The U.S. National Library of Medicine presents
"Mercury and Our Health,"
A short film by the
Environmental Health Student Portal
[Paul] Hi mom, thanks again for the sushi! I'll watch a little
bit of TV while I am eating, and then
I am going to go do my homework.
[Mom] Ok, but don't watch it for too long!
[From T.V.] This is Kate,
from "Food Science for Consumers."
Today's episode is about mercury in seafood.
There may be too much mercury in the seafood you are eating.
Watch to find out, and learn how to protect your health!
[Paul] Mercury in seafood? I wonder... Is the sushi seafood?
[Kate] It sure is, but don't be alarmed before you learn more!
[Paul] Mom! The T.V. characters are coming to life again!
[Mom] That's nice, dear.
[Kate] Do you know what mercury is?
[Paul] No, but it sounds like it's something bad.
[Kate] Mercury is a natural metal that's
found in the air, water and soil.
[Paul] What do you mean by natural?
[Kate] Natural means it's a part of the environment,
and is not made by humans.
It also exists in the Earth's crust.
[Paul] Wait! What do you mean by crust?
Cool!
[Kate] The crust is the outermost
rocky layer of the planet.
[Paul] Whoa! Cool! Where are we?
[Kate] We are on the periodic table of elements.
You see, we can find mercury on this
table of elements by looking over its chemical symbol.
[Paul] What's the chemical symbol of mercury?
[Kate] The chemical symbol of mercury is Hg.
This is how we can find it on the periodic table.
Remember that we can find mercury
in the environment in several forms.
Sometimes, atoms of mercury exist alone,
not connected with other elements.
This form of mercury is called metallic, or elemental.
People also call this kind of mercury "quicksilver"
or "liquid mercury"
because it's a shiny, silver liquid
that can evaporate into an invisible gas.
[Paul] Oh, I see.
[Kate] At other times, atoms of mercury combine with
other elements and create compounds, or chemical mixtures.
We may encounter mercury in different situations
depending on what form it is in.
Different forms of mercury also affect our health differently.
[Paul] How can mercury affect my health?
[Kate] If enough mercury gets into your body,
it could really make you sick.
[Paul] Oh, I don't like being sick!
[Kate] Of course you don't!
Luckily, if you live in the U.S., there are not that many
ways for you to have contact with a lot of mercury.
[Paul] But, what exactly does mercury do?
[Kate] Well, that depends.
[Paul] Depends on what?
[Kate] Several things!
Like, how much mercury gets into your body,
the form of mercury that gets into your body,
how the mercury gets into your body,
and how long you're exposed to mercury.
High levels of mercury in the body
can really hurt many body systems,
especially the brain and kidneys.
[Paul] The brain? How does it hurt the brain?
[Kate] These are some of the symptoms of
brain damage from mercury poisoning.
Tremors, or trembling and shaking, and
not being able to stop.
Walking impairments, or having difficulty walking.
Speech impairments, or having difficulty forming clear words.
Changes in vision or hearing.
Memory loss.
Loss of appetite, or not feeling hungry.
Feeling irritated, and psychosis,
or losing touch with reality, such as seeing or hearing
things that are not there.
[Paul] I don't like it.
Can it do this to anyone?
[Kate] Yes, mercury poisoning could happen to anyone,
but it is especially damaging to children and unborn babies.
[Paul] But I am a child! Why is it especially bad for children?
[Kate] Because their nervous systems are still developing.
The younger the child is, the more sensitive
he or she is to mercury.
You are more sensitive than an adult,
but young children and babies
are even more sensitive than you are.
[Paul] But you said that there are not that many ways for me to
have contact with a lot of mercury.
I guess that's the good news.
But then you also said that mercury
is a natural part of the Earth.
This makes the Earth a dangerous place!
[Kate] Mercury can only hurt us if we come in contact with it -
touch it, breathe it, and swallow it.
Mercury in the Earth's crust is hidden in the rocks.
So, the amount of mercury that's normally found in the
environment is very, very small and will not hurt us.
[Paul] That's good to hear.
[Kate] Yes. Unfortunately, people do things that make
mercury come out where we can come in contact with it.
[Paul] What do you mean, people do things
that make mercury come out?
[Kate] Let me give you an example.
I mentioned that mercury is found in many rocks,
including coal.
