn't protect against UV-B rays.
In fact, no sunscreen currently approved in the US is protective throughout the entire UV-A range (320-400). Thus, the term "broad spectrum" means that "most", but not all, of the skin damaging range of UV light (280-400) is absorbed.
WHAT IS THE S.P.F. RATING?
SPF stands for "sun protection factor." It's simply the ratio of the time required to produce sunburn erythema with and without sunscreen applied.
|SPF RATING ||EFFECTIVENESS|
AGAINST UV-B RAYS
|SPF 15 ||93%|
|SPF 30 ||96%|
Here is a critical detail to understand:
The SPF rating is based on the ability of a sunscreen to prevent sunburn, not other forms of skin damage (see next section). Because sunburn is mostly caused by UV-B rays (Preston DS, et al. 1992), the SPF rating is a reflection of how well the sunscreen absorbs UV-B rays...ie., not UV-A rays.
But how a commercial sunscreen product is formulated has a big impact on the SPF rating. For example:
Lotions and creams provide better protection than sprays. And some products might contain only one active sunscreen, while others combine several together. So the formulation will determine how long it stays on the skin and how effectively it protects against UV-B rays. Both of these factors affect the SPF rating.
This explains why Consumer Reports states that the SPF value of commercial sunscreen products isn't always accurate.
ARE SUNSCREENS EFFECTIVE?
This may be disturbing to read, but proof that sunscreens can prevent skin cancer is not very strong.
While there is good clinical research showing that sunscreens can reduce the risk of sunburn and squamous cell carcinoma, the evidence supporting their effectiveness in preventing melanoma is poor (Califf RM, et al. 2019). This doesn't mean that they don't work. What it says is that really solid evidence is lacking.
A 2003 review of 18 clinical studies concluded "no association was seen between melanoma and sunscreen use." (Dennis LK, et al. 2003). However, those 18 studies were published between 1966 and 2003. As mentioned above, the sunscreens that were developed decades ago were designed to only protect against UV-B rays. So, this older research doesn't accurately reflect the efficacy of newer agents used today.
Around 2003-2004, it became apparent that UV-A rays were a risk factor for skin cancer, too (Garland CF, et al. 2003). This led to the development of broader-spectrum sunscreens.
In 2011, an Australian study documenting the ability of a broad(er)-spectrum sunscreen to prevent melanoma was published (Green AC, et al. 2011). This was considered a landmark study because it was randomized and prospective. And, subjects were monitored for a long time: they used sunscreen daily for 4.5 years, and then they were followed for 10 more years after that.
The sunscreen they used was effective across the entire UV-B range (SPF rating was 16) but only half of the UV-A range (320-360) (Thompson SC, et al. 1993).
During those 15 years, 22 out of 809 subjects who used sunscreens intermittently or not at all developed melanoma. But only 11 of the 812 subjects who used it every day (during the first 4.5 years) developed melanoma. Here are 2 ways to interpret this:
a) If you use sunscreen daily, you can reduce your risk of getting melanoma by half (ie., 22 occurrences in the control group vs. 11 occurrences in the daily sunscreen group). That sounds pretty good, doesn't it?
Or, you could derive this conclusion:
b) Using sunscreen daily prevented melanoma in just 11 out of 1621 subjects. Summarizing it like this suggests that sunscreen use, while beneficial, is only marginally effective: 11 cases prevented during a span of 15 years doesn't seem very impressive, especially when you consider that Australia has the highest melanoma rate in the world.
Regardless, here is one critical detail: the people in the sunscreen group applied it EVERY SINGLE DAY! Those who only used it intermittently didn't obtain the same benefit.
This study raises other questions: What if sunscreen was used daily for the entire 15 years? What if the sunscreen had a higher SPF rating? What if a sunscreen that's more effective in the UV-A range (320-400) was used? (eg., avobenzone or ecamsule)
Thus, it becomes understandable why the authors of an editorial in the June 4, 2019 issue of the Journal of the American Medical Association (JAMA) flatly state that there needs to be better clinical (ie., human) research documenting the effectiveness of preventing melanoma with sunscreen use (Califf RM, et al. 2019). The Environmental Working Group also states that consumers need much better information on the effectiveness of specific products against UV-A rays.
Note that sun exposure can lead to (at least) 3 different skin responses:
- skin cancer
- accelerated skin aging
Currently, the FDA warns that sunscreen products that are (a) not broad-spectrum and (b) have an SPF rating less than 15 only protect against sunburn, not the other 2 skin responses.
