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No, You Can’t Make Your Own Sunscreen - Video học tiếng Anh
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No, You Can’t Make Your Own Sunscreen
No, You Can’t Make Your Own Sunscreen
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Legendas (316)
0:00
As the season turns from winter gloom to
0:02
the sunshine of spring and summer,
0:04
we’re all excited to get back outside
0:06
and enjoy the outdoors again.
0:07
But as you’re packing up the beach bag,
0:09
there’s one item that you might have
0:11
heard a lot of mixed messages about,
0:13
especially in online wellness spaces: Sunscreen.
0:17
So let’s reapply some knowledge to help you
0:19
sun-block any sunscreen myths this summer.
0:26
[♪INTRO]
0:27
Let’s start with the basics.
0:28
Despite what anyone else tells you, you absolutely need sunscreen.
0:33
Besides bringing us light and warmth for a gorgeous day at the beach,
0:36
the sun also brings ultraviolet, or UV,
0:39
rays that can cause sunburns and skin cancer.
0:43
UV rays are mainly categorized as UVA or UVB.
0:47
Both of them can cause cancer, but UVB is the one that leads to those
0:51
classic sunburns, whereas UVA contributes to premature skin aging.
0:56
Sunscreen blocks most of those harmful
0:58
UV rays from reaching your skin.
1:00
Which is super important because some researchers
1:02
think getting just one blistering sunburn could be enough
1:06
to increase your lifetime risk of melanoma by 50%!
1:10
Even if you’re someone that only tans and never burns,
1:13
that sun-kissed glow is still a sign
1:16
that you’re getting some skin damage.
1:18
Whenever your skin cells sense UV radiation,
1:20
they produce more melanin to protect
1:22
your DNA from further bombardment.
1:24
Melanin absorbs some of the radiation before it hits your DNA,
1:28
and it also makes your skin look darker, hence the tan.
1:31
That’s the same reason why people living closer
1:34
to the equator tend to have darker skin tones,
1:37
because the UV exposure is higher there
1:39
and their skin needs more protective melanin.
1:42
But here’s the thing.
1:43
All people regardless of age, race, sex, and whatever else
1:47
should be wearing sunscreen every time they go out in the sun.
1:51
And that’s not just me saying that.
1:53
Both the American Academy of Dermatology and
1:56
the Mayo Clinic state that all people need to use sunscreen.
2:01
Even though it’s true that having naturally higher
2:03
melanin means that dark skin doesn't burn as easily,
2:06
everyone/ can get sunburned, and everyone can get skin cancer.
2:11
That’s because melanin can’t protect you from 100% of UV rays,
2:16
meaning that no matter how dark someone’s skintone,
2:18
they’re still going to get at least some
2:20
UV exposure damaging their DNA.
2:23
This myth has led to a lot of people of color thinking
2:26
that they can’t get skin cancer, which leads to later
2:29
diagnoses and disproportionately poor outcomes.
2:33
It’s also worth mentioning that the warning signs of
2:35
skin cancer can look different on darker skin.
2:38
If you have a dark skin tone, it’s important to know
2:41
what a questionable spot looks like on your skin type.
2:44
So case closed! The American Academy of Dermatology
2:48
recommends that everyone should wear sunscreen.
2:51
But do we need it all the time?
2:52
Like, if it’s overcast, it can be tempting
2:55
to think that you don’t need sunscreen.
2:56
If I can’t see the sun, it can’t see me, right?
2:59
But no, if the sun is up, then UV rays are present, cloudy or not.
3:04
The official recommendation is that everyone should wear
3:07
at least SPF 30 on any exposed skin anytime they’re outside.
3:12
Even indoors, if you sit near a window,
3:15
some UV rays can still come through.
3:17
And the need for sun protection doesn’t
3:19
stop when summer break ends.
3:21
Just because there’s snow on the ground,
3:23
doesn’t mean you can skip your sunscreen.
3:25
Bright white snow reflects UV rays and bounces them all around,
3:29
meaning your skin gets UV from multiple
3:32
directions instead of just from above.
3:34
This reflective property is called albedo,
3:37
and it happens around sand and water too.
3:39
But usually when you’re on a beach vacay,
3:42
sunscreen is already on your mind.
3:44
It’s harder to remember when you’re bundled up
3:47
and can’t feel the tip of your nose, but it’s just as important!
3:50
In any case, dermatologists say you
3:52
need at least SPF 30 during the day.
3:55
Outdoors and indoors, summer and winter, sunny and cloudy!
4:00
Speaking of SPF, let’s talk about what those letters actually mean.
4:04
When you’re browsing the sunscreen aisle at the drugstore,
4:07
you’ll notice that the big number on the front of the bottle is its SPF.
4:11
SPF stands for sun protection factor, and that number is a ratio
4:15
for how well the sunscreen protects you from the sun’s rays.
4:19
A quick and dirty way to think of SPF is that
4:22
the number on the bottle equals how many times
4:24
longer you can stay out in the sun without burning.
