What You Eat Can Protect Your Skin from the Sun

By now you probably think you’ve heard all of the health reasons there are for eating your vegetables. But recently, researchers from Harvard University have announced that lutein — a potent antioxidant found in such dark green, leafy vegetables as spinach and kale — may protect the skin from sun damage.

“Lutein has been widely recognized for its eye health benefits for several years. But, our data is the first of its kind to suggest that lutein may have the potential to act as a preventative agent against UVB-induced skin cancer,” said Salvador Gonzalez, M.D., Ph.D., leader of the Harvard research team. “In addition, these data suggest that lutein protects the skin against damage caused by exposure to UVB light, further validating our position that lutein is a critical component to overall skin health.”

Lutein (LOO-teen) is a yellow pigment (the yellow is covered up by chlorophyll in green leaves) found predominantly in vegetables. It is also present in the eyes and skin of the human body. In women, lutein is found in the breasts and cervix. As an antioxidant, lutein protects the eyes from the damaging effects of aging. Lutein also acts as a light filter, protecting against the sun’s harmful rays.

UVA and UVB rays are two types of harmful rays found in sunlight. UVA rays contribute to wrinkling the skin, as well as to the development of skin cancer. UVB rays are the ones that are the primary cause of sunburn and skin cancer.

Good sunscreens block both UVA and UVB rays and are critical to skin health. But, you can do even more to protect your skin and eyes when you’re outside.

Safety tips to keep top of mind:

Wear UV-blocking sunglasses. Over time, exposure to ultraviolet light can cause cataracts and increase your risk of macular degeneration, a disease that causes irreversible blindness.

If you’re a parent, protect your children’s skin. Research indicates that one or more severe, blistering sunburns in childhood or adolescence can double the risk of skin cancer later in life.

Check the expiration date on your sunscreen. Sunscreen without an expiration date has a shelf life of no more than three years.

Eat a healthy diet comprised of green leafy vegetables. Consumption of 6 milligrams of lutein per day (approximately one-third cup of cooked spinach) has been linked to a reduced risk of cataracts and age-related macular degeneration. Vitamins and dietary supplements formulated with purified lutein provide another option for adding this nutrient to a daily diet.

It’s important to note that when lutein is consumed in foods or vitamins, it deposits in various tissues in the body — the eyes, the skin, fat tissue and so on. Therefore, it may also be beneficial to apply lutein directly to the surface of your skin. Several skin care products containing lutein are now available.

Risks and Benefits of Sun Exposure

Exposing skin to sunlight presents both health risks and health benefits. Sunlight is the major source of vitamin D-producing Ultraviolet B radiation, which has a wide range of positive health effects, including possibly inhibiting the growth of some cancers. On the other hand, long-term sunlight exposure is known to be associated with the development of skin cancer, skin aging, immune suppression and eye diseases such as cataracts. Sun exposure has also been associated with the timing of melatonin synthesis and reduced risk of seasonal affective disorder. A number of public health organizations state that there needs to be a balance between having the risks of having too much and the risks of having too little sunlight. There is a general consensus that sunburn should always be avoided.

However, not all physicians agree with the assertion that there is an optimal level of sun exposure, with some arguing that it is better to minimize sun exposure at all times and to obtain vitamin D from other sources.

Serum levels of 25(OH) D3 are below the recommended levels for a large portion of the general adult population and in most minorities, indicating that Vitamin D deficiency is a common problem in the United States.
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Benefits

According to the U.S. National Institutes of Health Office of Dietary Supplements, most people in the United States can meet their vitamin D needs through exposure to sunlight, even though a large portion have serum 25(OH)D3 levels below recommendations. Ultraviolet (UV) B radiation with a wavelength of 290-315 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3. Season, geographic latitude, time of day, cloud cover, smog, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D synthesis. The UV energy above 42 degrees north latitude (a line approximately between the northern border of California and Boston) is insufficient for cutaneous vitamin D synthesis from November through February; in far northern latitudes, this reduced intensity lasts for up to 6 months. In the United States, latitudes below 34 degrees north (a line between Los Angeles and Columbia, South Carolina) allow for cutaneous production of vitamin D throughout the year.

Complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60%. UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D. Sunscreens with a sun protection factor of 8 or more appear to block vitamin D-producing UV rays, although in practice people generally do not apply sufficient amounts, cover all sun-exposed skin, or reapply sunscreen regularly. Skin likely synthesizes some vitamin D even when it is protected by sunscreen as typically applied.

The factors that affect UV radiation exposure and research to date on the amount of sun exposure needed to maintain adequate vitamin D levels make it difficult to provide general guidelines. It has been suggested by some vitamin D researchers, for example, that approximately 5-30 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis and that the moderate use of commercial tanning beds that emit 2%-6% UVB radiation is also effective. Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement.

Risks

Despite the importance of the sun to vitamin D synthesis, it is prudent to limit exposure of skin to sunlight and UV radiation from tanning beds. According to the National Toxicology Program Report on Carcinogens from the Department of Health and Human Services, broad-spectrum UV radiation is a carcinogen thought to contribute to most of the estimated 1.5 million skin cancers and the 8,000 deaths due to metastatic melanoma that occur annually in the United States Lifetime cumulative UV damage to skin is also largely responsible for some age-associated dryness and other cosmetic changes.

It is not known whether a desirable level of regular sun exposure exists that imposes no (or minimal) risk of skin cancer over time. The American Academy of Dermatology advises that photoprotective measures be taken, including the use of sunscreen, whenever one is exposed to the sun.

Is there a safe level of sun exposure?

According to a recent study submitted by the University of Ottawa to the Department of Health and Human Services in Washington, D.C., there is not enough information to determine a safe level of sun exposure at this time.

There is no consensus on which component of Ultraviolet Radiation (UVA or UVB or UVC) actually is carcinogenic, and the composition of Ultraviolet Radiation changes throughout the day: At high noon, Ultraviolet Radiation reaching ground level is 95% UVA and 5% UVB, while before 10am and after 2pm this percentage changes over time to 99% UVA and 1% UVB. This is caused by the the reflection of UVB rays back into space due to sun angle as the earth slowly rotates on its axis. The rate of change is faster the farther the position moves away from the equator (ie more north or south) 99% UVA / 1% UVB sunlight is known as “bronzing” rays, as it provides the deepest colour tanning.

On average over a day, 98.7% of the ultraviolet radiation that reaches the Earth’s surface is UVA. UVC is almost completely absorbed by the ozone layer and does not penetrate the atmosphere in any appreciable quantities. As a result, only the combination (UVA, UVB, and UVC) known as “Ultraviolet Radiation” is listed as a carcinogen, the components are only “likely to become” known carcinogens. Solar radiation, also known as “sunlight” is also listed as a carcinogen because it contains Ultraviolet Radiation. This means also that the UV Index is a measure of total Ultraviolet Radiation, and not just Vitamin D-producing UVB.

Sunlight is therefore the only listed carcinogen that is known to have health benefits, in the form of helping the human body to make Vitamin D. This makes sunlight unique on the list of known carcinogens.

Homo sapiens evolved near the equator, and human skin color is a visible indication of direct sun exposure due to the pigmentation level. With new evidence of Vitamin D receptors in all body tissues, experts advise having a balance between Vitamin D from sun exposure and Vitamin D from supplements. The only way to quantify adequate levels of Vitamin D is with a serum 25(OH) D3 test.

How To Choose The Best SPF (Sun Protection Factor)

You know that you should use some form of sunscreen every day, right? Even during those colder winter month, sunscreen is vital to your skin’s health. But, how do you choose from all of those SPFs on the market? Is one sunscreen better than another? How do you know which one to select? This article will help to clear up that SPF confusion.

What Is SPF?

Quite literally, SPF stands for “Sun Protection Factor.” In every instance, the higher the SPF number, the more protection you will receive against the sun’s UVB rays. While this information might be old news to you, did you know that the SPF number also indicates the amount of time that you can safely stay out in the sun?

For example, if you happen to be a person with sun sensitive skin, a SPF of 15 will allow you to safely remain outside for 15 times longer than they normally would. This logic can be applied to any SPF number out there.