And stricter FDA regulations are on the horizon...
NEW FDA REGULATIONS FOR SUNSCREENS
On February 21, 2019, the FDA published major new rulings regarding the marketing and labeling of sunscreens. They propose the following:
• Titanium dioxide and zinc oxide are "Generally Recognized as Safe and Effective" (GRASE).
• Para-aminobenzoic acid (PABA) and trolamine salicylate are regarded as NOT safe.
• Insufficient safety and efficacy evidence exists for the other active sunscreen ingredients.
• Some formulations (eg., creams, lotions, gels) are considered GRASE, whereas other formulations (eg., body washes, shampoos, towelettes, wipes) are not.
• The maximum SPF value allowed on labeling is increased from 50 to 60.
• As the SPF rating increases, products claiming to be "broad-spectrum" must be able to provide increasing protection against UV-A rays, in addition to UV-B rays.
• Products with an SPF rating of 2-14 should be removed from the market, or, state that, while they may protect against sunburn, they do not reduce the risk of skin cancer or skin aging.
Keep in mind that, as of July 2019, these new FDA regulations are still just proposals. The deadline for adoption is November 26, 2019. However, it is likely the sunscreen industry will push-back on these proposals. So, revisit this review every 6 months or so for an update.
SOME SUNSCREENS ARE ABSORBED THROUGH THE SKIN
The other publication of significance was a study that appeared in the June 4, 2019 issue of JAMA. It revealed that 4 sunscreens -- avobenzone, ecamsule, octocrylene, oxybenzone -- were all absorbed after application to the skin and all 4 produced systemic concentrations higher than 0.5 ng/mL (Matta MK, et al. 2019).
Now, 0.5 ng/mL is a pretty small amount. (The abbreviation "ng" stands for nanogram. A nanogram is one one-millionth of a milligram!) Nevertheless, this concentration is an important threshold established by the FDA: for substances that produce concentrations below this limit, the FDA waives the requirement for some nonclinical toxicology studies to be conducted before the substance can be marketed. But now that it is known that these 4 sunscreen ingredients exceed this threshold, the FDA will likely require that manufacturers submit additional toxicology research.
It's surprising (concerning!) that new details regarding systemic absorption of sunscreens are still being reported in 2019...ie., some of these ingredients have been on the market for decades. According to WikiPedia (accessed July 9, 2019), oxybenzone was approved for use in the US in the early 1980's. Avobenzone was patented in 1973, approved for use in the EU in 1978, and approved for use in the US in 1988.
ARE SUNSCREENS SAFE?
It appears that the use of sunscreens has greatly surpassed the clinical research and FDA regulations ensuring their safety and efficacy.
The June 4, 2019 JAMA editorial (Califf RM, et al. 2019) points out that:
"...sunscreens have not been subjected to standard drug safety testing, and clinicians and consumers lack data on systemic drug levels despite decades of widespread use. Furthermore, appropriately designed trials have not yet been conducted to understand the optimal sunscreen dose needed to achieve a balance of risk and benefit when used to prevent skin cancer and melanoma."
So, are over-the-counter sunscreens safe to use?
As detailed above, the FDA, in its February 21, 2019 proposal, states that titanium dioxide and zinc oxide are "Generally Recognized As Safe and Effective" (GRASE). However, the FDA feels more research is required on all of the organic type sunscreens.
The Environmental Working Group agrees that titanium dioxide and zinc oxide are safe and effective. However, they have concerns about the safety of oxybenzone: not only is it absorbed through the skin, it's known to disrupt hormone balance, and it can also cause allergic reactions.
These concerns are exaggerated. According to an October 2017 review, oxybenzone has been used in the US for decades without any reports of endocrinologic side effects in humans and allergic reactions are rare (Mancuso JB, et al. 2017).
BUT FIRST, THIS DISCLAIMER...
The following tables are my attempt to summarize the fundamental details of the active ingredients in sunscreen products. But, here's a disclaimer:
I consulted numerous scientific resources to create these tables. I discovered that there was poor agreement between various references regarding the UV spectrum for some sunscreens.
Oxybenzone absorbs UV rays between 270 and 350. That includes the entire UV-B band, but less than half of the UV-A band. In my way of thinking, that's not very good UV-A protection. Yet, numerous resources list it as protective against both UV-A and UV-B rays. Even more confusing, in an otherwise excellent review, oxybenzone was described as having activity in both the UV-A band and the UV-B band, but in a table on the very same page, it was listed only as a UV-A sunscreen (Mancuso JB, et al. 2017)!
