

Is Sunscreen a Lifesaver or a Poison? - adamzerner
http://fivethirtyeight.com/features/is-sunscreen-a-lifesaver-or-a-poison/

======
mrbird
Since the title is linkbait-y, I'll share that after reading it, I think the
article boils down to these two quotes:

"The bottom line is that although there are holes in our knowledge, there is
no concrete evidence of any chemical risks of sunscreen at typical doses."

"In the case of melanoma, the more dangerous form of skin cancer, there’s no
data that tells us whether sunscreen works."

~~~
TrainedMonkey
What we do know is that sunburns are uncomfortable and mess up your skin for a
while, so for me choice between getting sunburned or applying sunscreen is
clear. If you are not going to get sunburned, sunscreen does not really
matter.

------
Moto7451
Does sunscreen have to be an all or nothing affair? This seems to be, to me,
the underlying assumption made on both sides of these arguments.

I live in Southern California and work by the beach. I put sun block on when I
know I'm going to be outside a lot and my exposure will be high... Like most
people I previously assumed. Not when I'm going to be outside for an hour. I
doubt I'm killing myself in either case.

~~~
a8da6b0c91d
Zinc oxide based sunscreen is totally safe with zero question marks. Just use
the white zinc oxide stuff on parts that are likely to burn or get over
exposed.

~~~
graeme
Do you know of any brands that don't get greasy? I've been using Green Beaver,
but it stays visible all day long. It's not white, but there's oil.

~~~
brandonmenc
I use Neutrogena Sensitive Skin Broad Spectrum. Gives the skin a healthy glow.
In fact, my sister sometimes uses it as a base for makeup because of this.

Whether or not you consider that "greasy," I don't know. It doesn't feel
greasy to me. Give it a shot.

~~~
ddeck
Although containing zinc oxide, that product includes ingredients that I
believe the parent post was looking to avoid. In particular, retinyl palmitate
[1].

As an aside, the EWG's Skin Deep database is a useful place to find
ingredients of potential concern for popular products:

[http://www.ewg.org/skindeep/](http://www.ewg.org/skindeep/)

[1]
[http://www.ewg.org/skindeep/product/567689/Neutrogena_Sensit...](http://www.ewg.org/skindeep/product/567689/Neutrogena_Sensitive_Skin_Broad_Spectrum%2C_SPF_60%2B/)

------
kourt
Aside from cancer, one needs to be concerned about aging: just look at the
difference between the sides of truck driver William McElligott's face:
[http://www.huffingtonpost.ca/2012/06/06/bill-mcelligott-
sun-...](http://www.huffingtonpost.ca/2012/06/06/bill-mcelligott-sun-
damage_n_1573546.html)

~~~
Symmetry
The UV frequencies that contribute most to that effect aren't really blocked
by the sorts of sunscreen you can buy in the US.

~~~
pyre
What places have said sorts of sunscreen?

~~~
dublinben
Europe and Japan. You can probably order some Garnier Ombrelle suncreen from
Canada that contains Mexoryl. That's the UVA-blocking ingredient that we're
missing in the US.

~~~
15characterlimi
Why is it not in the US?

~~~
doreo
Because the FDA works in mysterious ways apparently

[http://www.wnd.com/2013/03/fda-to-consumers-burn-for-all-
we-...](http://www.wnd.com/2013/03/fda-to-consumers-burn-for-all-we-care/)

------
jobu
Unfortunately the article doesn't delve into the controversy over sunscreen
limiting Vitamin D production, and all of the problems that can cause (thin,
weak and/or brittle bones, as well as possible cancer risks:
[http://www.webmd.com/cancer/news/20111004/low-vitamin-d-
leve...](http://www.webmd.com/cancer/news/20111004/low-vitamin-d-levels-
linked-to-advanced-cancers))

~~~
purephase
Except that all evidence points to the fact that sunscreen/sunblock usage
doesn't have an effect on vitamin D intake through sun exposure.

People that use it tend to spend more time in the sun than those that don't.
Also, vitamin D is more effective through ingestion as opposed to sun exposure
anyway.