The Higher the Better?

So, now the question is: what number should you be looking for? Well, most skincare experts tend to recommend a SPF that’s between 15-30. Any SPF number that’s higher than 30 generally doesn’t provide much more protection.

However, if you have extremely fair skin, you may want to seek an SPF or 15-30. This tiny bit of extra SPF may protect those with fair skin better than a lower number would. Even if you have dark skin, you should still wear sunscreen. Dark skin can burn just as easily as light skin can.

Powder, Liquid, or Spray?

Is there a difference between all of the powders, liquids, and sprays on the market? Is one type of sunscreen better than another? Generally, all types of sunscreen have been designed for mass use. Thus, the most important thing is to look at that SPF number.

However, you should also read sunscreen ingredients. If you use a sunscreen that’s integrated into another product (moisturizer or foundation), be careful about the ingredients included in that product. Some of these products may actually harm your skin.

Best Sunscreens

The best way to choose a sunscreen is to select one that is made from organic ingredients. These sunscreens do not contain a large amount of toxic chemicals. Instead, they are often composed of natural ingredients.

If you happen to have sensitive skin, choose a sunscreen that won’t make your skin break out. Likewise, if you intend to swim or sweat while wearing sunscreen, make sure to select a waterproof version.

Enjoy the Sun

The sun can be a welcomed thing. Sunshine feels great on skin, it gives us a boost of Vitamin D when we need it, and it has the ability to invoke positive feelings. In short, don’t avoid the sun completely.

Still, make sure that you wear a proper SPF every single time you venture outside – no matter what the season might be. This way, you can enjoy the sun without worrying about your skin.

SPF, UVB and UVA Protection Explained

Try this quiz:

• Is SPF 45 sunscreen three times stronger than SPF 15 sunscreen? Does it last three times longer?
• Do sunscreens provide better UVA protection than UVB protection?
• What works better, sunscreens or sunblocks?
• Do “broad-spectrum” sunscreens protect against all UV rays?

If you’re not certain of the answers, join the club. Recent research shows that people who buy sunscreens aren’t sure exactly what protection they offer, and are cloudy about the technical terms on their labels. A survey of 235 women who bought sunscreen found they did not know the difference between UVA and UVB or between SPF and UVA. They mistakenly believed that higher SPF ratings meant stronger UV protection, not longer protection, and the concept of “broad-spectrum” protection confused them further.

The U.S. Food and Drug Administration is urging sunscreen manufacturers to clarify the claims made on their products so that the public can make more informed purchases. In the meantime, we’d like to do our part. Here, from medical experts on The Skin Cancer Foundation’s Photobiology Committee, is a concise primer on the ABC’s of sunscreen protection:

UVA (ultraviolet-A): long- wave solar rays of 320-400 nanometers (billionths of a meter). Although less likely than UVB to cause sunburn, UVA penetrates the skin more deeply, and is considered the chief culprit behind wrinkling, leathering, and other aspects of “photoaging.” The latest studies show that UVA not only increases UVB ’s cancer-causing effects, but may directly cause some skin cancers, including melanomas.

UVB (ultraviolet-B): short-wave solar rays of 290-320 nanometers. More potent than UVA in producing sunburn, these rays are considered the main cause of basal and squamous cell carcinomas as well as a significant cause of melanoma.

Sunblocks and sunscreens: Sunscreens chemically absorb UV rays, sunblocks physically deflect them. Sunscreen has long blocked UVB effectively, but until recently provided less UVA protection. New ingredients such as octylcrylene and the benzophenones have improved sunscreen’s defenses against shorter UVA rays, and the revolutionary chemical avobenzone (Parsol 1789) works against all UVA wavelengths.

Sunblocks have also markedly improved. New preparations such as micronized titanium dioxide are less conspicuous on the skin and offer substantial protection against both UVA and UVB.

SPF (sun protection factor): measures the length of time a product protects against skin reddening from UVB, compared to how long the skin takes to redden without protection. If it takes 20 minutes without protection to begin reddening, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about 5 hours. (Actually, it may take up to 24 hours after sun exposure for redness to become visible.) To maintain the SPF, reapply sunscreen every two hours and right after swimming.

