Doctor Explains How Sunscreen Affects Your Body
Released on 07/11/2019
Summer is officially here.
The sun is out, it is shining and,
sorry to be a downer, but so are it's cancer causing rays.
Everybody knows protecting their skin from the sun
is important and most of us have heard our whole lives
that sunscreen is the best defense for that.
But a new study, backed by the Food & Drug Administration
has shown that some chemicals in some sunscreens
can actually penetrate the skin and wind up
in your blood stream.
So what does that mean for you and protecting
your skin this summer?
To find out we're talking with Kanade Shinkai,
she's a Dermatologist at UC San Francisco
and Editor in Chief of JAMA Dermatology.
So, I think this study raises a lot of questions
for people on whether they should continue
to wear sunscreen.
So just top line question;
is wearing sunscreen still a good idea?
Wearing sunscreen is still a good idea.
And sunscreen, though, is just one part of
protecting your skin from the sun
and that includes seeking shade,
trying not to do physical activities
or activities outdoors during the peak hours of the sun,
which are between 10 and two pm and then using
other protective mechanisms like using hats,
sunglasses, protective clothing,
so sunscreen's just one part of protecting
your skin from the sun.
Can you tell us a little bit about what the study
looked at and what it found?
Yeah, so the study's a small pilot study
that looked at the application of four different
commercially available formulations of sunscreen,
these are things that are available at most drug stores.
They measured the absorption of the key sunscreen
ingredients in the blood over time and also
after the application had stopped and what it found
was that there is notable absorption of the
sunscreen ingredients into your bloodstream
and that they reached levels,
really just after a few hours of applying the
sunscreen and will stay elevated for almost
a day or two after you stop using the sunscreen.
So this means that when we put sunscreen on our skin,
it's getting absorbed through the skin and it's
going into our bloodstream and it hangs around
for a lot longer than the application and the levels
that were found in the study were greater than
the levels that the Food & Drug Administration here
in the United States uses kind of as a threshold
to do safety testing.
But the safety testing has not been done,
so really, what it's telling us is that sunscreen
gets absorbed into the bloodstream,
it reaches levels that are higher than this
regulatory threshold and the safety testing
has not been done yet.
I think, when a lot of people first read about this study,
they read oh, there's chemicals in sunscreen,
it's getting into my bloodstream.
Chemical has become kind of an unhelpfully broad,
kinda scary term for a lotta people.
They'll hear it and think oh, chemical is bad and unsafe
and dangerous, but the fact is all physical matter
is chemicals, right?
So it helps to talk with specifics here.
So what kinds of chemicals did this study find
in people's bloodstreams?
Yeah, well there's two different types of sunscreen.
One type we call mineral sunscreen and these are
literally minerals; zinc oxide and titanium dioxide,
they coat the skin.
Technically, you could call it sunblock.
They also often leave a very white color on the skin
so a lot of people don't like to use it for that reason.
Those have been tested and don't have any
systemic absorption so we know that those are safe.
The other type of sunscreen is what we
colloquially call chemical sunscreen.
So these are literally chemical filters
that absorb ultraviolet light and these are the ones
that are in question, these are the ones that have
never been tested in terms of their safety,
or their systemic absorption, four of which were the ones
that were studied in this particular research article.
What ingredients, in sunscreens specifically,
was this study looking at?
This particular study looked at
four sunscreen ingredients:
Avobenzone, Oxybenzone, Octocrylene and Ecamsule.
What do these chemicals actually do inside the body?
Is that something we know?
Yeah, so we don't really know.
There's never been any research article that has suggested
that these chemicals are doing anything harmful
to the human body.
There are some studies, however,
that have been done in lavatory animals and, of course,
take it with a grain of salt because these studies
always use doses that are a lot higher than what
a person would be exposed to,
but there have been some data points that have suggested
changes to your hormone levels,
changes in reproduction and those have at least
raised the question of whether or not safety testing
should happen in humans.
But that safety testing has not happened yet.
Even if we take the animal studies with a grain of salt,
I think that not knowing is still an unsettling
prospect for people.
So the question that I would imagine a lot of people
are asking is; should I still wear sunscreen?
Is it safer to be exposed to the sun unprotected,
or to use this product on my body that
has effects I may not fully understand?
Yeah, well there is something absolutely certain,
which is that the sun and sun exposure,
and especially prolonged sun exposure can result in sunburn,
which is unhealthy, and also can lead to skin cancer.
That is not in question in this study.
I think what's in question is really about
how effective sunscreen is in protecting long-term
from skin cancer and melanoma, as well as whether it's safe.
A lot of consumers don't know that sunscreen's
actually considered a medication and so because of that
usually all over the counter medications are
subjected to a battery of testing but that has
never been done for these chemical sunscreens
and that's why this study is so important.
