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Males, blacks, and persons ages 18 to 24 had the highest rates of firearm homicide from 1993 to 2010.

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In 1994, Rick Nevin was a consultant working for the US Department of Housing and Urban Development on the costs and benefits of removing lead paint from old houses. This has been a topic of intense study because of the growing body of research linking lead exposure in small children with a whole raft of complications later in life, including lower IQ, hyperactivity, behavioral problems, and learning disabilities.

But as Nevin was working on that assignment, his client suggested they might be missing something. A recent study had suggested a link between childhood lead exposure and juvenile delinquency later on. Maybe reducing lead exposure had an effect on violent crime too?

That tip took Nevin in a different direction. The biggest source of lead in the postwar era, it turns out, wasn't paint. It was leaded gasoline. And if you chart the rise and fall of atmospheric lead caused by the rise and fall of leaded gasoline consumption, you get a pretty simple upside-down U: Lead emissions from tailpipes rose steadily from the early '40s through the early '70s, nearly quadrupling over that period. Then, as unleaded gasoline began to replace leaded gasoline, emissions plummeted.
Gasoline lead may explain as much as 90 percent of the rise and fall of violent crime over the past half century.

Intriguingly, violent crime rates followed the same upside-down U pattern. The only thing different was the time period: Crime rates rose dramatically in the '60s through the '80s, and then began dropping steadily starting in the early '90s. The two curves looked eerily identical, but were offset by about 20 years.

So Nevin dove in further, digging up detailed data on lead emissions and crime rates to see if the similarity of the curves was as good as it seemed. It turned out to be even better: In a 2000 paper (PDF) he concluded that if you add a lag time of 23 years, lead emissions from automobiles explain 90 percent of the variation in violent crime in America. Toddlers who ingested high levels of lead in the '40s and '50s really were more likely to become violent criminals in the '60s, '70s, and '80s.

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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."

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Like many good theories, the gasoline lead hypothesis helps explain some things we might not have realized even needed explaining. For example, murder rates have always been higher in big cities than in towns and small cities. We're so used to this that it seems unsurprising, but Nevin points out that it might actually have a surprising explanation—because big cities have lots of cars in a small area, they also had high densities of atmospheric lead during the postwar era. But as lead levels in gasoline decreased, the differences between big and small cities largely went away. And guess what? The difference in murder rates went away too. Today, homicide rates are similar in cities of all sizes. It may be that violent crime isn't an inevitable consequence of being a big city after all.

The gasoline lead story has another virtue too: It's the only hypothesis that persuasively explains both the rise of crime in the '60s and '70s and its fall beginning in the '90s. Two other theories—the baby boom demographic bulge and the drug explosion of the '60s—at least have the potential to explain both, but neither one fully fits the known data. Only gasoline lead, with its dramatic rise and fall following World War II, can explain the equally dramatic rise and fall in violent crime.

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For example, murder rates have always been higher in big cities than in towns and small cities.

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Males, blacks, and persons ages 18 to 24 had the highest rates of firearm homicide from 1993 to 2010.

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ORIGINAL: tazzygirl

lol.. sorta hard to argue with graphs [;)]

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Nevin’s study was extended using various violent crime data from the US, UK, Canada, Australia, West Germany, France and New Zealand. The 2007 paper showed a consistent relationship between preschool blood-lead levels and crime rate trends in nine so-called advanced nations. In the 2012 summary, the data series was updated to 2011, and the correlation persisted.

Meilke and Zahran evaluated lead emissions and latent aggravated assault behaviour in six US cities. Other things held equal, a 1% increase in tonnages of air Pb released 22 years prior corresponded with a 0.46% rise in the aggravated assault rate in the present period. Overall, they claimed that their model explained 90% of the variation in aggravated assault across the cities examined. Unless everyone implemented similar policing at the same time, it seems unlikely that policing methods are the cause of the change.

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It is well known that lead can affect the central, peripheral and autonomic nervous systems and induce sub-clinical and clinical encephalopathy. Increased lead levels in children are reported to have the effect of decreasing IQ. Thus there are possible neurotoxicological mechanisms that may explain these findings, even if the evidence for them is unspecific. Is this enough to establish the association as cause and effect? Many will say yes but others will be more sceptical; I think the answer is ‘just about’. If nothing else, this shows how little we know about the neurobehavioural effects of many chemicals and how difficult it is to investigate them. Serendipity and good monitoring seem to be the current detection methods.

What to conclude from all this? Firstly, be aware of the difference between association and cause and effect; secondly, be sceptical of politicians claiming victories in the fight against crime and political journalists debunking them; and thirdly, remember that the old saw ‘more research is needed’ may actually be true.

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ORIGINAL: YN

Criminal homicides, and serious assaults with deadly weapons are rather well reported worldwide. Dead bodies with stab wounds and bullet holes are hard to deny, as are those survivors who seek professional medical attention.

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ORIGINAL: Powergamz1

That's fantastic. Totally missed the point of what I posted, but enjoy.

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ORIGINAL: YN

Criminal homicides, and serious assaults with deadly weapons are rather well reported worldwide. Dead bodies with stab wounds and bullet holes are hard to deny, as are those survivors who seek professional medical attention.

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ORIGINAL: YN

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ORIGINAL: Powergamz1

That's fantastic. Totally missed the point of what I posted, but enjoy.

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ORIGINAL: YN

Criminal homicides, and serious assaults with deadly weapons are rather well reported worldwide. Dead bodies with stab wounds and bullet holes are hard to deny, as are those survivors who seek professional medical attention.

You had a point? The correlation between airborne lead and violent criminal conduct was made in a number of other countries, several of which had no sort of "baby boom."

Australia, Canada, the United Kingdom, Finland, France, Italy, New Zealand and West Germany, all had this correlation.

But by all means, it must be your United States elderly who are responsible, perhaps you should lower their Social Security and Medical benefits as a collective punishment for their group criminality, as a part of your economic plan to balance the federal budget.

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ORIGINAL: Politesub53

More on YN`s point about lead in petrol.

http://www.dailymail.co.uk/sciencetech/article-2256847/Did-outlawing-leaded-gasoline-cause-crime-rate-drop-Researchers-link-toxic-chemical-violent-behavior.html

The tragedy is that scientists new the dangers of many materials, long before they were banned. In house reports from the 1930s by US companies showed asbestos caused cancer, not just any cancer but a really agressive form called mesothelioma. It has only recently been banned. Money sucking scum hardly describes it.

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ORIGINAL: tazzygirl
The Baby Boomers.