this video is sponsored by skillshare there's a link in the description for a
free two-month premium membership hi it's michelle from lab muffin beauty
science chemistry phd and sunscreen connoisseur
it's that time again: spf myth busting time
because no matter how hard i try they keep turning up i did a video on spf
myths last year so check that out if you haven't already
if you like videos about the science behind beauty products click the thumbs
up subscribe to my channel and click the nerdification bell so you don't miss any
videos myth number one chemical sunscreens
absorb uv physical sunscreen scatter and reflect
uv i feel like i talk about this one a lot
but it won't die and i see a lot of really authoritative people repeat this
myth on really large platforms so here we go
again you've probably seen people say that physical sunscreens work like a
barrier they sit on top of skin like a shield
and they reflect or deflect or scatter uv rays
and then chemical sunscreens absorb uv and convert it to heat
in fact both physical and chemical sunscreens or more correctly
inorganic and organic sunscreens mostly work by absorbing uv and converting it
to heat the real picture is more like this
physical and chemical sunscreens both mostly absorb uv and convert it to heat
but physical sunscreens also scatter and reflect a tiny amount about 10 percent
of the incoming uv but this is only 10% so this isn't the
reason why we use physical sunscreens as sunscreens it's
mostly because they can absorb uv and convert it to heat just like with
chemical sunscreens both of these sunscreens have electrons
that can get excited to higher energy levels
with uv so they absorb the uv in that step
then when those electrons relax back down they release that energy in
different ways mostly heat the whole process is a bit technical so
i'm not going to go into too much detail here
but if you're interested i can do a more technical hardcore nerdy video about it
let me know in the comments if you want that there's also an organic or chemical
sunscreen that works a lot like zinc oxide and titanium dioxide
methylene bis benzotriazolyl tetramethyl butylphenol
also known as tinosorb m it's an organic sunscreen which means it's based on a
carbon structure and its structure looks a lot like other
chemical sunscreens but it doesn't dissolve in oil or water
and so that means you find it in sunscreens as a suspended particle
that means it also reflects and scatters some of the incoming uv
just like with zinc oxide and titanium dioxide even though it has a much
scarier name but these are really darn close to
organic sunscreens anyway so it's not a really useful distinction to make
once you realize that chemical and physical sunscreens work in pretty much
the same way then a lot of other myths about them
start to unravel so the myth that physical sunscreens are
better for hyperpigmentation and melasma this is based on the idea that heat
makes melasma worse but if you look at the difference in
heat for physical and chemical sunscreens it's only 10%
and so it doesn't make sense anymore so this means the heat difference
isn't a very good reason for choosing physical sunscreen over chemical
sunscreen then why does your face feel hot under
the sun when you're wearing sunscreen the reason is the sun the sunlight that
reaches your skin is about 50% visible light 40% infrared radiation and
9% uv so there's tons of heat around even without that tiny contribution from
uv being converted to heat the big problem with people picking
physical sunscreens over chemical sunscreens for that heat reason
is that chemical sunscreens are actually awesome for hyperpigmentation
chemical sunscreens can give much higher uva protection than physical sunscreens
especially if we're talking about the newer photostable uva filters
all of the sunscreens with really high uva protection use
organic filters to get there chemical sunscreens also give
less white cast which is really important because people with
hyperpigmentation tend to have darker skin
we are people of color and the thing that people usually do to prevent this
white cast is use less sunscreen which is bad
because then you have less protection which leads to even more
hyperpigmentation i have another video comparing physical and chemical
sunscreens if you want more info i'll put the link in the description
and if you want to learn more about legitimate reasons for picking one
sunscreen over the other then you can check out the lab muffin
guide to basic skincare there is a free sample of ther chapter on sunscreens again
linked in the description myth number two
a little goes a long way with sunscreens i see this
all the time in reviews sunscreens get a good review even though they're
expensive because a little goes a long way if you're a
regular here then you probably have the same reaction as me when you see that
sunscreen is the worst product to skimp on the protection you get with the
sunscreen depends on how much you apply and the relationship is pretty much
linear so if you apply two milligrams per
square centimeter you'll end up with the protection stated on the label
if you apply half of that one milligram per square centimeter then you'll get
half that protection two milligrams per square centimeter
converts to about a quarter teaspoon for your face
if you have less sunscreen on your skin then you're going to have gaps in your
protection you'll have less sunscreen particles on
your skin which means that incoming uv is going to have a better chance of
