1One single scientist created three inventions that accidentally caused the deaths of millions of people,
2including himself.
3Not only that, they decreased the average intelligence of people all around the world,
4increased crime rates, and caused two completely separate environmental disasters that we are still dealing with today.
5In 1944, as a young chemist who had just finished his Master's,
6Clair Patterson went to work on the Manhattan Project, building the first nuclear weapons.
7His job was to concentrate uranium-235, the fissile fuel for bombs from the much more common uranium-238.
8And this required huge machines, mass spectrometers,
9which separated the two types of uranium by their slight difference in mass.
10After the war, Patterson went back to grad school to get his PhD,
11he picked a research project that would take advantage of his experience with mass spectrometers:
12measuring the age of the Earth.
13Radioactive rocks are effectively clocks.
14Uranium-238, for example, decays into thorium and then protactinium, and then 12 more decays
15until it ends up as lead-206, which is stable.
16The rate of this decay is consistent and can be measured.
17It takes 4.5 billion years for half of a sample of U-238 to decay into lead-206.
18Patterson's PhD project was to determine the age of the Earth by measuring the ratio of uranium to lead in primordial rocks,
19but to calibrate his instrument, first he used zircon crystals whose ages were known.
20Zircon is ideal for this purpose, because when it forms it contains trace amounts of uranium but absolutely no lead.
21So any lead that you later find inside a zircon, you know must be the product of a uranium decay.
22Patterson was tasked with measuring the lead content, and another student, George Tilton, measured uranium.
23Tilton's uranium measurements were fine. They matched predictions.
24But Patterson's lead measurements were all over the place.
25And they were many many times higher than they expected.
26We'd take George's uranium and my lead... Not right Patterson!
27There was lead there that didn't belong there.
28So where was all this extra lead coming from?
29That mystery would take over the rest of Clair Patterson's life
30and bring him to the literal ends of the earth.
31In 1908, a woman was driving across the Belle Isle bridge in Detroit when her car stalled.
32A passing motorist stopped to help.
33In those days cars needed to be hand cranked to start.
34He knelt down and turned the crank, and the engine roared to life.
35A little too suddenly.
36The man couldn't get out of the way.
37The crank handle hit him in the face and broke his jaw.
38He died as a result of his injuries.
39His name was Byron Carter, and he was the founder of his own car company.
40So he was well connected in the Detroit Auto scene.
41He counted among his close friends, the founder of Cadillac, Henry Leland.
42Leland was so distraught over his friend's death that he resolved to eliminate hand cranks from his vehicles.
43Leland hired Charles Kettering to create a self-starting car.
44And by 1911, he had a working prototype.
45Hand cranking was difficult and dangerous, and best left to men,
46but a car that started itself changed everything.
47The world's first crankless car was the Cadillac Model 30.
48It was much more powerful than cars before it.
49It had a top speed of 45 miles per hour and 40 horsepower, double the Ford Model T.
50The Model 30 was a huge success for Cadillac,
51doubling the company's annual sales, but it had a problem.
52It was deafeningly loud.
53In internal combustion engines a piston compresses the fuel-air mixture,
54which is then ignited by a spark from the spark plug.
55The expanding hot gases push the piston back down.
56The problem with the Model 30 engine was it compressed the fuel-air mixture more than previous models.
57So much in fact, that often the fuel would spontaneously combust before the spark from the spark plug.
58So rather than orderly, perfectly timed explosions, you'd get multiple haphazard combustions
59leading to turbulent pressure waves inside the cylinder.
60The resulting sound led the problem to become known as engine knocking.
61Knocking wasn't just hard on the ears, it hurt the engine's performance,
62it reduced power output and lowered fuel efficiency.
63The vibrations also damaged the piston and walls of the cylinder, shortening the life of the engine.
64The good news was that engine knocking could be corrected by changing the fuel.
65Different fuels can withstand different levels of compression before detonating.
66N-heptane for example, will spontaneously combust under only a little compression.
67Iso-octane, on the other hand can withstand a much higher compression ratio before it auto ignites.
68So it's much less likely to cause knocking.
69To quantify how much compression a fuel can withstand scientists came up with the octane rating system,
70they arbitrarily set iso-octane to have a rating of 100 and n-heptane a rating of zero.
71Now real fuels aren't made up of only these two ingredients.
72They're a mix of lots of different hydrocarbons.
