One single scientist created three inventions
that accidentally caused the deaths of millions of people,
including himself.
Not only that, they decreased the average intelligence of people
all around the world,
increased crime rates,
and caused two completely separate environmental disasters
that we are still dealing with today.
Part of this video is sponsored by Wren.
More about them at the end of the show.
In 1944, as a young chemist who had just finished his
Master's, Clair Patterson went to work on the Manhattan Project,
building the first nuclear weapons.
His job was to concentrate uranium-235, the fissile fuel for bombs
from the much more common uranium-238.
And this required huge machines, mass spectrometers, which separated
the two types of uranium by their slight difference in mass.
After the war, Patterson went back to grad school to get his
PhD, he picked a research project that would take
advantage of his experience with mass spectrometers:
measuring the age of the Earth.
Radioactive rocks are effectively clocks.
Uranium-238, for example, decays into thorium and then protactinium,
and then 12 More decays until it ends up as lead-206, which is stable.
The rate of this decay is consistent and can be
measured. It takes four and a half billion years for half of
a sample of U-238. to decay into lead-206
Patterson's PhD project was to determine the age of the Earth by measuring
the ratio of uranium to lead in primordial rocks,
but to calibrate his instrument, first he used zircon crystals whose
ages were known.
Zircon is ideal for this purpose,
because when it forms it contains trace amounts of
uranium but absolutely no lead.
So any lead that you later find inside a zircon, you know must be the product
of a uranium decay.
Patterson was tasked with measuring the lead content,
and another student, George Tilton, measured uranium
Tilton 's uranium measurements were fine. They matched predictions.
But Patterson's lead measurements were all
over the place. And they were many many times higher than
they expected.
We'd take George's uranium and my lead...
Not right Patterson!
There was lead there that didn't belong there.
So where was all this extra lead coming from?
That mystery would take over the rest of Clair Patterson's life
and bring him to the literal ends of the earth.
In 1908, a woman was driving across the Belle Isle bridge
in Detroit. When her car stalled.
A passing motorist stopped to help.
In those days cars needed to be hand cranked to start.
He knelt down and turned the crank,
and the engine roared to life. A little too suddenly.
The man couldn't get out of the way. The crank handle hit him in
the face and broke his jaw.
He died as a result of his injuries.
His name was Byron Carter, and he was the founder of his own car company.
So he was well connected in the Detroit Auto scene.
He counted among his close friends, the founder of Cadillac, Henry Leland.
Leland was so distraught over his friend's
death that he resolved to eliminate hand cranks from his vehicles.
Leland hired Charles Kettering to create a self-
starting car. And by 1911, he had a working prototype.
Hand cranking was difficult and dangerous, and best left to men,
but a car that started itself
changed everything.
The world's first crankless car
was the Cadillac Model 30. It was much more powerful than
cars before it. It had a top speed of 45 miles per hour and
40 horsepower, double the Ford Model T. The Model 30 was a
huge success for Cadillac, doubling the company's annual
sales, but it had a problem. It was deafeningly loud.
In internal combustion engines a piston compresses the fuel-air mixture,
which is then ignited by a spark from the spark plug.
The expanding hot gases push the piston back down.
The problem with the Model 30 engine was it
compressed the fuel-air mixture more than previous
models so much in fact, that often the fuel would
spontaneously combust before the spark from the spark plug.
So rather than orderly, perfectly timed explosions,
you'd get multiple haphazard combustions leading to
turbulent pressure waves inside the cylinder. The
resulting sound led the problem
To become known as engine knocking.
Knocking wasn't just hard on the ears, it hurt the engine's
performance, it reduced power output and lowered fuel
efficiency. The vibrations also damaged the piston and
walls of the cylinder shortening the life of the
engine.
The good news was that engine knocking could be corrected by
changing the fuel. Different fuels can withstand different
levels of compression before detonating n-heptane for
example, will spontaneously combust under only a little
compression. Iso-octane, on the other hand can withstand a
much higher compression ratio before it auto ignites. So
it's much less likely to cause knocking. To quantify how much
compression a fuel can withstand scientists came up
with the octane rating system, they arbitrarily set
iso-octane to have a rating of 100 and n-heptane a rating of
zero. Now real fuels aren't made up of only these two
ingredients. They're a mix of lots of different
hydrocarbons. But the octane rating tells you what mixture
of octane and heptane gives equivalent performance. For
example, 98 octane fuel can withstand the same compression
as a mixture of 98% octane and 2% heptane. Now, I'm going to
take a little bit of 98 octane fuel and put it in this
piston. And when I compress it,
nothing happens which is exactly what you'd expect.
