According to a study conducted with over 1.5 million participants across the U.S. and Europe, children growing up in regions with higher atmospheric lead pollution developed less adaptive and less mature personalities. As adults, they were found to be less conscientious, less agreeable, and in some cases, more neurotic. It has been established for many years that exposure to lead in childhood has detrimental effects on brain development, leading to mental health issues and criminal behaviors that cost the U.S. over 1.2 trillion dollars.
The problems related to lead might be more extensive than previously realized, potentially affecting everyday personality traits. To assess whether lead exposure influences personality changes, my team and I compared personality traits before and after the U.S. 1970 Clean Air Act, which mandated the removal of lead from gasoline, significantly reducing atmospheric lead. We linked local changes in lead levels with shifts in the area’s average personality trait scores using an online personality questionnaire focusing on the Big Five traits: openness to experience, extraversion, conscientiousness, agreeableness, and neuroticism. The findings revealed that individuals born after the decline in lead levels had more mature personalities compared to those born during high lead levels, showing slight increases in conscientiousness, agreeableness, and less neuroticism. This indicates a potential effect of lead on personality changes. Similar effects were tested in Europe, where lead was gradually phased out of gasoline.
Europeans exposed to higher lead levels were also found to be less agreeable and more neurotic, though not less conscientious, demonstrating how psychological findings can vary across cultures. Since personality traits significantly impact various life aspects like happiness, career success, and longevity, the effects of lead exposure on personality are likely to have far-reaching implications. Fortunately, the study found lead exposure had a relatively small impact. However, given that millions of people have experienced some degree of lead exposure, these effects accumulate at a societal level. Addressing lead exposure is also a matter of social justice, as Black children are twice as likely to have high blood lead levels compared to white children.
By reducing childhood lead exposure, we can progress towards a fairer society. Following the Clean Air Act, children now face much less exposure to lead than in the 1960s and 1970s, however, further research is needed on continued sources of exposure like lead pipes and contaminated groundwater. Understanding modern sources of lead can help scientists better comprehend potential links to personality changes. Although personality traits are generally stable, research indicates they can alter due to life experiences. Because changes in personality have significant consequences, my team and I aim to study how experiences such as studying abroad in college or learning to use the internet in old age might influence personality.