Childhood Lead Exposure From Car Exhaust May Have Led to Greater Numbers of Mental Disorders: Study

Routine exposure to air pollution from leaded gasoline exhaust as children between the 1940s and 1990s may have contributed to more than 150 million mental health diagnoses in the U.S., according to the findings of a new study.

Lead is a toxic heavy metal that can cause many long-term health consequences. Childhood lead exposure is now known to change the brain’s structural integrity later in life, increasing the risk of attention deficit hyperactivity disorder (ADHD), as well as impaired learning and lower test scores.

Although lead was banned from gasoline in the U.S. in 1996, more than half of the current U.S. population had already been exposed to the heavy metal through car exhaust from leaded gasoline, which had been in use for decades.

In findings published in The Journal of Child Psychology and Psychiatry on December 4, researchers from Florida State University showed that exposure to lead from car exhaust may be responsible for causing greater rates of depression, anxiety, ADHD and other mental health conditions among millions of American adults.

A team of researchers, led by Dr. Michael J. McFarland, used blood-lead data from National Health and Nutrition Examination Surveys, and compared that information with historic leaded-gasoline data to estimate childhood blood lead levels from 1940 to 2015. They also used the same data to calculate mental health symptoms.

The study focused on overall mental health disorders, internalizing disorders like anxiety, depression, and ADHD, as well as differences in personality traits like neuroticism and conscientiousness.

McFarland’s findings indicate that more than 151 million excess mental health disorders could be linked to childhood exposure to lead from car exhaust.

Americans born between 1966 and 1986 had the highest number of mental health conditions or symptoms, according to the researchers, with Gen Xers born from 1966 to 1970 facing the greatest burden overall. Considering that the use of leaded gasoline peaked from the mid-1960s to the mid-1970s, that finding fits the data.

“Lead’s potential contribution to psychiatry, medicine, and children’s health may be larger than previously assumed,” McFarland said.

Lead Poisoning Risks for Children

As more information has been learned in recent decades about the long-term health risks of lead exposure, particularly among children with developing brains, the American Academy of Pediatrics now warns that there is no safe level of lead exposure for children. Therefore, there has been substantial effort in recent years to reduce levels of childhood lead exposure.

Although leaded gasoline was phased out in the mid-1990s, the heavy metal is still present in many consumer products, including toxic lead-based paint that is still found in many older homes and poses a particularly high risk if the paint chips or falls off the wall.

Many homes across the U.S. also have lead-tainted water service lines, which continue to pose serious health risks for a new generation of Americans. The risks posed by older lead pipes was highlighted with the Flint, Michigan water crisis, which is believed to have exposed between 6,000 and 14,000 children to toxic levels of lead.

In more recent years, a number of children’s toys imported from other countries have also been found to contain dangerous levels of lead, and some food products have also been tainted with the toxic metal.

Earlier this year, more than 500 reports of lead poisoning among children were linked to the widespread use of lead-tainted cinnamon in several popular applesauce products distributed throughout the U.S.