The Skin Cancer Foundation recommends SPF’s of at least 15, which block 93 percent of UVB. While SPF’s higher than 30 block only 4 percent more UVB, they may be advisable for sun-sensitive individuals, skin cancer patients, and people at high risk of developing skin cancer. They also allow some margin for error if too little sunscreen is applied.

While SPF is the universal measurement of UVB protection, no comparable standard exists for UVA. Scientists worldwide are working to develop a standardized testing and certification method to measure UVA protection.

Broad-spectrum protection: The phrase indicates that a product shields against UVA as well as UVB. It does not guarantee protection against all UVA wavelengths, however. Most broad-spectrum sunscreens and sunblocks with an SPF of 15 or higher do a good job against UVB and short UVA rays; if they also contain avobenzone, zinc oxide, or titanium dioxide, they should be effective against the entire UVA spectrum.

Even with the ideal sunscreen, some UV rays can get through to your skin and cause damage. The Skin Cancer Foundation considers sunscreen one part of a comprehensive sun protection program, along with sun-protective clothing, sunglasses, shade, and sun avoidance from 10A.M. to 4 PM.

What is Ultraviolet Radiation (UV) and UVA or UVB?

For a six billion-year-old star, the sun is certainly in the news a lot lately, mainly because it is still a source of uncertainty and confusion to many of us.The center of this confusion is the sun’s ultraviolet A (long-wave) and ultraviolet B (shortwave) rays. Our understanding of exactly what kinds of damage each causes to the skin, and how best to protect ourselves, seems to shift every year as new research comes out. For example, it was once thought that only UVB was of concern, but we keep learning more and more about the damage caused by UVA. And new, improved forms of protection against UVA keep emerging. Keeping up with these new developments is a worthwhile challenge that can help all of us prevent sun damage.

What is Ultraviolet Radiation?

UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye. These wavelengths are classified as UVA, UVB, or UVC, with UVA the longest of the three at 320-400 nanometers (nm, or billionths of a meter). UVA is further divided into two wave ranges, UVA I, which measures 340-400 nanometers (nm, or billionths of a meter), and UVA II which extends from 320-400 nanometers. UVB ranges from 290 to 320 nm. With even shorter rays, most UVC is absorbed by the ozone layer and does not reach the earth.

Both UVA and UVB, however, penetrate the atmosphere and play an important role in conditions such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system, reducing your ability to fight off these and other maladies.

UV Radiation and Skin Cancer

By damaging the skin’s cellular DNA, excessive UV radiation produces genetic mutations that can lead to skin cancer. Both the U.S. Department of Health and Human Services and the World Health Organization have identified UV as a proven human carcinogen. UV radiation is considered the main cause of nonmelanoma skin cancers (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These cancers strike more than a million and more than 250,000 Americans, respectively, each year. Many experts believe that, especially for fair-skinned people, UV radiation also frequently plays a key role in melanoma, the deadliest form of skin cancer, which kills more than 8,000 Americans each year.

UVA

Most of us are exposed to large amounts of UVA throughout our lifetime. UVA rays account for up to 95 percent of the UV radiation reaching the Earth’s surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. They are present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.

UVA, which penetrates the skin more deeply than UVB, has long been known to play a major part in skin aging and wrinkling (photoaging), but until recently scientists believed it did not cause significant damage in areas of the epidermis (outermost skin layer) where most skin cancers occur. Studies over the past two decades, however, show that UVA damages skin cells called keratinocytes in the basal layer of the epidermis, where most skin cancers occur. (Basal and squamous cells are types of keratinocytes.) UVA contributes to and may even initiate the development of skin cancers.

UVA is the dominant tanning ray, and we now know that tanning, whether outdoors or in a salon, causes cumulative damage over time. A tan results from injury to the skin’s DNA; the skin darkens in an imperfect attempt to prevent further DNA damage. These imperfections, or mutations, can lead to skin cancer.