~~~
bcebulla
That's not true. In the controlled setting, sunscreen affects ability of skin
to make vitamin D, by about half:
[http://www.ncbi.nlm.nih.gov/pubmed/22512875](http://www.ncbi.nlm.nih.gov/pubmed/22512875)

Sunbathers who use sunscreen tend to not have lower vitamin D levels than non-
sunbathers who don't use sunscreen, because, well, people who don't use
sunscreen don't get sun exposure anyhow.

Also, when the human genome was evolving, sun exposure accounted for 90%+ of
all vitamin D intake, diet accounted for less than 10%. We know this by
looking at the diets and vitamin D levels of hunter gatherers.

~~~
purephase
You're referring to a study that used 37 volunteers that were exposed for 20
min.

When I apply sunblock to me or my daughter, it's because we're going to be
outside for well over 20 minutes. For that length of time, depending on
conditions, I probably wouldn't even bother.

My point stands, if you apply sunblock intending to spend 1+ hour(s) in the
sun, then you'll likely benefit from the vitamin D exposure.

~~~
bcebulla
In a controlled setting, sunblock will always affect vitamin D production,
whether you expose for 20 minutes or 60 minutes or 120 minutes, or whether you
test 37 subjects or 370 subjects.

The reason is that 7-dehydrocholesterol is photolyzed by UV light in the
280-320nm range (mostly UVB) to previtamin D. Sunblock works to absorb UVB
(and usually UVA) to prevent it from penetrating your skin. Thus sunblock
limits the amount of UVB penetrating your skin, and limits your ability to
make vitamin D.

That being said, yes, you will still make some vitamin D with sunblock on
because sunblock is not perfect at absorbing UVB. Just not as much as you
would without.

~~~
majkinetor
You can't uniformly apply sunscreen on your entire body. Depending on type of
skin, vitamin D will hit maximal daily production from sunlight in range of
very fast to very slow.

So, yes, sunscreen might block some vitamin D production for some people, or
might not do it at all.

Its perhaps prudent to apply it to some skin parts that are most affected by
sunlight (face, shoulders) and leave other body parts without it. There you
have benefits of both worlds.

Furthermore, vitamin D is not the only substance produced by the skin via
sunlight (although we don't know much about other ones), so vitamin D from
diet is not a substitute for it. Furthermore, vitamin D from diet can easily
cause calcification depending on other factors (vitamin K and A in the diet
and genetics) while there is internal protection for body made one.

------
giardini
And no one has yet mentioned rickets!

Once virtually eliminated, rickets has increased markedly, in some studies as
much as five-fold. In the malls I now occasionally see children who obviously
have rickets. Unless corrected early, the adult will bear the scars of the
child.

Also there is mention that ingestion of vitamin D is superior to sun exposure
but AFAIK there is no evidence of that. The ingestive route has it's own
problems.

~~~
ryandvm
It's worse than that. There is reasonable evidence that vitamin D deficiency
contributes to a number of cancers and that heavy use of sunscreen has a
questionable benefit on net mortality rates.

[http://www.medpagetoday.com/HematologyOncology/SkinCancer/78...](http://www.medpagetoday.com/HematologyOncology/SkinCancer/7888)

------
micro_cam
Tech related aside, the design of sun resistant clothing that doesn't overheat
you is an area that is seeing a lot of advancement recently.

Polyester fabrics with texture to keep some air under the fabric and thin
merino wool poly blends (that have a bit of natural texture) really seem to
work. They can act almost like a mesh that still blocks the sun.

~~~
toomuchtodo
Do you have any example clothing products? I am in search of this sort of
active wear.

~~~
micro_cam
The patagonia sun shade hoody is my favorite for wearing at high elevation or
on the water when there is some wind though it can be too hot if their isn't
wind.

