LUKE BURBANK, host:
Well, keeping on the topic of lead and lead poisoning, could the decline of leaded gasoline actually be responsible for the big urban crime drop that we've seen since the 1990s?
There have been a lot of theories as to why crime has gone down like it has. Politicians like Rudy Giuliani say it was their innovative policies that did it in places like New York. The guys behind that book "Freakonomics" say that the legalization of abortion actually may have played a role. There's a new claim out, though, that traces things back to the gas pump.
Rick Nevin is an economist. He says the decrease in the use of leaded gasoline which started phasing out in the mid-1970s has led to the fewer rapes, fewer robberies and murders. And this is not just in the U.S., but in a bunch of countries around the world.
Nevin is an economist with the National Center for Healthy Housing in Columbia, Maryland, and he joins us now. Hi, Rick.
Mr. RICK NEVIN (Economist, National Center for Healthy Housing): Hi. How are you?
BURBANK: Great. Could you just give us sort of the basic upshots of your findings?
Mr. NEVIN: Well, in the second half of the century, the gas lead level soared after World War II, peaked in the early '70s, and then fell sharply in the 1980s. Gas lead was phased out in the U.S. in the mid-80s. And my research found that there was an absolute stunning fit between the rise and fall of gas lead, and the rise and fall of the violent crime rate with a time lag of 23 years.
Moreover, the same thing happened in the first half of the century with paint lead. The use of paint lead soared in the late 1800s, peaked in the very early 20th century, and then fell sharply. And although lead paint was actually banned in 1978, it had come down quite a bit by then.
The murder rate in the United States soared from 1900 to a peak in the early '20s, and then fell sharply, tracking the trend in paint lead with a 21-year lag.
BURBANK: So basically, what you tried to do was figure out these kids who were growing up with presumably less lead-based pollutants in the air, because as lead gas was going away, to see how these kids acted when they got into their teenage years, which is when a lot of sort of property crime and things like that get committed.
Mr. NEVIN: That's correct. And I found the same pattern now in nine other countries with very different lead exposure patterns. But a misconception is that it's lead in the air that was the key factor affecting the children. The reason why the pattern occurs with both paint lead and gas lead is that the main way the children are exposed is just crawling on the floor and the natural hand-to-mouth activity.
And both paint lead and the air lead fall out from gas lead would contaminate lead dust. It would contaminate the household dust in a way that would have the children ingesting dust contaminated with lead as they were crawling and playing.
When the brain is in a critical phase of development - and there is a great deal of research linking early childhood lead exposure with delinquent and aggressive behavior later in life.
BURBANK: Well, that's some of the sort of medically recognized effects of lead poisoning, I guess. Why - are there other reasons why it's worse for kids than adults?
Mr. NEVIN: The main factor that makes children extremely vulnerable is that the brain is going through an absolute critical stage of growth in the womb and through the first year or two, three years of life. And lead substitutes for calcium and does - it does a myriad of things to the developing brain, all of them bad. It affects IQ later in life. It affects learning behavior and educational achievement and attainment. All of these things have been documented by a number of other researchers preceding my work.
BURBANK: Well, as I look at your research and how it's sort of graphed out, it's certainly - it's pretty interesting stuff. If you line up the data, the decline of leaded gasoline and then the drop of crime rate, it fits together pretty nicely. But I guess the question is - I mean, you could set up exact same chart using the rise of Michael Jackson's solo career…
Mr. NEVIN: Yeah.
BURBANK: …which started around the same time. And you could - if you put that on the graph below the drop of the crime rate and you delayed it, you might say that led to it. What's the causal relationship between the decline in leaded gasoline and the decline in the crime rate?
Mr. NEVIN: Well, the causal relationship is the very well-documented medical effects of lead on early brain development. And very recent MRI studies have shown that the brain goes through another growth surge in - right after puberty through adolescence and the early 20s. And then white matter start to replace gray matters, where white matter wires the brain together more.
A number of these researchers have speculated that the more impulsive behavior typical of teenagers could be related to that second growth surge. And what I've hypothesized is that the damage done in early childhood during the first critical growth surge shows up when another transformative period in the brain is affecting behavior.
BURBANK: I guess, if your theory is correct, though, then doesn't it - isn't it also sort of moot? Because, you know, we're past the era of leaded gas. New homes don't have lead paint in them, hopefully. I mean, does it - are we out of the woods in terms of criminal behavior related to lead-based things?
Mr. NEVIN: I wish that were true. We are dramatically better off than we were 10 or 20 years ago. And for all the attention that we get with periodic scares about lead on toys, which is obviously a bad thing, or lead on mini-blinds, we have excellent data on where children are lead poisoned by the age of housing.
And my recent study with colleagues has shown that they are overwhelmingly, almost entirely concentrated in older housing. And what's happening is that those extremely high lead levels in paint in the early 1900s, in the first half of the 20th century, really, are still poisoning children today because windows create friction surfaces, and deterioration of paint causes contamination of dust. And that's where the real serious and pervasive lead poisoning problem is today. It's in older housing. Homes built before 1978 can have lead paint in them. And it's extremely common in homes built before 1960.
BURBANK: Well, if this hasn't been the most depressing 14 minutes of radio between the toys and the houses, I don't know what it is. But we do appreciate you coming on, Rick Nevin. He is an economist with the National Center for Healthy Housing in Columbia, Maryland. Thanks, Rick.
Mr. NEVIN: Thank you.
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