Tanning booths primarily emit UVA. The high-pressure sunlamps used in tanning salons emit doses of UVA as much as 12 times that of the sun. Not surprisingly, people who use tanning salons are 2.5 times more likely to develop squamous cell carcinoma, and 1.5 times more likely to develop basal cell carcinoma. According to recent research, first exposure to tanning beds in youth increases melanoma risk by 75 percent.

UVB

UVB, the chief cause of skin reddening and sunburn, tends to damage the skin’s more superficial epidermal layers. It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging. Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 AM and 4 PM from April to October. However, UVB rays can burn and damage your skin year-round, especially at high altitudes and on reflective surfaces such as snow or ice, which bounce back up to 80 percent of the rays so that they hit the skin twice. UVB rays do not significantly penetrate glass.

Persistent Pigment Darkening (PPD)

The Persistent Pigment Darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Originally developed in Japan, it is the preferred method used by skin care manufacturers.

Instead of measuring erythema or reddening of the skin, the PPD method uses UVA radiation to cause a persistent darkening or tanning of the skin. Theoretically, a sunscreen with a PPD rating of 10 should allow you to endure 10 times as much UVA as you would without protection. The PPD method is an in vivo test like SPF. In addition, Colipa has introduced a method which, it is claimed, can measure this in vitro and provide parity with the PPD method

As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a UVA PF of at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its phase-in period, so a sunscreen without it may already offer this protection.

Sun Protection Factor (SPF)

The SPF of a sunscreen is a laboratory measure of the effectiveness of sunscreen — the higher the SPF, the more protection a sunscreen offers against UV-B (the ultraviolet radiation that causes sunburn).

The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen. So, wearing a sunscreen with SPF 50, your skin will not burn until it has been exposed to 50 times the amount of solar energy that would normally cause it to burn. The amount of solar energy you are exposed to depends not only on the amount of time you spend in the sun, but also the time of day. This is because, during early morning and late afternoon, the sun’s radiation must pass through more of the Earth’s atmosphere before it gets to you. In practice, the protection from a particular sunscreen depends on factors such as:

* The skin type of the user.
* The amount applied and frequency of re-application.
* Activities in which one engages (for example, swimming leads to a loss of sunscreen from the skin).
* Amount of sunscreen the skin has absorbed.

The SPF is an imperfect measure of skin damage because invisible damage and skin aging are also caused by ultraviolet type A (UVA, wavelength 320 to 400 nm), which does not cause reddening or pain. Conventional sunscreen blocks very little UVA radiation relative to the nominal SPF; broad spectrum sunscreens are designed to protect against both UVB and UVA. According to a 2004 study, UVA also causes DNA damage to cells deep within the skin, increasing the risk of malignant melanomas. Even some products labeled “broad-spectrum UVA/UVB protection” do not provide good protection against UVA rays. The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum, as recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths between 340 and 380 nm.

Owing to consumer confusion over the real degree and duration of protection offered, labeling restrictions are in force in several countries. In the EU sunscreen labels can only go up to SPF 50+ (actually indicating a SPF of 60 or higher) while Australia’s upper limit is 30+. The United States does not have mandatory, comprehensive sunscreen standards, although a draft rule has been under development since 1978. In the 2007 draft rule, Food and Drug Administration (FDA) proposed to institute the labelling of SPF 50+ for sunscreens offering more protection. This and other measures were proposed to limit unrealistic claims about the level of protection offered (such as “all day protection”).

UV-B sunlight spectrum (on a summer day in the Netherlands), along with the CIE Erythemal action spectrum. The effective spectrum is the product of the former two.

The SPF can be measured by applying sunscreen to the skin of a volunteer and measuring how long it takes before sunburn occurs when exposed to an artificial sunlight source. In the US, such an in vivo test is required by the FDA. It can also be measured in vitro with the help of a specially designed spectrometer. In this case, the actual transmittance of the sunscreen is measured, along with the degradation of the product due to being exposed to sunlight. In this case, the transmittance of the sunscreen must be measured over all wavelengths in the UV-B range (290–320 nm), along with a table of how effective various wavelengths are in causing sunburn (the erythemal action spectrum) and the actual intensity spectrum of sunlight (see the figure). Such in vitro measurements agree very well with in vivo measurements. Numerous methods have been devised for evaluation of UVA and UVB protection The most reliable spectrophotochemical methods eliminate the subjective nature of grading erythema.

