Murder and lead exposure

Crime is always a major focus for governments and communities. Whenever I hear about efforts to reduce crime it is about increasing police numbers and resources or by improving employment opportunities for those at greatest risk. But why do some areas experience greater crime rates than others? Why do some have a particular problem with murder and assault? Sometimes it seems simple to answer- that lack of jobs and opportunities lead to people resorting to crime but what happens if there is a hidden factor, one that isn’t obvious? It turns out that another culprit could be at work: environmental exposures.

 Scene of the crime: image by AJC1 from Flickr


So what is the culprit?

A major culprit for criminality is lead poisoning and exposure. The negative impacts of lead are well documented, with continued exposure to high levels associated with blood-pressure and kidney problems. It has also been repeatedly shown that early childhood exposure can cause significant neurological and behavioral changes such as loss of muscle control and lower IQ scores.

Lead is an incredibly common metal and Australia is the world’s largest miner and exporter of it. It was used in paint and fuel up until recent law changes. Fuel was the major source of atmospheric lead until its removal, more so than all mining and smelting operations.

There is no safe level of lead exposure, with its effects seen as part of a spectrum, with more lead causing greater behavioral changes.

If lead can cause such a major alteration in a child’s development, could those changes lead to long-term behavioral issues? If so, could it be responsible for people committing crimes later on in life?


What is the science?

A study published in 2016 looked at how crime rates in specific suburbs and states varied according to air lead concentrations. It found that even accounting for socio-demographic factors such as income and education levels, 30% of all violent crimes could be attributed to higher lead concentrations in the air. It found this effect was apparent from early childhood exposure, up to around 21 years later. It showed that the more lead a child was exposed to, the more likely it was that they would commit a violent crime.

This effect was limited only to aggressive crimes such as assault and murder and did not impact fraud. It is thought that this difference is due to fraud being a pre-meditated and planned crime compared with assault.

Other studies, often looking at historical cases, have found similar associations between lead concentrations and crime rates.


What does it mean for the community?

What the studies show is that society and politicians need to realize that crime cant just be attributed to unemployment levels or education. Action must be taken to reduce exposure that can alter children’s growth, especially neurologically. Unfortunately most of the damage has already been done to the community, but hopefully with continued vigilance and removal of further lead exposure, murders and assaults should decrease.

One Response to “Murder and lead exposure”

  1. Simone says:

    Very interesting. I should investigate the lead level of some Melbourne suburbs before moving there!