getting in between these particles and not get absorbed
so you can think of sunscreen as foundation to hide your skin from the
sun if you have less sunscreen you'll have
patchy coverage and it's more likely that the sun can see your skin
if you have more sunscreen then it's more likely that you have even coverage
and you've got everything covered up from the sun's uv myth number three
we don't need sunscreen because we evolved to live with the sun
there are two big things wrong with this firstly we don't live where we evolved
most americans and most australians have lighter skin than the people that
evolved to live there even if you're living in a place where
your skin color evolved there are lots of different conditions in our modern
world firstly people didn't use to go on
beach holidays where they laid in the sun for hours
this sort of intermittent intense uv where you get sunburned once or twice a
year on holiday is actually linked to deadlier skin
cancers like melanoma melanoma has steadily increased over the
last 50 years in norway there's 11 times more melanoma
in 2019 than in 1953. people also like tanning these days
because a tan is seen as healthy and so people are more likely to go out
and seek sun exposure the environmental conditions these days are also different
so here's story time with michelle thomas midgley jr
is the unluckiest scientist who's ever lived he invented cfcs
these are super stable chemicals that are non-toxic and they're fantastic for
fridges aerosols air conditioners you can breathe it and you can drink it and
it is completely safe the problem is they're so stable that
they can last for decades and so they slowly migrate their way
up through the atmosphere into the stratosphere which is where our ozone
layer is it is a really thin layer but it is
absolutely vital for protecting us from uv
so in 1985 scientists discovered the ozone hole which is an area over the
south pole with very thin ozone and so in 1987 the montreal protocol was
enacted this got everyone in the world to stop
using cfcs but the damage that was done is still
recovering it still hasn't recovered yet there's also more nitrous oxide from
agriculture these days which also thins ozone
and so in general we have less ozone in the world and therefore more uv
so the ozone hole of antarctica is big enough to affect some parts of the world
like australia new zealand south africa chile
and argentina and so we didn't evolve with mass migration beach holidays or
thinned ozone we need sunscreen myth number four
sunscreens cause coral reef bleaching there is no good evidence that this is
happening where this comes from is misinterpretation of research
governments jumping on this as a way of avoiding dealing with tricky issues
and skin care companies jumping on this as a marketing opportunity for their
so-called reef safe sunscreens and this isn't just something
that people who like skincare and dermatologists are saying it's something
that coral scientists who have been studying coral their whole lives
are saying i quoted some coral scientists in my video on coral reefs
and sunscreen here are some more quotes from a more
recent opinion piece from some coral researchers including
the lead researcher of a recent study that went out and measured sunscreen
concentrations in lots of places in hawaii
i've linked this piece in the description and i recommend reading it
because it's a really good summary of the whole coral sunscreen thing
we're perplexed by the misguided distraction that a limited and
unreplicated study about one of the sunscreen chemicals oxybenzone is
gaining and we're frustrated that it's taking
the spotlight off scientifically proven concerns to reef decline
people are being led to believe there is extensive scientific evidence about the
impact of oxybenzone on corals and this is simply not true so there are
a bunch of studies where scientists put coral into high concentrations of
sunscreen ingredients and the corals bleached but you need a high enough
concentration to have a negative effect this is sometimes called the dose makes
the poison if you eat two atoms of arsenic nothing
happens so unless coral is getting a high enough concentration of sunscreen
then it won't be affected so scientists have been measuring the
amounts of sunscreen around coral reefs and in all of the studies except for
that one unreplicated study the concentrations have been too low to
have an effect so we're talking hundreds of thousands of times lower than you
need since my last video on coral reefs and
sunscreens there's been more studies doing this
and again the concentrations are still around the same they're still
too low "currently the limited scientific evidence for hawaii and florida
does not show that sunscreen chemical components exist
at concentrations that harm corals there's also no real world evidence of
sunscreen harming coral if sunscreen were a cause of coral die-offs we would
expect to see reef damage where sunscreen concentrations are highest
but there is no data to support that in fact the australian government found the
majority of recent coral bleaching occurred
where there is low to no human interaction and that coral is actually
healthy in tourist-heavy high traffic areas"
the only published evidence for sunscreens harming coral
is where some researchers said that they saw more coral damage where tourists
were the problem with this is that anecdotal
evidence isn't good evidence for causation as i explained in my anecdotal
