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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
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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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