Lead and crime, continued

Yesterday I returned to banging the (Kevin) drum about the pernicious effects of environmental lead. Both a note from a reader and comments elsewhere about Kevin’s latest post suggest that an earlier post of mine had created confusion.

Here’s the note:

Mark, in your latest post, you seem to be believing the lead hypothesis for violent crime again. But here I thought you said that Phil Cook changed your mind. Are there new data that tipped you back, or is there a hole in Cook’s argument?

There are two different claims here:

  1. Lead causes crime, and the effect size is large.
  2. Decreasing lead exposure was the primary cause of the crime decline that started in 1994.

#1 is certainly true, and nothing Cook has written or said contradicts it. We have both statistical evidence at the individual level and a biological understanding of the brain functions disrupted by lead.

Cook convinced me that #2 is not true, or at least is not the whole story, because the decline happened in all cohorts while lead exposure deceased only for the younger cohorts. You can still tell plausible stories about how the young’uns drove the homicide wave of the late 1980s/early 1990s and that less violent subsequent cohorts of young’uns reduced the overall level of violence, but that’s not as simple a story. In a world of many interlinked causes and both positive and negative feedbacks, the statement “X% of the change in A was caused by a change in B” has no straightforward empirical sense.

So I’m absolutely convinced that lead is criminogenic, in addition to doing all sorts of other personal and social harm, and strongly suspect that further reductions in lead exposure (concentrating on lead in interior paint and lead in soil where children play) would yield benefits in excess of their costs, even though those costs might be in the billions of dollars per year. What’s less clear is how much of the crime increase starting in the early 1960s and the crime decrease starting in the early 1990s (and the rises and falls of crime in the rest of the developed world) should be attributed to changes in lead exposure.

The original point of yesterday’s post stands: When you hear people complaining about environmental regulation, what they’re demanding is that businesses should be allowed to poison children and other living things. No matter how often they’re wrong about that – lead, pesticides, smog, sulphur oxides, chlorofluorocarbons, estrongenic chemicals – they keep on pretending that the next identified environmental problem – global warming, for example – is just a made-up issue, and that dealing with it will tank the economy. Of course health and safety regulation can be, and is, taken to excess. But the balance-of-harms calculation isn’t really hard to do. And the demand for “corporate free speech” is simply a way of giving the perpetrators of environmental crimes a nearly invincible political advantage over the victims.

Lead, evil, and corporate free speech

Kevin Drum, who’s been doing Pulitzer-quality science and policy reporting on the behavioral effects of environmental lead, has yet another item today, once again reporting a new paper by Jessica Wolpaw Reyes of Amherst, who’s been doing the fancy number-crunching on the topic. No real surprise: in addition to greatly increasing rates of criminal behavior, lead exposure also increase the risk of other consequences of poor self-command, such as early pregnancy. Kevin draws one of the right morals of the story: that biology matters, while liberals and conservatives tend to unite in blaming everything on society, economics, and culture:

It’s a funny thing. For years conservatives bemoaned the problem of risky and violent behavior among children and teens of the post-60s era, mostly blaming it on the breakdown of the family and a general decline in discipline. Liberals tended to take this less seriously, and in any case mostly blamed it on societal problems. In the end, though, it turned out that conservatives were right. It wasn’t just a bunch of oldsters complaining about the kids these days. Crime was up, drug use was up, and teen pregnancy was up. It was a genuine phenomenon and a genuine problem.

But liberals were right that it wasn’t related to the disintegration of the family or lower rates of churchgoing or any of that. After all, families didn’t suddenly start getting back together in the 90s and churchgoing didn’t suddenly rise. But teenage crime, drug use, and pregnancy rates all went down. And down. And down. Most likely, there was a real problem, but it was a problem no one had a clue about. We were poisoning our children with a well-known neurotoxin, and this toxin lowered their IQs, made them into fidgety kids, wrecked their educations, and then turned them into juvenile delinquents, teen mothers, and violent criminals. When we got rid of the toxin, all of these problems magically started to decline. This doesn’t mean that lead was 100 percent of the problem. There probably were other things going on too, and we can continue to argue about them. But the volume of the argument really ought to be lowered a lot. Maybe poverty makes a difference, maybe single parenting makes a difference, and maybe evolving societal attitudes toward child-rearing make a difference. But they probably don’t make nearly as much difference as we all thought. In the end, we’ve learned a valuable lesson: don’t poison your kids. That makes more difference than all the other stuff put together.

