Our IQs Are Six Points Higher Since We Stopped Putting Lead In Gas

Illustration for article titled Our IQs Are Six Points Higher Since We Stopped Putting Lead In Gas

I've always thought that if I'd been breast-fed, I'd be taller and better looking. And now it seems I could have been smarter as well, if I'd spent less of my childhood inhaling generous lungfuls of leaded gas.


A New York Times Op-Ed this week that discusses the puzzling trend of increasing IQs in people references the findings of Dr. Philip J. Landrigan, who found that since the removal of lead from gasoline in 1976, there's been an 80% drop in blood lead levels, and in that same period a six-point gain in children's IQs.

Six IQ points is a big deal — if I had an extra six points, I'd probably be allowed to use scissors and forks on my own. And when you look at the history of Tetraethyllead — the form of lead used in leaded gas — it's not all that surprising.

The lead was used in gasolines for two major reasons: One, it helps prevent valve wear, especially exhaust valves, as the high temperature of the exhaust gases can cause tiny micro-welds to form between the valve and the valve seat — and then when the cam moves the valve, these micro-welds break, leaving a rough surface on the valve seat. Modern cars use hardened valve seats and better valve materials to work around this.

Lead was also used as a knock-inhibitor, allowing higher octanes with the lead helping to inhibit pre-combustion. That's why some AV gas still uses lead.

Lead's been long known to be not so great for people — in fact, when it was first in use as a fuel additive, it had a bad enough reputation that, when GM figured out it was a good anti-knock agent back in the early 1920s, they patented it and called it "Ethyl" (after so many of our grandmothers) to avoid the negative connotations of the word "lead."


Once it went into production, there were more issues. According to Wikipedia, get this:

The toxicity of concentrated TEL was recognized early on, as lead had been recognized since the 19th century as a dangerous substance which could cause lead poisoning.[23] In 1924, a public controversy arose over the "loony gas," after several workers died and others went insane in a refinery in New Jersey and a DuPont facility in Ohio.


"Loony gas?" Workers going insane? That's pretty alarming. The reason lead seems to be so unpleasant for brains is that it gets in the way of the release of neurotransmitters, which is how neurons send signals to other cells. Again, Uncle Wiki tells me:

It interferes with the release of glutamate, a neurotransmitter important in many functions including learning, by blocking NMDA receptors. The targeting of NMDA receptors is thought to be one of the main causes for lead's toxicity to neurons.


So it interferes with the brain's own ability to communicate internally, which leads to crazy and stupid.

While the six-point IQ increase since the elimination of leaded gas hasn't been conclusively proven, most of the evidence and studies do seem to suggest some sort of beneficial link between less lead and smarter, saner people.


So be sure to thank your hardened valve seats today as you come up with six-point smarter thoughts today. They hardened for you.



Hold on. IQ is a number that basically shows your deviation from average. The average IQ in a sample has to be 100. So how can the average IQ of an entire population go up?