Exposure to toxic chemicals in childhood could have unlikely effects on personality, and behavioral traits in adulthood, says a new study by psychologists at the University of Texas at Austin. Coming into contact with lead could make individuals less friendly and sociable, less diligent, and more neurotic—traits that could have knock-on effects on their mental health and general wellbeing.
Data from the study was featured in the journal Proceedings of the National Academy of Sciences and detailed the analysis of a cohort of over 1.5 million people across the U.S. and Europe. These rigid personality traits were observed more frequently in those who grew up in regions known to have higher lead levels in the atmosphere. These levels were measured based on data provided by the Environmental Protection Agency, and personality data was captured via an online questionnaire.
“These three traits—conscientiousness, agreeableness, and low neuroticism—make up a large part of what we would consider a mature, psychologically healthy personality and are strong predictors of our success or failure in relationships and at work,” explained researcher Ted Schwaba, part of the study team, who added that people generally become more agreeable and less neurotic as they get older.
In the 1970s, the Clean Air Act saw atmospheric lead levels in these countries begin to plummet. The researchers found that individuals born after this period had more positive, balanced personalities than those who grew up before the Act was implemented.
While lead was always known to be harmful to human health, the outcomes of this research point to how environmental factors can have significant impacts on our mental health. While atmospheric lead is at an all-time low today, lead exposure tends to disproportionately affect people of color, who are twice as likely to have elevated lead levels in their blood. Simple finger-prick blood tests can be used to diagnose lead exposure, with levels above five mcg/dL thought to be unsafe for children.