This fuel can withstand a lot of compression. Diesel has an
octane rating of 20. So it acts like a mixture of 20%
iso-octane and 80% n-heptane. If I put a little bit of
diesel in there, let's see what happens with the same
compression ratio.
There you go. You get a little explosion in there. That's
because this is a low octane fuel. I mean, that's what
diesel is meant to do. You compress it and it ignites.
But you don't want this sort of fuel in an engine with
spark plugs. The reason fancy cars demand high octane fuel
is to prevent knocking in their high-compression
high-performance engines.
Kettering wanted to find an additive which would increase
the octane rating of ordinary fuel and eliminate knocking in
high-compression engines. So he hired a 27-year-old
engineer Thomas Midgley Jr. Midgley experimented with all
sorts of compounds from melted butter and camphor, to ethyl
acetate and aluminum chloride. He later wrote, most of them
had no more effect than spitting in the Great Lakes.
Ethanol was an interesting exception, it did stop the
knocking, but you needed a lot of it about 10% of the fuel
mixture for it to be effective, that much ethanol
would be expensive and hard to turn a profit on. And Midgley
was really after an additive that was cheap, easy to
produce and effective even at low concentrations. So he kept
trying. Then he hit on tellurium. It worked
wonderfully as an anti knock agent, but it had a terrible
smell. You couldn't get rid of it by changing clothes or
bathing. His wife was so offended by the stench that he
had to sleep in the basement for seven months, Midgley
wrote, I don't think that although this doubled the fuel
economy, humanity would suffer this smell.
On December 3 1921, after five years of working on the
problem, Midgley found what he thought was the perfect
solution, tetraethyl lead. That's a lead atom right there
in the center. This additive was exactly what he was
looking for. It stopped the knocking, it didn't smell. It
was cheap to produce and readily available. Best of
all, you only needed one part in 1000, for it to be
effective. In a call to Kettering, Midgley said, can
you imagine how much money we're going to make with this?
We're going to make $200 million, maybe even more. That
is over 3 billion in today's dollars. Now for his
discovery, the American Chemical Society gave him the
prestigious Nichols award, and they asked him to do a series
of public talks, but Midgley declined. He and Kettering
patented the process for making Tetra ethyl led, and
they called their new additive Ethyl, perhaps so it might be
confused with another common additive ethyl alcohol they
made no mention of lead. Then they teamed up with three of
America's largest corporations General Motors, DuPont and
Standard Oil of New Jersey to form the Ethyl Corporation.
Their marketing was brilliant. No man can look at the amazing
record of accomplishment here in this research division,
without confidence that these men are going ahead with an
eye to the future, looking for new facts and principles,
which will make things better and make life easier for all of us.
at the 1923 Indianapolis 500, the top three finishers all
used Ethyl and the demand for leaded gasoline took off. To
keep up Ethyl Corporation had to build a new chemical plant
in New Jersey. But the project began terribly. Within two
months of operating, dozens of workers fell ill with lead
poisoning. Five of them died.
To address the public outcry, Midgley held a press
conference. And there he poured Tetraethyl lead onto
his hands, and he inhaled it for a full minute. He claimed
he could do this daily without harm. But Midgley knew the
dangers. The reason he had turned down the public talks
was because he spent much of 1923 in Florida, where he
himself was recovering from lead poisoning. He didn't go
anywhere near his company's product if he could help it.
Lead is dangerous even in small doses, it mimics calcium
in our bodies, so there's no efficient way to get rid of
it. And like calcium lead can be stored in bones for years,
meaning it can continue to poison the body long after the
initial exposure. The organ most sensitive to lead is the
brain. Lead breaks down the myelin sheath around axons and
prevents the release of neurotransmitters. That's why
common symptoms of lead poisoning are headaches,
memory loss and tingling in the hands and feet. And
children are particularly susceptible, lead exposure can
cause permanent learning disorders and behavioral
problems, and the dangers of lead had been known for
hundreds of years. Already in 1786, Benjamin Franklin
remarked that lead had been used for far too long
considering its known toxicity, "you will observe
with concern how long a useful truth may be known and exist
before it is generally received and practiced on". He
would have been aghast to learn that nearly 150 years
later, scientists planned to add lead to fuel. Doctors and
public health officials from MIT, Harvard, Yale, and the US
health service, wrote to Midgley and warned them
against producing Tetraethyl lead. They called lead a
creeping and malicious poison and a serious menace to public
health. Their concerns were dismissed.
