A Toddler Chewed Lead Paint Off His Toys.
This Is What Happened To His Brain.
JP is a 4 year old boy, presenting to the emergency with a steady decline in coordination,
appetite, and speech.
His mother Sarah, tells the admitting nurse that he had lost 5 pounds over the last week
and had developed tremors in his hands.
JP was from a well off family, living in an old house.
He loved playing with antique toys given to him by grandma.
About a year ago, Sarah realized that JP was chewing the paint off his toys.
He seemed happy and healthy, so she didn’t think too much of it.
She replaced the toys with a different set, and life continued on.
But as the weeks went by, Sarah noticed JPs attention span shortening.
Maybe should limit his screen time, she thought.
Sometimes she’d call out his name and he clearly couldn’t hear her.
Maybe she should speak louder she thought.
Eventually, Sarah found her son chewing the paint off his new toys.
She took those away too, but this time, things didn’t seem right.
JP complained his tummy hurt.
Sarah thought his walk looked funny.
His speech started to slur.
His hands began to tremble.
His reaction time seemed to be blunted.
Sarah realized then that something was terribly wrong was happening to her son, and clinical
exam confirms this.
Hyperactive behavior was found in JP along with ataxia A meaning without and taxia meaning
order.
His movements were uncoordinated, with a marked tremor in his upper extremities.
High frequency sensorineural hearing loss was detected.
Higher pitched sounds were almost inaudible to JP.
Urine analysis revealed excessive proteinuria, indicating kidney damage.
A blood test reveals JP’s blood lead level is over 200 micrograms per deciliter, at least
40 times the level known to cause brain damage.
Clearly, his neurologic decline is because of lead poisoning.
But something’s wrong.
Typically, symptoms of lead poisoning are resolved after exposure has ceased.
Sarah took his toys away weeks ago, but his condition is worsening.
JP’s lead toxicity is chronic, meaning he had a constant exposure over a long time and
this excessive buildup has started to permanently damage him.
We can prove this.
We estimate his total blood volume to be about a liter given his weight of 14 kilograms,
measured at admission.
So there’s really over 2000 micrograms of lead total in his blood.
But, studies indicate that less than 25% of absorbed lead is in the blood.
So where is that other 75%?
Well, there’s some basic chemistry to be known here.
Lead is a heavy metal.
On the periodic table, it’s a member of group 14, so it shares some characteristics
with carbon, silicon and tin.
As you go down the group, the atomic mass of each element increases.
Heavier elements are less stable.
Less stable means more reactive.
And more reactive means lead preferentially binds to structures in the body, explaining
that other 75%.
But, elemental group 14 members tend to be inert in the body, meaning they don’t react
with anything.
Have you ever heard of metallic tin poisoning?
Because I haven’t.
How about this silica gel you find in packages that say do not eat.
That’s silicon dioxide, I’ve seen people choke on it but I haven’t seen that silicon
react with anything in the body.
So lets go back to the chemistry.
Group 14 elements can have a positive 4 charge, something that we call a tetravalent cation.
Tetra meaning four.
Valent from Latin Valentia meaning capacity and cation meaning positive charge, like something
that you see on batteries.
One reason why chemical reactions happen is to eliminate the charge.
So making it zero, makes it stable.
So to get rid of plus four, you need a minus four.
But nothing in the body is minus four, so carbon, silicon, germanium and tin don’t
really react in the body.
But lead is an exception.
Its significance is because of how heavy it is.
This is the number of particles at the center, or nucleus is called the atomic number.
Silicon is 14.
Germanium is 32, so that difference is 18.
Tin is 50, also a difference of 18.
But lead is 82, a difference of 32.
This means there’s a lot more particles in lead’s nucleus.
More particles means more mass.
And more mass means stronger forces pulling towards the center.
So instead of plus 4, lead is mainly plus 2, something we call a divalent cation.
And this explains why lead is toxic in humans.
As divalent lead flows throughout JP’s body, it mimics and competes with other divalent
cations, which are calcium, magnesium and zinc.
Important components of muscle contraction, cellular signaling and nerve conduction.
So as lead displaces these necessary cations, it blocks, twists and warps everything it
touches.
Lead preferentially binds to sulfhydryl groups, a binding of sulfur and hydrogen.
These are everywhere in proteins, which are the functional structures of cells.
So as lead disturbs these sulfhydryl groups, the proteins fold abnormally and no longer
function as intended, meaning that cells start to die.
Nerves are irreversibly damaged.
Lead displaces calcium at the point of synapse in nerve cells still alive, shutting down
their signals too.
As lead continues to creep into JP’s tissues, this cell death proliferates to his brain.
Divalent lead drives itself deeper into mitochondria, disturbing brain cell metabolism, uncoupling
ATP production in the brain, leading to hypometabolism and ending in permanent brain damage for JP,
because of lead paint that he chewed off his toys.
If 2000 micrograms in blood is just 25%, then there is actually more than 8000 micrograms
lead floating around in his body.
Given that just 200 micrograms is known to cause permanent brain damage and that his
neurologic condition is quickly deteriorating, JP is in trouble.
Can we somehow remove the lead from his body?
Maybe.
This brings us back to divalent cations.
Your body removes chemicals through a process called excretion.
