More than a million new cases of skin cancer are diagnosed each year. It is estimated that one in five Americans will develop skin cancer and 90 percent of those cancers will result from exposure to ultraviolet (UV) radiation from the sun and tanning beds. UV rays penetrate the dermis and generate free radicals that can alter our DNA, the genetic material of all living cells.
In reasonable amounts, sun exposure is beneficial. Natural sunlight has a germicidal effect and produces vitamin D in the skin. Ultraviolet radiation can be used to treat rickets, psoriasis, and acne. UV exposure also stimulates the production of melanin in the skin, which causes a tan and helps protect the skin from further damage. But deep tanning is another matter, and while a deep tan may seem healthy, it’s actually a sign that your skin is being attacked by UV radiation.
The erythema or redness of the skin is an inflammatory response, usually appearing within six hours of UV exposure. The degree of redness is an indication of the amount of damage done to the skin. With each searing sunburn, the chance of developing skin cancer increases by 10 percent. Smoking also increases the damage from UV rays due to the formaldehyde that is produced in cigarette smoke.
Sunlight is part of the electromagnetic spectrum. Sunlight is made up of different wavelengths of electromagnetic radiation. About 35 percent is visible light, 60 percent is infrared radiation, and 5 percent is made up of UV rays. UV wavelengths range from 200nm to 400nm and are divided as follows:
UVC rays (from 200 to 290 nm) are the most energetic, but the least penetrating. UVC rays are not a concern because most UVC radiation is blocked by ozone in the atmosphere and never reaches the ground.
UVB rays (290 to 320 nm) are often referred to as burning rays and are the wavelengths of UV radiation most responsible for causing erythema and tanning. Erythema is used to measure the effectiveness of sunscreens and to indicate the sunscreen’s ability to block UVB rays. This measure is known as the Sun Protection Factor (SPF).
An SPF 2 blocks 50 percent of UVB rays, allowing you to stay in the sun twice as long as without any protection. Increasing the SPF increases protection. An SPF of 15 blocks 93.3 percent of UVB rays and an SPF of 30 blocks 96.9 percent of UVB rays. But keep in mind that doubling the SPF does not double the protection. In this case, it only increases UVB protection by 3.6 percent; at higher SPFs, the increase is even less. Although doubling the SPF does not double the protection, it does greatly increase the potential for sensitivity due to the increased concentration of active ingredients. UVB sunscreens include: ethylhexyl methoxycinnamate, ethylhexyl salicylate, homosalate, octocrylene, phenylbenzimidazole sulfonic acid, benzophenone, and titanium dioxide.
UVA rays (320 to 400 nm) are the longest wavelengths of ultraviolet radiation and the closest to visible light. UVA is commonly known as “blacklight”. UVA rays play only a minor role in erythema and tanning, so while its effects may not be as obvious or sharp as UVB rays, UVA exposure is just as harmful. UVA wavelengths are the least energetic, but penetrate the deepest. Since UVA rays penetrate the dermis, they contribute substantially to chronic sun damage.
Remember that SPF only indicates protection against UVB rays and does not indicate protection against UVA rays. A high SPF sunscreen may provide adequate protection against UVB rays, but offers little or no protection against UVA exposure. Make sure the sunscreen you use contains both UVB and UVA protection. Approved UVA sunscreens include: avobenzone, benzophenone-3, oxybenzone, octocrylene, menthyl anthranilate, butylmethoxydibenzoylmethane, and zinc oxide.
The US Food and Drug Administration (FDA) published a new Sun Protection Monograph on August 27, 2007. The FDA proposal provides a rating system for UVA sun protection products on a scale of one to four stars. One star indicates low UVA protection, two stars indicate medium protection, three stars indicate high protection, and four stars indicate the highest UVA protection available in non-prescription sunscreen products.
Many sun protection products claim to use non-chemical sunscreens like titanium dioxide and zinc oxide. Although these inorganic sunscreens are still chemical, they protect by physically reflecting UV rays. Traditional organic sunscreens protect by chemically absorbing UV rays. Inorganic sunscreens decrease the potential for skin irritation and sensitivity that organic sunscreens can cause, especially in the high concentrations required for higher SPFs. There is also some concern about unwanted chemical reactions that can take place in the skin when organic sunscreens absorb UV rays.
Although ultraviolet radiation is often referred to as ultraviolet light, ultraviolet rays are above the visible spectrum of light. Ultraviolet radiation is invisible and is not really light at all. Because you can’t see the UV rays that cause sunburn, it’s a good idea to protect yourself from the sun even on cloudy days. Although clouds block visible light, they offer little protection from harmful UV rays.
Self-tanning products allow you to tan safely without the sun. Self-tanners contain the ingredient dihydroxyacetone that reacts with proteins on the skin’s surface to turn them golden brown and simulate a natural tan.
Current Food and Drug Administration (FDA) regulations governing the manufacturing and labeling of sunscreen products became effective on January 1, 2003. A proposed new FDA regulation will make some changes and improvements to the current regulations.
1. There is currently no acceptable definition of the term “broad spectrum” and no standard test for UVA protection. The new FDA ruling will provide a four-star rating system for UVA protection.
2. Consumers who want the highest sun protection often buy the product with the highest SPF. Most are unaware that SPFs higher than 30 provide little additional protection and greatly add to the concerns associated with high concentrations of organic sunscreen ingredients. The maximum SPF claim allowed on the product label is currently SPF30 or SPF30 plus. The new FDA proposal raises the ceiling for SPF values to 50+. For maximum protection, apply sunscreen 20 minutes before going out in the sun. Apply evenly and generously and reapply every hour.
3. Since there is no official definition of the term “natural” and all sunscreen products contain chemicals, the terms “natural”, “non-chemical” and “chemical-free” are considered false and misleading and are not approved. Titanium dioxide and zinc oxide are inorganic chemicals.
4. Because all sunscreens allow some UV rays to penetrate the skin, the term “sunscreen” is not approved.
