THE SUN AND OUR DILEMNA
Most people enjoy the sun; some people enjoy it a little too much. According to NASA, this star, which takes up 99 percent of the mass of our solar system and is over 100 times larger than Earth, is vital to human health and existence.2 While being a critical element in human lives, the sun can be harmful. With drastic climate changes, this danger has only gotten worse. The depletion of the ozone layer, the filter responsible for absorbing a portion of the sun's radiation from entering the atmosphere, is due to the contamination of mankind. How can an element that is needed for survival become so deadly? The science behind this majestic burning mass and how it affects the skin and human health is worth analyzing.3

ULTRAVIOLET RAYS
Ultraviolet radiation varies depending on environmental factors, such as the season, time of day, the latitude and altitude of where a person is, and presence of clouds and haze. UVA is considered to be the most damaging to the skin because the exposure to it is persistently high throughout daylight, no matter the time.4 UVB is responsible for vitamin D3 production. National Institutes of Health confirmed that if the conditions are just right, both UVA and UVB can be extremely harmful to the skin, causing photoaging and cellular damage to the extent of playing a key role in skin
cancer development.5

IS THE SUN THE BEST SOURCE OF VITAMIN D3?
The sun's UVB rays interact with a protein found in the skin, 7-dehydrocholesterol (7-DHC), causing the body to produce vitamin D3. Some experts say that obtaining UVB exposure is a long shot because most of its rays hit the United States between 10 a.m. and 4 p.m. from April to October. In some areas, it can be year-round because of its high altitude and on reflective surfaces like snow and ice. The pigment of the skin and the amount of skin that is exposed to UVB rays are also factors that must be taken into account.

With regard to vitamin D3 and sun care, there are scientists and medical experts with opposing views. Roy Geronemus, M.D., Ph.D., representing the Skin Cancer Foundation, states that using the sun as a source of vitamin D is not worth the risk because further ultraviolet exposure would destroy the vitamin D3 already present in the skin.6 However, the Vitamin D Council shared a study on a vitamin D deficiency treatment performed in Sweden that resulted in UVB therapy significantly outperforming vitamin D supplementation alone.7

Despite the fact that there are opposing views regarding sun care, both sides have strong arguments.

While the Skin Cancer Foundation focuses on the dangers of sun exposure that are causing about 90 percent of all skin cancer, the Vitamin D Council emphasizes awareness and teaching the public about vitamin D deficiencies and how to obtain vitamin D in the healthiest and safest way. Each side is based on their perception of what is important.

HOW DOES VITAMIN D AFFECT SUN CARE?
While some scientists have been encouraging people to perceive the sun as the "thing that gives you skin cancer," it is undeniable that the sun can assist in vitamin D absorption because it plays an important role in various biological functions. It supports cardiovascular health; enhances muscular strength; assists in maintaining optimal blood pressure levels; maintains a healthy immune system; and supports kidney function, healthy teeth, and strong bones.

HEALTH BENEFITS
Because vitamin D plays an important role in the immune system, it assists the skin in protecting its own health. It aids in decreasing inflammation and increasing antimicrobial defenses in order to be able to fight infections successfully. Skin, being the largest organ in the body, needs to be able to fight infections, which is only possible by strengthening its barriers. The Vitamin D Council suggests that studies are showing a correlation between vitamin D deficiency and eczema.8

Studies have shown effective results in the use of UVB ray therapy for acne treatment as its heat destroys organic compounds in the skin's bacteria. Who would have thought that a little sunshine can help with acne vulgaris?7 Vitamin D continues to be researched because of its intricate role in the different areas of the human body. In 2012, the National Institutes of Health published a study where, without having clear answers as to how or why, vitamin D was shown to slow down prostate cancer growth.9 It was concluded that plain vitamin D provides the necessary support for the body to take care of its own needs.

