My Homemade Sunscreen Experiment

Why, might you ask, did I attempt to try to make my own sunscreen?  Boredom on vacation?

I think many of us are attracted to do-it-yourself home remedies.  They seem cheaper and it might make sense to use things that are already in the cupboard. For instance, apple cider vinegar seems to be the internet/Facebook “cure-all” – it can fix everything!  Pretty soon I started noticing links for how to make your own sunscreen.  I haven’t tried apple cider vinegar yet, but had to try this one.

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My homemade sunscreen experiment.  Can anyone spot the most essential ingredient in the realization of this blog?  Hint – it’s in blue (baby monitor a.k.a nap time).
But does it really work?  In the case of sunscreen, I wanted to find out for myself.

Those looking for natural or organic solutions are particularly ripe for getting misinformation or potentially dangerous advice.  There are MANY excellent natural solutions, but usually those giving advice  (i.e. your friend on Facebook) don’t have any medical background, making it hard to vet what is SAFE and effective.

As many of you already know, I’m very passionate about sun protection, and wanted to make sure that people weren’t getting bad information.  I was optimistic, hoping to be surprised!  With this in mind, I set out to make my own sunscreen.

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Zinc oxide powder ready to be added to the base.
Here were the pros:

  • It was relatively easy and fast to make.
  • There were only a few ingredients, which should please simplistic and naturally oriented people. (Ingredients: coconut oil, shea butter, zinc oxide, pomegranate oil, and lavender oil).
  • I did not burn while wearing it for 2 hours in the noon Florida summer sun.

Here were the cons:

  • It cost me $57.70 to get all the materials!  
  • It was messy to apply.  Commercially formulated containers exist for a reason. Next time I would transfer it to a squeeze bottle.
  • Forget re-applying (one of the most common mistakes people make is not reapplying their sunscreen) – it would be way too messy to transport this DIY sunscreen.
  • I felt like a human version of “Slip-N-Slide” after applying.  The texture was way too greasy for my taste.
  • The true SPF of the concoction is unknown – a major no-no for me.
  • The stability and expiration date is unknown – I would guess that you could keep this mixture for 60 days, and then have to repeat the process. (I have absolutely no data to support this, which is the point… how do you know if it’s still good?)
  • The ingredients separated after mixing – not a big deal – just required mixing again before applying. A few days later the mixture was more consistent and paste like.
  • I would not recommend using this on your face if you are break-out prone. The oils might cause an acne flare.

My conclusions:

Save the $57.70, buy a $15 sunscreen with SPF 30+ and UVA protection, and use the rest of the $$ for a good sun shirt!  (Find my sun shirt picks here!)

And a last few words.  Some websites advocate using coconut oil alone as sunscreen – this is NOT OK!  Coconut oil has an SPF of about 4-6.  Would you ever consider buying a sunscreen with SPF 5?  No, so don’t consider it adequate protection for your skin.  The American Academy of Dermatology recommends a broad-spectrum sunscreen with an SPF of at least 30.  We are talking about a serious cancer risk (1 in 5 Americans will develop a skin cancer in their lifetime), as opposed to any hypothetical concerns about ingredients – see my in-depth post about sunscreen safety here.  The mixture above includes zinc oxide powder to beef up the SPF.  Even easier, you can also very easily find some simple commercial sunscreens with zinc oxide.

While my experiment “worked” in that I didn’t get burned, the practical aspects of the homemade sunscreen made it a no-go for me.  It was too expensive, too greasy, too messy, and in my humble dermatologist opinion, a little too risky for me.  I’m ok with using a homemade milk mask, but I don’t like risking DNA damage to my skin cells because I messed up the SPF formulation.  I’ll leave that to the experts.

It takes just two painful sunburns to increase your risk of melanoma, so for me, it’s really not ok to experiment with sun safety.  I did it for you, so that you won’t have to!

In the end, my main message is to use something that you know has an SPF of over 30, reapply every two hours, and practice sun safe behaviors.

Dr. Jacquelyn Dosal is a Board-Certified Dermatologist practicing dermatology in Miami, FL at Skin Associates of South Florida and is a voluntary Assistant Professor at the University of Miami.

The Best Sun Protective Clothing – and why you should wear it!

After many years of battling with unpleasant sunscreens, I have finally come around to the notion that sun clothes (clothes that have built in SPF, or more technically, UPF) are much more convenient and more effective and protecting from UV damage.  And most surprisingly, I am MUCH COOLER in the sun when I wear a long sleeve sun shirt!  New technology has made sun protecting clothing the ultimate multi-taskers; protecting from UV rays, cooling down the skin, wicking away moisture, and ventilating at the same time.