4:27
So if you would have burned in 5 minutes without any SPF at all,
4:31
slathering on SPF 30 means you could
4:33
kick it poolside for two and a half hours, no worries.
4:36
But that’s just a rule of thumb,
4:38
and the strength of radiation changes a lot during the day.
4:42
The more technical explanation is that
4:44
SPF 30 means only one-thirtieth of the sun’s
4:47
UV rays make it past the sunscreen to your skin cells.
4:52
So, one divided by thirty is about 3% of the rays hitting your skin.
4:57
In general, higher SPF numbers do
5:00
offer more protection than lower SPF,
5:02
but it’s not a linear relationship–
5:05
SPF 30 isn’t doubly as effective as SPF 15 in the way you might think.
5:10
Like, SPF 30 blocks 96.7% of UV rays,
5:15
while SPF 60 blocks 98.3%.
5:19
So doubling the SPF number only
5:21
increases the effectiveness by 1.6%.
5:25
The number of rays hitting your skin is cut in half,
5:28
but there’s only a marginal increase
5:29
in protection for a much bigger number.
5:32
Because of this, experts have proposed caps
5:34
on how high you can market your SPF.
5:37
This is to avoid misleading customers about
5:39
the degree of sun protection a product can provide.
5:42
Previously, the proposed cap had been SPF 50,
5:46
so the highest number brands could write was SPF 50+.
5:51
But in 2021, the US Food and Drug Administration
5:54
decided that the effective difference between SPF 50 and 60
5:59
was meaningful enough to update that proposed cap to SPF 60+.
6:04
But most specifically, SPF measures
6:07
how much UVB is able to reach your skin.
6:10
Remember, that’s the burn-y kind of radiation.
6:13
That’s important because even if you're using an SPF sunblock,
6:17
it won’t always have what it takes to block skin-aging UVA rays too.
6:21
To ensure your sunscreen also includes UVA protection,
6:25
look for “broad spectrum” or PA+ bottles.
6:29
As if all that wasn’t complicated enough,
6:31
I have another wrench to throw in this calculation.
6:34
The advertised SPF is the number manufacturers
6:37
get for perfectly applied sunscreen swatches.
6:40
In the lab, that’s a precise 2 milligrams
6:43
per square centimeter of coverage.
6:45
Or in normal people numbers, that’s about
6:48
a quarter of a teaspoon for your face, and about 1 ounce,
6:51
like two thirds of a shot glass, for your whole body.
6:55
Of course, people come in lots of different sizes,
6:57
so you might need more or less depending
7:00
on how much skin you need to cover.
7:02
But the shot glass method is a good reference point.
7:05
In reality, most of us are only using about
7:08
a quarter of the recommended sunscreen,
7:10
so we’re getting way less SPF than what’s listed on the bottle.
7:14
Plus, you’re supposed to reapply every 2 hours.
7:17
So if you’re a little patchy with your initial application,
7:20
or you’re sweaty or wet, or if you miss your 2 hour refresh,
7:24
you’re also not getting your full SPF power.
7:28
And if your sunscreen has expired, it’s even less effective.
7:32
So check your sunscreen bottles,
7:33
bulk up on application, and don’t F around with your SPF!
7:38
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We’ve talked about why too much UV exposure is bad.
9:26
And it is. But, there is one thing that a little UV is good for:
9:31
Making vitamin D.
9:33
When sunlight hits your skin,
9:34
the UV rays zap a certain type of lipid molecule in our bodies
9:38
that then breaks down into the biological precursor for vitamin D.
9:43
Then, your body takes that precursor
9:45
and finishes it up to make vitamin D.
9:48
So if we block most UV from reaching our skin,
9:51
then won’t we block most of that good vitamin-making power, too?
9:55
It’s true that sunscreen can lower vitamin D production.
9:59
BUT scientists think that in reality,
10:02
we aren’t using enough sunscreen for that to be a significant issue.
10:06
There’s definitely room for further research,
10:08
but with the way most people are actually using sunscreen,
10:11
scientists haven’t found any evidence that SPF
10:14
is significantly hindering our vitamin D production.
10:17
Overall, the benefits of wearing sunscreen vastly
10:20
outweigh the cost of slightly lower vitamin D levels.
10:23
Because you don’t actually need that
10:25
much UV to max out your vitamin D factories.
10:29
Remember that sunscreen can never block
10:30
100% of UV rays from reaching your skin.
10:33
So chances are, if you’re getting enough sun to warrant
10:36
wearing sunscreen, you’re probably also getting enough
10:39
UV to produce normal amounts of vitamin D.
10:41
If you’re tanning at all, then you’re definitely getting enough.
10:45
And the American Academy of Dermatology
10:47
does not recommend any kind of min-maxxing
10:50
to try to get the most vitamin D with the least risk of skin cancer.
10:55
Just, like, don’t do that.
10:57
Besides, you should also be getting vitamin D from your diet!
11:01
Fatty fishes, fortified dairy and cereal products,
11:04
and some mushrooms can help meet your vitamin D needs.
11:08
If you’re really concerned, you can also take supplements.