In 2011, the Institute of Medicine reviewed about 1,000 studies and determined that most Americans take in enough vitamin D and found no sound evidence that vitamin D insufficiency is currently leading to cancer, heart disease, diabetes, or other conditions. The Skin Cancer Foundation committee follows and supports these findings.10 Meanwhile, a study from the Women's Health Initiative found that vitamin D supplementation resulted in reduced melanoma risk, which indicates the importance of maintaining proper levels of vitamin D.11 In 2012, The Washington Post noted that vitamin D deficiency is soaring throughout the United States, affecting 42 percent of American adults, mostly African Americans and Hispanics.12

Perhaps vitamin D deficiency does not lead to any health problems. However, it would be foolish not to consider the possibility that vitamin D needs to be part of the sun care process, if only to aid in proper bodily function. Lastly, the fact that while experts focus on alarming the public with the dangers of the sun, the public continues to suffer from vitamin D deficiencies, something the body naturally produces with the help of the sun.

THE HISTORY OF SUN CARE
Going to the beach in the 1900s was an entirely different process than it is today. Both men and women would wear fully covered clothing as sun protection. Showing off skin and tanning were two practices that were not part of the culture. Men would wear trousers, overcoats, and wide-brimmed straw hats, while women usually wore light-colored long skirts and wrap-around bonnets, holding parasols while being out in the sun.13

During the ancient era, Egyptians avoided sun tanning. They considered light skin more beautiful than darkened skin, possibly because it was rare, due to the sun-saturating environment of Egypt. Modern science has been studying the ingredients the Egyptians would use to ward off sunburns and heal damaged skin, such as rice bran. They are testing them in sunscreen applications for their ultraviolet-absorbing properties; scientists are also testing jasmine for its healing properties at the cellular level, and Lupine extract as a skin brightener.14

The New York Times shared the "History of Sunscreen" and mentioned how the very first sunscreens were invented in the late 1930s and early 1940s.15 One product was created by a Swiss chemistry student who got a sunburn climbing Mount Piz Buin. The other sun-protection product, thick and unpleasant, was developed by an Airman and pharmacist and was intended to be used by soldiers during World War II; it worked primarily as a physical barrier between the skin and the sun. Even though sunscreen guidelines were initiated and began to be enforced in the late 1970s and early 1980s, the FDA proposed new regulations for sunscreens as new information has surfaced in the last century.

SUNSCREENS: THE MODERN SUN CARE
With an increase in outdoor activities, swimsuits shrinking in size, more skin exposure, and the existence of sunscreen products, the sun care industry has revolutionized. The use of sunscreen in the United States has increased with the existence of skin cancer. Sunscreens are products combining several ingredients that help prevent the sun's ultraviolet radiation from reaching the skin.10 The active ingredient, which is responsible for blocking ultraviolet rays, comes in two forms: mineral and chemical filters, both of which use different mechanisms. According to the Environmental Working Group, chemical filters are the most commonly used active ingredients in sunscreens and typically include a combination of two to six active ingredients. Some products combine both types of filters.16

Besides the ingredients, understanding how to use sunscreen and the SPF system is important in finding the right product.

WHAT IS SPF?
SPF, the sun protection factor, measures a product's ability to block UVB rays from damaging the skin.17 Many sunscreens, even SPF-tinted moisturizers, or face lotions that women wear on a regular basis, do not block UVA, a ray that can even penetrate glass. UVA protection is only possible using sunscreen that is labeled as broad-spectrum. Not to mention, there is a public misconception assuming that higher SPF means better. In reality, higher SPF does not necessarily offer greater protection.

EFFECTIVENESS OF SUNSCREEN
The primary concerns in sunscreens are their effectiveness to withstand ultraviolet radiation, breakdown due to water or sweat, and the presence of toxic ingredients that can be absorbed by the body and harm overall health. Dr. Morison and Dr. Wang, members of The Skin Cancer Foundation's Photobiology Committee, addressed some safety and effectiveness concerns in using sunscreen.10 They stated that about 90 percent of all skin cancers are associated with exposure to the sun's harmful radiation and that sunscreen is a key strategy in preventing excessive exposure. In 2010, their new research showed that sunscreen also helped protect against melanoma, the deadliest form of skin cancer.

