Lead exposure during childhood has been tied to a variety of developmental problems, but a new study suggests it may not be associated with higher odds of criminal behaviour later in life. The study set out to address a flaw in much of the previous research linking lead and crime: mainly that it's hard to determine how much of this connection might be explained by poverty and other socioeconomic circumstances that can influence both criminal activity and lead exposure.

Researchers followed 553 people born in Dunedin, New Zealand, in 1972 and 1973, when lead exposure was common among children of all economic backgrounds because of widespread use of leaded gasoline. All of the kids were tested for lead exposure when they were 11 years old, and the study team followed them until age 38 to see how many of them were convicted of crimes. By the end of the study, 154 participants, or 28 percent, had at least one criminal conviction, the researchers report in JAMA Pediatrics. But the odds of this happening were barely influenced by the amount of lead exposure people had during childhood. Just being male had a stronger effect than lead levels, the researchers note.

"Many studies have shown that higher exposure to lead could predict more criminal behaviour, but our study actually found that there isn't a clear connection between the two," said lead author Amber Beckley, a researcher at Duke University in Durham, North Carolina. The reason for the different results this time is that the current study found children from all walks of life had high lead levels, Beckley said by email. "In our study, socioeconomic status was not associated with childhood lead exposure," she added.

Copyright Reuters, 2018