Did you know that as much as 80 percent of your lifetime exposure to sunlight happens before the age of 18? This early sun exposure slowly causes DNA damage and puts us at risk for skin cancer later on. One of the biggest risk factors for developing melanomas is the frequency of sunburns as a child. In other words, your lifetime risk factors for skin cancer can be largely predicted even before you leave high school!

The obvious solution is to use protective sunscreen or clothes at all ages – but especially in childhood. Most parents are great at protecting babies and toddlers from the sun, but only 25 percent of teens use sunscreen. Appeal to your teen’s vanity by telling them that daily sunscreen use prevents wrinkles; if greasiness is the main “ick” factor, I recommend the Neutrogena line of sunscreens (including the men’s aftershave). They absorb into the skin with a dry, light feeling. Parents should also lead by example by putting on sunscreen every day during the summer months; don’t forget the oft-neglected ears and toes. After all, it only takes 20 minutes to get sunburned in midday.

Parents and teachers can find kid-friendly educational material at SunWise (www.epa.gov/sunwise), a website created by the US Environmental Protection Agency. Studies from countries with thinner ozone layers, such as Canada and Australia, showed that regular use of SPF 30 sunscreen over several years lowered children’s risk of forming moles – an early stage in the development of melanomas. Another study showed a 50 percent drop in melanoma rates among adults who regularly used sunscreen.

However, don’t go overboard with SPF ratings. Supermarkets are now filled with expensive sunscreens outdoing each other: SPF 70, 90, even 100! Is higher better? “Definitely not,” say most doctors, including dermatologists. Any SPF over 50 is overkill and a waste of money; at SPF 30, you’re already eliminating the majority of ultraviolet rays. Last year, the US Food and Drug Administration (FDA) decided to ban any sunscreen labels over SPF 50, forcing manufacturers to simply print “SPF 50+.”

That being said, a bit of sunlight is essential to good health. People who constantly use sunscreen may actually have low levels of vitamin D, which can cause a whole other set of health issues. I generally recommend vitamin D as a supplement for both kids and adults.

(This article was originally printed in Beijing Kids magazine, where I am a contributing editor. You can click here to read the rest of my BeijingKids “The Doc Is In” columns.)