The health benefits of sunlight may outweigh the risk of skin cancer

> A study published last year, for instance, examined medical data from 360,000 light-skinned Brits and found that greater exposure to UV radiation—either from living in Britain’s sunnier southern bits rather than the darker north, or from regularly using sunbeds—was correlated with either a 12% and 15% lower risk, respectively, of dying, even when the raised risk of skin cancer was taken into account.

Emphasis on “may” - this is hardly a gold standard study. Living in sunnier/warmer climates as a proxy for UV exposure as opposed to lifestyle differences afforded by such a climate, regional culture differences, etc. makes all of this very dubious to me.

I’m going to keep wearing my sunscreen most of the time when I need to be in direct sun, and continue regular screening for skin cancer.

Double-blind experiments on this are probably impossible, but it's not like large population studies are totally worthless. It's probably best to go where the evidence points, and the article mentions other studies with similar conclusions, as well as work on possible biological mechanisms.

My strategy is to get short sun exposures, use sunscreen only when I'm going to be out long enough to get burnt, and also do my dermatology appointments.

The helper verb 'may' should accompany any scientific result as the scientific method usually cannot prove causations but only negate the null hypothesis.

Sun good

Science is good, but restraining all decisions behind FUTON biased double-blind longitudinal meta-analysis is not only unreasonably cognitiviely expensive, but not even the greatest idea.

When making decisions to personally guide your life, you can also base them on values, heuristics, paternal advice, common wisdom, etc...

It's obvious that the ideal amount of sunlight is somewhere between 0 and 100% of the time, I don't need to read a "The Economist" article with a clickbaity, possibly misrepresented title of a nuanced meta-analysis.

The proof is on this comment, it's never enough data, the conclusion is always that you need more funding:

>360,000 light-skinned Brits

>Emphasis on “may” - this is hardly a gold standard study

I didn't even need 1 subject, you need more than 360,000. You are out there running kubernetes for a blog and asking for more EC2 instances on top of a 3M$ bill, I'm out here running the whole company on 2 raspberry pis.

If wealth can be achieved by increasing resources or reducing necessities, I have achieved the nirvana of wisdom of the second kind while you still strive to amass more information to make a decision:

Sun good

time of day and UV index is the most important thing, right? That is how you can accurately assess the “risk” of being exposed in direct sunlight.

Example: would you put on sunscreen when playing volleyball at the beach at 4:30pm, if the UV index at that time is 2 (UVI scale)? That seems completely unnecessary imo. And many people are vitamin d deficient anyway, so the minor sun exposure would certainly do more good.

If it’s around mid-day and/or the UV index is higher, say 4+, then i 100% agree with you that it’s prudent to apply sunscreen.

Two things can be true.

The study says sun good. But the studies being described in the UV are specifically comparing people who stay indoors vs people who get exposed to UV by being outdoors. The studies listed are not looking at application of sunscreen, or wearing clothes to block UV, etc.

This generally makes sense; stop being cooped up indoors and do things outside, but also wear UV protection.

How reliable are UV indexes? Genuine question. The iOS weather app is far from 100% reliable and I wonder the margin of error regarding the UV index number it provides.

The only time you will see anything stated as an absolute is when there is low or no scientific rigor.

Thinking you are somehow holding the authors into account is akin to doubting a paper's veracity because it has "too many authors" or some other meaningless if not ironic standard.

Bear in mind that this study is about the UK, and London is on the same latitude as Calgary, give or take.

The sun does get strong enough to burn here, but not for much of the year - especially considering the relatively high % cloud cover (not Seattle high maybe, but high). Skin cancer cases here are AFAIK most commonly related to overseas travel or people with outdoor lifestyles in the southwest of the country.

> but not for much of the year

Speak for yourself. Thanks to my Celtic genetics, I get sunburnt if I put my phone brightness too high. ;)

> I’m going to keep wearing my sunscreen most of the time when I need to be in direct sun, and continue regular screening for skin cancer

Sunscreen reduces vitamin D production, but it doesn't stop it. Wearn sunscreen. Get screened. And don't stay indoors for fear of UV.

great question! My understanding is the UV index shown online and in apps is “modeled” data, not realtime.

Basically it takes into account things like ozone measurements from satellites, latitude, forecasted cloud cover, and distance from sun (time of year).

See section “Calculating the UV index” here:

https://www.epa.gov/sunsafety/learn-about-uv-index

It’s not intended to be realtime. It’s more about understanding, generally, what the risk is.

On cloudless days it it very accurate because on those days UV strength depends almost entirely on the solar altitude, which can be calculated very accurately from the location, the date and the time.

A sibling comment mentions the ozone layer, but I severely doubt it varies enough to be a source of inaccuracy.

