Car Exhaust Lowered Our Collective IQ and May Have Done Even More Harm

Lead was added to gasoline in 1923 and banned from use in gas in the US in 1996.

It is now well known that lead is neurotoxic and can have harmful effects on human health. 170 million Americans, about half the population alive today, may have lost some IQ points due to exposure to leaded gas in car exhaust.

New research looks at how exposure to this lead from air pollution may have impacted people born between 1960 and 1996. The study looked at the available US data on childhood blood lead levels, leaded gas use, and population statistics. They determined the likely lifelong burdens of lead exposure and estimated the lead’s effect on public health by calculating IQ points lost from leaded gas exposure.

The findings:

  • More than 170 million Americans had concerning lead levels in their blood when they were children.
  • Lead exposure may have lowered the overall IQ of Americans by 3 points on average and for those with the highest levels of lead in their blood up to 7 points. These few points could make the difference between being classified as having a below-average IQ score or an intellectual disability.
  • The authors believe that people born before 1996 who are alive today may have higher risks for lead-related health problems such as reduced brain size, the likelihood of mental illness, and increased cardiovascular disease.

The takeaway:

Environmental toxins can seriously impact the health of millions of people. This study shows how one type of toxic metal potentially did just that for decades. Co-author of the study, Aaron Reuben, believes, “It appears to be an insult carried in the body in different ways that we’re still trying to understand, but that can have implications for life.” The research team plans to dig deeper into the long-term consequences of past lead exposure on brain health.

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