Lingering Mental Health Impact of 20th Century Lead Exposure

 A recent study found that exposure to leaded gas from car exhaust during childhood altered the mental health balance in the US, raising the risk of anxiety, depression, and inattention or hyperactivity in later generations of Americans. 

The report claims that over the past 75 years, lead exposure in children in America has resulted in 151 million cases of mental illnesses. Aaron Reuben, a postdoctoral scholar in neuropsychology at Duke University, and colleagues at Florida State University found that Americans born before 1996 were significantly more likely to experience mental health problems as a result of lead exposure. They also likely experienced personality changes that would have made it more difficult for them to succeed and recover in life.

The researchers assert that infants born before 1996, especially those born in the 1960s and 1970s, were exposed to dangerously high levels of lead, notwithstanding the United States' 1996 ban on leaded gasoline for automobiles. The Journal of Child Psychology and Psychiatry will publish the team's work the week of December 4. Because lead is neurotoxic, it can alter brain function and harm brain tissue once it enters the body. Therefore, there is no safe exposure level at any stage of life, according to medical experts. Young children are especially vulnerable to the detrimental effects of lead on their health and brain development. 

Unfortunately, regardless of age, our brains are not designed to protect lead poisoning. Because lead pipes are still found in the water systems of older American cities, the EPA issued regulations in October that allow localities 10 years and $2.6 billion to identify and fix lead plumbing. Since the EPA lowered the quantity of lead in soil it considers potentially hazardous earlier this year, an estimated 1 in 4 American households had soil that might need to be cleaned up.

"Humans are not adapted to be exposed to lead at the levels we have been exposed to over the past century," Reuben said. "We have very few effective measures for dealing with lead once it is in the body, and many of us have been exposed to levels 1,000 to 10,000 times more than what is natural."

Over the past century, lead has been used in paint, pipes, solder, and—most tragically—automotive gasoline. Numerous studies have linked lead exposure to neurodevelopmental and mental health problems, including conduct disorder, depression, and attention-deficit/hyperactivity disorder. The severity of the mental health issues linked to lead exposure has not yet been established, though.

In order to answer the complex issue of how utilizing leaded gas for more than 75 years would have permanently changed human behavior, Reuben and his co-authors, Michael McFarland and Mathew Hauer, professors of sociology at Florida State University, looked to nationally accessible data. Using historical data on leaded gas use, childhood blood lead levels, and demographic statistics, they determined the lifetime burden of lead exposure that each American alive in 2015 carried. Using this data, they estimated the attack of lead on personality and mental health by calculating "mental illness points" acquired by exposure to leaded gas as a proxy for the harmful effects of lead on public health.

Lead's effects on brain function have also been linked to personality changes that show up nationally. "We estimate a shift in neuroticism and conscientiousness at the population level," said McFarland.

More than half of Americans, or more than 170 million people, had blood lead levels that were clinically alarming when they were youngsters as of 2015. In addition to an increased risk of other long-term health impairments including cardiovascular disease, this probably resulted in lower IQs and greater mental health problems. Leaded gasoline use increased dramatically in the early 1960s and peaked in the 1970s. As a result, Reuben and his colleagues found that nearly everyone born during those two decades was most likely exposed to dangerously high levels of lead from automobile exhaust. The generation most exposed to lead, Generation X (1965–1980), would have suffered the greatest losses in mental health. 

"We are coming to understand that lead exposures from the past -- even decades in the past -- can influence our health today," Reuben said. "Our job moving forward will be to better understand the role lead has played in the health of our country, and to make sure we protect today's children from new lead exposures wherever they occur."

Source:

Duke University. "20th century lead exposure damaged American mental health." ScienceDaily. ScienceDaily, 4 December 2024. 241204114237.htm>.

Image: WNCTimes