hello everybody its Michelle from loud muffin beauty science here you might have
seen the news that Hawaii has banned some sunscreens that have been linked to
coral bleaching the two ingredients are the organic or so-called chemical
sunscreens oxybenzone and octinoxate. Are these ingredients that bad? should you
avoid them at the beach? should you avoid them in your daily sunscreens? is the
ban supported by the science? that's what we're talking about today: the
science behind sunscreen and coral. One of the main issues facing coral is
bleaching and that's the main harmful effect that's been linked to some
sunscreens coral bleaching happens when the coral turns white the stuff that
makes coral colored are microscopic algae called zooxanthellae these algae and
coral live in a symbiotic relationship it's a beneficial live in partnership
the algae live inside the coral and they play an important role
they absorb light from the Sun and photosynthesise and the nutrients that
they create provides the coral with about 90% of its energy but when the
coral gets stressed that's when bleaching happens the algae
leave the coral leaving the coral white and bleached without the algae the coral
don't have their main source of food and so they'll slowly starve to death
bleaching can be reversible if the stress goes away then the algae can go
back to the coral and everything is okay again but if there's too much stress or
if the stress goes on for too long then the coral stays bleached and eventually
it dies there are lots of different stresses that can cause coral bleaching
the main ones are temperature changes particularly the higher temperatures
that are associated with global warming from climate change
there's also ocean acidification when the pH of the ocean drops because
there's too much carbon dioxide again this is related to climate change they
might also be increased visible and UV light from the Sun and also if there's
too much pollution for example herbicides fertilizers from farming oil
spills and dirt
relatively recently it's been discovered that some sunscreen ingredients can also
cause bleaching the studies were conducted on isolated coral pieces of
coral were placed in a bag and the sunscreen ingredients were added to them
here are some of the studies Danovaro and co-workers found that hard corals
were bleached by oxybenzone, octinoxate which is also called octyl methoxy
cinnamate or ethylhexyl methoxycinnamate and enzacamene which is also known as
4-methylbenzylidene camphor or 4- MBC they also tested some other
sunscreen ingredients and found that they didn't cause any bleaching these
sunscreens were octocrylene, octisalate or octyl salicylate and avobenzone
a 2014 study found that titanium dioxide nanoparticles could also cause
slight bleaching a 2016 study from the Haereticus laboratory by Downs and
co-workers found that oxybenzone causes bleaching and deformities in multiple
coral species a 2017 study by Fel and co-workers at L'Oreal found that octocrylene
octyl triazone, ecamsule or Mexoryl SX and drometrizole trisiloxane
or Mexoryl XL had no effect on coral while
avobenzone only had an effect at a very high concentrations. zinc oxide
caused bleaching in this study. in 2018 a study by Corinaldesi and co-workers
found that uncoated zinc oxide nanoparticles caused rapid bleaching
while modified titanium dioxide nanoparticles had a minimal effect I've
put more details about each of these studies in the blog post that I have
linked to this video and the links to each of the studies are in there as well
it's in the caption now these studies sound pretty worrying especially since
the bleaching happened even with really low concentrations of sunscreen
ingredients we're talking parts per million and parts per billion
concentrations but the amounts of sunscreen in the ocean are also really
low so one of the key questions we should be asking is is there enough
sunscreen in the environment to harm coral?