73But the octane rating tells you what mixture of octane and heptane gives equivalent performance.
74For example, 98 octane fuel can withstand the same compression as a mixture of 98% octane and 2% heptane.
75Now, I'm going to take a little bit of 98 octane fuel and put it in this piston.
76And when I compress it,
77nothing happens which is exactly what you'd expect.
78This fuel can withstand a lot of compression.
79Diesel has an octane rating of 20.
80So it acts like a mixture of 20% iso-octane and 80% n-heptane.
81If I put a little bit of diesel in there,
82let's see what happens with the same compression ratio.
83There you go. You get a little explosion in there.
84That's because this is a low octane fuel. I mean, that's what diesel is meant to do. You compress it and it ignites.
85But you don't want this sort of fuel in an engine with spark plugs.
86The reason fancy cars demand high octane fuel is to prevent knocking in their high-compression high-performance engines.
87Kettering wanted to find an additive which would increase the octane rating of ordinary fuel and eliminate knocking in high-compression engines.
88So he hired 27-year-old engineer Thomas Midgley Jr.
89Midgley experimented with all sorts of compounds
90from melted butter and camphor, to ethyl acetate and aluminum chloride.
91He later wrote, most of them had no more effect than spitting in the Great Lakes.
92Ethanol was an interesting exception,
93it did stop the knocking, but you needed a lot of it.
94about 10% of the fuel mixture for it to be effective,
95that much ethanol would be expensive and hard to turn a profit on.
96And Midgley was really after an additive that was cheap,
97easy to produce and effective even at low concentrations.
98So he kept trying.
99Then he hit on tellurium.
100It worked wonderfully as an anti knock agent,
101but it had a terrible smell.
102You couldn't get rid of it by changing clothes or bathing.
103His wife was so offended by the stench that he had to sleep in the basement for seven months,
104Midgley wrote, I don't think that although this doubled the fuel economy, humanity would suffer this smell.
105On December 3rd 1921, after five years of working on the problem,
106Midgley found what he thought was the perfect solution, tetraethyl lead.
107That's a lead atom right there in the center.
108This additive was exactly what he was looking for.
109It stopped the knocking, it didn't smell.
110It was cheap to produce and readily available.
111Best of all, you only needed one part in 1000, for it to be effective.
112In a call to Kettering, Midgley said, can you imagine how much money we're going to make with this?
113We're going to make 200 million dollars, maybe even more.
114That is over 3 billion in today's dollars.
115Now for his discovery, the American Chemical Society gave him the prestigious Nichols award,
116and they asked him to do a series of public talks, but Midgley declined.
117He and Kettering patented the process for making Tetraethyl lead,
118and they called their new additive Ethyl,
119perhaps so it might be confused with another common additive ethyl alcohol.
120They made no mention of lead.
121Then they teamed up with three of America's largest corporations General Motors, DuPont and Standard Oil of New Jersey to form the Ethyl Corporation.
122Their marketing was brilliant.
123No man can look at the amazing record of accomplishment here in this research division,
124without confidence that these men are going ahead with an eye to the future,
125looking for new facts and principles, which will make things better and make life easier for all of us.
126at the 1923 Indianapolis 500,
127the top three finishers all used Ethyl
128and the demand for leaded gasoline took off.
129To keep up Ethyl Corporation had to build a new chemical plant in New Jersey.
130But the project began terribly.
131Within two months of operating, dozens of workers fell ill with lead poisoning.
132Five of them died.
133To address the public outcry, Midgley held a press conference.
134And there he poured Tetraethyl lead onto his hands,
135and he inhaled it for a full minute.
136He claimed he could do this daily without harm.
137But Midgley knew the dangers.
138The reason he had turned down the public talks was because he spent much of 1923 in Florida,
139where he himself was recovering from lead poisoning.
140He didn't go anywhere near his company's product if he could help it.
141Lead is dangerous even in small doses,
142it mimics calcium in our bodies, so there's no efficient way to get rid of it.
143And like calcium, lead can be stored in bones for years,
144meaning it can continue to poison the body long after the initial exposure.
145The organ most sensitive to lead is the brain.
146Lead breaks down the myelin sheath around axons and prevents the release of neurotransmitters.
147That's why common symptoms of lead poisoning are headaches, memory loss and tingling in the hands and feet.
148And children are particularly susceptible,
149lead exposure can cause permanent learning disorders and behavioral problems,
150and the dangers of lead had been known for hundreds of years.
