The toxic metal lead casts a long shadow on our collective well-being. A new study published Wednesday shows that exposure to lead in the 20th century significantly worsened Americans’ brain health and may have caused more mental illnesses than they would have otherwise. It shows.
Scientists from Duke University and Florida State University conducted this study based on previous research on the effects of lead on our health. They found that childhood exposure to lead, particularly during the decades when lead was most commonly found in gasoline, directly contributed to 151 million more cases of mental illness in Americans over the past 75 years. estimated. The results of this study show that lead is even more dangerous to humans than we thought.
Automakers began adding lead to gasoline in the 1920s to reduce engine wear. Leaded gasoline eventually became the single largest source of lead exposure for Americans, peaking in the 1960s. But while scientists have long known that large exposures to lead are bad for you, by the 1970s they realized that even small amounts of lead could be harmful, especially to the developing brains of children. One thing has been firmly established.
It would take several more decades for lead to be completely phased out from gasoline (1996 in the US). 2020 However, it does not include (for all countries in the world) and other general products. Now, scientists, including those behind this latest study, hope to quantify the subtle but meaningful health effects of lead, a constant presence in people’s lives throughout the 20th century. I’m still trying.
An earlier study conducted by the research team in 2022 found that, based on census data and known levels of leaded gasoline use in the country, about half of all Americans alive in 2015 had harmful levels of gasoline use during childhood. It is estimated that there is a high possibility that they were exposed to lead. Furthermore, they estimated that this lead exposure lowered Americans’ IQ by 824 million points overall, or about 3 points per person (those born in the 1960s may have experienced a drop of up to 6 points). ).
In a new study, researchers decided to examine the toll of lead on mental health. They used previous data on Americans’ collective lead exposure to estimate how much lead is needed to increase the risk of various mental illnesses, including schizophrenia, depression, and attention-deficit hyperactivity disorder. Cross-referenced with other data. From there, they created a proxy score for Americans’ vulnerability to mental illness, which they quantified as “general psychopathology factor” points.
Overall, they estimated that exposure to lead, particularly leaded gasoline during the peak period, added an additional 602 million points of vulnerability to Americans living in 2015. More practically, they estimated that lead was directly involved in causing an additional 151 million mental disorders. . The largest lead-related increases were seen in symptoms of anxiety, depression, and ADHD.
“Childhood lead exposure has likely made an underappreciated but significant contribution to mental illness in the United States over the past century,” the researchers wrote in their paper. published Wednesday’s Journal of Child Psychology and Psychiatry.
Ultimately, these findings only estimate how harmful lead is to our mental health, but this is not the first study to blame lead for widespread effects on the population. there is no. In other studies, found the evidence For example, rising lead levels are thought to have increased people’s propensity for violent, antisocial behavior and contributed to rising crime rates in the 20th century. And given that there is no truly safe lead exposure level, researchers say their calculations may still be underestimating how bad lead is for our brains. states.
Thankfully, lead levels in the environment are now much lower than they were in the 1960s. However, there are still areas of the country where levels are higher than normal, and there are areas where lead exposure occurs, such as damaged water systems (common during the Flint water crisis) and older homes built before 1978. There are also sources that can cause acute clusters due to an increase in To remove paint.
According to the Centers for Disease Control and Prevention, about 2.5% of children between the ages of 1 and 5 significantly higher level They have lead in their blood. And there are many parts of the world where lead regulations are much more lax. The researchers cite Recent data from the United Nations It is estimated that approximately 800 million children, one-third of the world’s population, are currently exposed to high levels of lead.
Of course, there is no doubt that there are many people alive today who suffer from lead-induced mental illness that would not have happened in a better world (and of course their families and caregivers who are also affected). (similar). So, while the worst of lead may be over, its effects will continue to be felt for a long time to come.