I think it would have been tough if I was still a teenager, dealing with the peer pressure to sunbathe in an itty bitty bikini, to instead wear a full coverage sun shirt.  But I should give our society more credit.  More and more people are starting to realize that the sunbathing you do as a youngster to “look good,” or “have a base tan,” is passé.  Pale is beautiful, and the very sunbathing done for aesthetic purposes has very ugly consequences even as short as 15 years later (think sun spots, wrinkles, blotchy skin).

Here are some benefits of UV clothing:

  1. You feel COOLER in the sun!  Amazing, but true.
  2. You don’t need to reapply sunscreen!  Who wants to reapply every two hours?
  3. You won’t miss any spots and have awkward geometric burns on your back.
  4. Prevention of skin cancer and skin aging.

So, here are my reviews and recommendations of some of the best sun protecting clothes that are cute and fashionable.

Coolibar – the company performs vigorous testing on all lots of clothing to ensure excellent UV protection. These were my first sun shirts.

Columbia – OmniShade and Omni-Freeze Zero – One of my personal favorites.  The Omni-Freeze Zero technology cools down a person when exposed to sweat.  We find it most commonly in their Performance Fishing Gear.  Great for the beach or any hot day.  My family knows that if it’s hot out, my hubby will only be wearing this shirt.  It’s now a joke that he doesn’t own any other clothes.

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Good dermatology family!  We are covered up and cool (both temperature-wise and figuratively). My hubby is sporting his favorite Columbia shirt.

UV Skinz – nice selection of outerwear for the family (nice kids selection), plus sun “sleeves” which are great for driving, gardening, golfing, etc.  I just bought some of the sleeves for myself and my husband!  Plus I LOVE their May Skin Cancer Awareness campaign – any purchase comes with a free baby sun shirt!

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UV Skinz Save a Baby’s Skin Campaign – free baby sun shirt with any purchase during Skin Cancer Awareness Month (May).

Lands’ End – I was surprised myself, but after seeing a tweet by Deborah Messing, I checked them out.  They have surprisingly cute swim wear!

SwimZip – As seen on Shark Tank.  This company makes it easy to find cute swimwear with zippers – we all know how hard it is to take off a wet bathing suit from a squirmy toddler!  SwimZip makes it super easy.

Mott50 Sun Protective Fashion – Co-founder Anne Reilly wanted to capitalize on the more noticeable trend of young ladies covering up.  Nice variety of casual and swim wear for women and kids.

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Dr. Dosal modeling a Bloxsun scarf at the Miami Open 2015

BloxSun – a local Miami company, offering beautiful UPF scarfs to cover you up in any occasion.  Check me out modeling my scarf at the Miami Open, where the sun can be unbearable.  This beauty kept me cool!  I also use their sun gloves while driving and gel manicure to keep my hands looking young.

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SunSoaked – Australian beach outwear line.  Designed to offer more fashionable, feminine, elegant sunwear.

Cover – Founded by the sister of a melanoma survivor and former investment banker, founder Lisa Moore offers luxury sun protective clothing that is runway worthy.

SanSoleil – makes golf, tennis, and other sports apparel out of Newport Beach, CA.

BloqUV – Excellent beach and sporting apparel. Great selections for golf, tennis, running, yoga, swim.

Any clothing with “Coldblack” – coldblack is a special dye added to clothing to reflect light and infrared heat.  Used to keep men cool in dark suits, it also provides a UPF factor of 30 to its clothing.  It can notably be found in Ermenegildo Zegna suits and in Under Armour golfing wear.

These retailers have earned the Skin Cancer Foundation’s Seal of Recommendation for sun protective clothing and hats.

  • Boys Scouts of America
  • Columbia Sportswear
  • Coolibar
  • J. Crew
  • Lands’ End
  • O’Neill Wetsuits
  • Quiksilver
  • Roxy
  • Specialized Bicycles
  • Sundrive
  • Wollaroo Hats Company (I like their hats a lot)
  • Whitworth Hats

I encourage you to pack (and wear) a sun shirt the next time you are going to be somewhere sunny.  I think you will be pleasantly surprised how much you like it!

References

The Skin Cancer Foundation Journal, Vol XXXII, 2014.  skincancer.org

Dr. Dosal is a practicing dermatologist at the Skin Associates of South Florida in Miami, FL.  She is also on voluntary faculty at the University of Miami.