For ecamsule, the details were outright contradictory:
WikiPedia states that ecamsule absorbs UV rays between 290 and 400 nm. That range includes all of the UV-A band and all of the UV-B band. Yet, they and other resources (Mancuso JB, et al. 2017) list it as only a UV-A blocker. In fact, ecamsule's activity peaks at 340-350 and drops off substantially both above and below that range (Fourtanier A, et al. 2008). It's strictly a UV-A sunscreen. Reporting its spectrum as 290-400 is misleading.
Other than typographical/editorial errors, here's an explanation for these discrepancies:
Except for zinc oxide, the effectiveness of a sunscreen varies depending on the wavelength of light. Zinc oxide is unique in that it provides consistent potency throughout the UV-B band, and the UV-A band right up to about 380-385. At wavelengths above that range, its efficacy drops off (More BD. 2007).
But for the other sunscreens, there is generally a specific wavelength where they have their highest activity. Above and below that wavelength they are less effective. If you look at a graph of their activity from 270 to 400, it would appear like an inverted "V".
It's just like if the front end of your car wobbled at 45 mph. But, if you drive slower, or much faster, the wobble goes away. This is how to think of UV protection from sunscreens: they have a specific wavelength of peak activity, with less activity at other wavelengths. Only zinc oxide has a flat graph...up to about 380.
If you had to define the exact range of speeds that your car wobbles, you could do that pretty accurately: between 42 and 48 mph, or, between 40 and 50 mph, etc. You can feel when the wobble is occurring.
But it's much more difficult to define the range of protection for a sunscreen. If its activity at a specific wavelength is only 50% of maximum, is it still effective against that wavelength? What if its activity is 40% of maximum?...30% of maximum? Keep in mind, you're not measuring the action of a drug on blood pressure, which is very easy to assess. You're trying to prevent skin cancer, something that takes years to show up.
I decided I would focus on how much of the UV band a sunscreen absorbed and ignore how effectively it blocked that wavelength. When I was able to find the actual UV wavelength of activity for a sunscreen, and verify it in other sources, I used the following criteria:
- if it absorbs at least half of the spectrum, then I listed that UV band (eg., UV-A or UV-B)
- however, if it absorbs less than half of the spectrum, then I clarified that by stating "partially"
Hopefully, if and when the new FDA guidelines become effective, we will have better information on sunscreens. Until then, here's what I hope are accurate details...
Titanium dioxide and zinc oxide are very simple inorganic molecules.
These 2 sunscreens max out at about SPF-30. That's actually pretty effective...for the UV-B band. And they remain on the skin longer than organic sunscreens (Varedi A, et al. 2019).
But note that zinc oxide provides better activity against the UV-A band than titanium dioxide does. In the 1990's, preparations were micronized and "nano-sized". (These nano particles do not appear to be absorbed through the skin.) This overcame the undesirable layer of white paste they leave on the skin, but it also changed the activity of titanium dioxide: UV-B protection improved while UV-A protection worsened (Mancuso JB, et al. 2017).
The FDA and the EWG rate titanium dioxide as "broad-spectrum", implying that it is protective against both UV-A and UV-B. However, WikiPedia lists it as only a UV-B sunscreen. Who's right?
Research supports classifying titanium dioxide as mainly a UV-B sunscreen: one study reported that the effectiveness of titanium dioxide in the UV-A spectrum was marginal (Couteau C, et al. 2009), and 2 other studies reported that it was less effective in the UV-A band than zinc oxide (Beasley DG, et al. 2010) (Pinnell S, et al. 2000).
Particle size may explain why different resources provide conflicting information regarding the UV-A activity of titanium dioxide: A graph in a paper by Dr. Balaji More clearly shows how particle size reduces the ability of titanium dioxide to absorb UV-A rays (More BD. 2007). In the past, titanium dioxide could be considered broad spectrum. But, today, the micronized formulations should be regarded as mainly effective in the UV-B range.
