Date of Award

December 2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Public Health

First Advisor

Lance S. Weinhardt

Committee Members

Ron A. Cisler, Amy E. Kalkbrenner, Mallory E. O'Brien, Alice F. Yan

Keywords

Childhood Lead Exposure, Firearm Violence

Abstract

Over 10,000 Americans are killed in firearm homicides each year, and an additional 40,000 are injured in nonfatal shootings. There is a significant public health need to identify risk factors that can be modified to prevent firearm violence. Environmental lead exposure is a demonstrated neurotoxicant which causes behavior changes that are known to be criminogenic. More recent research has demonstrated that homicides and nonfatal shootings differ by the circumstances that lead to the shootings (i.e. gang, domestic violence, arguments) and aggregating them could lead to biased results. Although studies have found a relationship between childhood lead exposure and criminal behaviors, no studies have examined individual-level childhood lead exposure and firearm homicide and nonfatal shooting risk, including in the context of shooting type, and there is limited conceptual understanding of this relationship.

For this study, I performed a comprehensive review of the literature and developed a conceptual model illustrating the corresponding factors involved in childhood lead exposure and firearm violence to deepen our conceptual understanding of the relationship. Next, I conducted a retrospective cohort study using linked longitudinal data from the Milwaukee Health Department, Milwaukee Public Schools and Milwaukee Homicide Review Commission on 89,129 individuals born between June 1st, 1986 - December 31st, 2003 who had at least one valid blood lead test result reported to the Milwaukee Health Department in the first 6 years of life and had stable childhood and adolescent residency to evaluate the association between childhood lead exposure and firearm violence victimization and perpetration. Victims or perpetrators of firearm violence were identified in the Milwaukee Homicide Review Commission homicide and nonfatal shooting database between January 1st, 2005 and December 31st, 2015. Last, I conducted a study on 1091 victims and 589 perpetrators of firearm violence identified in the Milwaukee Homicide Review Commission homicide and nonfatal shooting database who had at least one valid blood lead test result reported to the Milwaukee Health Department in the first 6 years of life to evaluate the association between childhood lead exposure and shooting type.

A conceptual model illustrating the relationship between childhood lead exposure and firearm violence is described with factors included at the Individual, Peer, Family, Multilevel, and Policy levels to guide future research, policy and practice. After adjustment for confounders, our results of the retrospective cohort study show that for every 1μg/dL increase in the mean or peak childhood lead level, the odds of an individual becoming a victim of firearm violence increases (Lead Mean: OR 1.04, 95% CI 1.03, 1.045; Lead Peak: OR 1.02, 95% CI 1.01, 1.03) and the odds of an individual becoming a perpetrator of firearm violence increases (OR 1.03, 95% CI 1.02, 1.04; Lead Peak: OR 1.02, 95% CI 1.01, 1.023). When childhood blood lead levels were categorized, a significant dose-response relationship was found. After adjustment for confounders, the results of our final study show that the relative risk of being a victim of Argument/Fight-related shooting compared to an Other type of shooting is 37% higher for each 5 μg/dL increase in the mean childhood lead level (RRR 1.37, 95% CI 1.02, 1.85). The relative risk of being a perpetrator of an Argument/Fight-related shooting compared to a Retaliation-related shooting is 27% higher for each 5 μg/dL increase in the mean childhood lead level, after adjustment for confounding (RRR 1.27, 95% CI 1.03, 1.55). Our findings confirmed earlier clinical observations and recent research that have linked childhood lead exposure with violent crime and, more specifically, argument-related firearm violence, creating greater urgency for primary and secondary childhood lead exposure prevention and paving the way for strategies to reduce the occurrence of firearm violence.

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