For warmer conditions there are some great pieces in their summer trail
running line (on clearance at the moment) including the air flow and gamut
shirts:

[http://www.patagonia.com/us/shop/web-specials-mens-trail-
run...](http://www.patagonia.com/us/shop/web-specials-mens-trail-
running?k=1D-3m-ga)

Edit: opt for the stuff with mesh zones, the straight cap 1 stuff doesn't
breath as well. Their merino 1 t shirts are also nice.

Also check out fly fishing clothing by them and others for sun protective
clothing with a less athletic look.

------
specular
It would be interesting to hear more about potential evidence linking sun
exposure and sunscreen to malignant melanomas as opposed to basal and squamous
cell carcinomas. BCCs and SCCs, while malignant, do not pose the same risks of
metastasis as melanoma, so I would be much more inclined to alter my behavior
given such evidence.

In general (but not always) I like to assume that balance is the key. Life is
carcinogenic, and too much of anything is probably harmful.

~~~
a8da6b0c91d
I think focusing in on skin cancers and skin aging is myopic. This is what
_all_ these analyses do. Yes, sunscreen probably reduces skin cancers and
aging from sun exposure. But there is evidence that depriving yourself of sun
exposure leads to a higher overall death rate. You dodge melanoma but increase
risk of a heart attack or various internal cancers. People who work outside
live longer, despite looking "weathered" in their old age.

~~~
kalleboo
Sun screen doesn't block sun exposure though. It screens it. You're still
getting sun exposure, just not amounts that are going to burn you.

------
secstate
Am I the only one troubled by a statement like this:

"As to whether I should be slathering my kid with sunscreen or not, the good
news is that I’m not causing any damage by doing so."

At the end of an article that otherwise claims to investigate the scientific
merit of the case against sunscreen?

It's fine if you want to say "I'm very likely not causing damage ..." But it
seems awfully unscientific to claim that the good is that I'm not causing ANY
damage by doing so.

Also, I feel like this is an endemic thought process in our post-modern
society. Humans want answers. Humans like answers. Scientific logic produces
very few slam-dunk answers. So while we all trot around claiming to be
"scientific" in our outlook, we rarely if ever apply truly scientific thought
to our daily routines. Not that it's easy to do, but it's frustrating when
people mis-associate belief with knowledge.

------
ascotan
It is known that cyclic aromatic compounds (like sterols) can pass through the
cell membrane layer. It is also known that cyclic aromatic compounds can bind
DNA (this is how steroid hormones work). It is also known that DNA breakage
can occur when ionizing radiation strikes alkylating agents intercalcated with
the DNA backbone.

Honestly, it wouldn't surprise me if sunscreen has sterol-derived compounds
that in the presence of ionizing radiation could cause skin damage. We hear
about this stuff all the time in things like cigarette smoke, charred meat,
etc. etc.

That being said, the article doesn't address the incidence of cancer caused by
NOT using sunscreen. Similarly, not all vaccinations are not 100% safe, but
the risk you take from not having the vaccination is far greater if you didn't
take it. Therefore, people will get scared off from using sunscreen from
articles like this, likely increasing the incidence of skin cancer.

------
r-cid
I'm super white, and I barely wear sunscreen. I put some on the other day for
a 4hr river float.. But I spent a full day fishing the river yesterday; in
direct sun, no sunscreen in 90 degree heat and I'm only mildly burned.

I remember burning a lot worse when I was a teenager.. But I think it had
something to do with drinking Mt. Dew all the time. I've pretty much entirely
removed high fructose corn syrup from my diet. I eat fruit for my sugar fix
more often these days. I also supplement vitamin-d now, perhaps that also has
something to do with it? This is all just anecdotal, but perhaps if you burn
quickly and easily you should take a look at your diet.

------
drpgq
I thought this was a little weird: "melanoma diagnosis increased by 1.9
percent annually between 2000 and 2009."