People burn coal for energy.
Unfortunately, when we burn coal, we release its mercury
into the air and the environment.
[Paul] Oh, I see.
[Kate] Mercury also has many properties that
people find useful, so we use it in commercial products.
[Paul] What kinds of properties?
[Kate] For example, pure, or elemental,
mercury conducts electricity.
It also combines with other metals,
into combinations that have many uses.
Other forms of mercury kill bacteria.
So, we use mercury in some commercial products.
[Paul] I am not sure I like this.
We use mercury in products?
[Kate] Yes, but less than we used to.
People have known about the helpful,
useful characteristics of mercury for a long time.
but the knowledge about its dangers to human health
is more recent.
In the past, people often used mercury in medicines,
because of its bacteria-killing properties.
[Paul] Oh, that's ironic.
[Kate] But in general, now that we know that
mercury can be dangerous,
we look for alternatives to it whenever we can.
[Paul] So, what products have mercury?
[Kate] Let me give you some examples:
Glass thermometers
Electrical switches
Fluorescent light bulbs
Dental fillings
Vaccine preservatives
Some medical equipment
Some batteries
And old paints.
[Paul] Wait! There's mercury in thermometers?
[Kate] In some glass thermometers.
Heat makes mercury expand, or grow, and this property of
mercury was used in mercury-in-glass thermometers.
These thermometers were used for centuries.
But now that we know that mercury can be dangerous,
they have become rare.
[Paul] I've seen them in pictures, inside books.
[Kate] That's right.
But the thermometer your parents use to take your temperature
probably looks like this and uses
an electronic temperature sensor.
[Paul] Did people get hurt a lot
by all those old glass thermometers?
[Kate] Remember, mercury is dangerous to us
only when we touch it, breathe it, or swallow it.
We cannot touch, breathe, or swallow
mercury inside a thermometer.
The danger happens when someone accidentally
breaks the thermometer.
[Paul] Glass things are easy to break! What happened then?
[Kate] Well, the shiny, silver elemental mercury would spill
and collect into silver balls - beautiful, but dangerous.
Someone cleaning up the spill could accidentally touch it.
Look how dangerous that is!
There was also risk of breathing it, because
liquid elemental mercury evaporated into invisible gas.
[Paul] What about batteries?
[Kate] For a long time, companies around the world used
mercury to make many kinds of batteries.
They did it because mercury prevented the buildup of
hydrogen gas in batteries, which can
cause the battery to bulge and leak.
Since the 1980s, the use of mercury in batteries
in the U.S. has been going down.
[Paul] What about the batteries in my TV remote?
Do they have mercury?
[Kate] Most batteries made in the U.S. today
do not have mercury in them, with few exceptions.
Your typical AA or AAA batteries for your remote control
do not have mercury in them.
[Paul] Oh, that's good.
But, which batteries have it then?
[Kate] One of the exceptions is button cell batteries.
These are very small batteries that look like
coins or buttons and are used in
small portable electronic devices, like wrist watches.
[Paul] Oh, my watch has a battery like that!
Should I get rid of it?
[Kate] Remember, mercury can only hurt you if you
touch it, breathe it, or swallow it.
You aren't touching the mercury, because it's
inside the battery inside the watch.
[Paul] But you said dental fillings have mercury!
Those definitely go inside our bodies.
[Kate] Have you ever heard of "silver fillings"?
They're called silver because of their silver color,
but they are actually an amalgam, or blend
of metallic mercury, silver, and some other metals.
Very small amounts of mercury are slowly released
from the blend over time.
For example, while you chew!
[Paul] See? I knew it!
[Kate] But you have to remember that the amount makes a big
difference in whether something is dangerous or not.
From what we know right now, amalgam dental fillings
do not harm people's health.
[Paul] I don't get it. It sounds like a lot of these products
that have mercury in them keep it hidden
or put in very small amounts.
So, does this mean that we have nothing to worry about?
[Kate] Not really.
Remember, a lot of the products I mentioned
eventually break or become useless,
so we'll need to get rid of them at some point.
[Paul] You mean, throw them in the trash! That's easy!
[Kate] It's not that simple.
[Paul] Ewww! Gross! It stinks!
[Kate] If we simply dump trash
that has mercury in it into the environment,
it will go into our soil and water, and build up there.