I LOVE my Gel Manicures! But should I worry?

I LOVE my gel manicures!  Lasting at least two weeks, gel manicures have finally made my pincers look pretty!  Like many of you, I had been wondering about the safety about the UV lamps that are used to cure the gel manicures.  They seem fairly benign, but there has been some press questioning its safety. nail polish

When I read a recent issue of JAMA Dermatology, I was relieved to read that the authors concluded that the risk of skin cancer was very very low with gel/UV manicures, even with regular use.  This is what I suspected, so I stopped worrying.  Additionally, my salon recently introduced an LED nail lamp, which also seemingly solved the issue of the UV lamp.

Well, imagine my surprise when this topic came up again at the most recent American Academy of Dermatology Annual Meeting.  Nail expert Dr. Chris Adigun reopened my concerns about the safety of UV lights. She argued that the lamps are notoriously variable in their UV exposure, nail salons hardly ever follow manufacturer recommendations, and that the UV exposure is more than we previously thought.

This really left me conflicted, since I adore my gel manicures, and I really hadn’t prepared myself to abandon them anytime soon. So I took it upon myself to read through all the relevant articles on the subject (I hate taking someone else’s word for it).  Luckily, several groups have studied a variety of nail lamps, with a variety of hand positioning and exposure times.

Here’s the summary:

The amount of UV exposure is WAY below anything close to skin-cancer-causing levels.  

Here are a few other important take-away points:

  • Out of 72,709 women getting regular manicures for 60 years (assuming generous exposure times), only one woman would develop skin cancer who wouldn’t otherwise (in statistics, this is called the “number needed to harm”).
  • It would take 250 years of weekly gel manicures to equal that of a therapeutic phototherapy session that I commonly prescribe for psoriasis (15–30 treatments over 5–10 weeks).  (Yes, phototherapy is often UVB, rather than UVA, but this JID study measured UV dose in J/cm2, and gives a risk comparison to something we already know to be safe).

From a skin cancer perspective, the risk of skin cancer from nail curing lamps is very low.  However, it is important to note that ALL lamps used to cure gel manicures emit UVA radiation, even the LED lamps.  Despite the lack of “UV” in the name, LED lamps are actually more intense than UV lamps and emit more UVA.

As a quick review: UVB rays cause sunburn and skin cancer, while UVA rays penetrate deeper into the skin, causing skin aging, cell damage, sun spots, and wrinkles by breaking down collagen and elastin (and to a lesser degree than UVB, also contribute to skin cancer).

UVA UVB infographic
UVA penetrates deep into the skin to affect collagen and elastin, causing wrinkling, blotchiness, and poor skin tone.
UVA radiation is responsible for the brown spots (“liver” spots or “sun” spots) on your grandmother’s hands, as well as the wrinkles and crepiness of the skin.

There’s nothing worse than a youthful face that has been preserved with good skin care, but “old” looking hands.  

While the risk of skin cancer is much less than ambient exposure to natural sunlight, the cumulative effects of UVA exposure can result in discoloration and premature aging of the skin.

 

Aging hands
The typical appearance of a photoaged hand.  Note the blotchy appearance of the skin, brown spots, and thinned skin overlying the veins and tendons of the hand.  This occurs with regular exposure to UV light, especially UVA, which is emitted in all nail curing lamps and penetrates windows.
So your gel manicure won’t significantly increase your risk for skin cancer, but why risk any UV exposure?

For the very sake of preserving the youthful appearance of your hands, I recommend at least the application of a broad-spectrum sunscreen with an SPF of 30+ (see here for recommendations), or sun gloves while having your hands in the lamp.  My feeling is the gloves are better.

  • I use these sun gloves made by BloxSun– I wear them driving and bring them to the salon. 
  • Screen Shot 2016-02-08 at 1.14.25 PM
  • YouVee sunshields are currently crowdfunding – they are very cheap disposable hand protectors that block 99% of all UV radiation.  Wouldn’t it be great if salons started carrying these?
    2e0973_49bb9c8432144cb7809de96894bdcdf2

 

In summary, I’m going to keep getting my gel manicures (thank goodness)!

For many of us women on-the-go, the gel manicure is here to stay!  Just be sure to protect those hands! And as with anything, it’s good to take a break once in a while from manicures to give your nails a breather.

Dr. Jackie Dosal is a practicing dermatologist in Miami, FL at the University of Miami and Skin Associates of South Florida.  

