Question: I sometimes get sunburns even with sunscreen on. Should I stay out of the sun completely?

Answer: To answer today’s questions I consulted with a colleague, Theresa Fukuda, a physician’s assistant who specializes in dermatology in Danvers.

There are pluses and minuses to sun exposure.

Let’s start with the pluses. Sunlight triggers our skin to make vitamin D (beneficial to many body functions), although most people get adequate vitamin D from food and supplements, so using sunlight to help the skin produce vitamin D is usually not needed (this is why it is typically not an issue in the winter). Spending some time outdoors may help decrease symptoms of depression and other mental health disorders, improve sleep quality, strengthen the immune system, be good for your eyes and has other potential benefits as well.

But too much sun exposure can lead to sunburns (an inflammatory response of the skin), increasing your risk for certain skin cancers, the most concerning of which is melanoma. The incidence of melanoma is increasing; in the 1930s it affected 1 in 1,500 Caucasians (it is 20 times less likely in people with dark skin), and now it affects about 1 in 50.

Melanoma develops from the cells that produce skin pigment. The risk of melanoma is increased 30-fold in people who have had multiple sunburns, especially if those occur at an early age. Most people get up to 80% of their total lifetime sun exposure before age 20; those who have had five or more blistering sunburns between the ages of 15 and 20 increase their risk for malignant melanoma by 80%. It is therefore vital to protect ourselves and our children from too much sun exposure.

How much sunlight exposure is too much? That depends on the specifics of your skin, your age, your prior history of sun exposure, your diet and your genetic predisposition to certain conditions. For infants less than 6 months of age, preventing as much sun exposure as possible by using light clothing, a hat to protect their head, and protecting hands and feet with shade is vital since an infant’s skin will burn very easily. Children over age 6 months should still wear a hat and light clothing to block the sun. Avoiding the peak hours of sunshine is a good idea, since the stronger the sun, the higher the risk. Estimates range from 15 minutes for fair skin/higher risk people to 30 minutes of sun exposure per day for most other adults may be optimal.

If you are outside and protected from the sun, say by covering your body with clothing or other shade, being out in the sun a little longer is likely OK. For older kids and adults, sunscreen with an SPF of at least 30 is the next line of defense. Most people don't apply enough sunscreen, only using 25-50% of the recommended 1 ounce for their entire body per application. Sunscreen should be applied 15-30 minutes before going outside and every 1-2 hours after that. Using SPF 100 does not spare you the need of reapplying.

Sunscreens are separated into physical and chemical sunscreens. Physical sunscreens contain active ingredients such as zinc oxide or titanium dioxide, recognized as safe and effective and working as a shield to protect your skin from both UV-A and UV-B, but can appear opaque or white on the skin. They are best for sensitive skin types and children. Chemical sunscreens work like a sponge to absorb UV-A rays and are often found in clear sprays. There is speculation (although limited data at this time) that these chemicals may have damaging effects and that they do not effectively block UV-A.

Broad spectrum, water resistant, SPF 30+ sunscreens are the most effective. Avoid sunscreens with fragrances, and check with your health care provider or pharmacist to make sure you are not taking any medications that could increase your sun sensitivity. Bug repellents with DEET may decrease the efficacy of your sunscreen.

So, enjoy the sunny outdoors in moderation, protecting yourself from too much sun. And remain vigilant of the ABCDE’s for identifying suspicious skin lesions:

• A: asymmetric shape

• B: irregular border

• C: change in color

• D: large diameter (typically greater than ¼ inch)

• E: evolving (noticeably changing) over time

If you note any concerning lesions consult your healthcare provider, since melanoma, if caught early, can be easily and effectively treated.

Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com