11:11
Some people might feel resistant to the idea of taking supplements,
11:15
given that your skin has built-in vitamin D factories as is.
11:18
But that myth plays into something called the naturalistic fallacy,
11:23
which states that natural things, like making your own vitamin D,
11:26
are always better than taking manufactured
11:28
supplements or slathering sunscreen chemicals on your skin.
11:33
But doing it the “natural” way means significantly
11:36
increasing your risk of skin cancer by not using SPF.
11:40
This is a case where we should be
11:41
willing to accept a little help from science.
11:44
So, while there is some evidence that
11:45
sunscreen can reduce vitamin D production,
11:48
the official recommendation isn’t to just stop using sunscreen.
11:51
You should definitely still use sunscreen.
11:54
But if you’re worried about your vitamin D,
11:56
dermatologists recommend adding a supplement to your routine.
11:59
Part of the naturalistic fallacy is an aversion to
12:02
anything that’s called “synthetic” or a “chemical.”
12:05
One chemical that has received considerably
12:07
bad press is called oxybenzone.
12:10
Sunscreens are generally sorted into two broad categories–
12:14
chemical or mineral.
12:15
Mineral sunscreens rely on ingredients like zinc oxide
12:19
or titanium dioxide that sit on top of your skin
12:22
and reflect the sun’s rays like a UV mirror.
12:26
Chemical sunscreens, on the other hand,
12:27
work by absorbing all the UV rays themselves
12:30
so your skin cells don’t have to.
12:33
Like a UV shock absorber!
12:35
Oxybenzone is one of the ingredients that
12:37
can do this absorption in chemical sunscreens.
12:40
And because oxybenzone needs to sink
12:42
into your skin in order to work,
12:44
it’s become a hotbed for naturalistic controversy.
12:48
In particular, people are worried
12:49
about oxybenzone disrupting hormones.
12:52
This myth seems to be based on a study conducted back in 2001,
12:56
where researchers fed large amounts of oxybenzone to rats.
13:00
But humans are not rats,
13:02
and you’re probably not eating your sunscreen!
13:05
To put this in perspective, you’d have to eat like
13:07
100 grams of oxybenzone a day for four days
13:12
in order to get the same relative amount as these rats.
13:15
If you’re using sunscreen on top of your skin,
13:17
because you should be, it would take you 277 years to get
13:23
the same amount of oxybenzone in your system as these rats.
13:26
There are some real concerns about oxybenzone.
13:29
It is banned in some countries because it can harm coral reefs.
13:33
And sometimes it can cause allergic reactions.
13:35
But that’s all different than causing disease!
13:38
It’s okay to avoid stuff for valid reasons,
13:41
but we shouldn’t be spreading total misinformation, either.
13:44
Another unfortunate myth that has sprung from the
13:46
naturalistic fallacy is that you can make your own sunscreen.
13:50
You cannot make your own sunscreen!
13:54
I’m looking right at you, raspberry and carrot seed oils!
13:57
Even though these have some natural SPF properties,
14:01
they’re only rocking a whopping SPF 2.
14:04
A study from 2020 made 15 different DIY sunscreen
14:09
recipes from across the internet, then analyzed their SPF.
14:13
3 of the 15 recipes didn’t contain any SPF at all.
14:17
And the other twelve clocked in at less than SPF 6.
14:21
Remember, the recommended coverage is at least SPF 30!
14:25
Most of the DIY recipes are concocted
14:27
from oils, beeswax, and zinc oxide.
14:30
Although zinc oxide is a sun-blocking
14:32
ingredient in many mineral sunscreens,
14:34
its quality and concentration is crucial for
14:37
the safety of the final product.
14:39
And the zinc oxide formulation also affects its sunblocking abilities.
14:44
Like in the pigment form, it hardly does a thing,
14:47
and the nanoparticle forms can vary drastically in size and quality.
14:51
But the microstructure of zinc oxide isn’t something
14:55
that most average folks who are trying to make
14:57
their own sunscreen would be able to tell apart.
14:59
Even worse, regulatory agencies warn against
15:02
inhaling zinc oxide in any amounts, so working with those
15:06
fine powders in your home kitchen could be hazardous.
15:09
Unless your kitchen is equipped with tools for factory-precise
15:13
measurement, lab quality environmental control, and perfectly
15:17
homogenous mixing, then every single swipe of your homemade
15:21
sunscreen could give you wildly different amounts of protection.
15:25
The impressively wide range of SPF 0 to 6!
15:29
Homemade sunscreen is basically
15:31
equivalent to just rubbing oil on your skin.
15:34
Good for moisture, but bad for UV protection.
15:38
For proper protection, professionally
15:40
manufactured sunscreen should be your go to.
15:42
Whether you’re soaking up some rays on the beach,
15:44
skiing on an overcast day, or just taking
15:47
a walk around the neighborhood,
15:49
it provides the UV protection that dermatologists say we all need.
15:54
Hopefully, this good healthy slather of knowledge
15:58
will help protect you from skin cancer and misinformation.
16:02
[♪OUTRO]