Mathematically, the SPF is calculated from measured data as

where E(λ) is the solar irradiance spectrum, A(λ) the erythemal action spectrum, and MPF(λ) the monochromatic protection factor, all functions of the wavelength λ. The MPF is roughly the inverse of the transmittance at a given wavelength.

The above means that the SPF is not simply the inverse of the transmittance in the UV-B region. If that were true, then applying two layers of SPF 5 sunscreen would be equivalent to SPF 25 (5 times 5). The actual combined SPF is always lower than the square of the single-layer SPF.

Measurements of UVA protection – Persistent Pigment Darkening (PPD)

The Persistent Pigment Darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Originally developed in Japan, it is the preferred method used by manufacturers such as L’Oreal.

Instead of measuring erythema or reddening of the skin, the PPD method uses UVA radiation to cause a persistent darkening or tanning of the skin. Theoretically, a sunscreen with a PPD rating of 10 should allow you to endure 10 times as much UVA as you would without protection. The PPD method is an in vivo test like SPF. In addition, Colipa has introduced a method which, it is claimed, can measure this in vitro and provide parity with the PPD method.

The UVA seal used in the EU

As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a UVA PF of at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its phase-in period, so a sunscreen without it may already offer this protection.

Making Sense of Sunscreen Products

Most people are understandably confused when it comes to choosing a sunscreen because of the baffling array of available choices. Common questions about sunscreens include

* How high should the SPF be?

* Should it block UVA or UVB?

* Does it matter whether it is a gel, cream, or spray?

* Should it be water-resistant or waterproof?

SPF stands for sun protection factor. The SPF numbers on a product can range from as low as 2 to as high as 60. These numbers refer to the product’s ability to screen or block out the sun’s burning rays. The SPF rating is calculated by comparing the amount of time needed to produce sunburn on protected skin to the amount of time needed to cause a sunburn on unprotected skin. The higher the SPF, the greater the sun protection. However, it is a common mistake to assume that the duration of effectiveness of a sunscreen can be calculated simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen, because the amount of sun exposure a person receives is dependent upon more than just the length of time spent in the sun. The amount of sun exposure depends upon a number of factors including the length of exposure, time of day, geographic location, and weather conditions.

The sun’s rays contain different wavelengths of ultraviolet (UV) light. The two types of UV rays that pass through the earth’s atmosphere and cause damage to the skin are UVB and UVA. UVB rays are the primary cause of sunburn and affects the outer layer of skin.

The strength of UVB radiation depends upon the time of day, season of the year, and geographic location. UVB rays are most intense from 10 a.m. to 2 p.m. and are stronger in summer, at higher altitudes, and closer to the equator.

Unlike UVB rays, which do not penetrate glass, UVA rays can travel through window glass and damage the deeper layers of the skin. Both UVA and UVB light contribute to age-related changes in the skin such as wrinkles, freckles, age spots, and prominent blood vessels. Both UVA and UVB exposure raise the risk of skin cancer.

Sunscreens can be broadly classified into two categories: chemical sunscreens and physical sunscreens. Chemical sunscreens absorb UV radiation while physical sunscreens act by physically blocking it. Chemical sunscreens can be UVA or UVB absorbers. Many sunscreens have a combination of ingredients and may contain both physical and chemical sunscreens.

Physical sunscreens are good blockers of both UVA and UVB radiation. The two most common physical blockers of UV radiation are titanium dioxide and zinc oxide. Examples of chemical sunscreens include:

* PABA (para-aminobenzoic acid): Rarely found in modern preparations, PABA was an early chemical sunscreen that often induced sensitivity reactions.

* PABA esters (glyceryl, padimate A and padimate O): These newer preparations have fewer side effects than the original PABA.

* Salicylates (homosalate, octyl salicylate)

* Cinnamates (cinoxate, octyl methoxycinnamate or octocrylene): Octocylene is a cinnamate with both UVA and UVB absorbing properties.

* Benzophenones: These can absorb both UVA and UVB rays.