But there’s another moral to be drawn.  The toxicity of lead has been known for at least a century. The introduction of tetraethyl lead into gasoline in the 1920s sparked a controversy, which the automobile industry, the petroleum industry, and Ethyl Corporation (a GM/Esso joint venture) won, using the usual mix of dirty tricks including lying and threatening scientists with lawsuits. A similar battle was fought over lead paint in the 197os, with the lead-paint vendors in the bad-guy role, and over lead emissions from smelters, with the American Iron and Steel institute trying to destroy Herb Needleman’s scientific career.
Then, mostly by the accident that leaded pain fouled catalytic converters, the battle was rejoined over lead in gasoline, with the old pro-toxin coalition fighting a drawn-out rearguard action to delay regulation as much as possible.
As far as I know, not a single executive, lobbyist, or scientist working for any of the companies that were making money by poisoning children and causing a crime wave spoke out in favor of public health and safety. Why should they? After all, they were just doing their jobs and paying their mortgages, and Milton Friedman had proclaimed that the only social responsibility of business was to make money (and that anyone who believed otherwise was a closet socialist): a morally insane proposition still widely repeated.
All of which makes me think of C.S. Lewis’s preface to The Screwtape Letters, explaining his image of Hell as the realm of the Organization Man:
I live in the Managerial Age, in a world of “Admin.” The greatest evil is not now done in … sordid “dens of crime.” … It is conceived and ordered (moved, seconded, carried, and minuted) in clean, carpeted, warmed and well-lighted offices, by quiet men with white collars and cut fingernails and smooth-shaven cheeks who do not need to raise their voices.

The plutocrat majority on the Supreme Court has ruled that, whatever the facts, as a matter of law using money to influence the outcome of elections does not constitute “corruption,” because “there is no such thing as too much speech.”  Soon it will probably rule that the companies can cut the comedy and make contributions directly from corporate coffers to campaign accounts, but by now the rules are so leaky that it hardly matters anymore. As a result, quiet men (and women) in pleasant offices, who have not only neatly-trimmed fingernails but utterly clear consciences – men and women most of whom would be psychologically incapable of injuring a child with their own hands - will continue to poison other people’s children (with environmental toxins, unhealthy foods, alcohol, tobacco, and, shortly, cannabis), call anyone who tries to interfere a socialist, and use everything short of explicit bribery to get their way.

And that, my friends, is what’s at stake this year, and in 2016, and – unless we’re very lucky – in every election for the rest of my lifetime.

Lead and crime: a hole in the theory

Kevin Drum, whose “Criminal Element” essay linking violence rates to lead exposure has been (as it deserves to be) extraordinarily influential, links to a BBC story in which a more-than-usually-dim criminologist explains that he disbelieves in the lead-crime link because all biological explanations of crime are outside “the mainstream” (presumably meaning “the mainstream of criminological research”). Kevin is right to say that the multiple levels of evidence for the lead-crime link (brain-imaging work, case-control studies at the individual level, studies of crime changes in neighborhoods that suffered greater and lesser increases in lead exposure after WWII and decreases in lead exposure after the mid-1970s, and cross-national studies) deserve more than a casual blow-off. It’s not, after all, as if “mainstream” criminology had a bunch of well-worked out causal theories with proven predictive power.

Like Kevin, I’ve been frustated that the evidence about lead hasn’t led to more action, if only some serious experimental work removing lead from randomly selected buildings or neighborhoods and then doing developmental measurements on the childen in the chosen areas compared to children in control areas. And I was puzzled when I heard that the hyper-sensible Phil Cook of Duke was among the skeptics.

Alas, Phil seems to have good reason to raise questions, especially about the ultra-strong claims sometimes heard about the percentage of the crime drop since 1994 attributable to changes in lead exposure. (Note that in a system with multiple positive feedbacks, the change-attribution factors needn’t sum to unity, so the claim that “the change in X accounts for 90% of the change in Y” is dubious on its face.)

Cook writes:

My skepticism about the “lead removal” explanation for the crime drop stems from the same source as my skepticism about the Donohue-Levitt explanation in terms of abortion legalization. They have an exact parallel to the previous explanations for the surge in violence of the late ‘80s by John DiIulio and others. The focus in both cases is the character of the kids – the belief that during the 80s the teens were getting “worse,” and during the 90s they were getting “better.” Even a fairly casual glance at the data demonstrates that whatever the cause of the crime surge, and then the crime drop, it was not associated with particular cohorts. It was an environmental effect – 10 cohorts were swept up in the crime surge simultaneously, and the drop has the same correlated pattern.