151Already in 1786, Benjamin Franklin remarked that lead had been used for far too long considering its known toxicity,
152"you will observe with concern how long a useful truth may be known and exist before it is generally received and practiced on".
153He would have been aghast to learn that nearly 150 years later, scientists planned to add lead to fuel.
154Doctors and public health officials from MIT, Harvard, Yale, and the US health service,
155wrote to Midgley and warned him against producing Tetraethyl lead.
156They called lead a creeping and malicious poison and a serious menace to public health.
157Their concerns were dismissed.
158This model shows how just the right amount of fluid containing Tetraethyl lead and dye is added to the gasoline.
159No one doubted that a lot of lead was bad for you.
160But how much harm could a little lead do?
161By the 1950s, millions of motorists globally were burning lead in their cars and releasing it into the air.
162Some of that lead ended up on Clair Patterson's zircon samples, preventing him from determining their age.
163In 1952, he moved to Caltech, where he built a new lab from scratch,
164suspicious of environmental contamination,
165he tore the electrical cables out of the walls to remove the lead solder.
166He cleaned the floors and benches daily with ammonia
167and made sure that air was always being blown out of the lab.
168To go inside, he had to wear a plastic bunny suit.
169Patterson basically invented the clean room.
170Inside that room, he turned his attention to the oldest rocks in the solar system:
171meteorites.
172All the original rocks on Earth had long since been destroyed by tectonic activity.
173But meteorites come from asteroids which formed around the same time as Earth.
174They have just been drifting through space until they entered the Earth's atmosphere.
175So the best way to measure the age of the Earth was to measure the age of meteorites.
176Patterson measured five meteorites, each with three different radiometric dating techniques,
177and he found they were all 4.55 billion years old.
178That number is within 0.15% of the currently accepted value for the age of the earth.
179You know, before Patterson's experiment, people thought the earth was a billion years younger.
180So Patterson had done it.
181He measured the age of the Earth, but he wasn't done getting rid of lead contaminants.
182Public concern about lead exposure had continued to grow.
183But President of Standard Oil, Frank Howard pushed back saying,
184"We do not feel justified in giving up what has come to the industry like a gift from heaven,
185on the possibility that a hazard may be involved in it."
186Scientists funded by the Ethyl Corporation claimed that lead was a natural part of our environment,
187and therefore not harmful to people.
188But Patterson wondered just how natural is the lead in our environment,
189and he had just the skills to find out.
190He began by measuring lead in the oceans.
191If it were natural, he expected the concentration of lead to be the same regardless of depth.
192But if lead pollution had increased recently, it would be more concentrated near the surface.
193He took samples in the Pacific and Atlantic Oceans down to a depth of four kilometers.
194And sure enough, lead concentrations were nearly 10 times higher near the surface.
195Lead pollution was clearly recent,
196but when exactly had it occurred?
197To find out Patterson had to go to Greenland and Antarctica.
198Ice cores record the level of lead in the air going back thousands of years,
199the levels of lead in the atmosphere have been elevated for the last 4500 years.
200All of it is due to human activity mainly smelting ores to make metal.
201You can see the rise and fall of the Greek and Roman Empires.
202The dip caused by the Black Death in the 1300s.
203And of course, the spike in the 20th century due to industrialization and Tetraethyl lead.
204So what did this do to people?
205Well, Patterson looked at the lead levels in the teeth and bones of recently deceased Americans.
206And for comparison, he measured the lead in bones and teeth of Peruvian and Egyptian mummies.
207Since they lived over 1600 years ago,
208they would have been exposed to much less lead in their lifetimes.
209He expected to find modern Americans had about 100 times as much lead in their bones.
210But results showed it was closer to a factor of 1,000.
21120th century Americans had 1000 times more lead in their bones than their ancestors.
212Studies of baby teeth revealed that even Lead exposure well below the level considered safe
213resulted in delayed learning, decreased IQ and increased behavioral problems.
214And 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.
215A 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.
216As a result of studies like these,
217the CDC's guidelines for the acceptable level of lead in children's blood dropped from 60 micrograms per deciliter down to 3.5.
218And as far as we know, today, there is no safe level of lead.
219Globally, lead is believed to be responsible for nearly 2/3 of all unexplained intellectual disability.
220According to a study published in 2022, more than half of the current US population,
221that's 170 million people were exposed to high levels of lead in early childhood.
