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 be the result of 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. Exposure to UV rays also stimulates the skin to produce melanin, which causes a tan and helps protect the skin from further damage. But a deep tan is another matter, and while a deep tan may look healthy, it is actually a sign that the skin is being attacked by ultraviolet radiation.
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 blistering sunburn, the chance of developing skin cancer increases by 10 percent. Smoking also increases UV damage from the formaldehyde that occurs 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 ultraviolet rays. UV wavelengths range from 200 nm to 400 nm and are divided as follows:
UVC rays (200-290 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 (290-320 nm) are often called fiery 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 indicate the ability of sunscreen to block UVB rays. This measurement 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 you could without any protection. Increasing SPF increases protection. An SPF 15 blocks 93.3 percent of UVB and an SPF of 30 blocks 96.9 percent of UVB. 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; with higher SPFs, the increase is even less. Although doubling the SPF does not double the protection, it greatly increases the potential for sensitivity due to the increase in the 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 rays are commonly known as “black light”. UVA rays play only a minor role in erythema and tanning, so while their effects may not be as obvious or acute as UVB rays, UVA exposure is just as damaging. The wavelengths of UVA rays are the least energetic, but they penetrate the deepest. Since UVA rays penetrate the dermis, they contribute substantially to chronic sun damage.
Remember that SPFs only indicate protection against UVB rays and do not indicate protection against UVA rays. A sunscreen with a high SPF can provide adequate protection against UVB rays, but offers little or no protection against UVA exposure. Make sure the sunscreen you use contains UVB and UVA protection. Approved UVA sunscreens include: avobenzone, benzophenone-3, oxybenzone, octocrylene, menthyl anthranilate, butylmethoxydibenzoylmethane, and zinc oxide.
The United States Food and Drug Administration (FDA) published a new sunscreen monograph on August 27, 2007. The FDA proposal provides a rating system for UVA sunscreen products on a scale of one to four stars. One star indicates low UVA protection, two stars indicate medium protection, three starts indicate high protection, and four starts indicate the highest UVA protection available in over-the-counter sunscreen products.
Many sunscreen products claim to use non-chemical sunscreens like titanium dioxide and zinc oxide. Although these inorganic sunscreens are still chemicals, they protect by physically reflecting ultraviolet rays. Traditional organic sunscreens protect by chemically absorbing UV rays. Inorganic sunscreens reduce the potential for skin irritation and sensitivity that can be caused by organic sunscreens, especially at the high concentrations required for higher SPFs. There is also some concern about unwanted chemical reactions that can take place on the skin when organic sunscreens absorb UV rays.
Although ultraviolet radiation is often referred to as ultraviolet light, ultraviolet rays are above the spectrum of visible light. Ultraviolet radiation is invisible and is not really light. Since you cannot see the ultraviolet rays that cause sunburn, it is advisable to protect yourself from the sun even on cloudy days. Although clouds block visible light, they offer little protection against 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 brown them and simulate a natural tan.
The current Food and Drug Administration (FDA) ruling regulating the manufacture and labeling of sunscreen products went into effect on January 1, 2003. A new ruling proposed by the FDA will make some changes and improvements to the regulations. current.
1. There is currently no acceptable definition of the term “broad spectrum” and no standard test for UVA protection. The new FDA resolution will provide a four-star rating system for UVA protection.
2. Consumers who want maximum sun protection often purchase the product with the highest SPF. Most are unaware that SPFs above 30 provide little additional protection and greatly increase the concerns associated with high concentrations of organic sunscreen ingredients. The maximum SPF statement allowed on the product label is currently SPF30 or SPF30 plus. The new FDA proposal raises the upper limit on SPF values to more than 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 ultraviolet rays to penetrate the skin, the term “sunscreen” is not approved.