Studies presented by Environmental Working Group show that sunscreen is most effective in blocking UVB while allowing UVA to reach the skin, leading to photodegradation of Vitamin D3.17 This conclusion indicates that a sunscreen that blocks only the UVB portion of the spectrum may both decrease the beneficial production of pre-vitamin D3 and break down the existing vitamin D3 through excess UVA exposure.

The average sunscreen may be offering a misleading and confusing presentation of the SPF system, blocking vitamin D production, not providing protection from UVA rays, and breaking down in extreme environments. Sunscreens are still a work in progress. There are many that may be effective, yet few that are safe to human health. For a sunscreen to be effective, it must be used as instructed and remain cognizant of photoprotective behavior. The use of mineral sunscreens, those that contain only zinc oxide and/or titanium dioxide as the active ingredients, have drastically increased in the last decade. As a result of new studies and reports, companies are now becoming more conscious about consumers' health. Mineral-based sunscreens are considered stable in sunlight, offering balance between protection from both UVA and UVB radiation.

IS SUNSCREEN SAFE?
Common types of ingredients found in sunscreens are "penetration enhancers," which assist skin absorption, resulting in traces of undesirable ingredients found in the blood, breast milk, and urine.16 Laboratory studies have indicated some chemical filters mimicking human hormones or causing allergies. Questions of long-term effects of frequent sunscreen applications have been raised and continue to be disputed among experts.

Ever since the Environmental Working Group began to call out skin care companies on their use of certain toxic ingredients, the skin care industry began to change. The Vitamin D Council agrees with the findings of various studies presented by Environmental Working Group and other researchers. They have been able to validate the scientific evidence that some chemical sunscreens are not safe to human health. Some of the ingredients in question are oxybenzone and retinyl palmitate and its derivatives.

Oxybenzone, a synthetic estrogen, has been used as a chemical filter in United States sunscreens since the early 1980s. While the Skin Cancer Foundation's Photobiology Committee reviewed this FDA-approved ingredient and declared to find no basis for concern about its use, other experts disagree. The Center for Disease Control (CDC) after a study, concluded that "nearly all Americans are contaminated with oxybenzone. A sunscreen chemical that has been linked to allergies, hormone disruption, and cell damage." On the contrary, the Skin Cancer Foundation has no evidence shown
that oxybenzone has any adverse health effects, claiming that oxybenzone is excreted and does not accumulate in the body.

Retinyl palmitate, also known as a form of vitamin A, is an antioxidant manufacturers add to skin products because it is believed to slow skin aging. The Skin Cancer Foundation reviewed that oral ingestion of vitamin A is known to reduce risk for skin cancer.10 However, topically, it is a different story. Although not definitive, various studies have shown that vitamin A, when used on the skin and exposed to sunlight, accelerates cancer growth, according to Environmental Working Group.19 The thought of this possibility being true has many experts confused as it would mean that these products can cause the same thing they are supposed to protect from (skin cancer). Health problems range from brittle nails and hair loss to liver damage, osteoporosis, and birth defects. With a high pre-formed vitamin A diet among many Americans and Europeans, Environmental Working Group calls for sunscreen makers to voluntarily stop adding this ingredient to sunscreens until there is proof that it can be safely used on sun-exposed skin. The European Scientific Committee of Consumer Safety (SCCS) has been evaluating this ingredient and discovered the possibility of bio-accumulation. In disbelief, the Skin Cancer Foundation claims there is no scientific evidence humans could be overexposed to retinyl palmitate or that it can potentially cause cancer.