222Those born between 1951 and 1980, are disproportionately affected.
223The author's estimate that in aggregate lead caused a loss of more than 800 million IQ points.
224The world is less intelligent today because of leaded gasoline.
225But there are even more troubling correlations.
226The US saw a steady rise in crime from the 1970s to the 1990s,
227then it abruptly declined.
228This graph looks eerily similar to a plot of preschool blood lead levels just offset by 20 years.
229The obvious question is did kids who were exposed to higher levels of lead grow up to commit more crimes than they otherwise would have?
230You might think this is just a spurious correlation.
231But the same pattern appears in many countries, including Britain, Canada, and Australia.
232And we know there's a causal connection between lead exposure and antisocial or violent behavior.
233A study of 340 Teenagers found that those who were arrested
234were four times as likely to have elevated lead in their bones than similar demographic controls who didn't have run ins with the law.
235Now, this doesn't mean that lead is responsible for all of the increase in crime,
236but it's very likely responsible for some of it.
237Now, it's tough to estimate the precise death toll of lead.
238One of its lesser known effects is a hardening of the arteries,
239leading to increased cardiovascular disease.
240A study from 2018 found lead was likely responsible for 250,000 heart disease deaths per year in the US,
241assuming a constant rate over the past century, that amounts to 25 million deaths in the US alone.
242Globally, the figure may approach 100 million.
243Most of those deaths are due to Midgley's decision to put lead in gasoline,
244a substance he knew firsthand was toxic, but he did it anyway to maximize profits.
245And the problem is not over.
246Current estimates of deaths caused by lead range from 500 to 900 thousand per year.
247The 2020 UNICEF report warns that one in three children globally,
248that's over 800 million children have blood lead levels at or above five micrograms per deciliter.
249A lot of this lead now comes from batteries and industrial processes,
250but some is still due to Midgley's invention.
251Now, after Midgley's success with Ethyl, he was put in charge of another engineering project.
252GM wasn't just making cars but also household appliances and fridges had a problem.
253The two most common gases used as refrigerants were methyl formate and sulfur dioxide.
254One is highly toxic, the other is flammable.
255Midgley was tasked with creating a safer alternative.
256And in 1928, he developed a non toxic and non flammable refrigerant: dichlorodifluoromethane,
257GM called this new product Freon
258and to demonstrate Freon's safety, during the unveiling at the American Chemical Society,
259Midgley inhaled a lung full of this gas and blew out a candle.
260In the following decades CFCs like Freon became very popular and were used as solvents and aerosols.
261The problem is CFCs are light and stable.
262When released into the atmosphere, they climb up into the stratosphere
263where they can remain for 50 to 100 years.
264But if a CFC molecule is hit by an ultraviolet photon of just the right energy,
265it breaks apart, releasing a chlorine atom and this chlorine atom can then react with ozone,
266breaking it apart into chlorine monoxide and oxygen gas.
267The result was another environmental disaster: the hole in the ozone layer.
268With less ozone more UV light penetrates the atmosphere increasing the rates of skin cancer and cataracts.
269Plus CFCs are potent greenhouse gases.
270Per kilogram they produce 10,000 times more warming than CO2.
271The historian John McNeil wrote that Midgley had more impact on the atmosphere than any other single organism in Earth's history.
272An agreement to phase out CFCs, the Montreal Protocol, went into effect in 1989.
273And the ozone layer is now showing signs of recovery,
274although it will take many more decades to fully recover.
275In 1940, at the age of 51, Midgley contracted polio and became physically disabled,
276so to help him get up, he devised a mechanical bed controlled by a series of ropes and pulleys.
277On November 2nd 1944, while using the contraption,
278he became tangled in the ropes and died of strangulation.
279Thanks to the work of Clair Patterson, it became clear that the lead in our environment is not natural.
280Burning lead in combustion engines spread the toxic element across the planet.
281Into the air, oceans, the snow at the South Pole and even our bones.
282Japan was the first to ban leaded fuel in cars in 1986.
283But other countries soon followed suit.
284Algeria was the last to do so in 2021.
285The UN calculates that the elimination of lead from gas saves over a million lives per year,
286and 2.45 trillion dollars.
287But leaded gas is still used, by the way in piston driven airplane engines.
288That's now the largest source of lead emissions into the air in the US.
289You will observe with concern how long a useful truth may be known and exist
290before it is generally received and practiced on.