A Toddler Chewed Lead Paint Off His Toys. This Is What Happened To His Brain.

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.


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