The reduction in particle size did not affect the spectrum of activity of zinc oxide. It is protective throughout the entire UV-B range (290-320), and it has a flat (ie., consistent) absorbance action throughout the UV-A range up to 380 (Mancuso JB, et al. 2017) (Mitchnick MA, et al. 1999) (More BD. 2007). Not only does zinc oxide provide much better protection against UV-A rays than titanium dioxide does, it beats most of the organic sunscreens in UV-A protection as well. Zinc oxide appears to be one of the best of all the sunscreens.
|PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• titanium dioxide ||depends on |
|• UV-B: full spectrum |
• UV-A: unreliable
|• zinc oxide ||290 - 380 ||• UV-B: full spectrum |
• UV-A: protective
up to 380-385
This category includes oxybenzone, one of the most commonly used sunscreens in commercial products. It is primarily a UV-B sunscreen, though it absorbs part of UV-A band: its activity range is 270-350 (Burnett ME, et al. 2011). Some believe that oxybenzone can cause photoallergic reactions. Because of this, the European Union requires products that contain this ingredient must display the statement "Contains Oxybenzone" on the package. However others believe this concern is exaggerated (Mancuso JB, et al. 2017). I found very little research on sulisobenzone. (Avobenzone, though it has a similar name, is not a member of this group.)
|BENZOPHENONES ||UV |
|PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• dioxybenzone ||unclear ||• UV-B: full spectrum |
• UV-A: protective
up to 340
|• oxybenzone ||270 - 350 ||• UV-B: full spectrum |
• UV-A: protective
up to 350
|• sulisobenzone ||unclear ||• UV-B: full spectrum |
• UV-A: partially
These sunscreens are UV-B absorbers. Octinoxate is considered a very strong UV-B agent (Mancuso JB, et al. 2017).
|CINNAMATES ||UV |
|PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• cinoxate ||unclear ||absorbs UV-B ||unknown ||Insufficient|
|• octinoxate ||290 - 320 ||strong UV-B ||unknown ||Insufficient|
This group includes homosalate, octisalate, and trolamine salicylate. These agents are weak UV-B absorbers with no UV-A activity (Mancuso JB, et al. 2017). Trolamine salicylate is not GRASE and is therefore no longer recommended.
|SALICYLATES ||UV |
|PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• homosalate ||unclear ||weak UV-B ||unknown ||Insufficient|
|• octisalate ||280 - 320 ||weak UV-B ||unknown ||Insufficient|
Decades ago, para-aminobenzoic acid ("PABA") was one of the main sunscreens. Derivatives include padimate A and padimate O. Subsequently, safety concerns were raised for PABA. Padimate O is a skin allergen. PABA and padimate O have been removed from the European market. These sunscreens are not recommended and are only included here for historical interest.
|AMINOBENZOATES ||UV |
|PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• padimate O ||290 - 315 ||UV-B ||unknown ||Insufficient|
|• para-aminobenzoic |
|290 - 320 ||UV-B ||unknown ||NO -|
Avobenzone and ecamsule provide good protection against UV-A rays, at least, part of that band. Avobenzone's activity is maximum between 350-360 nm (Kockler J, et al. 2013). Ecamsule's activity is maximum between 340-350 nm (Fourtanier A, et al. 2008). However, neither one is protective above 380 (Beasley DG, et al. 2010) (Fourtanier A, et al. 2008) (Kockler J, et al. 2013). Also, avobenzone breaks down rapidly: its activity is degraded 36% after 1 hour of sunlight.
|UV RANGE ||PROTECTS AGAINST |
UV-A or UV-B?
THRU THE SKIN?
|• avobenzone ||340 - 380 ||absorbs UV-A |
|• ecamsule ||320 - 370 ||absorbs UV-A |
|• ensulizole ||unclear ||absorbs UV-B ||unknown ||Insufficient|
|• meradimate ||320 - 340 ||weak UV-A ||unknown ||Insufficient|
|• octocrylene ||280 - 320 ||absorbs UV-B ||YES ||Insufficient|
G.R.A.S.E.: Generally Recognized As Safe and Effective
In 2015, a study published in the Archives of Environmental Contamination and Toxicology claimed that oxybenzone could damage sea coral. Even though this study was poorly done and is now widely disputed in the environmental community, in July 2018, Hawaii passed a law banning the use of octinoxate and oxybenzone. (How do officials plan to enforce this law?!!) So, as crazy as it sounds, if you plan on competing in an Ironman triathlon, a beach volleyball tournament, or a surfing competition in Hawaii, you might want to look closely at the Ingredients list on your sunscreen product.
6500 COMMERCIAL PRODUCTS!! HOW TO FIND A GOOD ONE
At this point, your head may be spinning trying to absorb all these details. Hang on, because the situation is actually even more confusing...
The authors of a review of sunscreen products published in the August 2016 issue of JAMA Dermatology reported that they found 6500 sunscreen products for sale on Amazon.com!! (Xu S, et al. 2016). Obviously, it's impossible to provide a reliable evaluation of every one of them. So, here are some ways you can find a quality sunscreen product...