Speaking of cancer, research analyzed by the Vitamin D Council has shown that sunscreen helps prevent squamous cell carcinoma, but that it has no effect in preventing basal cell carcinoma.11 For melanoma, research has been contradictory. Some research shows that sunscreen prevents melanoma, while others show that it increases the chances of getting melanoma. Then again, if some of the ingredients are being questioned for their safety, then it defeats the purpose to review the studies of whether sunscreen truly prevents skin cancer. In addition to the active ingredients, consumers should evaluate the rest of the ingredients in the products they use, not just sunscreen. With regards to choosing the right products, be sure to always do the research. Be up to date with validated information and stay tuned with respected organizations.

SUN CARE IN THE FUTURE
In an ideal world, sunscreens should not break down; they should protect the skin from ultraviolet-related damages. Most of all, they should be safe to consumers' health. Albert Einstein once said, "We cannot solve our problems with the same thinking we used when we created them." There will always be more than one perspective with valid information regarding how to avoid skin cancer and how to obtain vitamin D.

The Vitamin D Council encourages the public to eat healthy, take vitamin D supplements if deficiency is a concern, and use the sun wisely. Despite their opposing views, The Skin Cancer Foundation and the Vitamin D Council both agree on the fact that in addition to staying out of the sun, wearing clothing and hats as sun protection while outdoors for long periods will always be the best option to avoid sunburns and, consequently, the development of skin cancer.

In other words, the improvement of photoprotective behavior is vital. Learn how and when to safely enjoy the sun, choose a good sunscreen, wear extra clothing, use shade to avoid overexposure, and
maintain normal levels of vitamin D. These simple principles are the best way to utilize the power of the sun.

References
1 University of Cambridge. (n.d.). "Darwin Correspondence Project. Six things Darwin never said – and one he did".
2 NASA. (n.d.). "Why do we study the sun?"
3 Stratospheric Ozone Monitoring and Research in NOAA. (n.d.). "Science: Ozone Basics".
4 Skin Cancer Foundation. (n.d.). "UVA & UVB".
5 Panich, U., Sittithumcharee G., Rathviboon, N., & Jirawatnotai, S. (2016, April). "Ultraviolet Radiation-Induced Skin Aging: The Role of DNA Damage and Oxidative Stress in Epidermal Stem Cell Damage Mediated Skin Aging". Stem Cells International.
6 Skin Cancer Foundation. (n.d.). "Make Vitamin D, not UV, a Priority".
7 Vitamin D Council. (n.d.). "UVB therapy vs supplementation for vitamin D deficiency".
8 Vitamin D Council. (n.d.). "Eczema".
9 Garland, C., Garland, F., Gorham, E., Lipkin, M., Newmark, H., Mohr, S., & Holick, M. (2006, February). "The Role of Vitamin D in Cancer Prevention". American Journal of Public Health, 96(2): 252-261.
10 Morison, W. and Wang, S. (2011, November). "Sunscreens: Safe and Effective?". Skin Cancer Foundation.
11 Vitamin D Council. (n.d.). "Melanoma".
12 Butler, Carolyn. (2012, August 27). "Vitamin D: Something you're likely to lack". The Washington Post.
13 Skin Cancer Foundation. (2015). "As America modernized, sun exposure soared". 14 Random History. (2009). "Protecting your Skin. The History of Sunscreen".
15 The New York Times. (2010, June 23). "Sunscreen: A History". June 23, 2010.
16 Environmental Working Group. (n.d.). "The trouble with Oxybenzone and Other Sunscreen chemicals".
17 Frack, L. and Andrews, D. (2009, August 10). "Sunscreen series: Does sunscreen use prevent skin cancer". Environmental Working Group.
18 McNeill, A. and Wesner, E. (2016, May 18). "Sun Protection and Vitamin D". Skin Cancer Foundation.
19 Environmental Working Group. (n.d.). "The Problem with Vitamin A".

Karym Urdaneta is a biomedical engineer and managing partner of Pink Horizons Botanical Skin Care, a Green America certified company that formulates safe, high-performance products for health practitioners and the end-consumer. They are considered industry leaders, proudly maintaining a 'Champion' status with the Campaign for Safe Cosmetics and teaming with socially responsible organizations to educate the community on holistic living and sustainable business practices. pinkhorizons.com