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?
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If you want to understand the causes of crime - and be tough on them - you need to start with lead, says Dr Bernard Gesch, a physiologist at Oxford University who has studied the effect of diet and other environmental factors on criminals.
"Lead is a very potent neurotoxin," says Gesch. "It has a range of effects on the brain that have been demonstrated through hundreds of different biological studies. Lead alters the formation of the brain. It reduces the grey matter in areas responsible for things such as impulse control and executive functioning - meaning thinking and planning."The article goes on to discuss how the amount of lead in the environment corresponds to whether there is lead in gasoline, citing this study by Rick Nevin, published in 2000 in Environmental Research, as an early example of research on the issue.
The article notes that studies carried out in different countries reveal crime rates corresponding with the amount of lead exposure. For example, "[l]eaded petrol was removed from British engines later than in North America - and the crime rate in the UK began to fall later than in the US and Canada."
The theory remains difficult to test, and there are those who question the validity of connecting health impacts from environmental factors to criminal, rather than behavioral, activity. But the article raises some interesting points, and is worth reading in full.