Widespread Childhood Lead Exposure from Car Exhaust Affects Gen X IQs
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The Impact of Leaded Gasoline on Gen X IQ
Recent research has unveiled alarming findings regarding the effects of lead exposure from car exhaust on the cognitive abilities of Generation X. A study published on March 7 in the Proceedings of the National Academy of Sciences by researchers from Duke University and Florida State University reveals that childhood contact with leaded gasoline has collectively cost over 170 million Americans approximately 824 million IQ points.
Although the United States prohibited the use of leaded gasoline in 1996, the repercussions of exposure linger, particularly for individuals born during the 1960s and 1970s. Those generations might face heightened risks of health issues linked to lead, including diminished brain volume, increased chances of mental health disorders, and a higher likelihood of cardiovascular diseases in later life.
Lead Exposure and Its Neurotoxic Effects
Historically, automotive exhaust was a primary source of lead exposure. The neurotoxic properties of lead indicate that no level of exposure is deemed safe, especially for young children, who are particularly vulnerable to cognitive impairments and developmental hindrances. The use of leaded gasoline peaked in the U.S. during the 1960s and 1970s, ensuring that many individuals born in those decades faced significant childhood exposure to harmful lead levels from car emissions.
Incredibly, this exposure could have led to an average IQ reduction of nearly three points per person. For those born between the mid-1960s and mid-1970s, the average decline could reach nearly six IQ points. Among children during this time who exhibited the highest blood lead levels—eight times above the current clinical concern threshold—the potential IQ loss could soar to almost seven and a half points.
Even slight declines in IQ can significantly affect an individual's educational and career success, as well as their overall well-being. Despite people born after the ban experiencing lower lead exposure than previous generations, current lead levels in children still exceed those of preindustrial ancestors. Numerous regions in the U.S. continue to grapple with legacy lead issues similar to those highlighted in Flint, Michigan, due to its water crisis.
Long-Term Consequences and Future Research
“Millions of us carry a history of lead exposure,” stated Aaron Reuben, a co-author of the study and a Ph.D. candidate in clinical psychology at Duke University. “This isn’t akin to a car accident where a rotator cuff injury heals, leaving you fine afterward. It seems to be a lasting impact, manifesting in various ways that we are still striving to comprehend, with potential life implications.”
Future studies will focus on racial disparities in childhood lead exposure and the long-term effects of past lead exposure on brain health as individuals age.