The study, published in Proceedings of the National Academy of Sciences, looked at the personalities of people across the United States and Europe and compared the results against levels of atmospheric lead in the area. The investigation of lead is an important endeavor, as disasters such as the Flint water crisis, climate change, and flooding across Europe and China put more people in contact with this toxic metal. This exposure, while healthy for no one, has wider implications for the health of children. Studies continue to find that exposure to lead early in life has a range of negative effects including life-long neurological changes. The results of such exposure often have consequences such as a higher likelihood of violent crime, drug use, lower IQ, and now, negative personality changes. Specifically, this recent study showed that lead exposure was related to lower levels of conscientiousness and agreeableness, and higher levels of neuroticism.
The Research
While past research has shown the danger lead can have on physical health, there is surprisingly little information on the long-term emotional and psychological impact of exposure. Ted Schwaba, PhD, lead author of the study, aimed to change that. In this longitudinal study, researchers collected personality data from 1.5 million people from across the U.S and Europe. While most studies struggle to find a large participant set, this study excelled by using online tools. “People love taking personality questionnaires,” Dr. Schwaba said. The personality information was then compared to the location each participant was born and how much atmospheric lead was in that area, according to EPA data. A surprising pattern began to emerge. When people grew up in communities with higher levels of atmospheric lead they were more likely to develop more negative personality traits. To further prove the findings, the researchers wanted to see what impact the Clean Air Act of 1970 had on the association between lead and personality. The act worked to reduce air pollutants, including those from leaded gasoline. With the removal of these pollutants and a reduction in atmospheric lead, the associated negative personality effects decreased.
What a Personality Change Means
“One of the important things about personality is that you have your personality everywhere you go,” says Dr. Schwaba. He notes that even small personality changes can have a deep impact on day-to-day interactions. Suggesting that if each little interaction is a bit more negative, someone could have a severely negative life outcome as a result. The personality traits that were changed in response to lead exposure were neuroticism, conscientiousness, and agreeableness. These traits often tie into what we would consider a healthy personality, where someone would function normally in society. Changes in the levels of these personality traits have been linked to aggressive attitudes and violence. Prior research has shown that lead exposure is associated with a higher likelihood of committing crimes, violence, and other delinquent behavior, which is consistent with the current study. Additionally, Dr. Schwaba says, “Conscientiousness is tied really strongly to things like how long you live,” which could be due to a change in how decisions are made. But why might these changes occur? The answer may lie in the brain. Tomas Guilarte, PhD, a neurotoxicologist at Florida International University, says that brain scans have been performed on people who have been exposed to lead. The images show that in these people, some brain areas are smaller than usual, including the frontal lobe, hippocampus, and temporal lobe. The brain areas directly affected by lead exposure are vital for learning, memory, and cognitive functions, including self-control. “Many parts of your life are going to be affected [by lead exposure], the way you make decisions is going to be affected,” says Dr. Guilarte.
The Vulnerable and Underrepresented Are the Most Affected
The use of lead in industry, construction, and recreation has always been damaging, but not always equally so. “You see effects that are making this an issue of social justice where some people are being disproportionately harmed by lead exposure,” says Dr. Schwaba. While historically, the main source of lead exposure was gasoline, since 1970 this has not been the case. Once lead had been removed from gasoline and paint, the areas most affected were often home to those who didn’t have the ability to voice their concerns. “Black children are twice as likely to have high blood levels,” says Dr. Schwaba. Older, inner-city homes are often left with the remnants of lead used in construction prior to the 1970s. Additionally, older metropolitan areas are more likely to have lead pipes that carry the municipal water supply. The combination of these can lead to cognitive and personality issues resulting from exposure. While recent victims of lead exposure have been those in low-income areas, the next wave of lead exposure could also be those most impacted by climate change. Lead from the era of leaded gasoline has found its way into the soil and can have high concentrations in industrial areas. When these areas flood due to climate change in places like Europe and China, the lead is carried with that water. People are then exposed to this lead in the streets, as it seeps into drinking water, and once the runoff goes into agricultural fields. “Climate change could be a big player in the redistribution of contaminants, and not just lead,” says Dr. Guilarte.
There’s Work That Needs to Be Done
While lead issues may seem transient, the effects are long-term and pervasive. Dr. Guilarte notes that there is a tendency for people to forget about the issues lead has had on communities. “This might set little kids growing up in Flint up for worse outcomes 20, 30 years down the road,” says Dr. Schwaba, talking about the water crisis that occurred in Flint, Michigan. The negative outcomes lead exposure has on a community are often not seen until long after a disaster has occurred. Trouble with learning, behavior and mental health issues aren’t necessarily apparent until an exposed child becomes an adult. While there may be hope in the reversal of some adverse reactions, a change in personality is likely life-long. “The magnitude of this study is one of the important things to note, these are not trivial numbers,” Dr. Guilarte says. This study has only worked to highlight the continued need for lead research, assistance, and prevention measures. There is still a need for lead removal and regulation throughout the United States, as well as the rest of the world. There have been no safe levels of lead reported, as even low levels have produced some of the results found in this study. Nothing except a complete removal of lead can ensure the safety of children’s future mental health. Policy regarding an update to infrastructure is needed to renovate old homes with lead paint, remove lead pipes from municipal water supplies, and encourage the cleanup of lead in soil. Dr. Guilarte notes, “This is not an issue of the past, this is an issue of the present, and this is going to remain for many years to come."
