вторник, 18 сентября 2012 г.

Health wise: summer 2010, helping students make healthy choices. - The Science Teacher

Q No matter what I tell my students, they insist it's safe to go to the tanning salon. What are the real effects of tanning beds?

A Whether preparing for prom, spring break, or the next cast of Jersey Shore, teens today are no stranger to the tanning salon. In fact, 2.3 million teens tan indoors in the United States each year (Skin Cancer Foundation 2010).

But despite the large number of tanning bed--going teens, many are unaware of the real risks involved. Here are a few things teens--and all of us--should know before hopping into that tanning bed.

Tanning beds, like the Sun, emit ultraviolet (UV) radiation. Short-term exposure to UV radiation can cause burns and other skin damage. Longterm exposure can cause premature aging (think wrinkles, sun spots, and leathery skin), eye damage, immune system suppression, and skin cancer (FDA 2009).

In fact, the International Agency for Research on Cancer now places tanning beds in its highest risk category--Group 1 carcinogens ('carcinogenic to humans')--along with cigarettes and asbestos.

In addition, studies have shown that using a tanning bed before the age of 35 increases your risk of developing melanoma--the deadliest form of skin cancer--by 75% (WHO 2010a; Lichtenfeld 2010): So teens who tan, take note.

Proponents of tanning bed use often argue that 'controlled' tanning is safer than tanning outdoors--however, there is no laboratory, behavioral, or epidemiologic data to support this claim (Balk and Geller 2008). The UV rays emitted from tanning beds can be 10--15 times stronger than those of the midday Sun (Balk and Geller 2008).

For these reasons--and the increased sensitivity to UV radiation in childhood and adolescence (Balk and Geller 2008)--the World Health Organization, the American Medical Association, and the American Academy of Dermatology support legislation that bans tanning bed use for those under the age of 18 (Balk and Geller 2008). The U.S. Food and Drug Administration, which has regulated tanning bed use for over 20 years, is now considering a federal ban on tanning beds for minors (Perrone 2010).

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Now that you know the risks of tanning beds, if you still can't resist that Sun-kissed look, try a self tanner or spray tan. These products spare you the UV radiation, but should not be ingested or inhaled and should not come into contact with the eyes, nose, or mouth.

Remember that whether you choose the tanning bed, a spray tan, or no tan at all, it is important to protect your skin--especially if you burn easily; have blonde, red, or light brown hair; or have a family history of skin cancer.

Before you head outside, apply a sunscreen with an SPF (sun protection factor) of 15 or greater, and reapply often. Avoid the Sun from 10:00 a.m. to 4:00 p.m. if you can, and protect your eyes, too.

Skip the tanning bed--and avoid the age spots, wrinkles, and leathery skin that come with prolonged UV exposure. Years from now, when you look as young as you feel, you'll be glad you did!

Do you have a question for the Health Wise column to answer, or feedback? Send an e-mail to sliberatore@nsta.org.

Acknowledgment

Sincere thanks to Bernard 'Buddy' Cohen, director of Pediatric Dermatology at the Johns Hopkins University School of Medicine in Baltimore, Maryland, for reviewing this column.

Note to teachers

In addition to its relevance for biology and health classes, the interdisciplinary nature of this topic makes it well suited for chemistry and physics courses as well. For chemistryrelated classroom activities involving sunscreens, see the Keen-Rocha (2005), Wise et al. (2009), Roy (2009), and Sullivan (2009) articles listed in the References section.

References

Balk, S.J., and A.C. Geller. 2008. Teenagers and artificial tanning. Pediatrics 121 (5): 1040-1042.

Keen-Rocha, L. 2005. To tan or not to tan? The Science Teacher 72 (6): 46-50.

Lichtenfeld, L. 2010. Should we ban tanning beds? The FDA is listening. American Cancer Society. www. cancer. org/aspx/blog/Comments.aspx?id=347

Perrone, M. Associated Press. 2010. FDA panel mulls tanning bed ban for teens under 18. March 25.

Roy, K. 2009. Sun safety: The stats. The Science Teacher 76 (8): 12-13.

Skin Cancer Foundation. 2010. Skin cancer facts. www.skincancer.org/Skin-Cancer-Facts

Sullivan, M. 2009. Health Wise: What are the risks of sun exposure--are there any benefits? The Science Teacher 76 (5): 66-67.

U.S. Food and Drug Administration (FDA). 2009. Tanning. www.fda.gov/Radiation-EmittingProducts/ RadiationEmittingProductsandProcedures/Tanning/default.htm

World Health Organization (WHO). 2010a. Ultraviolet radiation and human health. www.who.int/ mediacentre/factsheets/fs305/en/index.html

WHO. 2010b. Sunbeds, tanning, and UV exposure. www.who.int/mediacentre/factsheets/fs287/en/index.html

Wise, A., P. Schank, T. Stanford, and G. Horsma. 2009. The science behind nanosunscreens. The Science Teacher 76 (6): 46-51.

Health-related content appearing in these pages is intended for information only and is not presented as a substitute for individual medical advice, diagnosis, or treatment by a qualified health professional.

Top five tanning bed myths.

1. Tanning beds provide me with essential vitamin D. Although it's true that 5-15 minutes of exposure to ultraviolet (UV) rays twice a week can help your body produce vitamin D (FDA 2009)--a nutrient that promotes bone development and a strong immune system--it's much safer to get it from fish, eggs, or dietary supplements. Most of us get a healthy amount of vitamin D through our diet and through incidental Sun exposure (WHO 2010b), but people who live in the northern half of the country or have darker pigmentation may need oral supplementation, particularly during the winter months.

2. If I don't burn in the tanning bed, I'm not doing my skin any harm. There's no such thing as a healthy tan. When UV rays penetrate the skin, your cells produce a pigment called melanin that darkens the skin to protect it from further damage. What you might think of as a healthy glow is actually your body's response to injury.

3. A base tan will prevent me from getting burned. Contrary to popular belief, a base tan will not protect you from sunburn. The extra melanin in tanned skin provides an SPF (sun protection factor) of about 3 or less--well below the recommended SPF of 15 (Balk and Geller 2008).

4. UVA rays are safer than UVB rays. Most tanning beds emit both UVA and UVB rays, although some only emit UVA. Both types of rays damage the skin, but do so in different ways. UVB rays have shorter wavelengths that penetrate the outer layer of the skin (the epidermis); UVA rays have longer wavelengths that can reach the middle layer of the skin (the dermis) (FDA 2009). Both UVA and UVB rays have been shown to cause cancer (WHO 2010b; Lichtenfeld 2009).

5. I have darker skin, so I don't have to worry about UV rays. Although those with darker skin are less susceptible, they are still at risk for sunburn, skin damage, and skin cancer. The melanin in African American skin, for example, can provide an SPF of about 13, compared to about 3 in Caucasian skin (FDA 2009).

On the web

Choose Your Cover program: www.cdc.

gov/cancer/skin/chooseyourcover Sun Wise program: www.epa.gov/sunwise/index.html