Ultraviolet Radiation

EVERYTHING YOU NEED TO KNOW ABOUT UVR AND PROTECTING YOURSELF

Ultraviolet solar radiation (UVR) is linked to 90% of all skin cancers as well as sunburns and photoaging. It is characterized by broken blood vessels, wrinkles, rough, leathery skin and brown spots. It changes DNA, suppresses the immune system and is the main cause of cataracts.

There are three types of UVR but only two that currently concern you:

UVA are long wavelengths that penetrate window glass and travel more deeply into the skin. They constitute more than 90% of all ultraviolet rays. They are present all year long and bear major responsibility for aging of the skin, most skin cancers including malignant melanoma, and suppression of the immune system. UVA is present in the same amount all day long, all year long and is independent of altitude, atmospheric or weather conditions. About 50% of UVA exposure occurs in the shade.

UVB causes most sunburn, synthesizes vitamin D and results in delayed tanning. UVB is prevalent only when the sun is high in the sky – between 10 AM and 4 PM. UVB exposure increases 8-10% for every 1000 feet above sea level, so it is very important to use protection at higher elevations. Since snow reflects up to 80% of UV, it nearly doubles the exposure.

STATISTICS IMPORTANT TO YOU

One in five Americans will get skin cancer in his/her lifetime.
Actinic keratoses (precancers) are most prevalent cell abnormality followed by basal cell carcinoma (over 1 million annually in the US), squamous cell carcinoma (>200,000), and malignant melanoma. (~70,000 invasive and >46,000 limited to the top layer of skin).
A recent study of 1621 Australians found that regular use of sunscreens reduced the risk of malignant melanoma by 50-73%.
In the US, people sitting on the left side of the car receive approximately 6 times the dose of UV radiation on the left side of the head, neck, arm and hand as compared to the right side. As would be expected there are more basal cell, squamous cell and melanoma skin cancers on the left side of the face and left arm due to driving. This can be lessened by regular sunscreen use.

TIPS TO PROTECT YOURSELF

While UVR peaks in the summer, more than half the annual total is emitted during the rest of the year. Basic, daily, year-round, sustained protection is the key. There is no such thing as a healthy tan. Tanning is the skin’s response to DNA cell damage.

There are ways to protect yourself, including:

Seek shade when out and schedule outdoor activities before 10 AM or after 4 PM
Wear protective clothing and sunglasses. Consider purchasing specially made clothing with ultraviolet protection factor (UPF) labeling. The UPF should be at least 30 meaning that the fabric will only allow 1/30^th of the sun to penetrate it. Dark colored, tightly-woven fabrics offer better sun protection than light ones. A white T shirt has a SPF of 7 and if it becomes wet, the SPF drops to 3. A long-sleeved, dark denim shirt has an estimated SPF of 1,700. Hats with a 3 inch brim all around are also recommended.
Regularly and liberally apply sunscreen. The average person should apply two tablespoons (one ounce) to the sun exposed skin with 1/3 of that applied to the head and neck 15-30 minutes before exposure. Most people apply 25-75% less sunscreen than the amount used in testing, thereby, getting only 20-50% of the protection shown on the label. Therefore, reapplication 15-30 minutes after sun exposure to compensate for insufficient initial application, and every two hours or more often following swimming, toweling or heavy sweating is recommended.

NEW SUNSCREEN REGULATIONS

The Food and Drug Administration recently issued its final monograph on sunscreens. These requirements take place in 2012 for most sunscreen makers, but smaller manufacturers have an additional year to comply. The major points are:

The terms ”sunblock,” “ sweatproof” and “waterproof” will not be permitted.
“Water resistance” can be claimed if the duration of action is specified (either 40 or 80 minutes).
Only sunscreens that block both UVA and UVB can claim to be broad spectrum and when used properly with other protective measures can reduce the risk of skin cancer and limits premature aging of the skin. Very few sunscreens available in the US today provide adequate UVA protection.
Sunscreens with an SPF <15 can claim to be broad spectrum but must carry a warning that they do not protect against skin cancer or premature aging.
If sunscreens provide no UVA protection, the must be labeled as such.
UVA protection would be rated by stars with one star meaning low level UVA protection, 2-medium, 3-high, and 4-highest level of protection.

WHAT DOES IT MEAN?

SPF (Sun Protection Factor) measures UVB protection only. An SPF of 15 or higher is recommended for daily use and 30 or higher for active exposure. There is diminished return with higher SPFs. For example, SPF of 15 provides 94% protection and SPF 30 provides 97% protection. SPF 50 or 100 only offers about 1% more protection. These higher SPF sunscreens are not recommended because they are not cosmetically elegant and therefore, often not used properly.

UVA: It is imperative that sunscreens provide good UVA protection. There are only a few sunscreen ingredients that provide good UVA as well as UVB protection. You should look for sunscreens that contain Ecamsule (Mexoryl SX) or Helioplex (avobenzone with octocrylene) or zinc oxide (>6%) and titanium dioxide and in appropriate concentrations. The latter two physically block sun penetration.

Studies have shown that fears of nanoparticles penetrating the skin and being dangerous are unwarranted as they do not penetrate living skin. Avobenzone (Parsol 1789) alone blocks UVA, but it breaks down by 36% within 15 minutes of exposure, so it must be combined with octocrylene or oxybenzone to stabilize it. Some examples of sunscreens with both UVA and UVB protection are Anthelios (La Roche Posay), Neutrogena with Helioplex and Aveeno.

When applying medication, moisturizers, sunscreens and makeup to the same area, they should be applied in the preceding order.

Tanning beds are carcinogenic and dangerous. On November 11, 2009, Brazil became the first country to prohibit the use of tanning beds for cosmetic purposes and made it illegal to receive, import, donate or rent tanning equipment. The U.S. should do the same.