Does lead poisoning make you violent?
It may sound fanciful, but a growing body of evidence seems to suggest there may be a link between violent crime and - no, not policing strategy, or sentencing reform, or even trends in drug abuse, but - exposure to lead.
Yes that's right, the base metal element lead, Pb, or more exactly the lead-based chemical compound Pb(CH2CH3)4 added to petrol to make car engines run more smoothly.
Research in America shows a strong correlation between the build up of lead in the environment and - some 20 years later - levels of violent crime.
Crucially the correlation persists even when the figures are adjusted for confounding factors like social deprivation and drug use, but what's really remarkable is that they even seem to reflect the speed at which lead additives in petrol were phased out.
In states and cities where additives were banned outright the subsequent drop off in violent crime was equally dramatic, but where lead was phased out over time criminality tailed off less abruptly.
Of course correlation is not causality, but speaking on the Today programme this morning Alastair Hay, a professor of environmental toxicology at Leeds University, described the research as compelling.
"I'm very impressed with the studies that have been done. The authors have been very cautious and careful to exclude other factors associated with criminality, and the thing that stands out is this rise and fall in lead levels and a subsequent rise and fall in crime.
"It's very convincing."
There's plausibility here too. We've known for some time that lead is a potent neuro-toxin that can cause significant damage to a number of organs in the body, including the central nervous system, and can lead to behavioural problems in children. After all that's why it was banned in both paint and petrol in the first place.
So perhaps we shouldn't be so surprised to find it plays a significant role in violent crime.