Thomas Midgley was a chemical engineer.
But not just any chemical engineer.
He has been credited with having “more impact on the atmosphere than any other single organism in Earth’s history.” And not in a good way.
He’s also accused of being the man most responsible for the rising crime rates throughout the 20th century.
Like most “evil” men he did not set out to harm humanity. Quite the opposite. He wanted to help.
But his inventions would have far-reaching consequences, which he couldn’t possibly have known about at the time.
He is perhaps best known for his development of Freon, the world’s first chlorofluorocarbon (CFC).
Up until his invention of Freon in 1929, toxic gases were used in fridges, and they were killing many people.
So when Midgley invented Freon, it was hailed as a “miracle compound”. It was colourless, odourless, non-flammable and noncorrosive.
It wasn’t until over 50 years later that the world learned it was also tearing a hole in the ozone layer above Antarctica.
If you remember the panic about this discovery in the late 1980s, you’ll know all about CFCs.
It took a worldwide concerted effort to ban CFCs in 1989. And since then the ozone layer hole has been repairing itself.
I often think climate change lobbies should make more of this achievement.
This was a time when the world came together to fix a gargantuan problem that threatened our existence – and succeeded.
It’s very different from the “we’re already doomed” rhetoric many climate change activists run with today. If we’re already doomed, what’s the point in changing?
If they instead said, “We can turn this around, just like we did with the hole in the ozone layer. It’s just going to take some effort.” People would be far more likely to get behind them.
But that’s a topic for another day. Today, we’re talking Thomas Midgley. Because CFCs and a hole in the ozone layer weren’t his only legacy.
How Midgley became the leading cause of crime around the world
As the BBC wrote in 2014:
For most of the 20th Century crime rose and rose and rose. Every time a new home secretary took office in the UK – or their equivalents in justice and interior ministries elsewhere – officials would show them graphs and mumble apologetically that there was nothing they could do to stop crime rising.
Then, about 20 years ago, the trend reversed – and all the broad measures of key crimes have been falling ever since.
Offending has fallen in nations whose governments have implemented completely different policies to their neighbours.
If your nation locks up more criminals than the average, crime has fallen. If it locks up fewer… crime has fallen. Nobody seems to know for sure why.
But there are some people that believe the removal of lead from petrol was a key factor.
Yes, it may sound strange at first. But the evidence is clear. Lead is highly likely to be responsible for high crime rates throughout the 20th century.
I’ll show you why in just a second. But first, let’s look at how lead came to pollute so many people. Because as you’ve no doubt guessed, Midgley is the answer.
Before he invented Freon, Midgley invented another miracle compound: leaded petrol.
Leaded petrol was great. It made cars run smoother, faster and more reliably. But it also killed people. About 5,000 people a year in the US alone.
As The Nation wrote in 2000:
A 1985 Environmental Protection Agency study estimated that as many as 5,000 Americans died annually from lead-related heart disease prior to the country’s lead phaseout. According to a 1988 report to Congress on childhood lead poisoning in America by the government’s Agency for Toxic Substances and Disease Registry, one can estimate that the blood-lead levels of up to 2 million children were reduced every year to below toxic levels between 1970 and 1987 as leaded gasoline use was reduced. From that report and elsewhere, one can conservatively estimate that a total of about 68 million young children had toxic exposures to lead from gasoline from 1927 to 1987.
Midgley created leaded petrol in 1921, and it wasn’t phased out until the mid-1970s.
He also managed to give himself lead poisoning in the process.
In 1923 he took a long holiday to Florida, saying “my lungs have been affected and that it is necessary to drop all work and get a large supply of fresh air.” So it’s not like he didn’t know lead petrol was dangerous.
However, today we’re more concerned with the less immediate effects of lead getting into your body. Because there is strong evidence to suggest that being dosed with lead in childhood makes you more likely to commit crime as an adult.
From the BBC article:
If you want to understand the causes of crime – and be tough on them – you need to start with lead, says Dr Bernard Gesch, a physiologist at Oxford University who has studied the effect of diet and other environmental factors on criminals.
“Lead is a very potent neurotoxin,” says Gesch. “It has a range of effects on the brain that have been demonstrated through hundreds of different biological studies. Lead alters the formation of the brain. It reduces the grey matter in areas responsible for things such as impulse control and executive functioning – meaning thinking and planning.”
