Lead is a sneaky little element.
It’s malleable and durable, so it’s no
wonder that for years we used it in piping
and added it to paint.
But it’s also extremely poisonous.
It can create problems all over the body—from
rashes, to abdominal pain, to anemia.
But the most serious effects occur in the
brain—and especially in the brains of children.
It can cause headaches, memory loss, learning
disabilities, behavioral issues, and seizures.
And kids don’t even have to be exposed directly.
Women who wind up ingesting lead can store
it in their bones.
And if they get pregnant, that lead can be
passed on and damage the brains of their children.
Lead poisoning is still a big problem in the
US today—and not just in communities you
may have heard of, like Flint, Michigan.
So, what’s actually happening to the brain
when you have lead poisoning?
And is there anything we can do to stop it?
I’m Anna and this is Gross Science.
Lead messes with our brains in a few different
But to understand what they are, let’s look
really quickly at how brain cells—or neurons—communicate:
and I promise, this will be short, sweet,
and hopefully deeply enlightening.
Ok, so neurons have a long tail called an
“axon” at one end, and branch-like structures
called “dendrites” at the other.
They talk to one another when the axon from
one cell sends chemical signals to another
The receiving cell can then pass the message
on to yet another neuron.
And all that communicating happens in this
tiny gap between the cells called the “synapse.”
One thing lead can do is block those chemical
signals from being sent, which sounds bad
But, lead does another thing that can have
even more long-term effects.
It can make the synapse—that connection
between your neurons—become weaker over
You see, in order for neurons to maintain
a strong connection, the axon needs to know
that the dendrite is receiving its messages.
So the dendrite produces a molecule that lets
the axon know it’s being heard loud and
That molecule is called BDNF, and you can
kind of think of it like the best-friends
It makes the axon and dendrite’s relationship
But, in order for the cell to produce BDNF,
it needs calcium.
Calcium usually enters the dendrite through
channels, which act like a door that opens
for a little while when a signal is received.
When the door’s unlocked by the right set
of molecules, calcium flows through freely.
But when lead’s present, it jams the door,
preventing calcium from entering and keeping
BDNF from being made.
That means that the connections between brain
cells start to wither.
In adults, having poor connections between
your neurons is harmful enough.
But in children, with their fast growing brains,
it’s especially dangerous—not to mention
that the amount of lead needed to cause brain
damage in kids is much smaller, in part because
their brains are making (and removing) new
connections at much faster rates.
Sadly, in the past there haven’t been great
treatments for lead poisoning—and especially
not for its effects on the brain.
But recently, scientists have shown that simply
by adding a BDNF substitute, neurons may be
able to bounce back.
Here’s a video showing this process in action.
On the left are normal cells, in the middle
are cells exposed to lead, and on the right
are cells exposed to lead that have been given
When the green dye disappears, it means that
the neurons are able to send their chemical
signals—so when the video turns black you
know everything’s working properly.
You can see that the green starts to disappear
in the cells with additional BDNF, even though
they’ve been exposed to lead.
Now, we’re still far from using BDNF as
a cure for lead poisoning—this isn’t even
being tested on humans yet.
Certainly, preventing the exposure to lead
in the first place should be the primary goal.
But this research offers hope that one day,
lead poisoning may be much more treatable.
And that’s a great thing, since today, at
least 4 million American households with kids
are exposed to high levels of lead.
And that’s gross.