Bottom Line: Researchers found no consistent association between childhood lead exposure and adult criminal behavior in New Zealand where low socioeconomic status, which confuses the association in settings with socioeconomic disparities, is less of a factor.

Why The Research Is Interesting: Lead has well-documented effects on the brain and there is no safe level of exposure. Some research suggests lead may be linked to criminal behavior but that association may be explained by low socioeconomic status, which is associated with both lead exposure and criminal behavior. This study removed low socioeconomic status as a factor because high blood lead levels were observed among children from all socioeconomic groups in New Zealand.

Who and When: 553 individuals from New Zealand born between 1972-1973 who were followed up to age 38.

What (Study Measures): Blood lead levels measured at age 11 (exposure); cumulative criminal conviction, self-reported criminal offending, recidivism, and violence up to age 38 (outcomes).

How (Study Design): This is an observational study. Researchers were not intervening for purposes of the study and they cannot control the natural differences that could explain the study findings.

Authors: Amber L. Beckley, Ph.D., of Duke University, Durham, North Carolina, and coauthors

Results: Childhood lead exposure was weakly associated with conviction and self-reported criminal offending up to age 38; lead exposure was not associated with recidivism or violence.

Study Limitations: Childhood blood lead levels were measured only one time at age 11.

Study Conclusions: There is no clear association between higher childhood blood lead levels and a greater risk for criminal behavior (a dose-response relationship) in settings where blood lead levels are similar across low and high socioeconomic status.

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Related Material: The following material also is available on the For The Media website:

The editorial, "The Need to Include Biological Variables in Prospective Longitudinal Studies of the Development of Criminal Behavior," by David P. Farrington, Ph.D., of Cambridge University, England JAMA Pediatrics Patient Page, "What Parents Need to Know About the Risks of Lead Exposure for Children"

For more information, contact JAMA Network Media Relations at 312-464-JAMA (5262) or email mediarelations@jamanetwork.org.