Children who grew up exposed to high levels of lead are more prone to suffer from mental health issues later in life, according to a new study out of Duke University.
While previous studies have explored the impacts of lead exposure on intelligence, the latest research, published this week in the journal JAMA Psychiatry, was a look into the impact of lead exposure in children on long-term personality and mental health. Researchers found that the more lead in a person’s blood at age 11 has some correlation with heightened chances of showing signs of mental illness by the time they are 38 years old.
“Lead exposure decades ago may be harming the mental health of people today who are in their 40s and 50s,” the researchers said in a statement.
The link between the heavy metal and mental health is modestly strong, the researchers noted in the study, emphasizing the need for more studies. Still, they contend that evidence of a link is strong enough to continue taking steps to remove lead from common, day-to-day-to-day sources. Today, exposure to lead most notably comes from older buildings with lead paint on the walls and in places that are still outfitted with lead-based plumbing (here’s a guide on how people can approach responsible filtration). But back in the early 1960s through the 1980s, high-in-lead gasoline was the main contributor, coming into contact with people through automotive exhaust that was released into the air and into the soil.
The research involved following 579 people—born between April 1972 and April 1973—for decades. The group, who all lived in living in Dunedin, New Zealand, spanned the full range of socioeconomic statuses. Blood samples were collected 11 times throughout their lives, including at birth and when they were 38 years old. Those samples were then analyzed through a method called “graphite furnace atomic absorption spectrophotometry,” which is a fancy way of saying it was vaporized to make it easier for the researchers to measure the elements (including lead) within it.
The scientists also tested participants’ mental health and personality throughout their lives, looking for 11 psychiatric disorders:
- dependence on alcohol, cannabis, tobacco, or hard drugs
- conduct disorder
- major depression
- generalized anxiety disorder
- fears and phobias
- obsessive-compulsive disorder
The researchers write in the study that the results “suggest that early-life lead exposure in the era of leaded gasoline experienced by individuals who are currently adults may have contributed to subtle, lifelong differences in emotion and behavior.”
Past research has come to similar conclusions. One study based out of Cincinnati, Ohio in 2001, for instance, found that young adults who had high exposures to lead as children were more likely to display psychological traits that included impulsivity and egocentricity—traits that ultimately impact a person’s ability to regulate their emotions.
There are limitations to the latest study. The group of people tested in the New Zealand cohort were predominantly white, for example, and the level of lead exposure in New Zealand in the 1970s and 1980s was generally higher than in many other developed nations. Still, the work should be of interest to public health officials in America and Europe, places that were also using leaded gasoline at about the same levels around the same time.