Understanding Sunscreen Labels
Read the label carefully. First, make note of the specific active ingredients. Then, consider other claims that might appear on the package:
• A high SPF value is not synonymous with "broad spectrum": As explained above, the SPF rating is based on the ability to protect against only UV-B rays. This is why the FDA recommends that a commercial product has both an SPF rating of at least 15 AND also state that it is broad-spectrum.
• "Sunblock" is a misleading term: In the past, titanium dioxide and zinc oxide were sometimes referred to as sunblocks. However, the FDA now feels that this term conveys "complete" protection to consumers, which is misleading. So, in 2013, they banned the use of the term "sunblock". In fact, it's much more accurate to think of sunscreens as sunlight "absorbers" than as "blockers."
• "Waterproof" is a misleading term: No sunscreen is waterproof...eventually, swimming and especially sweating will remove it from the skin. Instead, the terms "water-resistant" and "sweat-resistant" should be used.
Several sunscreens that are very effective within the UV-A spectrum are available only in Europe. For these, a circular logo displaying "UVA" appears on the label.
Resources that Evaluate Sunscreens
In addition to carefully reviewing details on the product's label, here are several resources that evaluate and rank sunscreens:
• Consumer Reports publishes an annual guide on sunscreens. But note that, in March 2019, researchers from the University of Utah criticized how Consumer Reports evaluates sunscreens and argue that Consumer Reports should not ignore inorganic (mineral) sunscreens titanium dioxide and zinc oxide (Varedi A, et al. 2019).
• Another useful resource is the "Annual Guide to Sunscreens" from the Environmental Working Group (EWG). The Environmental Working Group might not be as well-known as Consumer Reports, but their guide is very good.
Until the new FDA proposed rulings go into effect, and better clinical studies are performed on organic (chemical) sunscreens, here are some recommendations:
The American Academy of Dermatology recommends that all sunscreens meet these 3 criteria:
- possesses broad-spectrum efficacy (ie., ability to block both UV-A and UV-B)
- has an SPF rating of 30 or higher
- is water/sweat resistant
In the JAMA Dermatology study mentioned above, researchers evaluated the top 1% of those 6500 sunscreen products. They found that nearly 40% (26 out of 65) did not meet these AAD guidelines (Xu S, et al. 2016).
In 2013, Consumer Reports began recommending that you use sunscreens with an SPF rating no less than 40.
The AthleteInMe.com® Perspective
When I started digging into sunscreens, I never expected that proof of safety and effectiveness wasn't better established. After all, we've been using sunscreens for decades! Nevertheless, here are a couple fundamental concepts to keep in mind:
• You can't beat zinc oxide: Zinc oxide has been used for sun protection for centuries. It blocks both UV-A and UV-B rays, and, it offers reliable and consistent protection across those 2 UV bands. Within the UV-A band, zinc oxide clearly beats titanium dioxide and most of the organic sunscreens as well. The development of zinc oxide products in "nano particle" form means that you no longer have to deal with a layer of white cream all over your body. So, whatever commercial product you choose, I would recommend that it contains zinc oxide.
• Opt for more protection over less protection: Zinc oxide has an SPF rating of 30. That translates to blocking 96-97% of UV-B rays, which is pretty good. Regarding the UV-A band, zinc oxide provides very reliable protection against UV-A rays up to 380-385.
However, simply focusing on the widest amount of the UV spectrum with just a single agent may not be good enough. And, to be safe, Consumer Reports now recommends using a product with an SPF value of at least 40.
Researchers at L'Oreal in France have shown that combining avobenzone and ecamsule (both UV-A absorbers) with titanium dioxide provided better UV-A protection than a combination of zinc oxide with titanium dioxide (Fourtanier A, et al. 2008). This is interesting because zinc oxide's UV-A activity range extends to 380-385, pretty much the best UV-A coverage of any sunscreen. Avobenzone appears to have UV-A activity up to that wavelength, though its potency decreases sharply from its peak of 350-360 (Kockler J, et al. 2013). Ecamsule appears to not have much activity past 370-375 (Fourtanier A, et al. 2008).
In other words, it's possible that additive, or synergistic, actions occur when multiple agents (eg., avobenzone and ecamsule) are used together, and, this might be more effective than a single agent (eg., zinc oxide), even if that single agent has a very wide spectrum of activity...like zinc oxide does.