first off we're going to have to talk more about these extremely low
concentrations there's extremely low and then there's
extremely extremely low here are some of the numbers involved ppm means parts per
million or milligrams per liter this is the equivalent of about 1/50th of a drop
diluted in one liter which is about a quarter gallon for you US people it's
about this much ppb means parts per billion or
micrograms per liter 1 ppb is a thousand times more dilute than 1 ppm. ppt means
parts per trillion or nano grams per liter 1 ppt is a thousand times more
dilute than 1 ppb and a million times more dilute than 1 ppm a fundamental
principle in toxicology or the science of how bad stuff is is that the dose makes
the poison the long version of this is that everything can be a poison in large
enough amounts and everything is safe in low enough amounts ppm ppb and ppt are
all extremely low and tiny to us but the difference between ppm and ppt is 1
million so to go from 1 ppm to 1 ppt you take your liter with 1/50th of a drop and
throw it into half of an Olympic swimming pool this massive difference is
really important when we're looking at the amounts of sunscreen in the
environment are the concentration is low enough to be safe or are they high
enough to be harmful? in these studies the coal was exposed to sunscreen in the
parts per million and parts per billion range and while these are really low
other coral researchers have pointed out that these concentrations are actually
much higher than the amounts of sunscreen that you find in the vast
majority of the environment for example the lowest concentration of pure
sunscreen filter used in the 2008 Danovaro paper that had an effect was about
1 ppm of enzacamene or 4-MBC one part per million sounds
really small but if you think about it it actually turns out to be quite a lot
if you apply 30 grams of sunscreen which is the
recommended amount for an adult-sized body and it has 3% enzacamene in it and
all of it washed off your body into the water, to get one part per million you'd
be swimming in about 900 liters of water which is only about three bathtubs full
to get 2.28 parts per billion of oxybenzone one of the lowest
amounts tested in the 2016 Downs study your 30 grams of sunscreen
containing 6% oxybenzone would have to completely wash off in 790,000 litres of
water or about 1/3 of an Olympic swimming pool these estimates are
actually on the high side since studies have found that people usually wear less
than half the recommended amount of sunscreen and the amount that dissolves
in water is a lot less than 100% one study estimated that only about a
quarter of your sunscreen washes off during a 20-minute swim the ocean is
also incredibly incredibly massive ridiculously unimaginably mind-blowingly
massive it contains about 97% of the world's water which is 1.34 times 10 to
the 21 litres that's about 200 times more liters than there are grains of
sand in the world it's 70,000 Olympic sized swimming pools for each of the 7.44
billion people living on earth there are also ocean currents that mix
this water around so it shouldn't be surprising that sunscreen is only found
in almost undetectable concentrations in most of the environment that's in the
ppt range and a lot of the time it can't actually be detected but in some
situations in some environments there could be higher concentrations of
sunscreen that could realistically affect coral generally this is in the
more enclosed bays in areas with lots of tourists where there might be hundreds
of sunscreen covered people swimming in a small area of water for example
there's been high concentrations of oxybenzone measure near popular beaches
in the US Virgin Islands at Hawksnest Bay and Trunk Bay
75 parts per billion and 1.4 parts per million of oxybenzone have been measured
during busy times of the day there's also a possibility that even though the amounts
in water are low bioaccumulation might happen this is when the coral takes in
and collects the sunscreen ingredients so they build up and form a much higher
concentration inside the coral so there are only really low concentrations in
the environment although in some places there might be higher but there's
another big question mark in the data there isn't any solid evidence of
sunscreens having caused harm to coral reefs yet some researchers have
mentioned that they've seen that coral reefs in a few areas with more swimmers
are more degraded than in areas with less swimmers or they're worse in areas
with more sunscreen use but this is anecdotal evidence at the moment so it
isn't really convincing there could be other factors at plays so for example
the tourists might trample on the coral reefs so all the headlines that you
might have read that sunscreen kills coral reefs oxybenzone causes major
damage to coral reefs the sunscreen ban will save coral reefs this isn't what
the studies say some scientists have tried to estimate the amount of damage
that sunscreens might cause to coral in aquatic recreational areas in Hong Kong
near snorkeling hotspots it's been estimated that the risk of bleaching by
oxybenzone is 21% and the risk of bleaching by octinoxate is 11% a 2008
study estimated that 10% of the world's reefs are threatened by sunscreen
pollution and this numbers been cited in a bunch of other papers this sounds
pretty concerning but marine scientists who research the wider causes of coral
reef damage say not so fast a lot of marine scientist are actually pretty
critical of the sunscreen ban if we zoom out and look at the wider picture it
turns out that the possible harm from sunscreens is really really tiny in
recent textbooks and reviews on coral bleaching sunscreens don't even rate a
mention instead there's tons and tons of data showing that climate change and
agricultural management have wreaked havoc on coral reefs and will continue
to do so professor Terry Hughes a massively
