Ultraviolet rays from the sun are a constant presence on the earth. These rays can permanently damage the largest organ of the human body, the skin. The most obvious sign of this damage is sunburn, which can range from a mild irritation to a serious burn requiring medical treatment or even hospitalization. A sunburn can take days to heal and can result in permanent mottling of the skin, age spots, and melanoma.

Sunscreen or Sunblock

Limiting exposure and covering the skin protects the body from sunburn. Modern chemists have developed two basic types of sun protection formula, sunscreen and sunblock (Kunin 2005). Sunscreen is a chemical solution, classified by the Food and Drug Administration as a drug, which absorbs ultraviolet radiation before it can harm the skin.

Sunblock, however, protects the skin by reflecting and scattering the sun's rays. The best-known example of a sunblock is zinc oxide, the thick white substance that lifeguards apply to their noses. Sunblocks are highly effective, but are typically sticky creams that are impractical for full body use.

Ancient Protection

Ancient humans desired to avoid sunburn and look attractive. For example, Egyptians considered light skin more beautiful than dark skin. Egypt’s sun-drenched environment made it difficult to maintain light, luminous skin. Recently translated papyri and tomb walls reveal the ingredients of potions used to ward off a tan and heal damaged skin (Shaath 2005).

Some of the ingredients used by the Egyptians have been rediscovered by modern scientists. For example, the Egyptians used rice bran extracts in some of their sunscreen formulas (ibid). Today, gamma oryzanol is extracted from rice bran because of its UV-absorbing properties. The Egyptians also used jasmine, recently shown to heal DNA at the cellular level in the skin, to mend skin damage. Lupine extract was also used to lighten the skin, an ingredient still used for that purpose (ibid).

Discovering the Cause of Sunburn

Prior to the discovery of ultraviolet light, scientists believed that sunburn was caused by heat damage. However, scientists in the 19^th century and early 20^th century made great advances in determining the nature of light and its effects on the human skin.

Johann Wilhelm Ritter of Germany discovered ultraviolet rays in 1801. His experiments were based on previous work by Carl Wilhelm Scheele, who published his results in a 1777 study. Scheele demonstrated that paper strips dipped in a silver chloride solution became black after exposure to sunlight. Scheele also showed that the paper strips were affected more by blue light than by red light. Ritter measured the effects of light below the visible blue, leading to the discovery of the ultraviolet spectrum, which he called “infraviolet” (Roelandts 2007).

In 1820, Englishman Everard Home sought to answer why the darker skin of people in hot climates was better protected than the skin of white people, even though black absorbed more heat. Home exposed his hands to sunlight after covering one hand with a black cloth. The exposed hand burned, although the covered hand registered a higher temperature. He concluded that the melanin in darker skin absorbed heat and protected the skin (Norlund 2006).

Otto Veiel of Linz, Austria, published one of the first reports of a substance being used to protect skin from ultraviolet rays in 1878. He discovered that tannin worked as a kind of sunscreen. However, the staining properties of tannin limited the usefulness of his find.

Karl Eilham Hausser und Wilhelm Vahle reported in 1922 that sunburn in human skin is caused by the part of the ultraviolet spectrum between 280 and 315 nanometers (Roelandts ibid). They realized that the skin could be protected by filtering out those wavelengths. This led to the first commercially available sunscreen, produced in 1928 in the United States. It was an emulsion made of PABA benzyl salicylate and benzyl cinnamate. Sunscreens were soon widely available, although not widely used.

Modern Developments

In the early 1930's, Milton Blake, a South Australian chemist, experimented unsuccessfully with a sunburn cream. Around the same time, another chemist, Eugene Schueller, was more successful. Schueller, who went on to start L'Oreal, is often credited as the inventor of the modern sunscreen. Others give that honor to Austria's Franz Greiter, who was inspired to create a product named Gletscher Crème (Glacier Cream) by a sunburn he received while mountain climbing at Piz Buin.

In the United States, Miami pharmacist Benjamin Greene prepared a red jelly-like substance in his home oven in the 1940's. After testing his sticky formula on his own bald head, Greene supplied it to the soldiers in World War II. Known as "red vet pet," the veterinary petroleum-based compound was less effective than today's sunscreens. It also stained fabrics, which made it impractical as a commercial venture. Greene later developed a more consumer-friendly formula and founded Coppertone.