 

References

Shipp et al.  Further investigation into the risk of skin cancer associated with the use of UV nail lamps.  JAMA Dermatology 2014;150(7):775-6.
Diffey BL.  The risk of squamous cell carcinoma in women from exposure to UVA lamps used in cosmetic nail treatment.  British Journal of Dermatology 2012;167:1175-1178.
Markova A, Weinstock MA.  Risk of skin cancer associated with the use of UV nail lamp.  Journal of Investigational Dermatology 2013;133:1097-1099.
Macfarlane DF, Alonso CA.  Occurrence of non melanoma skin cancers on the hands after UV nail light exposure.  JAMA Dermatology 2009;145(4):4479.
Curtis J, Tanner P, Judd C, Childs B, Hull C, Leachman S.  Acrylic nail curing UV lamps: High-intensity exposure warrants further research of skin cancer risk.  J Am Acad Dermatol 2013;69(6):1069-70.
Dowdy JC, Sayre RM.  Nail curing UV lamps: Trivial exposure not cause for public alarm.  J Am Acad Dermatol 2015;6(64):e185-6.

The dangers of sunscreen – A dermatologist’s perspective.

Is my sunscreen going to kill me? Perform a search on sunscreen safety and some scary stuff shows up! Retinyl palmitate causes skin cancer. Oxybenzone causes estrogen-like effects on the body. I have seen these statements repeated over and over again all over social media and in real life. I recently heard from a patient, “I was using Neutrogena but then stopped because I heard it wasn’t so good for you.” How do we protect ourselves and our families from skin cancer without any nasty side effects?

avocado organic

I’d like to offer up my take — from a organic-loving, Whole-Foods-shopping, yoga-practicing, green-tea-drinking MD (dermatologist), with an eye for interpreting both media and science…

For those not able to read the whole post (we are all busy, I know!), here’s the quick summary of my findings. You can read on for more info too!

Sunscreen won’t cause hormonal disruption — it would take 200 years of application to even reach questionable levels of exposure.

Sunscreen won’t cause skin cancer — the use of sunscreen is directly correlated to the prevention of skin cancer. Retinyl palmitate is an anti-oxidant that occurs naturally in the skin.

Nanosize sunscreens are safe for use, as they clump in real life, preventing them from being absorbed.

I’ve researched the issues of sunscreen safety personally, and WOW! It’s confusing and contradictory. I’ll at least say this— we always need to critically and scientifically analyze the sunscreen ingredients we use for both efficacy and safety. And just as important, let’s not perpetuate myths that are based on unsound science. If you are interested in sorting through the muddy waters of sunscreen information — read on!

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Environmental Working Group’s Rankings of Sunscreens.

Most of the information about safety stems from the Environmental Working Group’s sunscreen rankings. The Environmental Working Group is a not-for-profit organization that searches to identify harmful chemicals in our environment. While I applaud the intentions of the EWG to find safe and environmentally responsible materials, we need to be fair and look at these issues seriously, and not just solely how presented by the EWG.

Do sunscreens cause hormonal disruption?

The EWG advises avoiding any products with oxybenzone (an excellent UVA and UVB blocker) as it may cause effects similar to estrogen. The concern comes from a study performed in rats, where the rats were fed supratherapeutic doses of sunscreen (let me say that again, the rats ATE sunscreen at megadoses), and the size of their uterus enlarged.

graph from oxybenzone study 4
Edited graph from PMID 11333184

There is a monstrous difference between eating super high doses of sunscreen and applying it to your skin daily — and concluding that topical use in human sunscreen causes estrogenic effects is an unrealistic stretch. A study in 2011 in JAMA Dermatology showed that it would take 200 years of daily sunscreen application to reach the same amount of exposure as the rats in this study. To the author’s credit, their word-for-word conclusion in the abstract was: “Our findings indicate that UV screens should be tested for endocrine activity…” The authors do not say that the UV screens cause hormone activity in humans… they can’t. In order to substantiate their EWG’s claim, you would need to show hormone disruption in real live humans.

Luckily, such a study was performed. Human patients applied more than 3 times the real-life quantity of a high percentage oxybenzone sunscreen (10% oxybenzone, compared to the commercially available 6% oxybenzone) to their whole body daily for one week. Oxybenzone was in fact detected in the urine of the volunteers (as have some other sunscreen agents). Sound the alarm bells! — this is concerning. It indicates that there is some absorption from topical use (medications that are applied directly to the surface of the skin). However, the body quickly excreted it through the urine (which is a good thing). Much can be said about the fact that it was absorbed, but the take-home message was that the researchers were UNABLE to show a hormone disruption despite this absorption (again, this was at 3 times real-life dosage). There was no accumulation of the ingredients over time.