evidence video there are a million things that could
explain this observation people might be trampling the coral
people also go there because it might be closer to civilization which means it's
closer to things like sewage which have been linked to coral damage
that's why we need studies to show us that there's a likely link between
sunscreens and coral damage and this just isn't happening the biggest factors
contributing to coral reef damage according to coral scientists
are climate change biological imbalances from things like overfishing and runoff
from land-based pollution there's loads of evidence for this
studies in labs studies in the environment
not just a couple of lab studies like there is for sunscreen
then why are places like hawaii focusing on the thing with the flimsiest evidence
and not the things that coral scientists have been pointing out for
decades? it's because government policy isn't
always based on good science there are tons of examples of this so
the war on drugs the choice to give australians bad internet
but these bigger problems climate change overfishing and land pollution are
really hard for governments to fix there are huge industry interests at
stake and on an individual level tourism is usually a big income maker
for places with coral reefs the government's not going to tell you
to stop going there it's much easier to tell people the convenient lie
that if you just use the right sunscreen then it's
fine even though air travel is one of the biggest contributions to your
environmental footprint and as a consumer this is a really nice
feel-good idea and so of course skin care companies are
going to take advantage of that in their marketing
"while it's enticing to think that an urgent problem like coral reef decline
could be impacted by something as easy as choosing a different sunscreen the
reality is not so simple" if you want to do something much
more meaningful to help save coral reefs the coral scientists suggest this
"instead of purchasing a reef save sunscreen
a marketing claim that is not regulated by the federal trade commission
consumers can eliminate their use of fertilizers government leaders can push
for better wastewater solutions and invest in renewable energy
in addition to funding environmental research protection and restoration
energy spent trying to enact ineffective solutions may be well
intentioned but is wasted and damaging let's not waste more time and money
fighting the right problem with the wrong solution"
myth number five moisturizer with spf doesn't work as well as sunscreen
if a product is labeled with an spf then the words sunscreen and moisturizer
don't really have different legal meanings
both types of products are tested with the same methods provided they have the
same regulated labels these are spf the regulated uva ratings
are whether that's broad spectrum the uva logo the boots star rating or
the pa or ppd rating and the water resistance label in
different parts of the world you'll also have different types of regulations so
in australia for example they're both
regulated as listed therapeutic products which means they'll both have an
AUST L registration number in the US both are regulated as drugs so they'll
have a drug facts label the names are just marketing it doesn't
really matter there's a lot of overlap between the two categories
so sunscreens that aren't marketed as moisturizers
usually have moisturizing ingredients as well some people say that it's easier to
apply the right amount of sunscreen compared to applying the right amount of
moisturizer but i disagree from the sunscreens and moisturizers
i've tried on the market i don't think there's any sort of
consistent trend there there is a study where people applied less of an spf
moisturizer than a sunscreen but they only used
one single moisturizer and one single sunscreen the study is misleadingly
called application of spf moisturizers is
inferior to sunscreens and coverage of facial and eyelid regions
i don't think the study actually shows what the title says
myth number six you need to avoid alcohol in sunscreens
alcohol is an ingredient that has a lot of myths around it in skin care
that it's pro-aging and inflammatory that it's irritating that'll dry out
your skin i talked about the science behind
alcohol and skin care in my collaboration with kind of stephen which
i've linked in the description we looked at a bunch of studies where
really high concentrations of alcohol so 60, 80%
alcohol was applied to skin 25 50 100 times a
day way more exposure than we get in skincare they found that even in these
really extreme conditions there wasn't a significant amount of inflammation or
irritation even for skin dehydration there were
mixed results so skin wasn't always more dehydrated if they treated it with tons
of alcohol compared to treating it with tons of water
with sunscreens you only really have 5 to 10% alcohol and you're not applying it
100 times a day and so you wouldn't expect there to be
much inflammation or irritation if you're worried about dryness there's
a study that found that humectants made up for the effects of drying alcohol
and so just look for humectants in your sunscreen so if there's a sunscreen that
you love but the only thing that's holding you
back from using it is the word alcohol on the label then
it's probably fine to keep using it i hope you liked this video
let me know in the comments if there's a myth that you'd like to see me bust
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