In other words – lead poisoning leads to bad decisions. The lead theorists say the poison has a time-lag effect which could not be understood until recently.
The delay between lead exposure and violent crime increases is thought to be around 20 years. And when you plot it on a graph, as economist and housing consultant Rick Nevin famously did, you get a startling result.
Now, I would be among the first to stress that correlation does not imply causation. If you’ve ever doubted this fact, Spurious Correlations is a great webpage to visit.
Here’s one of its best:
So although the graph looks convincing, we can’t really draw a firm conclusion.
However, when we add in the known effects of lead on the body, the lead-crime hypothesis, as it’s known, becomes more convincing.
Medical analysis of the role of lead exposure in the brain note increases in impulsive actions and social aggression as well as the possibility of developing attention deficit hyperactivity disorder (ADHD). Those conditions likely influence personality traits and behavioral choices, with examples including having poor job performance, beginning a pattern of substance abuse, and undergoing teenage pregnancy.
Evidence that lead exposure contributes to lower intelligence quotient (IQ) scores goes back to a seminal 1979 study in Nature, with later analysis finding the link particularly robust.
Proof the lead-crime hypothesis is true
I first heard about the lead-crime hypothesis a number of years ago. I remember thinking it was intriguing, but I wasn’t convinced.
How can you draw conclusions when you can’t control the variables?
Then when researching this piece I found some much better evidence.
In June last year the Brookings Institution published an article that cited a number of scientific studies into this phenomenon.
As it wrote:
The main challenge in measuring the effect of lead on crime is that lead exposure is highly correlated with a variety of indicators related to poverty: poor schools, poor nutrition, poor health care, exposure to other environmental toxins, and so on. Those other factors could independently affect crime. The challenge for economists has been to separate the effect of lead exposure from the effects of all those other things that are correlated with lead exposure. A true experiment — where some kids are randomized to grow up with high lead exposure and others not — is out of the question. So economists have gone hunting for natural experiments — events or policies that divide otherwise-similar kids into comparable treatment and control groups.
And they’ve found them. Three recent papers consider the effects of lead exposure on juvenile delinquency and crime rates, using three very different empirical approaches and social contexts. All have plausible (but very different) control groups, and all point to the same conclusion: lead exposure leads to big increases in criminal behavior.
One of these papers tracks the use of lead pipes in cities for drinking water. Not all cities had lead pipes. If they were far from a lead refinery, they used other materials.
So the authors of the study compared violent crime rates between the cities with lead pipes and those without lead pipes.
And they managed to create a control group because lead only seeps into water when the water is acidic. So cities with lead pipes but non-acidic water, and cities with acidic water but non-lead pipes, are the control groups.
The authors found that:
“Exposing populations to lead in their drinking water causes much higher homicide rates 20 years later, relative to similar places where kids avoided such exposure.”
You can read the study for yourself here.
The second study tracked the link between pre-school blood lead levels and school data on suspensions and incarcerations. Again, this study found lead exposure lead to more suspensions and incarcerations.
You can read that study here.
And the final study they cited:
“Comes at the lead-crime hypothesis from a different direction, and asks whether government programs that aim to reduce lead exposure can protect kids from lead’s negative effects.”
The authors of the study found:
“Relative to the control group, kids who receive the intervention exhibit substantially less antisocial behavior, including suspensions, absences, school crimes, and violent crime arrests.”
You can read that study here.
The Brookings Institution concluded that there is compelling evidence that the lead-crime hypothesis is true. And perhaps more optimistically, that helping kids who are exposed to high levels of lead can prevent future crime.
So, now we know that lead exposure leads to crime and generally harms society, reducing and treating people’s exposure to lead should be a government priority.
And nowhere is this policy more needed than Flint, Michigan.
In Flint’s case, help has been promised not by the government, but by tech billionaire Elon Musk.
It’s a strange story that involves Musk’s efforts to rescue the trapped (and now rescued) Thai schoolboys with a space submarine, and a taunt aimed at Musk on Twitter.
And I’ll be writing about it on Monday.
Editor, Exponential Investor
PS Thomas Midgley also died a somewhat ironic accidental death, at the hands of himself. At the age of 51 he contracted polio and was left somewhat paralysed. He invented a harness that could lift him from his wheelchair to his bed, and one day that harness strangled him to death.