Is There Any Such Thing As a Safe Sun Tan?
The question about whether any sort of sun tan is safe is one that's asked constantly and brings a different answer depending on who you ask.
Recently U.S. and British researchers reviewed published studies and noticed that both tans and skin cancer start with changes to the DNA that comes from ultraviolet light. "The signals in the cells that induce sun tanning appear to be DNA damage," said Dorothy Bennett, a cell biologist at St. George's University of London. She insists that anything that causes mutations in the cells will increase your risk of cancer. The link between skin cancer and tans that come from the sun or tanning booths is well documented, but the new study presents the idea that even a little bit of exposure of either kind can be dangerous.
The World Health Organization estimates that 60,000 people die each year from exposure to too much ultraviolet light. According to the information provided on the site, "A large number of studies indicate that the risk of malignant melanoma correlates with genetic and personal characteristics, and a person's UV exposure behaviour."
Beyond the skin cancer risk, exposure to the sun speeds up aging, cataracts and other eye problems, and may even reduce the effectiveness of the immune system.
Here are some surprising things you might want to know about sun tanning:
- Your tan is your body's defense against further UV damage.
- The protection of sunscreens depends more than anything on applying them correctly.
- A deep tan only provides an estimated SPF of 4.
- UV exposure is cumulative over a day.
- UV radiation can't be felt; a hazy sky or water can enhance your exposure.
But don't we need some sun exposure?
The sun brings us light, heat and UV radiation, which aren't all bad. UVB rays from the sun help our bodies convert precursor chemicals into vitamin D - giving us about 90% of what we need. Deficiencies of vitamin D are very common, and without enough of this essential nutrient, you're at risk for developing many serious diseases including osteoporosis and some cancers, infectious disease and heart disease.
"Sun is crucial to your overall physical and mental well-being," says Dr. Michael F. Holick, author of The UV Advantage, and professor of Medicine, Dermatology, Physiology and Biophysics at Boston University Medical Center. Holick is the expert who uncovered evidence that vitamin D is produced by sun exposure and is necessary to say healthy.
So what to do? Too much sun exposure increases your skin cancer risk, too little puts you at risk for not having the vitamin D your body needs.
Here's the way to strike a balance:
- Get natural sunlight in the off peak hours - early morning or later in the afternoon. Be sure to apply (and re-apply) any sunscreen you use when you're out in the sun during peak hours - 10:00 am to 2:00 pm.
- Avoid tanning beds and the risks of UV exposure (and DNA damage), especially important for younger women.
- Get that golden, sun tan glow from sunless tanning products that are safe to use (they don't enter the body) so long as you follow the package directions.
What Causes Darkness of the Skin?
Skin darkness is caused by the compound melanin. There are several things that can cause increased production of melanin including sun exposure. Here you will learn about melanin and what stimulates its production. Then we will learn about How to Lighten Dark Skin.
**What is Melanin?
Melanin is a pigment or color. In humans, it is responsible for the color of the skin and hair. It is found in other parts of the body as well, including some glands and portions of the eyes, brain and inner ear.
Melanocytes are specialized cells responsible for melanin production. The skin's melanocytes are found in the bottom layer of the skin's epidermis, which is known as the stratum basal.
Most humans have between 1000 and 2000 melanocytes per square millimeter or stratum basal, constitution between 5 and 10% of the cells in that layer. The difference in skin-color seen in different races is not due to the number of melanocytes, but to the type of melanin produced and the presence of an enzyme called tyrosinase. A lack of tyrosinase results in the very pale skin-color present in albinos.
**Differences in Melanin Level
Differences in melanin production are responsible for the slight differences in skin-color seen in people of the same race. That brings us to the causes of increased melanin production.
**Sun Exposure Cause
Sun exposure is the most common cause. Overexposure for long periods of time can lead to skin roughness, as well. The skin roughness is not specifically due to melanin, but to changes in cellular DNA caused by free radical activity and to the drying effect of the sun.
UVB rays of sunlight can cause direct or indirect damage of the melanocytes' DNA. Direct DNA damage results in a tan. Indirect DNA damage can lead to cancer of the melanocytes, which is known as melanoma.
Other causes of increased melanin production include hormonal activity and exposure to toxins. Excessive intake of beta-carotene can cause a skin darkness that appears to be an orange-colored tan. Vitamin D and B-5 can enhance the tanning process and are sometimes used as naturally tanning
aids.
**Freckles and Skin Spots
Age spots and freckles are ultimately caused by clumps of melanin. Most of the clumping is due to sun exposure. Free radicals damaging the melanocytes' DNA are believed to be involved.
Rough patches sometimes appear as people age. In some cases the rough patches look a little darker than the surrounding epidermis.
Heavily pigmented patches of varying shapes and sizes may be due to increased hormonal activity due to pregnancy. This is sometimes referred to as the "mask of pregnancy". Hormonal changes that occur during menopause are associated with an increased incidence of age spots, although excessive sun exposure is likely involved as well.
**Uneven Skin Tone
Generalized unevenness of pigmentation is commonly found in older people. While melanin is involved in these changes, another factor is involved.
The outermost layers of the epidermis are constantly replaced throughout a person's life. Mother cells also found in the stratum basal are responsible for this replacement process.
The new cells produced are referred to as keratinocytes. If melanin production has been stimulated, the keratinocytes will be darker in color. If not, they will be lighter in color.
Age, irregular sun exposure and decreased production of new keratinocytes combine to create uneven pigmentation and skin darkness. Now that you know about the causes, you correct the problem. That is the subject of my next article.