Everywhere you go, you hear about the benefits of sunscreen. When I was younger, I wore sunscreen when I needed it, but I also rubbed the dark tanning oil (SPF 6) all over myself in order to get a better tan. Now, I don’t go anywhere without sunscreen at least on my face.
But how do you know what the best sunscreens are? What’s the difference between SPF 15 and 50? Do all sunscreens block both UVA and UVB rays? What the heck are UVA and UVB rays? And why do we care??
I did a little research and found that in June 2011, the FDA changed some of the regulations for sunscreen. With these new regulations, the FDA recognizes that sunscreens (as long as they are approved by the FDA) help to prevent sun burns, skin cancer, and early skin aging- all the things you want from a sunscreen! Also, no new sunscreen can be labeled as SPF (sun protection factor) higher than 50. If it’s lower than 15 it must carry a warning that it may not prevent skin cancer or skin aging. These changes will take effect in December 2012.
All new sunscreens are going to be ‘broad spectrum’. What this means is that the lotion will block both UVA and UVB rays. In general, UVA rays are thought to contribute to skin again while UVB rays are the ‘bad’ ones that cause burning and cancer. But, now we know that UVA rays over time can contribute to skin cancer as well. You might wonder how exactly the sun rays are causing all these problems like aging, cancer, and sunburns. Here’s a simplified explanation:
When sunlight hits your skin, there is energy in the light particles (photons) that can do a few different things. The light energy from UVA rays doesn’t penetrate your skin as deeply as UVB and therefore doesn’t directly damage DNA. But it does cause indirect damage. It does this by creating free radicals and reactive oxygen species. If chemistry class was 10 years ago for you, all that means is that the light hits different molecules in your body, knocks off electrons and causes molecules to become charged. These charged particles are super reactive and run around injuring proteins, cell membranes, and even causing strand breaks in your DNA.
UVB rays can directly hit your DNA and cause nearby base pairs to form thymine dimers. Thymine what? A thymine dimer means that 2 bases in your DNA pair next to each other instead of across from each other and form a little bulge out of the side of your DNA. That mis-pairing causes your DNA to function improperly. When your body tries to repair these dimers, it can accidentally replace the bases with different ones and suddenly you have a mutation in your DNA! When enough of these little mutations add up, your risk for skin cancer sky rockets.
Source:
Many people are concerned about the potential negative health effects from the ingredients in sunscreen. PABA, Oxybenzone, and other chemicals have raised public attention for some negative side effects seen in animal studies. These studies were done using extremely high oral doses and therefore don’t represent the risk to humans from topical application. As of today, the FDA considers these ingredients to be safe at the doses authorized for sunscreen. It’s great to be wary of chemicals and what you put into and on your body- but the benefits of using sunscreen definitely outweigh the risks.
Some eye-opening statistics:
1 in 5 Americans will develop skin cancer in their lifetime
13 million people are living with a history of either squamous or basal cell carcinoma
58 million Americans are affected by actinic keratosis (a pre-cancerous lesion)
Current risk for developing invasive melanoma is 1 in 58
Some controversies:
Many people say that because sunscreen reduces sunburns, it encourages people to stay outside longer and therefore increases the risk of cancer. In 2010, a study by Green et al. followed 1,621 Australians over 4 years. Half of the participants were instructed to apply sunscreen daily and the other half were instructed to apply sunscreen at their discretion. 10 years after the 4 year study was complete, there was a 50% reduction in melanoma in the group that applied sunscreen daily.
Vitamin D has been shown in countless studies to benefit one’s health in about a billion ways- it’s basically the new wonder vitamin. So does wearing sunscreen deprive you of all that great D?? This is actually a huge topic and one that I’d like to write about in another science post.
What do you think?
Do you wear sunscreen every day? Do you worry about skin cancer or skin aging? Do you worry about harmful chemicals in sunscreen?
Let me know!!
