Health experts say the effects of leaded gasoline in cars, although banned since 1996, still persist today after a new study found that Americans exposed to this highly toxic metal could have a lower IQ.
Researchers from Duke University and Florida State University analyzed publicly available data on American children’s blood lead levels, lead gas use and demographic statistics and determined the likely burden of lead exposure throughout the lifetime of every American living in 2015.
They found that more than 170 million Americans – more than half of the US population – had “clinically concerning” blood lead levels as children, according to the study published Monday in Proceedings of the National Academy of Sciences.
They estimated that this level of lead exposure may have lowered a person’s IQ by an average of three points, or a total of about 824 million points among all Americans exposed to lead.
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“I was frankly shocked,” said co-author Michael McFarland, a sociology professor at Florida State University. “And when I look at the numbers, I’m still shocked even though I’m preparing for it.”
Lead is a nerve metal that can erode brain cells after entering the body, according to health experts. There is no safe level of lead exposure, and children are particularly vulnerable to impaired brain development.
The current blood lead value that would trigger clinical concerns and case management is 3.5 micrograms per deciliter, said the study’s lead author, Aaron Reuben, doctoral candidate in clinical psychology at the Duke University.
“We found that over 4.5 million Americans had levels over 30 to 10 times what is considered alarming,” he said.
Previous studies have found a strong association between blood lead levels and IQ, the study authors said, but few have attempted to measure this impact.
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Researchers say anyone born before the leaded gasoline ban in 1996 may have suffered the cognitive consequences of lead exposure. At worst, people born during the peak of leaded gasoline use in the 1960s and 1970s may have lost up to seven IQ points.
“The problem with health is that it often takes a long time for health to show exposure,” said Hannes Schwandt, a human development and social policy expert and professor at Northwestern University, who doesn’t did not participate in the study. “It’s not like you’re exposed to lead and the next day the problem shows up. It resurfaces throughout people’s lives.
Although the study demonstrates the impacts of average exposure, he said, not all Americans are exposed to the same level of lead. Children from vulnerable communities who live near busy streets and highways are more likely to be exposed and affected by the toxic metal. Schwandt hopes that future studies of lead and other pollutants will take a closer look at this population.
Reuben says it’s important for patients and their doctors to understand the potential consequences of lead exposure because it can affect half the country.
“It’s hard to know if you’re one of those Americans, but if you grew up around lead emissions, you might just take a proactive approach,” he said. “Let your primary care physician know this is a concern and may warrant further monitoring for conditions that may arise later in life.”
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Cars haven’t used leaded gasoline for more than 26 years, but health experts say children today are still suffering harm from lead exposure.
Lead is still used in aviation fuel for some planes, Reuben said, and children can also be exposed to lead paint and contaminated water.
“We are documenting a history of issues, but this is by no means a historical issue. It’s very current,” he said.
“It’s not cheap to replace lead service lines, it’s not easy to provide requirements for fuel change. But studies like ours add to the weight of evidence that whatever the cost of removing lead from our communities…the benefits are far greater.
Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.
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