So we have a study in humans of real-life sunscreen use that shows no hormonal effect, or a study where rats ate sunscreen — which do you believe?

To be fair, when researching this blog post, I did come across an alarming number of lab and animal studies showing absorption of various sunscreen agents, with some experiments suggesting hormonal disruption. There were almost as many studies that showed no absorption nor hormone disruption. A good summary of those studies can be found here. But we have to look at what’s important… no human studies have shown hormonal disruption, and that is what counts.

Of note, it is important to mention that oxybenzone can cause allergic skin reaction in a fair percentage of people, so there should be some caution with its use.

And by the way, soy is weakly estrogenic. Where are the cries for banning or avoiding soy milk because of hormonal activity? There are many natural skin care products on the market containing soy, several of which I recommend and are excellent. A little perspective is important, and we need to remember that topical use is very different from ingestion.

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Let’s move on to sunscreen and skin cancer.

sunscreen bottle

Does my sunscreen increase my risk of skin cancer?

A few years ago there was media buzz about a toxicology study that suggested that retinal palmitate, a common inactive ingredient in sunscreens, may actually increase your risk for skin cancer by increasing oxidative damage, or reactive oxidative species (ROS). Oxidative damage is like rust on metal — it corrodes our body and makes us more prone to inflammation and cancer. Let’s dive into this deeper.

Retinyl palmitate is an interchangeable form of retinol that is present naturally in our skin, and this should already be a clue that it’s not dangerous. Retinyl palmitate is not just in sunscreens; is approved by the FDA for use in prescription and over the counter medications, as well as a food additive in dairy products and cereals. It was selected for testing due to its prevalent use in common agents, not for any concerns of safety up to that point.

Once again, we have to look at the details of the study that created the buzz. It was never published in a peer-reviewed journal (the standard for medical literature — data needs to be vetted by people in-the-know), and was not performed in humans (also a huge red flag). It was performed in hairless mice, known to have an already increased risk of skin cancer, and these mice were burned with and without retinyl palmitate (RP). The studies showed the production of oxidative damage and increased risk of malignancy. However, these studies take RP out of human context, which is a very complex interactive antioxidant system. According to Dr. Steven Wang, the lead investigator in the study, “when a sunscreen with retinyl palmitate is applied to the skin, a number of antioxidants work together to alleviate the risk of free radical formation seen in these in vitro experiments. If studied on its own — outside of this environment — its antioxidant properties can rapidly be exhausted, allowing the production of oxygen radicals. In these non-human studies, retinyl palmitate was the only compound studied — making the biological relevance of these findings to humans unclear.” Even the lead investigator is not ready to recommend avoiding retinyl palmitate.

The final and probably most convincing evidence of the safety of retinyl palmitate comes from real life use in humans. We often use the family of retinoids (of which retinyl palmitate is a member), as a pill for the prevention of skin cancers in those most at risk (immunosuppressed organ transplant patients). We also have decades of experience using retinoids in acne medications; and topical retinoids are one of the best anti-aging creams on the market — I personally use one (Retin-A) every night. Undeniable human research shows it can reverse oxidative damage and signs of aging, keeping the skin healthy and youthful.

If you are interested in more, I encourage you to read this summary by the Journal of the American Academy of Dermatology detailing the properties of retinyl palmitate and discussing its safety.

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What are nano particles, and are they safe?

Nanoparticles are molecules that have been divided into nanometers (one billionth of a meter). By making the molecules small, it makes sunscreens more cosmetically acceptable and elegant, thus making it more attractive for people to use (i.e. not thick, sticky, or opaque like the old sunscreens found on lifeguards’ noses).

lifeguard troll nose
Photocredit: http://etsy.me/1D3PcyJ

Concerns arose that these molecules might be small enough to penetrate through the skin into the bloodstream. Time and time again, human studies have shown that these particles are unable to penetrate through the skin because, in nature, these nanoparticles aggregate into clumps that are too large to penetrate the skin. There was also some thought that these ingredients could increase reactive oxidative species (ROS). We now know that this is meaningless if tested outside of the complex human antioxidative system. With this in mind, we should all embrace these new technologies that makes sunscreens less opaque, pastey, and more consumer friendly!

nanoparticle aggregates
Nanoparticles clump on the skin.  Photo credit: PMID 22123418

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Be Cautious of Media Sound Bites

mediaThe EWG extrapolates data (usually from animal studies, not humans), and uses scare tactics to make us feel like we are hurting our children if we use certain products. What I don’t like is that they ignore actual sound studies that show safety in humans. Their sound bites are alarming and catchy for headlines. I’ve actually seen website titles citing the EWG reading: “The Most Dangerous Sunscreens For Kids (And They’re Probably Hiding in Your Beach Bag).” Talk about mommy guilt!