This model shows how just the right amount of fluid
containing Tetraethyl lead and dye is added to the gasoline.
No one doubted that a lot of lead was bad for you. But how
much harm could a little lead do?
By the 1950s, millions of motorists globally were
burning lead in their cars and releasing it into the air.
Some of that lead ended up on Clair Patterson's zircon on
samples, preventing him from determining their age. In
1952, he moved to Caltech, where he built a new lab from
scratch, suspicious of environmental contamination,
he tore the electrical cables out of the walls to remove the
lead solder. He cleaned the floors and benches daily with
ammonia and made sure that air was always being blown out of
the lab. To go inside, you had to wear a plastic bunny suit.
Patterson basically invented the cleanroom. Inside that
room, he turned his attention to the oldest rocks in the
solar system. meteorites. All the original rocks on Earth
had long since been destroyed by tectonic activity. But
meteorites come from asteroids which formed around the same
time as Earth. They have just been drifting through space
until they entered the Earth's atmosphere. So the best way to
measure the age of the Earth was to measure the age of
meteorites. Patterson measured five meteorites, each with
three different radiometric dating techniques, and he
found they were all 4.55 billion years old. That number
is within 0.15% of the currently accepted value for
the age of the earth. You know, before Patterson's
experiment, people thought the earth was a billion years
younger. So Patterson had done it. He measured the age of the
Earth, but he wasn't done getting rid of lead contaminants.
Public concern about lead exposure had continued to
grow. But President of Standard Oil, Frank Howard
pushed back saying, "We do not feel justified in giving up
what has come to the industry like a gift from heaven, on
the possibility that a hazard may be involved in it."
Scientists funded by the Ethyl Corporation claimed that lead
was a natural part of our environment, and therefore not
harmful to people. But Patterson wondered just how
natural is the lead in our environment, and he had just
the skills to find out.
He began by measuring lead in the oceans. If it were
natural, he expected the concentration of lead to be
the same regardless of depth. But if lead pollution had
increased recently, it would be more concentrated near the
surface. He took samples in the Pacific and Atlantic
Oceans down to a depth of four kilometers. And sure enough,
lead concentrations were nearly 10 times higher near
the surface. Lead pollution was clearly recent, but when
exactly had it occurred?
To find out Patterson had to go to Greenland and
Antarctica. Ice cores record the level of lead in the air
going back 1000s of years, the levels of lead in the
atmosphere have been elevated for the last 4500 years. All
of it is due to human activity mainly smelting ores to make
metal. You can see the rise and fall of the Greek and
Roman Empires. The dip caused by the Black Death in the
1300s. And of course, the spike in the 20th century due
to industrialization and Tetraethyl lead.
So what did this do to people? Well, Patterson looked at the
lead levels in the teeth and bones of recently deceased
Americans. And for comparison, he measured the lead in bones
and teeth of Peruvian and Egyptian mummies. Since they
lived over 1600 years ago, they would have been exposed
to much less lead in their lifetimes. He expected to find
modern Americans had about 100 times as much lead in their
bones. But results showed it was closer to a factor of
1,000. 20th century Americans had 1000 times more lead in
their bones than their ancestors. Studies of baby
teeth revealed that even Lead exposure well below the level
considered safe resulted in delayed learning, decreased IQ
and increased behavioral problems. And there's a broad
consensus on the part of everybody except the lead
industry and its spokesmen that lead is extremely toxic
at extremely low doses. A follow up study showed that
those with higher levels of lead in their baby teeth were
many times more likely to fail out of high school. As a
result of studies like these, the CDC's guidelines for the
acceptable level of lead in children's blood dropped from
60 micrograms per deciliter down to 3.5. And as far as we
know, today, there is no safe level of lead. Globally, lead
is believed to be responsible for nearly two thirds of all
unexplained intellectual disability. According to a
study published in 2022, more than half of the current
US population, that's 170 million people were exposed to
high levels of lead in early childhood. Those born between
1951 and 1980, are disproportionately affected.