Resources:
Making Sense of Sunscreen Controversies from Medscape Education Dermatology
Archives of Dermatological Research: DNA Damage After Acute Exposure of Mice Skin to Physiological Doses of UVB and UVA light
Halliday GM, Byrne SN, Damian DL (Dec 2011). “Ultraviolet A radiation: It’s role in immunosuppression and carcinogenesis”. Semin Cutan Med Surg 30 (4):214-21
Eva Victoria says
Hi Andrea,
I have a few comments to your article here:
“The light energy from UVA rays doesn’t penetrate your skin as deeply as UVB and therefore doesn’t directly damage DNA.”
This is wrong. UVA (320-400 nm) has longer wave-length than UVB (290-320nm). UVA has less energy than UVB. Both UVA and UVB rays can damage DNA. UVB damages DNA that is reversible by the repair enzymes of the body. UVA damages DNA that is irreversible.
“As of today, the FDA considers these ingredients (PABA, Oxybenzone, and other chemicals) to be safe at the doses authorized for sunscreen. It’s great to be wary of chemicals and what you put into and on your body- but the benefits of using sunscreen definitely outweigh the risks.”
This is wrong too. We now know that many sunscreen agents are more oxidizing than UVR rays can be alone. Sunscreen agents like OCR and AVO are the most notorious free-radical producers in the presence of UVR.
The FDA should act and allow modern sunscreen agents like Tinosorb S and M to be marketed in sunscreens in the US as well. These sunscreen agents are photo-stable as well.
The only US alternative today is ZnO (Zinc Oxide) that provides reliable and photo-stable UVA protection covering the whole UVB and UVA II and nearly the entire UVA I spectrum.
(I still agree with you that using a broad-spectrum photo-stable sunscreen every day will have more benefits for your skin in the long run than not using any. Though the main line of defense should be avoiding the sun and protection with clothes, broad-rimmed hat, sunglasses and sunscreen on areas that cannot be covered).
“If it’s (sunscreen) lower than 15 it must carry a warning that it may not prevent skin cancer or skin aging. ”
It is also a misinformation. An SPF 15 sunscreen cannot be labeled as prevent skin cancer and skin aging according to the new regulations. The sunscreen has to be greater than SPF 15.
Good luck with your work! 🙂
Kindest regards,
Eva V. Sandnes
(R&D, sunscreens from Norway, who actually knew you as a child back in Sarasota 🙂 )
aawenzel says
Hi Eva! Thank you so much for your comments. I really appreciate it. You know so much about this field! I want to address some of the things you wrote.
I agree with you that UVA rays are longer than UVB rays. I also agree with you that UVA has less energy- and therefore penetrates less of the skin. I went on to write that both UVA and UVB rays damage DNA but in different ways. If you read on in that section, you will see that I wrote about UVA rays causing indirect damage through free radicals and UVB rays causing damage by creating dimers in the DNA.
In your next comment, I think it is your personal opinion when you write “the FDA should act and allow modern sunscreen agents…”. Whether or not the sunscreen agents are safe, I was simply reporting what the FDA has approved for sunscreen. My information is correct.
I wrote that SPF lower than 15 cannot be labeled as preventing skin cancer and skin aging. What I should have written is SPF 15 and lower. Thank you for pointing this out.
Thanks again for your comments! 🙂
Andrea
Eva Victoria says
One more thing: the ideal sunscreen would have an even protection in the UVB and UVA II and UVA I range. Most US sunscreens are UVB-biased. Most EU sunscreens at least protect 1/3 of the given SPF (UVB protection) in the UVA range (min. up to 370 nm).
It you are interested in sunscreens I can mail you some very interesting presentations from Uri Osterwalder (the “father” of the Tinosorb filters, researcher at Ciba Chemicals, Basel now part of BASF).
Artwelo says
the general rule is that you suhlod use at least a 30 SPF sunscreen. If you want a really good sunscreen, you suhlod look under the ingredients for sunscreens that have zinc oxide, titanium dioxide, or oxybenzone. The sunscreen suhlod also protect against UVA and UVB rays. UVB rays cause sunburn and UVA rays penetrate the skin on a deeper level. Both rays can cause cancer. As for the SPF, for a person that would be burned after 10 minutes in the sun unprotected, they would be able to stay in the sun for 250 minutes without being burned if they applied a sunscreen with 25 SPF. The reccomended time between sunscreen applications in 2-3 hours.Hope this helps!
