Lead was added to gasoline in 1923 to keep car engines healthy. Our own health and well-being came at the expense of automotive health.
A new study shows that exposure to car exhaust from leaded gas as a child stole a collective 832 million IQ points from more than 170 million Americans today.
According to findings from a PhD candidate in clinical psychology at Duke University and colleagues at Florida State University, Americans born before 1996 may be at greater risk for lead-related health problems. The use of lead gas for cars was banned in the U.S. in 1996, but the researchers say that anyone born before that time had high lead exposure.
The paper was published in the journal on March 7.
Lead can cause damage to brain cells after it enters the body. Health experts say there is no safe level of exposure. Young children are particularly vulnerable to the effects of lead on brain development. Our brains are not good enough to keep it at bay.
Lead can reach the bloodstream if it is swallowed, eaten, or consumed in water.
Lead was used to invade bloodstreams through automotive exhaust.
To answer the complex question of how leaded gas use for more than 70 years may have left a permanent mark on human health, the authors decided to use a simple strategy.
They used publicly available data on childhood blood-lead levels, leaded-gas use, and population statistics to calculate the lifetime burden of lead exposure carried by every American alive in 2015. They calculated IQ points lost from leaded gas exposure as a proxy for its harmful impact on public health from this data.
The researchers were shocked by the results.
I was shocked even though I was prepared for it.
More than half of the US population had clinically concerning levels of lead in their blood when they were children, putting them at higher risk for other long-term health impairments.
Leaded gasoline consumption peaked in the 1970s. Everyone born during those two decades is most likely to have been exposed to levels of lead from car exhaust.
The toll on intelligence may have been caused by childhood lead exposure, which may have hurt America's IQ score by an estimated 825 million points. The researchers calculated that people born in the late 1960s may have lost up to six IQ points, and children with the highest levels of lead in their blood, could potentially lose more than that.
The authors note that dropping a few IQ points could potentially shift people with below average cognitive ability to being classified as having an intellectual disability.
Black children were exposed to lead at a higher rate than white children, and this led to health inequalities.
The next step will be to examine the long-term consequences of past lead exposure on brain health in old age, based on previous findings that adults with high childhood lead exposure may experience accelerated brain aging.
Millions of us are walking around with a history of lead exposure. It appears to be an insult carried in the body in different ways that we are still trying to understand but that can have implications for life.
The story was told
Duke University provided the materials. Dan Vahaba wrote the original. Content can be edited for style and length.
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