respected coral expert and the director of the ARC center of excellence for
coral reef studies says he would put sunscreen all the way down and number
200 on a list of bad things that humans can do to coral reefs he points out that
the worst coral bleaching is happening in areas where tourists don't go so for
example in the massive 2016 Great Barrier Reef bleaching event the worst
bleaching by far happened in the remote northern region where and the severe
bleaching patterns matched the areas with higher water temperatures higher
water temperatures caused by climate change
researchers Kelvin Gorospe and Austin Humphries at the University of Rhode
Island also say that the damage from sunscreen is negligible when you look at
how climate change threatens coral reefs they say that if you want to do
something to save the reefs in the ocean you shouldn't be worrying about
sunscreen banning sunscreens to try to save coral reefs is a bit like
rearranging deck chairs on the Titanic or polishing a scratch on your doorknob
when your house is burning down yes technically every little bit helps
but is it worth spending time and effort and resources dealing with sunscreen
when there are much much bigger issues to work on and many of these scientists
think that it's actually a bit of a sneaky trick by politicians to hype up
the sunscreen issue it's an easy way for them to show us that they're doing
something while distracting us from the real issues climate change and
agricultural management which are much harder to fix and something that their
corporate donors probably don't want them to fix because it cuts into their
profits so they encourage us to think that sunscreens are much bigger issue
than they actually are so that we might get off their backs and ironically if
you're throwing out unused sunscreens and driving around looking for the right
sunscreens with the right ingredients you're actually making the climate
change problem worse okay so what can we actually do to help the reefs firstly in
terms of sunscreen you don't really need to do much except when you're planning
to swim in an area close to coral if that's the case you should try to use
more sun protective clothing and stay in the shade more so that you can use a bit
less sunscreen for the bits of your skin that are still exposed you should look
for sunscreens that don't have ingredients that have been found to be
harmful to coral the common sunscreen ingredients that have been found to be
harmful are oxybenzone, octinoxate, enzacamene or 4-MBC and zinc oxide the
common sunscreen ingredients that have been found to cause minimal harm or no
harm at all are octocrylene octisalate, avobenzone octyl triazone, ecamsule
or Mexoryl SX drometrizole trisiloxane or
Mexoryl XL and titanium dioxide the sunscreen ingredients that haven't been
tested on coral yet are bemotrizinol or Tinosorb S bisoctrizole or Tinosorb M
DHHB or Uvinul A Plus ensulizole and homosalate there are lots of
brands that have coral safe sunscreens in their range even if they don't say
coral safe so for example Supergoop La Roche Posay Sunsense Stream2Sea
Coppertone and Headhunter it's important that you actually check the
ingredients of the sunscreen and don't just look for labels that say reef
friendly or biodegradable these terms aren't regulated so they don't
necessarily mean anything so there's a lot of sunscreens that say they're reef
friendly but might contain oxybenzone a lot of sunscreen brands also assume that
all organic or chemical sunscreens are harmful
while all inorganic or mineral sunscreens are safe even though zinc
oxide has been found to be worse for coral than many chemical sunscreens I
talk a little bit more about why I think that it's not just nanoparticle
zinc oxide that harms coral in my blog post so check that out if you're
interested in the nerdy nitty gritty biodegradable also
doesn't mean reef safe both zinc oxide and titanium dioxide are non
biodegradable since living organisms can't break them down but zinc oxide has
been found to be harmful to coral in some studies while titanium dioxide has
been relatively safe you should try to limit how much sunscreen comes off your
body into the water as well look for a highly water-resistant sunscreen and
apply your sunscreen 20 minutes before you go into the water so it has a chance
to dry down and stick to your skin better
the other big thing we should all be doing for coral and for the rest of the
environment is to do something about climate change
climate change is a huge and scary problem but there are some things that
we can all do to help we can try to cut down on our biggest contributors to our
own carbon footprints for most people this is owning and driving a car going
on long flights and eating meat you can also switch to an energy company that
uses green energy you can also vote for political parties who firstly recognize
that climate change is a problem and who have policies that actually tackle
climate change and you can contact your local representatives about climate
change if you feel like your voice isn't that important and you're just one small
person it might make you feel better to know that because most people don't
contact them they assume that for every one person who does contact there are
ten or twenty silent people who feel the same way and that's all for today sorry
that was a bit of a depressing video but the politics around climate change are
pretty depressing my next video is going to be a lot more cheerful I've put the
link to the blog post for this video with all the info and links to the
studies and further reading and everything in the caption if you enjoyed
this video please like and subscribe to my channel you can also find out more
about the science behind skincare and other beauty products on my blog and you
can follow me on Facebook and Instagram as well see you next time for more
beauty science
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