* Ecamsule (Mexoryl) is a potent UVA blocking compound.

Since both UVA and UVB radiation can be damaging, an ideal sunscreen provides protection from both types of radiation. The SPF system measures only the degree of protection from UVB rays. No rating system exists that measures the degree of protection from UVA exposure.

Most experts recommend reading the list of ingredients in a sunscreen to see if it has broad-spectrum (UVA and UVB) coverage. Many products labeled as “broad spectrum” or “UVA blockers” do not adequately block UVA rays. A good broad-spectrum sunscreen should contain avobenzone, ecamsule (Mexoryl), titanium dioxide, or zinc oxide for significant UVA protection.

Whether you choose a lotion, stick, gel, or cream sunscreen depends largely on your skin type and personal preference. Oil-free gels are good solutions for facial skin prone to breakouts, and sprays may make application to the back and shoulders easier.

“Water-resistant” sunscreens should retain their protective ability for at least 40 minutes in water. Those labeled “waterproof” should protect the skin for 80 minutes in water.

The American Academy of Dermatology recommends using a broad-spectrum sunscreen with an SPF of at least 15 on a daily basis throughout the year. An important note is that no sunscreen can be effective unless it is properly and frequently applied. About 1 ounce (5-6 teaspoons) of sunscreen is recommended to cover the entire body. Further, sunscreen must be reapplied every two hours when staying outdoors for a prolonged period of time.

The Chemistry of Tanning

It’s no coincidence that the process of turning animal skins into leather is called tanning. When people tan, UV radiation from the sun breaks down protein in our skin cells and causes, over time, wrinkles and leathery-looking skin. According to the American Academy of Dermatology (AAD), most sun exposure occurs before the age of 18. With major summer “beach time” remaining, here’s some information from the American Chemical Society, the world’s largest scientific society, on how consumers can protect themselves and their families from the sun’s harmful rays:

Perfect tan made in the shade: Everyone knows that too much exposure to the sun can cause skin cancer and premature aging. Everyone from Jennifer Aniston to your neighbor is using self-tanners to recreate that coveted bronze glow. But how do they work and are they safe? According to Chemical & Engineering News, self-tanners contain an active ingredient called dihydroxyacetone (DHA), a nontoxic, simple sugar found in baby formula and fish oil. DHA turns skin brown in a process called the Maillard reaction, better known to food chemists for making beer golden brown. Proteins in our skin interact with sugars to create brown or golden-brown compounds. DHA doesn’t penetrate further than the outermost, dead layer of skin.

Making sense of sunscreens: From moisturizers to lipsticks, sales of personal care products formulated with sunscreen have exploded. The sun’s rays are more damaging now then ever because the earth’s protective ozone layer is depleted, but with 17 active sunscreen ingredients approved for use in the United States, how do you choose? According to Chemical & Engineering News, sunscreens with inorganic ingredients such as titanium dioxide and zinc oxide reflect and scatter UV light. Sunscreens made with organic ingredients like OMC and avobenzone absorb UV light and dissipate it as heat. SPF (sun protection factor) measures how effectively a sunscreen protects against UVB rays that burn skin.

Newer sunscreens offer greater protection against sun’s rays: Craig Bonda, a chemist at the C.P. Hall Company in Bedford Park, Ill., has developed a longer-lasting sunscreen that protects wearers against both UVB and UVA radiation. Until recently, most sunscreens protected only against UVB — the ultraviolet rays that cause sunburn. The newest sunscreens absorb or reflect the full spectrum of ultraviolet radiation, including UVA, which causes skin to age and wrinkle prematurely and may also cause certain skin cancers. Avobenzone, a chemical used in many full-spectrum sunscreens, loses its effectiveness upon prolonged exposure to the sun. Bonda found that avobenzone breaks down more slowly when the chemical DEHN is added.

Photosensitivity : Another Reason for UVA Skin Protection

We react normally to sun exposure by developing a tan or sunburn. But some of us react abnormally from photosensitivity. For instance, during the last two summers, I have broken out in a rash from the sun. My doctor said it is contact dermatitis, preciously, photocontact dermatitis. The allergen could even be a sunscreen ingredient.

