London, Oct 28 (UNI) The introduction of unleaded petrol has not just helped cut health risks related to the heavy metal but is also responsible for declining crime rates in Britain, the US and other countries.
In a startling new study, published in Environmental Research, scientists suggest a ''very strong association'' between the exposure of young children to the toxic metal and crime rates 20 years later when they are young adults.
The astonishing conclusion threatens to overturn current thinking on crime and punishment.
The study says the association holds true for a wide variety of countries with differing social conditions, law and order policies.
Rates of violent and other crimes began falling sharply in the US in the early 1990s, and have continued to do so, followed by similar trends elsewhere.
The toxic metal has long been known to damage brain and to lead to criminal and aggressive behaviour.
Research at Pittsburgh University found that adolescents arrested for crime in the city had lead levels four times higher than their law-abiding contemporaries, and a study of 3,000 possible causes of criminality in 1,000 young people by Fordham University, New York, found that high lead levels were the best predictor of delinquent and violent behaviour.
The metal was first added to petrol in the 1920s to boost engine power and its use grew rapidly: levels in blood rose in parallel.It was phased out first in the US, starting in 1974, to be followed by other countries.
Britain -- one of the last to get rid of the toxic metal -- is one of the latest to enjoy a decline in crime.