A Midwestern Dermatologist Responds to A Midwestern Doctor

A Midwestern Doctor, which I assume is the alias/pseudonym/nom de plume of Pierre Kory, has a wide readership on Substack. We received this essay from Dr. Bernhard Ortel, a dermatologist who has spent a career studying the physics and medical effects of solar radiation as well as treating its consequences.

Adam Cifu

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After reading A Midwestern Doctor’s essay, Dermatology's Disastrous War Against The Sun, I was motivated to share my view on the role of solar ultraviolet radiation in human biology. Some of the claims could have been restated as headlines from the National Enquirer:

Doctor’s veins bulge in craving for ultraviolet exposure

Spectacles harm your health by blocking ultraviolet radiation

Health benefits of sun and ultraviolet radiation exposure

Avoiding the sun will allow cancer to kill you

Some of the other claims should be addressed:

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“What’s critically important to understand about melanoma is that while it’s widely considered to be linked to sunlight exposure—it’s not.”

I am not an epidemiologist, but I know a bit about ultraviolet radiation. The lack of sun exposure is not likely to make Australians and New Zealanders the champions in developing melanoma and dying of it. They are only rivaled by the Danish who, due to their Northern habitat, have little sun in the winter; however, Danes successfully compensate by getting Mediterranean sun exposure at every opportunity. So, there are already a few cracks in the epidemiologic reasoning here. These facts support that cumulative sun or ultraviolet (UV) exposure plays a role in the development of melanoma.

It is worth stating clearly: we do not understand the exact interactions of solar exposure with the pathogenic steps in melanoma development; however, there is clearly a role, and it is not a protective one.

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“I learned a pioneering researcher found significant alternations (sic?) would occur in the health of people who wore glasses that blocked specific light spectrums (e.g., most glass blocks UV light) from entering the most transparent part of the body that could be treated by giving them specialized glasses which did not block that spectrum from entering.”

I am intrigued by the claim that UV blocking spectacles cause negative health outcomes. It is true that most glass absorbs UVB (about 99% at 300 nm) but transmits UVA. Incidentally, most UVB is absorbed by the cornea in unprotected eyes. Many modern lens materials also block UVA (315-400 nm), which is good because, along with infrared radiation, UVA is a cause of cataract formation. This pathogenetic effect is behind the high rates of blinding cataracts in high altitude populations, such as in Nepal where the prevalence of cataracts is a serious economic issue. UVA is so potent in harming the lens because the lens absorbs almost 100% of UVA radiation. Taken together these facts explain why UVB and UVA do not reach the retina. Thus, UV radiation is not likely to exert any effect (positive or negative) through this path. Consistently UV radiation does not contribute to the management of SAD (seasonal affective disorder), for which bright visible light is used.

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“One of the oldest “proven” therapies in medicine was having people bathe in sunlight (e.g., it was one of the few things that actually had success in treating the 1918 influenza, prior to antibiotics it was one of the most effective treatments for treating tuberculosis and it was also widely used for a variety of other diseases).”

Our practice of sun exposure for human benefit has a long history and I agree that benefits of sun exposure go beyond vitamin D formation. We are still developing our understanding of the benefits of sun exposure and the risk associated with excessive UV exposure.

For his role in developing the treatment of skin tuberculosis by solar and artificial UV exposure, Niels R. Finsen was awarded the 1903 Nobel Prize in Physiology or Medicine. This successful approach was based on the germicidal effect of UV radiation. The treatment modality was abandoned once antibiotics for tuberculosis treatment became available. We know today that a dose strong enough to “sterilize” lupus vulgaris (skin tuberculosis) would also have resulted in excessive skin phototoxicity.

Because we know that the treatment did work, we think now that it was not UVB that killed the germs. Rather UVA and short visible wavelengths were absorbed by endogenous porphyrins inside the mycobacteria resulting in germicidal reactive oxygen species. This is based on analyzing the collimating lenses that Finsen used: his glass lenses transmit almost no UVB but let UVA pass through.

Another aspect of the success of sunlight and UV therapy in the late 1800s and early 1900s is the high prevalence of vitamin D deficiency in Northern European populations during that period. The beneficial effect of UV lies in part in increasing vitamin D levels. Consistently, vitamin D supports crucial steps in cellular immunity against mycobacterium tuberculosis.

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“As I got older, I started to notice that beyond the sun feeling really good, anytime I was in the sun, the veins under my skin that were exposed to the sun would dilate, which I took as a sign the body craved sunlight and wanted it to draw into the circulation.”

Let’s look now at UV blood irradiation, an interesting concept. UVB only barely penetrates the epidermis, the longer UVB wavelengths around 310 nm reach slightly deeper and can expose small volumes of blood in very superficial dermal capillaries. UVA (320-400 nm) penetrates more deeply into the dermis and can expose surface blood vessels. UVR does not travel in the blood, because it is absorbed with high efficiency by highly concentrated biomolecules. There is one medical treatment (extracorporeal photochemotherapy, also known as photopheresis) where isolated white blood cells are treated with a photosensitizing drug and exposed to UVA outside the body in thin sheets of flowing cell suspensions. This shows that exposing your blood to therapeutic levels of UV is quite difficult and will not work easily without getting it out of our bodies.

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“Sunlight is critical for mental health. This is most well appreciated with depression (e.g., seasonal affective disorder)”

Most people feel good with sun and UV exposure. Endorphin release has been experimentally linked to this feeling. However, we all know that not everything that feels good is also good for our health. Have you experienced a long afternoon when you fell asleep resting exposed to the sun. When waking up after a while, the leaden feeling of exhaustion is likely based on sunlight-induced methemoglobin formation. This supports the truism that for drugs – including sunlight or UVR – ‘dosis sola facit venenum '- only the dose makes the poison.

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Dr. Bernhard Ortel is a dermatologist. He is interested in photosensitivity diseases with a special interest in photodynamic therapy.  He is a lifetime member of the American Society for Photobiology.

Photo by Engin Akyurt