UVA is a major trigger for photosensitivity. These rays can penetrate glass, so you’re exposed to UVA when you are near a window or driving your car. UVA penetrates deeper into skin than UVB and can cause premature aging. It can also contribute to skin cancer.

When UV radiation is absorbed by photosensitizer molecules, they in turn elicit a reaction in chromophores, molecules in the skin. The result is an abnormal skin reaction, such as a rash.

Photosensitizers can be either allergens or toxins. Phototoxins can be drugs, plants or coal tar derivatives. They cause sunburn like reactions, and are dose-dependent. Photoallergies elicit immune responses and tend to cause more severe skin reactions. Photoallergens can be drugs or topical agents and can spread beyond the sun exposed region of the skin. These molecules cause a rash like symptom. They are not dose-dependent.

Patients can react to sensitizers that originate outside or inside the body. Various drugs can cause photosensitivity. Cosmetics or other materials may contain potential photosensitizers that are deposited on the skin or given internally, whereas an immune disorder, such as lupus, can cause an abnormal reaction to the sun that originates inside the body.

Some organic sunscreen chemicals absorb UVA, UVB or both. Ingredients, such as octocrylene, protect against UVB. Ingredients, such as avobenzone (Parsol 1780) or a benzophenone (such as dioxybenzone, oxybenzone or sulisobenzone), protect partially against UVA. Some sunscreen ingredients provide physical sun protection that reflect or absorb UVA and/or UVB. These ingredients include zinc oxide and titanium dioxide. Most sunscreens contain a combination of active, as well as inactive ingredients.

“The physical blocking agents have not been reported to cause contact dermatitis, ” writes Daniel More, M.D., in his about.com column and who currently practices allergy and clinical immunology in Salinas, California and is an Assistant Clinical Professor in the Department of Family and Community Medicine at the UCSF School of Medicine. Also, studies have found that inorganic agents, such as zinc oxide, are photostable; they don’t degrade rapidly; however, organic agents tend to be less stable.

“Photostability depends not only on the sunscreen active ingredients but also on the inactive ingredients,” says Susan Cruz, spokesperson for the FDA. “You can compare two different sunscreens with the same active ingredients at the same concentration, and the sunscreens can have different SPF values,” says Susan Cruz, spokesperson for the FDA.

Sunscreen product labels don’t list the percentage of ingredients along with their synonyms. Example: Amyl dimethyl PABA (padimate A, isoamyl-p-N,N-dimethylaminobenzoate, Escalol 506, pentyldimethyl PABA). The FDA limits the percentage of sunscreen active ingredients. For example, zinc oxide is limited to 25%, Avobenzone, 3%.

FDA’s Office of Nonprescription Products within the Center for Drug Evaluation and Research (CDER) is developing UVA testing and labeling requirements for sunscreens. It is currently in final clearance. But in the meantime, avoid the sun between 10 and 4 when UV radiation is more intense, and use sunscreen properly by:

* checking the expiration date.
* applying sunscreen every 2 hours from sunrise to sunset all year round and every hour if you sweat or bathe since sunscreen wears of and loses effectiveness over time.
* applying sunscreen if you are near a window that gets sun or when you’re drying a car. Glass windows don’t block UV-A radiation.
* applying lip balm with broad spectrum sun protection.
* applying sunscreen when you plan to be in the shade since sun light is scattered in all direction, even under an umbrella.
* reapplying sunscreen after rubbing, such as towel drying. Rub the sunscreen in gently or you may rub it off.
* applying evenly a generous amount of sunscreen with broad spectrum sun protection, but don’t rub hard or you may rub it off. About an ounce is required to cover the entire body.

In addition to sunscreen, Cyndi Yag-Howard, M.D., a Florida dermatologist and spokesperson for the Skin Cancer Foundation, recommends that patients at high risk of skin cancer, which includes those who are photosensitive, wear under clothing a broad spectrum sunscreen with an SPF of at least 30, or purchase sun protective clothing that is labeled. And everyone should wear a wide brim hat and sunglasses that filter at least 98% of UV.

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