Sunscreen use is very important, but it’s not the only tool necessary to reduce your risk of developing the most common cancer of all — skin cancer, according to the American Cancer Society (ACS).

The ACS now has a promotional catch-phrase: "Slip, slop, slap." That’s shorthand for slip on a shirt, slop on the sunscreen, slap on a hat — and look for shade in the middle of the day. Since sun exposure is the primary risk factor for skin cancer, ACS offers skin-cancer prevention information.

Make sure you protect yourself and your children from the sun every time you go outside, not just at the beach, pool, or boat, advises Alan Geller, RN, MPH, research associate professor of dermatology and epidemiology at Boston University. Geller is a member of the ACS national skin cancer advisory committee.

"All parts of the skin should be covered with some kind of protection," Geller says; if kids wear a shirt, that’s fine — in most cases — unless they are very prone to sunburn."

Most people are not aware that you can get significant ultraviolet (UV) light exposure (that’s what causes skin damage from the sun) through clothing, such as T-shirts. In fact, white T-shirts provide only modest protection from the damaging effects of the sun. Blue shirts give the highest rate of protection, according to a recent study published in the Journal of the American Academy of Dermatology. Researchers at the New York University Medical School found that white shirts dyed blue raised UV protection 544%. They also tested Tinosorb, a detergent additive, and found that it makes clothing more UV absorbing by 400% after washing.

In spots that the shirt does not cover, such as the upper part of the neck and the arms from the sleeve line to the hand, should be covered with sunscreen, Geller recommends.

"While you could possibly argue that it is easier to burn at the beach because the sun’s rays reflect off the sand, that probably misses the point," Geller says. "The sun can cause equal damage if your child is on their bike in the driveway if they are not protected," he emphasizes.

"My daughter is very fair, and like many fair-skinned children, will burn within 12 to 15 minutes of outdoor exposure," Geller cautions.

With entire aisles devoted to sun protection products at some drug stores, and an array of SPFs (sun protection factor), what do you choose?

"The best recommendation is to use SPF 15 or greater, but use it well," Geller says; "this means a one-ounce application, every two hours. One ounce means a palmful of sunscreen."

Be especially on guard during peak sun exposure hours — from 10 am to 4 pm, Geller notes.

"We have good evidence that children who are protected all six hours of peak sun exposure, as opposed to fewer hours, are 50% less likely to get a sunburn during the summer," Geller says.

A study conducted last Fourth of July weekend at a public beach in Galveston, Texas, investigated the use of sunscreen, and determined that 73% of the people interviewed who applied sunscreen got sunburned. This study was featured recently in the Journal of American Academy of Dermatology.

Mostly, this was not the fault of the sunscreen, but the people who misapplied it. The researchers at the department of dermatology, University of Texas Medical Branch in Galveston, report that many of those who got sunburned went swimming and the sunscreen washed off, or they only applied it once. The authors note that people who waited more than 2.5 hours to reapply their sunscreen had five times more chance of getting sunburned, than those who reapplied every two hours.

Use of stronger sunscreen may be giving some young people a false sense of security that is causing them to prolong the amount of time they spend in the sun, as noted in ACS News Today.

Only about one-third of teen-agers aged 11 to 18 routinely takes steps to protect themselves from sunburn on sunny days, according to findings from a youth skin cancer risk behavior survey.

Because people aren’t taking proper precautions, it is likely that the incidence of melanoma will continue to increase for the foreseeable future.

Some nutritional supplements on the market — including vitamin C, vitamin E, carotenoids, folate and astaxanthin — claim that they may provide additional protection from sunburns. Any such claims emphasize that they would augment, never replace, sunscreens and other protection.

But so far, no one has proven that you can swallow a pill that will protect you from skin cancer, says Allan Halpern, MD, chief of dermatology service at Memorial Sloan-Kettering Cancer Center in New York City. "Randomized, controlled trials have not confirmed the efficacy of such pills in preventing skin cancer," says Halpern.

"Protecting against sunburns is the most preventable risk factor for melanoma," Geller emphasizes. "We can’t change our skin type, our color of our hair, or our parents’ or grandparents’ past family history for skin cancer. But we can prevent sunburns in our children."

So remember this Fourth of July and throughout the year to "slip, slop, slap." By preventing sunburn, you will enjoy yourself more, and perhaps save your life and the lives of your loved ones.