Sunlight has many health benefits. The human body has 6 or 7 types of photosensitive cells, presumably evolved to benefit from irradiation (photobiomodulation) and particularily infrared light, plus UV-B for Vitamin D production. Our sleep is governed by photo-sensitive cells for the day/night cycle, and jet lag can be fixed by exposure to daylight. Infrared can heal wounds and sunlight can heal some diseases, mitochondria in the eye benefit, etcetera.
Ironically, with the preponderance of evidence showing that Vitamin D has a major role to play for COVID-19, I see most people shrouded in clothing so as to almost entirely avoid sun exposure. Risk assessment is apparently not a thing for these people. Nor for most dermatologists in my experience, whose tunnel-vision skin-centric practice offers a lopsided view of total health vs human body as a whole—an anti-scientific anti risk-assessment approach.
Sun exposure (moderate, no burning) sure seems like the smart move, rather than slathering on a potential cancer-promoting chemical goo (sunscreen). The amount of exposure should vary by skin tone to avoid burning.
Benzophenone-3 is a putative endocrine disrupting chemical and common ingredient in sunscreens. The potential of endocrine disrupting chemicals to act as agonists or antagonists in critical hormonally regulated processes, such as mammary gland development and mammary tumorigenesis, demands evaluation of its potential in promoting breast cancer...
...we found that BP-3 elicits both promotional and protective effects on mammary tumorigenesis dependent upon dietary regimen and tumor histopathology. However, even in instances where this analysis shows an ostensibly protective effect, other parameters suggest the potential for greater risk. For example, while BP-3 treatment enhances tumor-free survival in mice fed LFD, the spindle cell tumors that do occur display a higher level of proliferation and a lower level of apoptosis, properties associated with a poorer prognosis in human cancers. We also found that pubertal exposure to HFD was sufficient to counter the ostensibly protective effect of BP-3 in mice fed LFD. Thus, our studies contribute to an existing literature suggesting that puberty is a critical window of susceptibility for later mammary tumorigenesis.
Taken together, these findings suggest that BP-3 exposure may have adverse consequences in mammary tumorigenesis. They point to a need for further studies of BP-3 in both animal models and humans as a potential risk factor in breast cancer. They also point to the more general need to evaluate endocrine disrupting chemicals in the context of varying diets. Future studies are needed to identify the mechanistic basis for BP-3 effects on mammary tumorigenesis and how dietary fat interacts with BP-3 to alter outcomes.
WIND: one study should never be taken as definitive of anything.
Using sunscreen on children prior to puberty might be a bad idea from a risk assessment viewpoint. That is, trading off the risk of skin cancer versus the risk of breast cancer.
The idea that than slathering on a potential cancer-promoting chemical goo (sunscreen) beats out a million years of human evolution is a bit far fetched.
I studiously avoid sunscreen except for multi-hour or all-day efforts. My dermatogists (several over the past decade) all say my skins is quite good for my age—and it has had a great deal of sunlight exposure.
It is my personal belief that a nutritionally dense diet will largely forestall most cancers, including skin cancer. However, the modern diet cannot come close to meeting magnesium requirements, magnesium being critically important to up to 1000 physiological processes. Accordingly, magnesium supplementation and possibly a few other things might be required to give the body what it needs to be healthy.