By: Fayne Frey, MD
News stories about sunscreen abound. They claim that they get into your bloodstream, reduce vitamin D, and even kill coral. What’s true and what’s not?
Sunscreen is in the news again. You have probably seen the stories. They proclaim:
Sunscreen is safe!
Sunscreen is not safe!
Sunscreen protects against skin cancer!
Sunscreen causes vitamin D deficiency!
Sunscreen ingredients get into my blood — that can’t be good!
Sunscreen is killing the coral!
And yet, every dermatologist on the planet recommends sunscreen.
How can you know what is true and what is not? Let’s review the data.
But first, let’s go over the basics
What is sunscreen?
Sunscreens are products that help protect the skin from the sun’s harmful ultraviolet (UV) rays. There are two types of UV rays that reach the earth’s surface: UVA and UVB.
UVA are long wavelength rays that can penetrate through glass and can reach deep into the skin surface. Although these rays have traditionally been known to cause skin wrinkling, sagging and tanning, they are now known to cause skin cancer as well.
UVB rays are shorter wavelength rays that do not penetrate as deep into the skin surface. However, they are the major contributor to sunburn and skin cancer.
What is SPF?
SPF stands for Sun Protection Factor. SPF indicates how much solar energy (ultraviolet radiation in the form of UVB rays) is required to cause sunburn on skin that has been protected with sunscreen. This is compared to the amount of energy required to cause sunburn on unprotected skin.
Solar energy is influenced by many factors including time of day. For example, an hour of sun exposure at 9:00 am may be equivalent to 15 minutes of solar energy obtained at noon. It also depends on a number of other factors such as location, the amount of time in the sun, and weather conditions (clouds can absorb solar energy making the sun’s rays more intense on clear days).
SPF is a relative indicator of the amount of sunburn protection a sunscreen provides. As SPF increases, so does the protection from UVB rays. It is important to note that SPF labels on sunscreens are often not accurate.
An SPF of 30 prevents 97% of UVB rays from reaching the skin’s surface. An SPF of 50 prevents 98%. No sunscreen is able to provide 100% protection.
SPF does not provide information about protection from UVA rays. Sunscreens that provide protection against both UVA and UVB may be labeled “broad spectrum.”
What are sunscreen filters?
Sunscreens contain one or several active ingredients called sunscreen filters. In the United States, the Food & Drug Administration (FDA) has approved 16 sunscreen filters.
Each filter can protect the skin from different wavelengths of ultraviolet radiation. For this reason, it is common to see multiple “active ingredients” or sunscreen filters listed on the ingredient listing of any given sunscreen product.
Sunscreen filters can be divided into two classes, organic and inorganic. The classification depends on how they prevent the sun’s UV rays from reaching the skin surface. Organic or “chemical” sunscreen filters absorb the rays. Inorganic or physical sunscreen filters, of which there are only two, titanium dioxide and zinc oxide, reflect and scatter them.
What are the different sunscreen filters?
In the United States, only half of sixteen approved sunscreen filters are actually being used today. I have marked them with an asterik (*) in the alphabetical list of filters below.
The eight approved filters that are not used have adverse properties. They are cosmetically unpleasing, cause allergic reactions, have unlikable properties, like turning the skin blue. Some are no longer manufactured.
Of the eight filters that are being used, only two can cover the UVA spectrum adequately: avobenzone and zinc oxide.
Which sunscreen filters are FDA approved?
1. Aminobenzoic acid
Aminobenzoic acid is also well known as PABA. It is approved for use up to a concentration of 15%. It was one of the first filters used in sunscreens after its UVB absorbing properties were discovered. PABA is a “natural” chemical found in the vitamin folic acid as well in many foods like grains, eggs, and milk.
Although PABA is an effective sunscreen filter, it is also a strong sensitizing agent. In addition, in the 1980s studies showed that PABA might increase the risk of cellular UV damage. PABA is seldom if ever, used in today’s sunscreen formulations.
Avobenzone is also known as Parsol1789. It is one of the most commonly used sunscreen filters in sunscreen formulations today. Avobenzone degrades in light and is very photo-unstable. Therefore is often formulated with a stabilizing agent such as octocrylene, another sunscreen filter, or stabilizing agent. It is approved for use in Europe, Australia, Japan, and in the US where it can be used in formulations up to 3%.
Cinoxate is an approved sunscreen filter for its broad-spectrum UVA and UVB protection. It is a very ineffective filter and therefore, no longer manufactured or used in sunscreen formulations.
Dioxybenzone is an effective sunscreen filter with an unfortunate side effect. When exposed to ultraviolet light, it turns the skin blue! This filter is no longer used in today’s sunscreen formulations.
