Lead exposure and antisocial behavior: A systematic review of human and animal evidence

Despite decades of research and interventions, lead (Pb) exposure remains a global public health concern. In addition to well-documented impacts on cognition, there is growing evidence of Pb's impacts on antisocial behaviors, including aggression, conduct or antisocial disorders, and violation of social norms. We conduct a systematic review on the association between Pb and antisocial behavior from human and animal data.

We followed our protocol with selected modifications for practicality. Peer-reviewed epidemiology and toxicology literature from PubMed, BIOSIS, and Web of Science were searched through June 2024 and screened for relevance, leveraging machine-learning. Details for each Population, Exposure, Comparator, Outcome (PECO)-relevant study were summarized. Studies were evaluated for potential bias and sensitivity according to predefined metrics through the Health Assessment Workspace Collaborative (HAWC) system. Evidence was synthesized by sub-outcome (human: aggression; antisocial diagnoses or domains; violation of social norms; animal: aggression; social behavior) and then integrated across evidence streams, based on approaches adapted from the U.S. EPA.

More than 15,000 studies were identified. After screening and scoping refinements, 43 epidemiological and 37 animal studies were included for narrative review. In the epidemiological database, there was lack of comparability in outcome assessment methods, precluding quantitative meta-analysis. Human and animal evidence for impacts on aggression was slight. Human and animal evidence for impacts on antisocial-related disorders or domains and social behavior, respectively, was moderate. Human evidence for impacts on violation of social norms was moderate.

From our updated review of epidemiological and toxicological data, we find that evidence indicates a likely causal association between Pb and antisocial behavior.