There is a natural inclination to assume that the reason the murder rate is increasing is because there are more murderers, and the reason we have fewer is that there are fewer murderers. It’s not that I rule out such explanations – I’m open to the idea of lead removal and abortion legalization – it’s just that I don’t think it explains the actual pattern of the youth violence epidemic, either up or down. More generally, my instinct is to look to the social and economic environment to explain large shifts in population outcomes.

Here’s Cook’s paper with John Laub.

Now, since youth violence surely has impacts on adult violence, finding that all the cohorts decreased their violence at the same time doesn’t quite rule out the idea that the younger cohorts were largely driving the train. And those brain-imaging, case-control, neighborhood, and cross-national results are still out there. But Cook’s objection remains a powerful one: the theory predicts that we should have seen the crime declines specifically in the birth cohorts exposed to less lead, and that’s not what we saw in fact.

I’d still like to see some experimental work to figure out how much additional lead removal would turn out to be cost-justified (with crime-reduction benefits a significant, but but not the dominant, part of the benefit story), but the simple story “Crime declined because lead declined” now has a major hole in it. That’s too bad, because attempts to find the relevant social and economic causes haven’t gotten very far. To my mind, the crime boom that started in the late 1950s or early 1960s and the crime bust that started in the mid- 1990s (and other large-scale, decades-long swings up and down in crime rates elsewhere) remain largely unexplained in retrospect, as they were entirely unpredicted in prospect.

Footnote And that, of course, is the difference between science and policy analysis on the one hand and mere advocacy on the other. Of course scientists and analysts are influenced by their values and prejudices. I don’t pretend that Jessica Reyes’s work didn’t make me happy or that Cook’s response doesn’t make me sad. The lead-crime story fits all my political prejudices, as well as my taste for simple and surprising explanations with clear policy implications. And I’ve been a loud advocate for it. But I don’t want to believe it if it isn’t true.

Getting the (remaining) lead out

Shorter Kevin Drum:

1. Lead is remarkably nasty stuff. In minuscule quantities (measured in the single digits of micrograms per decliter of blood) it damages both IQ and the capacity for self-command.

2. The rise of lead exposure from gasoline, and its subsequent decline, accounts for a large share of the crime boom of 1960-90 and the crime decline that started in 1994.

3. Children are still being exposed to lead from two major sources: residual lead in soil, and lead paint in homes, especially window-frames.

4. Substantially eliminating those sources of exposure would require a one-time expenditure of about $400 billion. (That sounds like a lot of money, until you look at Treasury bond rates and translate it to $12 billion a year.)

5. The return on that investment would be at least in the high tens of billions of dollars per year.

Kevin’s piece, the cover story in the current Mother Jones, is a model of science/policy journalism. He carefully chases down both the biology and the social science supporting the claims about the effects of lead, identifies the main remaining sources, and documents the abatement processes, with cost estimates. (The quantification of benefits is mostly hand-waving; neither the outcome predictions nor the valuations are convincing. But it’s more than adequate to show that the benefit-cost analysis would come out hugely positive.)

It remains to be seen whether a crime-control and educational initiative that doesn’t fit the intellectual categories or feed the budgets of the criminal-justice and educational systems can obtain any political purchase. The answer so far seems to be no.

Getting the lead out

Kevin Drum makes a strong case for spending the money to remove the remaining sources of environmental lead: old lead paint and residential water pipes. Eliminating lead paint an lead pipes each would have costs in the tens-of-billions range. In each case that would mean either (1) requiring private parties to spend substantial amounts of money or (2) spending substantial amounts of public money to fix up private property, somewhat unfairly to those who prudently spent their own money to fix it.  But neither problem could possibly justify allowing the ongoing damage from lead exposure; those are one-time expenditures, and the flow of damage from lead is a continuing cost.

One source Kevin doesn’t mention is smelters, which used to be a major source. I’m not current enough to know whether most of the smelter business has moved abroad, but I’m sure there are still some domestic smelters, and they’re inevitably bad news on the lead front.

As Kevin notes, one consequence of lead exposure is higher crime: lead reduces IQ and also specifically attacks some of the brain functions that support self-control. But consider what a horse-laugh a politician would get if he listed de-leading among his crime-control proposals.