As long as I don't let myself get in a red, sunburn situation.
So almost anything that is "UV-blocking" (sunscreen, UV-treated glass) gets rid of all of the beneficial UVB before UVA starts getting reduced. So you are actually enriching your exposure to the most harmful UV type, and not making Vitamin D.
This might explain the paradoxical finding that people who use sunscreen more can have higher rates of skin cancer
People who spend more time outdoors are more likely to try to wear sunscreen, as are people who already got a lot of pre-existing risk to excessive sun exposure.
Key word on try as its greatly assuming there isnt a wide audience who do use sunscreen, then just apply it in poor amount, or never re-apply but enjoy staying out far longer than most do in the sun feeling they're oh so very protected.
Spray sunscreens for example are just about useless, as are those solid stick applicators. They only get a fraction the amount you need for the rated protection. The biggest issue with sunscreen relates to companies selling sub par "convenience" slop, often right beside their other products some of which might actually be half decent.
Secondly, if sun exposure is really that bad then how do you explain why most skin cancers are on the trunk and thighs rather than more exposed areas like hands and arms?
The simplest answer is it’s not sun exposure that’s bad but sudden high exposure after non-exposure (repair mechanisms can’t keep up with damage).
Not sure why I’m being downvoted. I guess there’s a lot of sheep among us. If anything I said is incorrect, please show me the evidence.
A critical factor for doing a screening is how many bad burns you've had on the chest and back which would probably be similar to many times the burns on the arms in terms of surface area x added probability.
Anterior head + legs + arms = 31.5% Anterior + Posterior torsos = 36%
> which would probably be similar to how many times the burns on the arms in terms of surface area x added probability
I disagree, my whole point is that frequent low/moderate exposure (such as arms) reduces the chance of burning during high exposure
I looked up the number, and after normalizing by surface area it looks like the skew towards torso is only for basal cell carcinoma (BCC) not (SCC).
https://jamanetwork.com/journals/jamadermatology/fullarticle...
For melanoma the trunk was the dominant site in men, while the legs were the dominant site in women
https://pmc.ncbi.nlm.nih.gov/articles/PMC2939095/
Unfortunately, that I know of there are not many studies that compare 'frequent low/moderate exposure followed by high exposure' vs 'very low exposure (high sunscreen use) followed by high exposure'
Here is what I found:
1. https://pubmed.ncbi.nlm.nih.gov/9335442/
These results show the specificity of the positive association between melanoma risk and intermittent sun exposure, in contrast to a reduced risk with high levels of occupational exposure.
Both the low-intermittent (HR = 1.26; 95%CI = 1.17–1.38) and high exposure groups (HR = 1.13; 95%CI = 1.01–1.26) had higher rates of melanoma than indoor workers.
The low-intermittent exposure group had elevated melanoma rates on the arms and trunk (body), while the high exposure group had an elevated rate on the head and trunk.
Head: 0.99; Arms: 0.95; Trunk: 1.00; Legs: 0.90
Why would the low-exposure group have a higher rate on the arms and trunk? Could it be because when they do go to the pool/beach, their arms are not protected? Whereas in the high exposure group, their arms are protected due to everyday exposure, but their trunk is only exposed when they go to the pool? Then again, you would think the low-exposure group would also have high trunk incidence, so there might be some confounding factors like ethnicity/behavior/dress.
Anyway, hopefully I convinced you that it's not as simple as more sun = always bad.
High sunscreen use (assuming rational choices for when to use it) and left arm truck driver risk is very consistent with a microeconomics model of UVR x filter factor on each cell determining probability for any given cell.
Some other problems with a study of Ontario work exposure are covered in the study itself. In essence this is low exposure compared to leisure time sun bathing that may be more desirable depending on work environment.
If you say so.
> left arm truck driver risk
Truck driver sunlight exposure is spectrally different from ordinary sunlight. It is all UVA, over many hours a day. To repeat myself, moderate exposure to preferentially UVB likely yields the highest reward/risk.
> a microeconomics model of UVR x filter factor on each cell
I'm not quite sure what you mean by the economics stuff but in addition to not mentioning the UVA/UVB difference, your model doesn't seem to take into account host repair pathways, which actually require some moderate damage to be activated, but are overloaded by too much damage (similar to the effect of exercise on the body).
Enhancement of UVB-induced DNA damage repair after a chronic low-dose UVB pre-stimulation
https://www.sciencedirect.com/science/article/abs/pii/S15687...
> Some other problems with a study of Ontario work exposure are covered in the study itself.
Some other potential problems, sure, along with a mention of potential benefits of vitamin D from optimal sunlight levels.
Since sunlight is associated with a lower risk of almost all cancers (including recovery from melanoma), not to mention autoimmune diseases, and skin cancers are amongst the easiest to catch early and to treat when caught early, it is very irresponsible to argue against the benefits of sun exposure. The idea that every additional unit of "UVR" carries an identical marginal risk is especially harmful.
Trying to hide low but perpetual UVR risk for people who think they are going to be immortal is counterproductive compared to fixing the delusion that would make someone avoid life expecting to get more of it.
you might want biology be really simple and describable by simple equations but in my experience it's not
paradoxically your sentences are complicated and hard to parse, I have less of an idea of what you are saying the more you say
I'm not hiding anything, if anything your gibberish hides the nuances of biology, causes unnecessary stress, and is probably actively harmful
"every dose of UVR is a roll of the dice" is an insane position not supported by the data
The worst thing to do is to go from low exposure (i.e. winter months, or just constant indoor time) to long periods of exposure, even with sunscreen.
Tourists stay and get burn to a crisp
Tourists are an especially bad example since they often work indoors all year or come from less sunny countries, so the sudden sun exposure is doubly bad for them.
Spain is sunnier yet has lower melanoma incidence than Northern Europe..almost like moderate sun exposure is protective, or that going from a cloudy country to a sunny area for a few weeks is especially bad - you can analyze it how you wish.
I've also noticed some correlation between my diet and how fast I burn. Whenever my metabolism is running at/near ketogenesis, it seems like it takes a lot longer for the sun to affect me.
With that said, folks who are pregnant are discouraged from using any retinoids out of an abundance of caution.
There's no anti-sun obsession, either. Sunscreen isn't anti-sun, and people are well aware that Vitamin D synthesis is an issue in farther northern/southern latitudes. There's definitely an increased recognition scientifically that excessive sun is extremely bad, though.
I let my 2-year old child (she is also taking Vit D - 300iu a day) under the sun in the garden quite a lot on/off (I'd say probably 1h a day in total) and I find that she sleeps much better and is more calm in the evening as well, I can't say the same if we do an outing to the mall, something is clearly different/rewarding.
The more you're able to build up a base tan the less you need it to avoid a burn at least.
(It's largely irrelevant to myself, I pretty much burn immediately and don't / can't really tan, but my wife and her family tan well).
Always been that way for me at least.
[1] https://jamanetwork.com/journals/jama/fullarticle/2733085?gu...
I get can get sunburnt from as little as 30 minutes in the sun at times, and I almost always wear sunscreen in the summer for that reason.
(Biggest issue is wearing sandals and forgetting to cover my feet, or when jumping in the lake after sauna and not covering up again quickly enough.)