Ensulizole is an effective filter against UVB rays. It is water-soluble so it feels light and non-greasy on the skin. But because it is water-soluble, it is not water-resistant — a quality desired by consumers who are swimming or sweating from heat or exercise. This sunscreen is rarely used in sunscreens. But it may be found in daily wear moisturizers that contain sun protection.
Homosalate is an effective sunscreen filter against UVB rays and is found is almost half of all sunscreens on the market, Homosalate is a compound that belongs to a class of chemicals called salicylates. Salicylates have an analgesic property, an ability to numb the skin when applied topically.
Although homosalate has never been approved as an analgesic. However, there is some concern by knowledgeable chemists that the use of this product may minimize any pain or discomfort that could warn the user of a developing sunburn. Homosalate has also been accused of being an endocrine disruptor and an agent that increases the absorption of certain chemicals into the skin. This filter is approved in Europe, Australia, Japan and in the United States where it is considered safe up to a concentration of 15%.
Meridamate is an effective UVA sunscreen filter that has been approved in both the United States and Australia. Meridamate is barely used in sunscreen formulations as it can cause allergic skin reactions and because it smells like bubble gum.
Octocrylene is an effective UVB filter. It is used to stabilize other UV filters. Octocrylene is a thick stable compound that tends to feel greasy. The maximum FDA approved concentration is 10%.
Octinoxate is a widely used UVB sunscreen filter. It degrades over time especially when exposed to ultraviolet light. It is approved in Europe, Australia, Japan, and the United States up to 7.5%. Octinoxate is one of two filters that have recently been banned in Hawaii as of 2021 due to its presumed damage to coral reefs.
Octisalate is another widely used UVB sunscreen filter in the class of salicylates. It shares the same concern by experts that its analgesic properties may minimize discomfort or pain sensation from a developing sunburn. Octisalate has an oily consistency and offers a mild floral fragrance. It is approved in Europe, Australia, Japan, and the United States up to 5%.
Oxybenzone is an effective UVB and partial UVA sunscreen filter. It is photostable but has recently been shown to possibly cause DNA damage when exposed to ultraviolet light. It is approved in Europe, Australia, Japan and in the United States up to 6%. Oxybenzone is the second sunscreen filter recently banned by Hawaii as of 2021 due to its presumed damage of coral reefs.
12. Padimate O
Padimate O is a derivative of the once used PABA sunscreen. This controversial sunscreen filter was shown to possibly cause DNA damage when exposed to ultraviolet light. It is no longer used in sunscreen formulations.
Sulisobenzone is an effective UVB and partial UVA sunscreen filter. It can be used to stabilize other UV filters, however, it is water-soluble. Therefore it is not ideal for use in water-resistant sunscreens that are desired by swimmers and those sweating due to high ambient temperatures and exercise. This filter is not commonly used.
14. Trolamine salicylate
Trolamine salicylate is a salicylate and an effective UVB filter. It is an approved active ingredient for over-the-counter temporary relief of muscle and joint pain. It shares the same concern for diminishing the pain of developing sunburn with the other UV filter salicylates. This filter is rarely used in sunscreen formulations.
15. *Titanium dioxide
Titanium dioxide is one of only two inorganic/physical sunscreen filters approved by the FDA. It filters UVB rays as well as a portion of the UVA spectrum. Sunscreen formulations with titanium dioxide tend to leave a “white cast” on the skin. The FDA recently deemed this filter Generally Recognized As Safe (GRAS).
16. *Zinc Oxide
Zinc oxide is the other inorganic/physical sunscreen filter approved by the FDA. It is the most broad-spectrum of all the approved filters protecting the skin from both UVA and UVB rays. Like titanium dioxide, it also tends to leave a “white cast” on the skin. The FDA recently also deemed this filter as Generally Regarded As Safe (GRAS).* Ecamsule (Mexoryl SX) is a water-soluble UVA sunscreen filter that has been approved in the United States up to 3% in limited L’Oreal formulations.
Chemical vs. physical sunscreens: Which is better?
Physical sunscreens are formulated with the approved filters titanium dioxide and/or zinc oxide only. All sunscreens formulated with any combination of the other 14 approved filters are considered “chemical” sunscreens.
Dermatologists often recommend physical sunscreens for individuals with eczema or sensitive skin and for young children. This is because the tendency to develop allergic reactions to these more inert compounds is far less than the chemical sunscreens.