Waste is eliminated by dissolving it in water as the kidneys filter blood and concentrate
the urine.
The problem with lead is that it accumulates in the kidneys where it collects inside the
duct and injures the tubules.
And even worse, it stays for more than 120 days, where it accelerates cell death.
So, if lead mimics calcium, then we need a molecule bound to calcium so that lead can
displace it.
And on the outside, we need the molecule to be water soluble so it can dissolve and concentrate
in the urine.
JP is given calcium disodium ethylenediaminetetraacetic acid.
The calcium is swapped by lead on the inside.
The outside mixes well with water allowing it to be removed by the kidneys.
He receives several doses and it’s found to be working because JP’s blood lead levels
decrease rapidly over the next few days and it’s repeated for a few weeks.
But it’s not enough.
Pediatric neurology finds JP’s hearing is still impaired.
His neurocognitive deficits are still wide.
His seizures have stopped, but he’s starting to miss developmental milestones.
If we’ve removed lead from his blood, what could still wrong?
Less lead is good, right?
Well, it is.
But at this point, we’re only preventing further damage.
Removing the lead from his blood doesn’t reverse the damage already been done.
If chelation wasn’t given in time, this excess lead would have caused his brain to
swell with water causing cerebral edema.
The expansion of the brain would crush up against the skull, smashing blood vessels,
and ending in death, but luckily, it was caught in time, but the irreversible damage has been
done.
At the time of diagnosis, it was thought maybe the home environment or that the water supply
could have been the problem.
But further analysis showed otherwise.
JP’s parents had no detectable blood lead levels, so the exposure was isolated to him.
Analysis of his toys found paint containing 0.8 weight percent (g/g) lead.
This means just 1 gram of paint contained the 8000 microgram level that was found in
JP’s body, and that he likely chewed more as it had been accumulating in his body over
several months.
Why was lead in the paint to begin with?
Well, it was commonly added in to dry it faster and to resist moisture and corrosion.
That paint is common in old art, and old homes.
But unfortunately, today, lead is still found everywhere in our surroundings, and inside
everyone too, including you.
The European Food Safety Authority in 2010 estimated that average adult consume takes
in about 0.8 micrograms of lead per kilogram bodyweight per day from regular diet.
So a 70 kilogram European male takes in about 54 micrograms of lead per day orally.
Adults absorb about 1% of lead through the GI tract, so the actual amounts that end up
in the body are really lower.
But where adults absorb more lead, is through the lungs.
Lead was added to gasoline as an anti-knockback agent until the 1990s when unleaded became
law of the land.
The 60 years with leaded gas resulted in airborne deposition, so some US urban areas today can
classify their soil as hazardous waste because of all the toxic metal in it.
Today, we know blood lead levels as low as 5 to 10 micrograms per deciliter, that is
less than 5% of JP’s, results in permanent IQ loss.
Children raised with lead in their blood have reading disabilities, poorer hand-eye coordination,
longer reaction times, with wider neurobehavioral deficits.
In the long term, there’s a markedly increased risk high school dropout and limited job prospects.
For JP, it still isn’t finished.
The largest stores of bodily calcium are not in soft tissue, but in the bone.
Because kids grow fast, calcium storage rates are high.
When blood lead levels are elevated in these early years, instead of calcium, it’s lead
that entrenches and embeds itself into the bones.
It takes several years for bone to turnover.
As JP grows into an adult, that lead will slowly leech out into his blood, serving him
a baseline level.
During times of acute stress that he’ll inevitably live through in his adult life,
those lead stores in bone can suddenly unleash a bolus load, poisoning him all over again.
If JP was a girl, the bone lead will leech out into her bloodstream during pregnancy
and cross into the fetus, poisoning the child, and repeating the cycle all over again.
There’s no good long term answer to JP’s problems.
His acute exposure was addressed with chelation therapy.
But that doesn’t reverse the damage that was already done over those months he chewed
paint off his toys.
This particular patient was lucky he came from a well to do family.
It’s not even clear if his parents told him he was poisoned with lead as a kid.
Many others aren’t so fortunate, and this is a case lost to follow-up.
More recently, Consumer Reports released an analysis of heavy metal presence in children’s
fruit juice commercially available.
In their analysis, half the juices tested contained lead concentrations of less than
1 part per billion.
That is 1 microgram per liter of juice.
Given that children absorb about half the lead they consume orally, a child would have
to drink 16000 liters or 4226 gallons of juice in 1 sitting to get to JP’s levels.
But since we know less than one-fortieth of his levels can cause permanent IQ loss, 50
to 100 gallons of juice doesn’t seem implausible for a kid to drink over months to years because
lead accumulates in the body over time.
To be fair, heavy metal levels in US fruit juices have been going down since year 2000.
The American Academy of Pediatrics recommends parents do not give children under 1 year
of age any juice.
No more than 4 ounces daily (118 mL) for toddlers aged 1-3 years.
No more than 4-6 ounces daily (118-177 mL) for children aged 4-6.
And no more than 8 ounces daily (237 mL) for children aged 7-18 because in the end, no
blood lead level at all in a child is acceptable.
Prevention to any kind of exposure, while easier said than done is really the best and
only way to avert a tragedy, like that of JP.
Thank you so much for watching.
Take care of yourself. And be well.