Yeah, I agree. This always seemed pretty obvious to me but it was also obvious that it's nuanced and can be highly variable depending on skin type, medical history, locale, lifestyle and preferences.

But when it comes to things which are very probably "mostly beneficial for most people most of the time - but (obviously) not always beneficial for all the people all the time", there's a reluctance to say anything unless you've got study data to fully support everything you say into "the nines". But the world is full of things that are hard, expensive or impossible to study experimentally with that kind of rigor.

I am in a unique position to confirm that they are a load of bunk. I have solar urticaria and develop hives in response to UV exposure, directly proportional to how much UV is getting through. I’ve developed hives in minutes while the UV index was supposedly only 4 and gone for relatively too long without erupting in hives the next day even when the UV index was supposedly 10.

i hate to be that person that quotes chatgpt, but this seems VERY relevant to your complaint:

“Solar urticaria is a rare condition where the skin reacts to specific wavelengths of light rather than the overall UV intensity. The UV index is a general measure of the total amount of erythema-causing UV radiation (mainly UVB) that can cause sunburn in the average person.

But in solar urticaria, the trigger might be UVA, visible light, or even a narrow band of wavelengths — and the UV index doesn’t capture that nuance.

So it’s not that the forecast is wrong — just that the UV index isn’t designed to reflect the sensitivity profile of solar urticaria.”

In other words, you’re (literally) a special case. :)

Agree - my original comment was trying to highlight the actual info from the study in contrast to the suggestive headline: That there’s no causal link being claimed by the study that UV exposure decreases all-cause mortality, or in other words, sunscreen isn’t killing us.

Yep this about lines up with my current approach.

But also let’s not forget the things that tend to correlate with moderate sun exposure: Fresher air, exercise, social activity, daylight exposure on the eyes, stimulation of all the senses, etc.

I still think “increased sun exposure correlates with decreased all cause mortality” makes a better headline, but then maybe that’s why I’m not an editor.

> I didn't even need 1 subject, you need more than 360,000

If you read my whole comment, my point was that I will continue to enjoy the sun, with sunscreen. Sun good. You say sunscreen bad? No. We agree.

Thank you, this is a much better comment than my original one, but this was exactly my point. Go outside more. Sunscreen probably isn’t killing you.

I think it’s difficult to study this sort of thing because people and behavior is so different. I lost someone dear to me to melanoma and one of the things we learned was that a single blistering sunburn as a child increases cancer risk significantly. So small variations have big impacts.

I’d love to see a study where people wear a meter to sample exposure. My mom was an avid gardener who never wore sunscreen - she dressed appropriately with a hat.

Yes, dubious indeed.

How about looking at descendants of fair-skinned Britains in sunnier climes?

Australia has the highest rate of skin cancer in the world. This is due to a combination of factors: very high levels of ultraviolet (UV) radiation, outdoor lifestyles, and a largely fair-skinned population that is more vulnerable to sun damage. Rates of both melanoma (the deadliest form of skin cancer) and non-melanoma skin cancers are higher in Australia than anywhere else. New Zealand follows closely behind.

> Australia has the highest rate of skin cancer in the world.

It also has excellent life expectancy.

The key question is: For all-cause mortality, do the benefits outweigh the risks?

Also, getting sunburnt is not the only way to get vitamin D. Wear sunscreen and go out. Enjoy the sun. And eat healthy foods that contain vitamin D.

The word 'correlates' in a title is borderline click bait-y due to possible intended confusion with 'causes'. Also it has little value. Consider the equivalent "decreased all cause mortality correlates with increased sun exposure". The word play is crazy. 'May' captures the relation and is correct philosophically.

People don’t have a nuanced view of when to use sunscreen. You can see for yourself in the comments, there’s plenty of loud certainty and context is left behind. And I’d have expected this group to at least understand that the need for sunscreen is based on the position of the sun during the day.

> Double-blind experiments on this are probably impossible, but it's not like large population studies are totally worthless.

Large population studies in itself are fine, it's just the quoted study is worthless. Socially there's just so many differences between the two groups that it becomes almost impossible to validly compare these two.

A better study design would be to treat each region separately. And compare 'time spent outside' with health outcomes in each region. That would give a much more reliable and useful insight in if time spent outside equals better/less health. Bonus points if you also ask them if they regularly use sunscreen.

That data would actually be useful. That way you could compare if spending time outside is healthy in itself, or if it has to do with the sun. For example if the sun would be a net negative, you would find relatively more skin cancer in the groups in sunnier climates that spend a lot of time outside versus those in greyer regions. If the sun would be a net-benefit, you would see less skin cancer instead. And quite likely you would see that people who spend more time outside have better health outcomes no matter which region you are in, although the size of those groups may differ greatly depending on the climate.