I love this story which explains why we need to critically interpret how the media presents headlines: Chocolate Causes Weight Loss!

chocolateweightloss
http://io9.com/i-fooled-millions-into-thinking-chocolate-helps-weight-1707251800

Background: A scientist wanted to show just how easy it was to convince the media to pick up a poorly designed faux scientific experiment that was catchy for headlines. It was a completely fake, but intriguing idea — eating chocolate can help loose weight. It turns out, it was really easy to get experienced journalists to pick up the headline! Read here: I Fooled Millions into Thinking Chocolate Helps Weight Loss. A critical eye is really needed in these days of rapid information sharing.

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What does this all mean?

I don’t agree with the EWG rankings. Many of the poorly ranking sunscreens are very reputable and excellent brands. You can’t take the data from one animal or lab study and ignore other science and human experiments that are in disagreement. That’s not how science works. That’s the reason why thousands of drugs that work in animals never get to the market — because animal studies and in vitro studies often don’t translate into efficacy in the complex environment of the human body.

While in general, I’m in favor of the organic movement, real foods, and responsible farming practices, I often laugh when I see websites recommending chemical-free everything, including sunscreens. Chemicalsare in everything, and there is no such thing as a purely chemical-free susncreen. Of course, live in moderation — extreme use of any susbtance can lead to some bad effects, but to say that normal day-to-day use of products causes the same effect seen with extreme use or oral ingestion doesn’t make any sense.

As this EXCELLENT video describes, the dose is the poison, not the chemical itself. Almost any substance, including natural or beneficial substances, can be toxic under certain conditions, such as high temperatures, pH, concentrations, or when in the presence of other chemicals. Even too much Vitamin C can be lethal to skin cells at certain doses. The age-old mantra still holds true — everything in moderation.

Let’s thank the EWG for their laudable efforts in keeping us safe, but ask them not to demonize valuable products when the science shows otherwise. I completely agree that more testing needs to be done on household and cosmetic ingredients, but I wish they were a little more unbiased when it came to promotion of their agenda. And the media perpetuates these news snippets with negligible investigation into the validity of the EWG claims. It serves our society poorly.

Feel good about protecting your family — and apply that sunscreen this summer!

This article was originally posted on http://www.medium.com/@jackiedosalmd on July 29, 2015.

Dr. Jackie Dosal is a board-certified dermatologist practicing in Miami, FL.  About Dr. Dosal: http://goo.gl/hbgqZW

References

www.EWG.org/2015sunscreen

Hayden CG, Roberts MS, Benson HAE. Systemic absorption after topical sunscreen. The Lancet. 1997;350:863–4.

Janjua NR, Mogensen B, Andersson AM, et al. Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl-benzylidene) camphor after whole-body topical application and reproductive hormone levels in humans. J Invest Dermatol. 2004 Jul;123(1):57–61.

Janjua NR, Kongshoj B, Andersoon Am, Wulf HC. Sunscreens in human plasma and urine after repeated whole-body topical application. J Eur Acad Dermatol Venereol. 2008 Apr;22(4):456–61.

Krause M, Kilt A, Blomberg Jensen M, et al. Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV-filters. Int J Andrology. 2012:35:424–436.

Schlumpf M, Cotton B, Conscience M, et al. In vitro and in vivo estrogenicity of UV screens. Environmental Health Perspectives 2001;109: 239–244.

Wang SQ, Burnett ME, Lim HW. Safety of oxybenzone: Putting numbers into perspective. Arch Dermatol 2011;147(7):865–866.

Wang S, Dusza SW, Lim HW. Safety of retinyl palmitate in sunscreens: A critical analysis. J Am Acad Dermatol 2010; 63;903–6.

Wang SQ, Tooley IR. Photoprotection in the Era of Nanotechnology. Semin Cut Med & Surg. 2011;30:210–3.

http://www.cosmeticsandtoiletries.com/regulatory/uvfilters/49695482.html