The success of Coppertone resulted in less fear of sunburn, and sunbathing became more popular than ever. This original Coppertone might have helped prevent sunburn, but it did not provide enough protection against radiation. As extended exposure to the sun increased, so did the number of cases of skin cancer.

In 1962, Franz Greiter re-emerged, developing a way to measure a product's ability to block ultraviolet rays, known as the Sun Protection Factor, or SPF. Soon afterward, sun protection became a big business, with several companies profiting from providing various levels of protection. In 1990, Americans spent $525 million on sun protection products (Kenet 1994), a figure that continues to grow.

Recently, clothing companies have entered the competition for the sun-aware consumer. Some fabrics, such as cotton, do not effectively block the sun’s rays. There are now complete clothing lines that are sold with SPF ratings. This protective clothing, along with a good hat, sunglasses, and a sun-blocking lip balm offer a nearly impenetrable fortress when sun exposure cannot be avoided.

Active Ingredients

There are several active ingredients used in modern sun protection products. PABA is still used, as it was in 1928, because it is effective at blocking UVB rays. However, PABA does not sufficiently guard against UVA rays, which have been shown to have longer-lasting negative effects and damage collagen more quickly than UVB rays. One PABA, Padimate A, has been eliminated from the FDA list of approved ingredients because it causes skin irritation when exposed to sunlight.

Cinnamates, salicyclates, and anthranilates are also used as UVB blockers. Cinnamates should not be used by individuals who are allergic to cinnamon. Another popular ingredient, homomenthyl salicylate, has been shown to have limited effectiveness for partial or complete sunburn protection (Walzer 1989).

Sunscreens typically use benzophenones such as oxybenzone, or other chemicals like dibenzoyl methane, to absorb some types of UVA radiation. Zinc oxide and titanium dioxide, on the other hand, are the most common ingredients in sunblocks, which are often considered chemical free and are less likely than sunscreens to cause allergic reactions. However, they are also thick and greasy and leave an oily residue.

The Future of Sunscreen

Scientists continue to search for more effective ways to protect the human body against the sun. One goal is to develop a sunscreen pill (Science Daily 2007). Significant attention has been given to a substance called astaxanthin, found in red ocean plants and animals, such as salmon. Astaxanthin is considered the most effective protection against free radicals found to date in nature. Astaxanthin is an antioxidant that also reduces the pain and swelling associated with sunburn. Astaxanthin pills, when used with other measures, effectively protects against the sun’s ultraviolet rays (ibid).

Although they do not yet offer the same level of protection as sunscreens and sunblocks, astaxanthin and other antioxidants continue to be studied and are likely to provide the next advances in sun protection. Whether protection is provided in a pill, a cream, or by some other method, scientists and medical professionals will continue to search for better methods to defend the skin until sun-induced skin cancer is no longer a major cause of death.

-- Posted April 28, 2009

References

Davis, Julie. 1995. Young Skin for Life. Emmaus, PA: Rodale Press, Inc.

Kenet, Barney and Patricia Lawler. 1994. Saving Your Skin. New York, NY: Four Walls Eight Windows.

Kunin, Audrey, M.D. 2005. The DERMAdoctor Skinstruction Manual. New York, NY: Simon & Schuster.

Leffel, David J. 2000. Total Skin. New York, NY: Hyperion.

Norlund, James J. and Jean-Paul Ortonne. 2006. “The Normal Color of Human Skin.” In The Pigmentary System, Second Edition,  edited by James J. Norlund, Raymond A. Boissy, Vincent J. Hearing, Richard A. King, William S. Oetting, and Jean-Paul Ortonne, 504- 520. Lake Oswego, OR: Blackwell Publishing.

Novick, Nelson Lee. 1988. Super Skin. New York, NY: Clarkson N. Potter, Inc.

Roelandts, Rik. 2007. “History of Human Photobiology.” In Photodermatology, edited by Henry W. Lim, Herbert Hönigsmann, and John L.M. Hawk, 1-13. Boca Raton, FL: CRC Press.

Science Daily. 2007. “Dermatologists Discover Sun Protection Under The Sea.” Accessed December 20, 2008.

Shaath, Nadim A., ed. 2005. Sunscreens: Regulations and Commercial Development. Third Edition. Boca Raton, FL: Taylor & Francis Group.