I would have thought that this would have went down through this period. I was
born in 1973 and wore some sunscreen as a kid and I would assume the amount of
sunscreen wearing has increased over time and sun exposure has decreased. Some
time before that people were barely wearing sunscreen or limiting exposure so
as they die out I would expect the melanoma rate to decrease.

Of course there would be a lot of compounding factors, like longer lifespans,
a higher percentage of Americans living in the South, etc. Just seems a little
odd.

~~~
bcebulla
The reason melanoma incidence is increasing is because of a "diagnostic
drift," similar to what we see in the rise of psychological disorders:
[http://www.ncbi.nlm.nih.gov/pubmed/19519827](http://www.ncbi.nlm.nih.gov/pubmed/19519827)

We are more routinely getting skin lesion check ups and dermatologists and
oncologists are more and more cautious, leading to an ever-increasing
incidence of stage I melanoma. However, we're not really seeing an increase in
later stage melanoma, meaning that the "true" incidence of melanoma is not
increasing.

It's sort of a huge public health scam. The dermatologists are using this
vanity metric of increased diagnoses as evidence that we're in the middle of a
melanoma/skin-cancer epidemic, when it's simply not the case. Not that safe
sun exposure practices shouldn't be promoted, but the motor behind these
messages is a bit of a scam.

------
bluedino
I wear sunscreen so I don't get a burn. I'm not a particularly fair-skinned
person but a day out on a boat will burn me to a crisp.

Also helps keep the freckles and moles down.

------
CreRecombinase
Nice example of Betteridge's law[0] here. While as a biologist, I am supremely
aware that plausible biological mechanism alone shouldn't be sufficient to
drive public policy, UV induced DNA damage causing melanoma is one of the
better understood mechanisms for oncogenesis. The real question to me is not
whether sunscreen works at preventing UV damage, and thus skin cancer, but to
what extent acute, high dose UV exposure, especially at a young age, can do to
lifetime cancer risk. If it is the case that one or two bad sunburns can
dramatically increase risk of skin cancer, it will be very difficult to design
a randomized clinical trial to demonstrate the effectiveness of sunscreen in
adults. [0]:
[http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines](http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines)

~~~
dllthomas
_" Nice example of Betteridge's law[0] here."_

"Is sunscreen a lifesaver or a poison?"

"No."

...

~~~
lazugod
What Betteridge's law really means is "Questions in headlines have boring
answers."

~~~
dllthomas
That's a reasonable generalization, but certainly isn't the original form.

------
VLM
"An obvious initial complaint in applying these findings to humans is that
people typically do not eat sunscreen."

Yet the story begins with anecdotes about smearing it all over three year old
kids. The author apparently does not have children.

One convenient probably fairly low risk solution for sun exposure is clothing.
Cuts back a lot on mosquito bites and minor cuts -n- scrapes. I've been told
over and over that my baggy pants and baggy long sleeve shirts will give me
heat exhaustion on the hiking trail, exclusively by people who refuse to try
it, and are instead smeared with a 1/4 inch layer of sunscreen and bug spray
goo which makes them look more miserable than I actually feel. This probably
won't help on the beach but for the other 99.9999% of life time it does help.
It is true that they can survive 90 degree weather when I quit at 85 degrees,
but when its 85 degrees out, going for a couple mile hike in direct sunlight
is not my first choice of leisure activity anyway, so it doesn't really
matter.

Personally UV caused cataracts leading to blindness or a financial death
penalty scare me more than a mere easily detectable and removable skin tumor,
so I reach for the UV proof glasses before I even think about sunscreen
anyway.

~~~
kalleboo
In Australia they say Slip Slop Slap[0] - slip on a shirt, slop on suncream,
slap on a hat.

[0]
[https://www.youtube.com/watch?v=tGgn5nwYtj0](https://www.youtube.com/watch?v=tGgn5nwYtj0)

edit: apparently Seek shade and Slide on sunglasses have been added in later
years
[https://www.youtube.com/watch?v=YzYHwzSE1VY](https://www.youtube.com/watch?v=YzYHwzSE1VY)

