It leads to crime

[Gob]

Many Western nations have experienced significant declines in crime in recent decades, but could the removal of lead from petrol explain that?

Working away in his laboratory in 1921, Thomas Midgley wanted to fuel a brighter tomorrow. He created tetraethyl lead - a compound that would make car engines more efficient than ever.

But did the lead that we added to our petrol do something so much worse? Was it the cause of a decades-long crime wave that is only now abating as the poisonous element is removed from our environment?
Find out more

For most of the 20th Century crime rose and rose and rose. Every time a new home secretary took office in the UK - or their equivalents in justice and interior ministries elsewhere - officials would show them graphs and mumble apologetically that there was nothing they could do to stop crime rising.

Then, about 20 years ago, the trend reversed - and all the broad measures of key crimes have been falling ever since.

Offending has fallen in nations whose governments have implemented completely different policies to their neighbours.
More here.

[Sue U]

Although it is unquestionable that removing lead from gasoline is a good thing, the causal link to crime rates two decades on is at best highly speculative and poorly supported. A much better case can be made that the increase in crime is causally related to the number of siblings in the population.

For example, here is the researcher's graph showing the correlation between leaded gasoline supply and crime rate:



And here is a graph showing US birth rates:



Note that the violent crime rate from 1964 to 2004 closely tracks the fertility rate from 1944 to 1984. The higher the fertility rate (indicating number of births per woman) the more siblings there are. As those siblings enter adulthood, they become violent criminals at a higher rate than children raised with fewer siblings. The continuing lower fertility rate of the last 40 years means we will be in a period of lower violent crime rates for at least several decades to come. The data clearly show that the sibling rivalries of the large Baby Boom families made it the most violent generation on record.

ETA:

Alternatively, it appears that 1) the supply of leaded gasoline directly causes increased fertility, or B) fertility rates directly affect the supply of leaded gasoline, as both appear to track each other even more closely than either do the rate of violent crime.

Do I need smilies or whatever here?

[MajGenl.Meade]

I blame the growth of DSTV, video games and internet porn. Keeps the kids off the streets

[rubato]

I started a thread a while ago about the connection between lead poisoning and violent crime. There is actually a lot of evidence linking the two which is very detailed. I don't have time to re-do the links &c.

Steven Levitt had shown a correlation between the effects of Roe v Wade and the drop in violent crime but the connection to lead is much stronger and has a better proven mechanism.


http://www.forbes.com/sites/alexknapp/2 ... -epidemic/

... There are three basic reasons why this theory should be believed. First, as Drum points out, the numbers correlate almost perfectly. “If you add a lag time of 23 years,” he writes. “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.”

Second, this correlation holds true with no exceptions. Every country studied has shown this same strong correlation between leaded gasoline and violent crime rates. Within the United States, you can see the data at the state level. Where lead concentrations declined quickly, crime declined quickly. Where it declined slowly, crime declined slowly. The data even holds true at the neighborhood level – high lead concentrations correlate so well that you can overlay maps of crime rates over maps of lead concentrations and get an almost perfect fit.

Third, and probably most important, the data goes beyond just these models. As Drum himself points out, “if econometric studies were all there were to the story of lead, you’d be justified in remaining skeptical no matter how good the statistics look.” But the chemistry and neuroscience of lead gives us good reason to believe the connection. Decades of research has shown that lead poisoning causes significant and probably irreversible damage to the brain. Not only does lead degrade cognitive abilities and lower intelligence, it also degrades a person’s ability to make decisions by damaging areas of the brain responsible for “emotional regulation, impulse control, attention, verbal reasoning, and mental flexibility.”

The bottom line, as Drum points out, is that “even moderately high levels of lead exposure are associated with aggressivity, impulsivity, ADHD, and lower IQ. And right there, you’ve practically defined the profile of a violent young offender.” ...

I'm surprised no one here recalled the earlier thread? Well, here is the link to the Mother Jones article:

http://www.motherjones.com/environment/ ... k-gasoline

... Nevin had kept busy as well, and in 2007 he published a new paper looking at crime trends around the world (PDF). This way, he could make sure the close match he'd found between the lead curve and the crime curve wasn't just a coincidence. Sure, maybe the real culprit in the United States was something else happening at the exact same time, but what are the odds of that same something happening at several different times in several different countries?

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."

Just this year, Tulane University researcher Howard Mielke published a paper with demographer Sammy Zahran on the correlation of lead and crime at the city level. They studied six US cities that had both good crime data and good lead data going back to the '50s, and they found a good fit in every single 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."
Location, Location, Location
In New Orleans, lead levels can vary dramatically from one neighborhood to the next—and the poorest neighborhoods tend to be the worst hit.
Maps by Karen Minot

Put all this together and you have an astonishing body of evidence. We now have studies at the international level, the national level, the state level, the city level, and even the individual level. Groups of children have been followed from the womb to adulthood, and higher childhood blood lead levels are consistently associated with higher adult arrest rates for violent crimes. All of these studies tell the same story: Gasoline lead is responsible for a good share of the rise and fall of violent crime over the past half century.
When differences of atmospheric lead density between big and small cities largely went away, so did the difference in murder rates.

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. ...

It was also reported in C&E News the weekly magazine of the American Chemical Society,



yrs,
rubato