So, if you live near the equator, and spend many hours outdoors (especially if you are fair-skinned), then use a product that combines zinc oxide with another sunscreen. Because UV-A rays are now known to also contribute to skin cancer, select a 2nd sunscreen that's effective in the UV-A spectrum. Unfortunately, there's no clear winner in this category. Avobenzone and ecamsule are protective in the UV-A band. However, neither one is active above 380 (Beasley DG, et al. 2010) (Fourtanier A, et al. 2008) (Kockler J, et al. 2013). Also, avobenzone breaks down rapidly. Oxybenzone is the most common active ingredient in commercial products. It absorbs UV-B nearly completely but only part of the UV-A band.
Here's how to think it through: Start with zinc oxide, and then add additional sunscreens:
- For additional UV-A protection: add avobenzone or ecamsule
- For additional UV-B protection: add octinoxate or oxybenzone or titanium dioxide
Avoid These Products
It's a bit easier to identify products to avoid:
• Avoid products with an SPF value less than 15, particularly if you are fair-skinned: The FDA feels these products don't provide enough protection. The American Academy of Dermatology recommends using products with a minimal SPF rating of 30.
• Avoid products that contain para-aminobenzoic acid (PABA) or trolamine salicylate: The FDA has rated these sunscreens as not GRASE. (It is likely that these ingredients have already been removed from marketing.)
• Avoid products that contain derivatives of vitamin A: Retinyl palmitate is an antioxidant that may combat skin aging. However, when applied to the skin and skin is exposed to sunlight, retinyl palmitate may actually increase the risk of skin tumors. For this reason, the Environmental Working Group recommends not using sunscreen products that contain retinyl palmitate. Other vitamin A derivatives to avoid include retinyl acetate, retinyl linoleate, and retinol.
• Avoid products that combine insect repellants with sunscreens: The FDA has rated these products as not GRASE.
• Avoid products marketed as body washes, powders, shampoos, towelettes, or wipes: The FDA does not have any efficacy data on these product forms.
• Avoid products marketed as sprays: The Environmental Working Group recommends not using sunscreen products formulated as sprays; they feel that this formulation doesn't provide enough protection. However, sprays are a good choice for tennis players and pole vaulters. Creams and lotions require athletes to spread them with their hands. Greasy hands are not what these athletes want!
• Discard products that are past their expiration date. If no expiration date is seen on the container, discard if more than 3 years old.
HOW TO USE SUNSCREENS
Even a high-quality product won't be very effective if you don't apply it properly. Here are some tips:
• For best results, apply sunscreens 15 minutes before going out in the sun.
• Apply a very generous layer!
• Don't forget ears, the back of the neck, and, if you're barefooted, the tops of your feet.
• Reapply sunscreens every 2 hours, and more often if swimming or perspiring.
• Do not spray aerosol forms directly to the face: they may get into your eyes. Instead, spray on your hand and wipe your hands on your face. (Note that the Environmental Working Group does not recommend sprays.)
No sunscreen is 100% effective. So, also wear a hat and protective clothing.
FOR MORE INFORMATION
The American Cancer Society's web site doesn't have much consumer information on sunscreens. But the FDA does:
The full February 21, 2019 FDA proposal appears in The Federal Register, though it is 72 pages long! Their Press Release and Fact Sheet, issued on the same date, provide a decent overview.
The FDA offers this informative consumer resource on sunscreens: "Sunscreen: How to Help Protect Your Skin from the Sun."
The Environmental Working Group (www.EWG.org) has 8 helpful tips on sunscreens here.
WikiPedia has a thorough monograph on sunscreens. See: "Sunscreen".
Readers may also be interested in these reviews:
EXPERT HEALTH and FITNESS COACHING
Stan Reents, PharmD, is available to speak on this and many other exercise-related topics. (Here is a downloadable recording of one of his Health Talks.) He also provides a one-on-one Health Coaching Service. Contact him through the Contact Us page.
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ABOUT THE AUTHOR
Stan Reents, PharmD, is a former healthcare professional. He is a member of the American College of Lifestyle Medicine (ACLM) and a member of the American College of Sports Medicine (ACSM). In the past, he has been certified as a Health Fitness Specialist by ACSM, as a Certified Health Coach by ACE, as a Personal Trainer by ACE, and as a tennis coach by USTA. He is the author of Sport and Exercise Pharmacology (published by Human Kinetics) and has written for Runner's World magazine, Senior Softball USA, Training and Conditioning and other fitness publications.
DISCLOSURE: Neither the author, nor AthleteInMe, LLC, has any relationships or affiliations with any of the products or manufacturers mentioned in this review.
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