While I must admit the article is well written and that the rise and fall of both levels is extremely close in correlation, I still have some doubts (as any good scientific observer should).

The real fall in crime levels also correlates with the induction of both the passage of the civil rights act and the introduction of Johnson's great society - where we also introduced food stamps, and welfare. This would point to crime being on the decline since the collective society had decided that we could not longer discriminate against specific classes, and that we do the best to insure a social safety net to provide the basics of life to the people.

This correlation is also present in ancient culture. Ancient Rome had riots when the bread ration wasn't met, and later emperors would also add olive oil and wine to the ration. Crime while prevalent should have been staggering, as the main cooking vessels were made of lead as well as most drinking cups. Crime among women at the time should have seen unprecedented numbers as most cosmetics were lead based. The lead did lead to higher mortality rates at the time, but the crime, while present, was equal in contrast to ours, both in occurance and violence.

While I won't say that lead isn't harmful, I think the underlying socio-econmic factors have a greater influence.

As for the connections to ADHD, I read that study as well and the connections are spurious at best. The study offered no control group and only tracked the blood levels of those who were diagonosed. Considering there has been a rise in those diagnosed with ADHD in the U.S. since the removal of lead from the gas, one could acutally argue that a "little lead" is good for maintaining proper brain chemistry.

It'd a good article, but I'm not 100% sold.

It was an exciting conjecture, and it prompted an immediate wave of…nothing. Nevin's paper was almost completely ignored, and in one sense it's easy to see why—Nevin is an economist, not a criminologist, and his paper was published in Environmental Research, not a journal with a big readership in the criminology community. What's more, a single correlation between two curves isn't all that impressive, econometrically speaking. Sales of vinyl LPs rose in the postwar period too, and then declined in the '80s and '90s. Lots of things follow a pattern like that. So no matter how good the fit, if you only have a single correlation it might just be a coincidence. You need to do something more to establish causality.

As it turns out, however, a few hundred miles north someone was doing just that. In the late '90s, Jessica Wolpaw Reyes was a graduate student at Harvard casting around for a dissertation topic that eventually became a study she published in 2007 as a public health policy professor at Amherst. "I learned about lead because I was pregnant and living in old housing in Harvard Square," she told me, and after attending a talk where future Freakonomics star Levitt outlined his abortion/crime theory, she started thinking about lead and crime. Although the association seemed plausible, she wanted to find out whether increased lead exposure caused increases in crime. But how?
In states where consumption of leaded gasoline declined slowly, crime declined slowly. Where it declined quickly, crime declined quickly.

The answer, it turned out, involved "several months of cold calling" to find lead emissions data at the state level. During the '70s and '80s, the introduction of the catalytic converter, combined with increasingly stringent Environmental Protection Agency rules, steadily reduced the amount of leaded gasoline used in America, but Reyes discovered that this reduction wasn't uniform. In fact, use of leaded gasoline varied widely among states, and this gave Reyes the opening she needed. If childhood lead exposure really did produce criminal behavior in adults, you'd expect that in states where consumption of leaded gasoline declined slowly, crime would decline slowly too. Conversely, in states where it declined quickly, crime would decline quickly. And that's exactly what she found.

This study shows a very strong association between preschool blood lead and subsequent crime rate trends over several decades in the
USA, Britain, Canada, France, Australia, Finland, Italy, West Germany, and New Zealand. The relationship is characterized by best-fit
lags (highest R2 and t-value for blood lead) consistent with neurobehavioral damage in the first year of life and the peak age of offending
for index crime, burglary, and violent crime. The impact of blood lead is also evident in age-specific arrest and incarceration trends.
Regression analysis of average 1985–1994 murder rates across USA cities suggests that murder could be especially associated with more
severe cases of childhood lead poisoning.
r 2007 Elsevier Inc. All rights reserved.

Nevin collected lead data and crime data for Australia and found a close match. Ditto for Canada. And Great Britain and Finland and France and Italy and New Zealand and West Germany. Every time, the two curves fit each other astonishingly well. When I spoke to Nevin about this, I asked him if he had ever found a country that didn't fit the theory. "No," he replied. "Not one."

In fact, Mielke has even studied lead concentrations at the neighborhood level in New Orleans and shared his maps with the local police. "When they overlay them with crime maps," he told me, "they realize they match up."

Proposing a different theory, does nothing to reduce the confidence of this one. Without showing the same kinds of controls, ie that smaller environs with different levels of the substance matched levels of violence is not very compelling.

Which makes this study very compelling IMHO. I need to take some more time with the data before I put my own opinion behind it, but it is FAR more promising then anything else I have seen.

Your social theory (civil rights etc) can do nothing with international data. That makes your theory much weaker than this one if the data really supports it.

Hmmm, sure does make sense of the data I have seen.

That is unreal, has any other violent crime study EVER been able to do this? To map a correlation at such a granular level with on contradicting data?

So lead is a double whammy: It impairs specific parts of the brain responsible for executive functions and it impairs the communication channels between these parts of the brain. For children like the ones in the Cincinnati study, who were mostly inner-city kids with plenty of strikes against them already, lead exposure was, in Cecil's words, an "additional kick in the gut." And one more thing: Although both sexes are affected by lead, the neurological impact turns out to be greater among boys than girls.

We have the causative factors right here.

The phrase "an 'additional kick in the gut.'" in and of itself demonstrates that it is "a" causative factor and not "the" causative factor. Once again, I'm not denying it is a contributor just not the entire cause.

Your international argument is compelling until you look up the implementation of social welfare in European and British Commonwealth countries, in which you find a fairly similar trend of implementation and crime rate reductions.

Basically, the civilized world became more civilized at a general time in respects not only to our environment, but also in social responsibility. The fact that both of these coincided might help explain the dramatic fall as opposed to an to a much slower recline in either connection taken individually.

My observation, as there was no theory presented as denoted by the lack specific data to support a claim, just notes that these happenings coincided with other major events in Western Civilization. The data presented is once again compelling, but is not necessarily an all encompassing fundamental law of crime reduction.

My association with ancient societies, while there can be little evidence of actual blood/lead levels, is still valid. The reasoning is a known higher exposure to the heavy metal through ingestion. A prime example being the introduction of tomatoes to Europe - where they were thought to be poisonous do to the fact that when cooked in lead pots, the tomatoes acidity caused enough lead to be put into the human body as to actually be lethally toxic. One cannot deny the adverse affect of lead on the human body nor the adverse effect to brain function, but neither can one deny the effect of squalor or social conditions when related to crime. A hungry man will steal food, a freezing man will steal a coat or blanket. This has been true even in societies of ancient times where earthenware was used in place of lead. To say, as this article does that all crime is the result of lead is preposterous.