Physical sunscreens, however, may leave a “white cast” on the skin. No physical sunscreens made the Consumer Reports 2019 recommended list of the best sunscreens. Although many physical sunscreens were effective, they weren’t as effective as chemical sunscreen formulations when used comparatively. None of the physical blocks provided both top-notch SPF and UVA protection. In fact, there was minimal variation from the labeled SPF.
Now, about those news stories
1. Does sunscreen cause vitamin D deficiency?
A comprehensive review of the literature from 1970 to 2017 assessed the association between sunscreen use and vitamin D deficiency. When sunscreen is used in real-life conditions, they found little evidence that sunscreen use caused a deficiency in vitamin D. The review also stated that there was no evidence to negate current skin cancer prevention advice.
2. Do sunscreen ingredients get absorbed into the blood?
A recent study in the Journal of the American Medical Association looked at plasma concentrations of active ingredients of various types of commercially available sunscreen formulations under maximal use conditions.
All four active ingredients tested, avobenzone, oxybenzone, octocrylene, and ecamsule, were absorbed into the bloodstream. Although they were found in concentrations higher than the 0.5 ng/ml FDA threshold for potential safety concerns, the study concluded the following:
- Further studies to determine the significance of these findings are warranted
- Individuals should NOT refrain from using sunscreen.
3. Does sunscreen really kill coral?
In July 2018, Hawaii passed a law that prohibits the sale of sunscreens that contain oxybenzone or octinoxate, claiming that these two ingredients have a detrimental impact on marine life. In particular, they are said to cause deformed coral larvae and contributed to coral bleaching. The claims were based on a study, originally published in the Archives of Environmental Contamination and Toxicology, https://link.springer.com/article/10.1007%2Fs00244-015-0227-7. Of note, the study was done in a laboratory using artificial seawater.
In October 2018, The National Oceanic and Atmospheric Administration (NOAA) announced that global coral bleaching was occurring. Coral bleaching is a phenomenon where the coral releases the algae that live within the coral tissue turning the coral white. Experts believe the main cause is global warming is an elevation of seawater temperature. They also believe that overfishing and pollution likely contribute to coral bleaching far more than sunscreen filters.
Terry Hughes, director of the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University, said, “The conclusion from the media is sunscreen is killing the world’s coral, and that’s laughable.” Conclusion: there is insufficient evidence that sunscreen use harms coral reefs. So before you throw away oxybenzone containing sunscreens, lobby your local politicians for practices that decrease global warming.
The bottom line question: Should I wear sunscreen?
Yes! Emphatically YES! apply sunscreen daily.
The benefits outweigh the risks!
The American Academy of Dermatology (AAD) recommends wearing a broad-spectrum sunscreen with an SPF of 30 or higher on all exposed skin surfaces.
Scientific studies show that sunscreen usage decreases the development of skin cancer. It also decreases premature aging of the skin. The benefits of wearing sunscreen on all exposed surfaces, applied liberally and daily, far outweigh any risks of doing so.
Sunscreen application is only part of a comprehensive sun protection program. It is NOT permission to seek sun or prolong your time in the sun. Limit the amount of skin that is exposed to the sun’s harmful ultraviolet rays by wearing protective clothing and hats. And, seek shade when possible.
So, which sunscreen should I use?
The BEST sunscreen is a broad-spectrum sunscreen with an SPF of 30 or higher that is used liberally, daily and often.
For individuals with sensitive skin or for those with certain skin conditions like eczema, physical sunscreen formulations are preferable.
The average adult in a bathing suit should apply 1 ounce (a shot glass full) to cover all exposed skin surfaces. Sunscreen should be reapplied every two hours if swimming or sweating excessively for continued protection.
The choice of using a sunscreen spray, stick or bottle is personal preference. It’s more important that an adequate amount of sunscreen is applied to obtain the SPF protection printed on the product label.
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Fayne Frey, M.D., is a board-certified clinical and surgical dermatologist practicing in West Nyack, New York, where she specializes in the diagnosis and treatment of skin cancer. She is a nationally recognized expert in the effectiveness and formulation of over-the-counter skincare products, and, as a speaker, has captivated audiences with her wry observations regarding the skincare industry. She has consulted for numerous media outlets, including NBC, USA Today, and, the Huffington Post, and has shared her expertise on both cable and major TV outlets. Dr. Frey is the Founder of FryFace.com, an educational skincare information and product selection service website that clarifies and simplifies the overwhelming choice of effective, safe and affordable products encountered in the skincare aisles. Dr. Frey is a graduate of the Weill Cornell Medical College and is a fellow of both the American Academy of Dermatology and the American Society for Dermatologic Surgery.
Originally published at https://thedoctorweighsin.com on July 18, 2019.