One thing we have learnt this week

Was the oil age responsible for crime?  This is an extraordinary idea, but was it lead (mainly in petrol) responsible for the rise in crime after the second world war?  George Monbiot drew attention to a variety of research that suggests a very statistically strong correlation between the rise in exposure to lead (mainly in petrol although it was in paint amongst other things) and the crime rate at a national, local or even neighbourhood level.  Lead was added to petrol as tetrethyl lead to give the fuel a higher “octane” number.  This is a measure of the resistance of the fuel to self ignite due to compression in the cylinder during the engine combustion cycle.  Pre-ignition which I believe was called pinking would occur with the piston in the wrong place, this can lead to engine wear and damage.  Adding  tetrethyl lead would make the temperature the fuel would explode at higher, stopping this.  Lead is well known for being toxic, at low levels reducing intelligence and making people aggressive.  If you take in enough it will kill you.  I’ve always understood its effects are cumulative since you cannot excrete it.  Countries started to phase lead out in the 1970’s and my own country did so in 1992.

For most of the last 70 years crime in the Western World has been rising inexorably.  However, since lead was phased out crime rates have fallen (there is a roughly 20 year lag).  In the UK all categories of crime have fallen (its the same in the US) and the same across the Western world.  Just as no one could explain the rise – delete as appropriate immigration (a racist idea)/decline of Christianity (and hence moral values)/ the 1960’s permissive society/demographics (young people are statistically more likely to commit crime, so the post-war baby boom led to a rise), people are struggling to explain the fall.  (The financial crash and global recession has made no difference to the trend by the way.)  One explanation I’ve heard put forward by the police was that car crime was an entry point into crime for teenagers, since the manufacturers have made it almost impossible to steal a car, this has cut crime.  When I was a teenager it was a standard rumour that one prominent US manufacturers cars (made in Europe) only had three different keys.

Correlation is the statistical idea that data sets “move” together.  It does not mean a link is proved, but may suggest one.  The researchers have apparently taken a variety of confounding factors (social, economic and legal) into account.  On the BBC’s Radio 4 today programme this week a lead poisoning expert was very impressed with the work of the researchers mentioned by Monbiot.  While I think this research is probably correct, some questions for me remain though.  First lead was used to make water pipes and tanks in houses.  Is there any kind of link between the phaseout of these and crime?  Second I must have been exposed to quite high quantities of lead.  Lead exposure cannot be the only explanation, I’ve never committed a crime beyond jumping a red light and a bit of speeding.  I grew up in a middle class suburb where there were more cars than in  poorer areas.  So why do lower socio economic groups still commit more crime?  Whilst I can see local factors affecting this – for example the wind blowing lead into poorer areas, the suggestion is that this correlation is pretty tight.  In my view this cannot be the only reason for the fall in crime, better technology and demographic changes must explain some of it.

What do you think?


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