Why hasn't that been done for sunscreen?
You know, sunscreens have been around for a long time
and they really preceded, kind of the standard way
that we evalsuate over the counter medications
in this country and so usually in history and time
we find out that a medication has some side effect
that might be dangerous to people and it gets
taken off the market, now what we try to do
is do those safety studies in advance of the
medication coming out.
However, that hasn't been done for sunscreen
because, in large part, the sunscreens predated
that type of drug regulation.
Over time, and in fact as early as 1999,
the Food & Drug Administration asked sunscreen companies
to do these regulatory studies but for various reasons
they have not been able to see that data.
What are alternatives to sunscreen,
or sort of ways of supplementing the sun blocking
effects of sunscreen?
Right now, there are sunscreens that we know are safe
and these are the mineral sunscreens that we
talked about earlier and those are not in question at all
and those have been tested.
If people are choosing between chemical sunscreen
and mineral based sunscreen,
is there a cost difference?
There's no cost difference.
Are they as effective as one another?
Well, as far as we know they're as effective.
One of the things that we, as dermatologists,
are still trying to determine is what is the
effective dosage of sunscreen?
I think common sense would say you wanna put it on,
and we all know it rubs off when we go swimming,
or when we towel off or when we sweat.
It still needs to be determined whether or not
there's a particular dose of mineral or chemical sunscreen
that is ideal for the prevention of
skin cancer and melanoma.
I think one important piece of this study,
the research article that we're talking about,
is that this was idealized conditions.
So the subjects put the sunscreen on and they sat
in climate controlled environments,
so they weren't swimming, they weren't sweating
or even moving around and they weren't actually
exposed to the sun and so we don't know what,
in the real world and under real world conditions,
what those systemic absorptions are like,
whether they're the same or not to those found
in this particular study.
Speaking of real world conditions and the
question of dosage,
there's also this factor of behavioral psychology, right?
Which is, I know there have been some studies
that look at people who apply sunscreen and think
that they're getting the protection in some cases,
and in some cases get burned worse than people
who are taking protective measures to protect themselves
knowing that they haven't applied sunscreen.
So that's, the real world scenario is a really big variable
that is hard to account for.
It is and this has actually been shown in studies.
People put on about half the amount of sunscreen
as on a sunscreen label, so that's one important
real world condition as well but we don't actually know
whether those real world conditions,
for example, if you just use less sunscreen
to get less absorption, whether that would impact
its safety and effectiveness as a tool to prevent
skin cancer and melanoma.
What are the next steps for the
Food & Drug Administration?
So in February of this year there was a proposal
put forth that the Food & Drug Administration will
really mandate that sunscreen companies provide
the safety testing.
So the onus is really on the sunscreen companies,
not on the Food & Drug Administration.
What are the next steps for sunscreen manufacturers.
Yeah, so the sunscreen manufacturers are now
going to be required to test their products
for safety testing.
So that safety testing will begin with
systemic absorption, so looking to see if it gets
absorbed into the sunscreen,
and that's for 12 ingredients in this particular FD ruling,
and if there is evidence of systemic absorption
past the, or above, the safety threshold
that the Food & Drug Administration has for all,
it's common to all medications,
then it will trigger additional safety testing,
which included toxicity studies, cancer risk and
effects on things like hormones and reproduction.
How soon could this realistically affect what
people see on the shelves at their local
pharmacy or supermarket?
Well, in theory, if the sunscreen companies
don't provide this data by November of 2019,
in theory these products could be pulled from the market.
I think we would all agree this would be
a very extreme measure given that we don't actually have
any data right now that they're unsafe.
However, this is sort of what is being set up
by this current proposed ruling.
That being said, I think companies also need time
to do the studies and likely there will be an opportunity
for them to request extensions as long as they're
working on doing the testing that's been requested.
What is sort of the one big takeaway people should
have from this study?
It's really important for people to know that
it's really essential for them to protect their skin
from the sun and there's lots of different ways to do that.
And sunscreen is an important piece of that
so people should still wear sunscreen.
If they have concerns about the chemicals that
were in this particular study,
they can choose things that we know are safe,
including the mineral sunscreens that we
talked about earlier.
But the real key here is that we don't know,
especially from this study,
that the four sunscreen ingredients that were studied
are actually dangerous, we don't know that yet.
And we do know that sun exposure is dangerous.
We absolutely know that.
That is not in question.
Well, thank you very much for joining us today.
It sounds like sunscreen is still a good idea.
If you don't wanna use sunscreens that have these
sort of chemicals in them,
the effects of which are kind of unclear,
you have other options and people can, of course,
stay out of the sun and wear protective clothing too.
Absolutely.
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