Beneath the Sun: The Sunscreen Controversy

My dermatologist had me strip down to my underwear while her nurse watched, then had me lie down on the examination table while she scanned my skin with a black light. The white spots on my well-tanned arms gave her no cause for concern; the moles on my extremities seemed normal. But then she took out a can of freon and sprayed an area on my left cheek bone.

“There was only one pre-cancerous area,” she announced. “It’s gone now.” She went on to explain that it wasn’t unusual for basal cells to form on the left side of the face because that is the unshaded side when we drive. After she told me to make an appointment for next year, she told me to get some sunblock and use it.

Now there is another test that I routinely get: my endocrinologist measures my Vitamin D levels. A few years ago, they were lower than they should be, so she urged me to start taking supplemental doses to bring them up. The main symptom that I felt was a sustained, moderate depression. Weeks after I began taking the extra gel tabs, I started feeling better. I also started wearing shorts when I walked so that a larger area of skin would be exposed to the sun.

We get our Vitamin D from two sources, primarily: fortified milk and the sun. Vitamin D production is our version of photosynthesis. This is why psychiatrists and other doctors recommend that we get enough sunlight. But the recommendation clashes with what the dermatologist wants of us. Too much sunlight gives us skin cancer.

Hairlessness is part of our hominid heritage. It allows us to run faster because our bodies are cooler. But the legacy of the millions of years our ancestors spent in a coat of hair also remains with us. Our skin wasn’t made to receive so much sunlight. Skin cancer happens when the DNA in our skin cells is mutated by ultraviolet radiation. The broken cells mutate, causing their numbers to multiply into ugly tumors. My dermatologist had caught a clump of such cells preparing to mound themselves into a sarcoma.

I came close to joining the ranks of those one in five Americans who develop skin cancer in their lifetime. There are as many cases of skin cancer each year as breast cancer, lung cancer, prostate cancer, and colon cancer combined. Many are relatively harmless but melanomas are a death sentence. Most skin cancers remain in the skin, but melanoma metastasizes throughout the body. Though a genetic profile shows that I am at low risk for melanoma, I still let my dermatologist have a look over of my skin every year to stop any incipient lesions before they do damage.

Vitamin D is an essential part of my mental health care. Researchers still don’t fully understand why Vitamin D helps with depression, but they know it regulates adrenaline, noradrenaline, and dopamine production in the brain. People with Vitamin D deficiencies are at an increased risk for suicide. Self destruction is not the only threat. You can’t expect the calcium you take to strengthen your bones to work effectively if you don’t take it with Vitamin D. Cancer patients benefit from taking Vitamin D as do heart patients. Infections hector those with low Vitamin D levels. Your risk of developing Type 2 diabetes is lower if your levels are up to snuff. And Vitamin D helps with many other conditions including multiple schlerosis, tuberculosis, allergies, sleep apnea, dental caries, and, possibly, erectile dysfunction.

So naturally medical scientists were drawn to the question: Does sunscreen inhibit the body’s production of Vitamin D?

The best sunscreens contain both physical and chemical elements. The physical elements — inorganic particles, such as titanium dioxide or zinc oxide — block or reflect the sun’s rays. Chemical components absorb UV rays and release their energy as heat. (So, does sunscreen cause overheating? No one seems to have asked this question.)

Controversy surrounds sunscreen use. We know for certain that it protects us from developing skin cancers. But some say that it also inhibits Vitamin D production. One recent study, for example, discovered that women who spent their lives indoors away from the sun are twice as likely to die as those who sun themselves on the beach. Other studies, however, find that the effect of sunblock on Vitamin D levels is negligible — mostly because people don’t apply it properly.

A paradoxical result of a recent study shows that while the sun did its damage during daylight hours, the actual cancer cells formed after dark:

Douglas E. Brash, clinical professor of therapeutic radiology and dermatology at Yale School of Medical, and his co-authors first exposed mouse and human melanocyte cells to radiation from a UV lamp. The radiation caused a type of DNA damage known as a cyclobutane dimer (CPD), in which two DNA “letters” attach and bend the DNA, preventing the information it contains from being read correctly. To the researchers’ surprise, the melanocytes not only generated CPDs immediately but continued to do so hours after UV exposure ended. Cells without melanin generated CPDs only during the UV exposure.

This finding showed that melanin had both carcinogenic and protective effects. “If you look inside adult skin, melanin does protect against CPDs. It does act as a shield,” said Brash, also a member of Yale Cancer Center. “But it is doing both good and bad things.”

The researchers next tested the extent of damage that occurred after sun exposure by preventing normal DNA repair in mouse samples. They found that half of the CPDs in melanocytes were “dark CPDs” — CPDs created in the dark.

In searching for an explanation of these results, Sanjay Premi, associate research scientist in the Brash laboratory, discovered that the UV light activated two enzymes that combined to “excite” an electron in melanin. The energy generated from this process — known as chemiexcitation — was transferred to DNA in the dark, creating the same DNA damage that sunlight caused in daytime. Chemiexcitation has previously been seen only in lower plants and animals.

While noting that news of the carcinogenic effect of melanin is disconcerting, the researchers also pointed to a ray of hope: The slowness of chemiexcitation may allow time for new preventive tools, such as an “evening-after” sunscreen designed to block the energy transfer.

I don’t know what to think about sunscreen. Don’t tell my dermatologist, but I don’t use it. It is sloppy, it must be continually reapplied, and it is easy to forget. Due to my problems with Vitamin D, I am leery about skimping on sunlight. Some dermatologists recommend supplementing the lost sunlight with pills, but this can lead to the problem of too much Vitamin D which causes its own, severe problems.

What do I do? Wear long,loose sleeves and long pants. Cover my eyes with sunglasses. Wear a hat on my head and a bandana around my neck. (I wear it Boy Scout style with the large flap in the back so as to cover more skin.) I see my dermatologist annually and wait for better understandings and treatments that balance the need to protect skin cells with the health of the rest of my body. I cannot afford skin cancer and I cannot afford the many symptoms of a Vitamin D deficiency. Fear of the sun hasn’t been enough to propel me into using sunscreen. Not yet.

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One thought on “Beneath the Sun: The Sunscreen Controversy

  1. Derek (100 Peaks)

    I encountered this last year. I spend a LOT of time in the sun, but well-protected by both clothing and sunscreen. At the time, I walked to work 10 minutes each way every day with no sunscreen.

    My panel came up with low Vitamin D. Everywhere is a reminder that us hairless humans were never built to be happy or live a long life. We were only made to live long enough to reproduce. I think this as I slather on sunscreen, then eat pills to compensate for the Vitamin D that the sunscreen apparently filters out.


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