Dentine lead levels in childhood and criminal behaviour in late adolescence and early adulthood

Introduction: There have been claims in the literature that lead exposure makes a strong contribution to criminal behaviour. Objectives: To examine linkages between lead exposure in childhood and crime in late adolescence/early adulthood to (a) determine whether higher levels of lead exposure were associated with increased levels of criminal behaviour and (b) estimate the extent to which lead exposure was responsible for increases in criminal behaviour. Methods: Negative binomial regression models were fitted using data from a longitudinal birth cohort of New Zealand-born children studied from birth to age 21. Results: There were statistically significant (p < 0.05) bivariate associations between dentine lead levels at ages 6 - 9 and (a) officially recorded violence/property convictions (ages 14 - 21) and (b) self-reported violent/property offending (ages 14 - 21). The mean rate of convictions was 1.89 (SD 6.86) and the mean rate of offences was 15.24 (SD 49.24) for those with the highest level of exposure. Those with the lowest level of exposure had a mean rate of convictions of 0.0, and a mean rate of offending of 1.97 (SD 6.34). Adjustment for confounding factors reduced the magnitude of these associations, but the associations remained statistically significant. Further analyses suggested that the associations were largely explained by the linkages between lead exposure and educational underachievement. Lead exposure accounted for less than 1% of the variance in crime. Conclusions: These results suggest that, although lead exposure was associated with criminal behaviour, the associations were somewhat weak, and were largely explained by linkages between lead exposure and educational underachievement.