[Paul] So, what are we supposed to do
with the mercury containing products?
We can't keep the broken stuff forever!
[Kate] We have special ways to get rid of mercury waste.
Many cities and towns now have
hazardous household waste facilities or events,
but many products that have mercury still end up in
landfills or incinerators that burn trash.
Which means mercury is eventually released
into the environment and often ends up in rivers and oceans,
which is really bad.
[Paul] Why is it so bad?
We don't drink water directly from rivers and oceans.
We clean it before it gets into our faucets.
I learned about that at school.
[Kate] But fish don't get it cleaned for them.
In the United States,
the most common way to be exposed to mercury
is by eating fish or shellfish that have
high levels of mercury. Come. Let me show you.
Let's take a closer look at the environment.
[Cheerful, playful music begins]
[Music stops] When people burn coal for energy,
the mercury in the coal rocks is released into our environment.
See? Look how the mercury is getting into the environment.
Once the mercury is in the environment,
it eventually gets into the soil and water.
[Paul] But how exactly does it get into fish?
[Kate] Let's take a closer look at the contaminated water.
Once mercury is in the water, some microorganisms
convert it into a very toxic form of mercury,
called methylmercury, which looks like this.
Then the methylmercury gets into fish by going up the food chain
through a process called biomagnification.
First, some tiny aquatic plants and animals
absorb the methylmercury that is in the water.
Fish and other animals feed on these tiny aquatic
plants and animals, so the methylmercury
gets passed on to them.
Next, bigger fish eat the smaller fish and
absorb the methylmercury, and so on and so forth.
The higher up the food chain we go,
the more mercury a fish accumulates.
[Paul] Yuck! Look at all that methylmercury
in the tilefish, sharks, and swordfish!
[Kate] The longer these fish have been alive,
the more time they've had to eat other fish -
and the more methylmercury they have in their bodies.
Bigger, older fish that eat other fish
usually have the highest levels of mercury.
[Paul] Is it bad for people?
[Kate] Well, if people eat a lot of seafood
that's high in mercury, this can be bad!
Remember, I've said before that mercury
is especially bad for babies and unborn children.
That's why pregnant women have to be careful about how much
mercury-containing fish they eat.
[Paul] Oh, no! My sushi! Are the fish in sushi
high up in the food chain?
Do they accumulate a lot of mercury?
Should I stop eating fish?
[Kate] There are many benefits to eating fish.
Also, your mom used salmon and shrimp to make that sushi.
They usually have lower levels of mercury.
If you want to learn more about being safe while eating seafood,
click on the links that are on our page.
[Paul] But how? We're inside a video - inside a TV!
[Kate] It's ok to stop the video,
or finish watching and then come back.
I'm also posting these links on the webpage
on our video so you can read more about mercury.
[Paul] Wow, I've learned a lot today.
[Kate] What did you learn?
[Paul] I learned that mercury is a natural metal.
People used to use it in many products,
but now they use it less and less.
Most products we use at home are safe for us.
Still, much mercury ends up in the water and
accumulates in fish, and that's bad for fish and bad for us.
[Kate] That's right!
[Paul] Is there anything else I should know?
[Kate] Some cosmetic creams imported from other countries
could have mercury at levels much higher
than allowed for creams manufactured in the U.S.
Also, some alternative medicine remedies contain mercury,
and some spiritual and religious traditions
use it in their practices.
[Paul] That's interesting.
Where can I learn more about all this?
I know there's a lot of information on the Internet,
but some things are difficult to read,and
sometimes I don't know who to believe!
[Kate] You're absolutely right!
We need good, reliable information
that was written for someone your age.
This video is part of the National Library of Medicine's
Environmental Health Student Portal.
The portal has a section on the
effects of mercury on human health.
You can also learn there about other chemicals in the
environment and about environmental health.
[Paul] Wow, I'll definitely check them out. Thank you!
[Kate] You're very welcome! Now, let's get you back home!
[Cat Meowing]
[Paul] Mom! Hurry!
There's a TV character in our living room!
[Mom] Be there in a second!
Where is this TV character?
[Paul] Mom - she was just here!
[Mom] Sure she was! Just finish up your sushi!
This short film was brought to you by the
Environmental Health Student Portal
of the Division of Specialized Information Services
at the U.S. National Library of Medicine.
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