Anonymous says
Since you are interested in sun protection, I would recommend you reading this very interesting publication.
Clinical Guide to Sunscreens and Photoprotection (Basic and Clinical Dermatology)
http://www.amazon.com/Clinical-Guide-Sunscreens-Photoprotection-Dermatology/dp/1420080849
Mauro Budzyna says
Usually, sunburn symptoms continue to get worse in the first 24 to 36 hours after the sunburn. Sunburns start to go away over 3 to 5 days. Severe sunburns can be serious in babies, small children, and older adults because of their sensitive skin and their high risk for other problems.`^`.
See all of the latest post at our very own web site
<http://healthdigest101.com/
Wilburn Willwerth says
During the past decades doctors have become increasingly aware of the increase in skin cancer in the United States and that all people need to protect themselves from ultraviolet radiation (UV). The harm caused by UV includes premature aging (such as wrinkling and age spots), skin cancer, and permanent, sometimes blinding, damage to eyes.-“..^
My web-site
<http://healthdigest101.com/index.php
Michael Polidori says
Mayo Clinic recently stated that despite sunscreen use over the past 40 years melanoma has increased 6 fold (8 fold in women and 4 fold in men).
The American Cancer Society, while primarily blaming sunlight for skin cancer doesn’t address the rising incidence. The ACS does admit that immune supressing drugs can play a role (like Humira, for psoriasis) Immune suppression increases diagnosed skin cancers by interfering with the bodies natural ability to detect & destroy cancerous cells. There is large class of drugs which suppress our immune systems to stop damaging autoimmune diseases (some of which are caused by drugs or vaccines). Humira, Enbrel, Remicade, Singulair, Corticosteroids… dozens of others. Many of these drugs lead to cancers, and the use of these type drugs has been dramatically increasing in the last few decades
Additionally The Environmental Working Group has tied sunscreen ingredients to increased cancer incidence & virulence – http://www.naturalnews.com/032996_sunscreen_cancer_risk.html
While sun exposure is correlated to skin cancer it is not necessary for skin cancer to develop. Most or all of us get skin cancer… it is immune suppression or impairment that allows these common cancers to progress to a diagnosable stage.
In addition to certain drug use, common in “modern” affluent societies, other conditions can lead to immune problems. Genetic defects (rare), nutritional problems (certain vitamin/mineral deficiencies or lack of food) or toxic environmental/pre natal exposures can also impair immunity.
At this point it is not simply a matter of sunscreen or even the proper sunscreen. The entire issue needs to be revisited and the slant with which we must look at the question of skin cancer & sunlight is through the lens of immune system effects & possible photo-sensitive toxins in sunscreen.
Sunscreen is not the security blanket we thought it was.
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Anonymous says
Did you take any AP or Honors level classes in school? I would just like to know if they would help me a bunch. Thanks a lot and by the way, congratulations on your graduation and marriage! All the best to you and your family!
aawenzel says
I took a few, but my school didn’t offer many because it was so small. I don’t think it can hurt you, and if you do well it helps in college because you can skip some classes! Thank you so much for your kind comment!
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Dr. Tooley! It’s the high school student again… The one that asked you about taking AP/honors classes. I was wondering how you made this blog? What program? Was this free? I ask because I am interested in the medical field and I feel as though I have a lot of information to share with others on the topics of health science, diet, and cellular biology! And of course… Daily life 🙂 On another note, the breakfast over at Sandals looks absolutely amazing!! I hope you and Kyle enjoyed yourself! I can’t wait to see how residency goes for you, another door open for you and your future!
aawenzel says
Hi! I used wordpress.com to start the blog! I wanted my own domain so I purchased a-doctor-in-the-house.com. I think it was less than $20. That sounds like an awesome blog you want to start!!! Let me know so I can read it!
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