The author's estimate that in aggregate lead caused a loss
of more than 800 million IQ points. The world is less
intelligent today because of leaded gasoline. But there are
even more troubling correlations. The US saw a
steady rise in crime from the 1970s to the 1990s, then it
abruptly declined. This graph looks eerily similar to a plot
of preschool blood lead levels just offset by 20 years. The
obvious question is did kids who were exposed to higher
levels of lead grow up to commit more crimes than they
otherwise would have? You might think this is just a
spurious correlation. But the same pattern appears in many
countries, including Britain, Canada, and Australia. And we
know there's a causal connection between lead
exposure and antisocial or violent behavior. A study of
340 Teenagers found that those who were arrested were four
times as likely to have elevated lead in their bones
than similar demographic controls who didn't have run
ins with the law. Now, this doesn't mean that lead is
responsible for all of the increase in crime, but it's
very likely responsible for some of it.
Now, it's tough to estimate the precise death toll of
lead. One of its lesser known effects is a hardening of the
arteries, leading to increased cardiovascular disease. A
study from 2018 found lead was likely responsible for 250,000
heart disease deaths per year in the US, assuming a constant
rate over the past century, that amounts to 25 million
deaths in the US alone. Globally, the figure may
approach 100 million. Most of those deaths are due to
Midgley's decision to put lead in gasoline, as substance he
knew firsthand was toxic, but he did it anyway to maximize
profits. And the problem is not over. Current estimates of
deaths caused by lead range from 500 to 900 thousand per
year. The 2020 UNICEF report warns that one in three
children globally, that's over 800 million children have
blood lead levels at or above five micrograms per deciliter.
A lot of this lead now comes from batteries and industrial
processes, but some is still due to Midgley's invention.
After Midgley's success with Ethyl, he was put in charge of
another engineering project. GM wasn't just making cars but
also household appliances and fridges had a problem. The two
most common gases used as refrigerants were methyl
formate and sulfur dioxide. One is highly toxic, the other
is flammable. Midgley was tasked with creating a safer
alternative and in 1928, he developed a non toxic and non
flammable refrigerant dichlorodifluoromethane, GM
called this new product Freon and to demonstrate Freon's
safety, during the unveiling at the American Chemical
Society, Midgley inhaled a lung full of this gas and blew
out a candle. In the following decades CFCs like Freon became
very popular and were used as solvents and aerosols. The
problem is CFCs are light and stable. When released into the
atmosphere, they climb up into the stratosphere where they
can remain for 50 to 100 years. But if a CFC molecule
is hit by an ultraviolet photon of just the right
energy, it breaks apart, releasing a chlorine atom and
this chlorine atom can then react with ozone, breaking it
apart into chlorine monoxide and oxygen gas. The results
was another environmental disaster: the hole in the
ozone layer. With less ozone more UV light penetrates the
atmosphere increasing the rates of skin cancer and
cataracts. Plus CFCs are potent greenhouse gases per
kilogram they produce 10,000 times more warming than CO2.
The historian John McNeil wrote that Midgley had more
impact on the atmosphere than any other single organism in
Earth's history. An agreement to phase out CFCs the Montreal
Protocol went into effect in 1989. And the ozone layer is
now showing signs of recovery, although it will take many
more decades to fully recover.
In 1940, at the age of 51,
Midgley contracted polio and became physically disabled, so
to help him get up, he devised a mechanical bed controlled by
a series of ropes and pulleys. On November 2 1944, while
using the contraption, he became tangled in the ropes
and died of strangulation.
Thanks to the work of Clair Patterson, it became clear
that the lead in our environment is not natural.
Burning lead and combustion engines spread the toxic
elements across the planet. Into the air, oceans, the snow
at the South Pole and even our bones. Japan was the first to
ban leaded fuel and cars in 1986. But other countries soon
followed suit. Algeria was the last to do so in 2021. The UN
calculates that the elimination of lead from gas
saves over a million lives per year, and $2.45 trillion
dollars.
But leaded gas is still used, by the way in piston driven
airplane engines. That's now the largest source of lead
emissions into the air in the US.
You will observe with concern how long a useful truth may be known and exist
before it is generally received and practiced on.
When I first learned about Thomas Midgley and Clair
Patterson, I was amazed by how much harm or how much good a
single person could do to the environment. Which brings me
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