WHY AMERICANS ARE DUMB
Half of US adults exposed to harmful lead levels as kidsBY DREW COSTLEY
This Sept. 13, 1979, file photo shows motorists as downtown parking lots fill up in Los Angeles. Over 170 million of people born in the United States who were adults in 2015 were exposed to harmful levels of lead as children, according to a study published in the Proceedings of the National Academy of Sciences on Monday, March 7, 2022. The researchers looked only at lead exposure caused by leaded gasoline, the dominant form of lead exposure from the 1940s to the late 1980s, according to data from the U.S. Geological Survey. (AP Photo/Wally Fong, File)
Over 170 million U.S.-born people who were adults in 2015 were exposed to harmful levels of lead as children, a new study estimates.
Researchers used blood-lead level, census and leaded gasoline consumption data to examine how widespread early childhood lead exposure was in the country between 1940 and 2015.
In a paper published in the Proceedings of the National Academy of Sciences on Monday, they estimated that half the U.S. adult population in 2015 had been exposed to lead levels surpassing five micrograms per deciliter — the Centers for Disease Control and Prevention threshold for harmful lead exposure at the time.
The scientists from Florida State University and Duke University also found that 90% of children born in the U.S. between 1950 and 1981 had blood-lead levels higher than the CDC threshold. And the researchers found significant impact on cognitive development: on average, early childhood exposure to lead resulted in a 2.6-point drop in IQ.
The researchers only examined lead exposure caused by leaded gasoline, the dominant form of exposure from the 1940s to the late 1980s, according to data from the U.S. Geological Survey. Leaded gasoline for on-road vehicles was phased out starting in the 1970s, then finally banned in 1996.
Study lead author Michael McFarland, an associate professor of sociology at Florida State University, said the findings were “infuriating” because it was long known that lead exposure was harmful, based on anecdotal evidence of lead’s health impacts throughout history.
Though the U.S. has implemented tougher regulations to protect Americans from lead poisoning in recent decades, the public health impacts of exposure could last for several decades, experts told the Associated Press.
“Childhood lead exposure is not just here and now. It’s going to impact your lifelong health,” said Abheet Solomon, a senior program manager at the United Nations Children’s Fund.
Early childhood lead exposure is known to have many impacts on cognitive development, but it also increases risk for developing hypertension and heart disease, experts said.
“I think the connection to IQ is larger than we thought and it’s startlingly large,” said Ted Schwaba, a researcher at University of Texas-Austin who studies personality psychology and was not part of the new study.
Schwaba said the study’s use of an average to represent the cognitive impacts of lead exposure could result in an overestimation of impacts on some people and underestimation in others.
Previous research on the relationship between lead exposure and IQ found a similar impact, though over a shorter study period.
Bruce Lanphear, a health sciences professor at Simon Fraser University in Vancouver who has researched lead exposure and IQ, said his 2005 study found the initial exposure to lead was the most harmful when it comes to loss of cognitive ability as measured by IQ.
“The more tragic part is that we keep making the same ... mistakes again,” Lanphear said. “First it was lead, then it was air pollution. ... Now it’s PFAS chemicals and phthalates (chemicals used to make plastics more durable). And it keeps going on and on.
“And we can’t stop long enough to ask ourselves should we be regulating chemicals differently,” he said.
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Follow Drew Costley on Twitter: @drewcostley.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
Lead from gasoline blunted the IQ of about half the U.S. population, study says
Leaded gas was banned in 1996, but exposure to the toxin cost people born before then several IQ points on average, researchers estimated.
Lead can be inhaled or ingested, with children particularly susceptible to its poisonous effects. Children’s blood lead levels have been dramatically lowered in the U.S. in recent decades, but lead exposure still happens, and Black children are exposed more often than white children. Monday’s study, too, estimated that most Black adults under age 45 experienced “considerably higher” levels of blood lead levels in early life than their white counterparts.
The racial disparities are generally due to environmental contamination and infrastructure issues that affect drinking water in low-income and minority neighborhoods, with the water crisis in Flint, Michigan, one of the most egregious examples in recent years.
And while children are the most vulnerable to getting very ill from lead, the toxin’s damage can show up years later, Park said. Lead exposure is believed to put people at risk for chronic and age-related diseases, including cardiovascular disease and dementia.
“Lead is a never-ending story,” he said.
There are medical interventions available for children who have recently been exposed to high amounts of lead, but those wouldn’t work for adults born before 1996. Still, the study findings should not be a major cause for concern, McFarland said.
“There are a host of things that go into IQ,” he said. “This is one that is obviously negative, but if you also have a nurturing home environment, that helped your IQ.”
Leaded gas was banned in 1996, but exposure to the toxin cost people born before then several IQ points on average, researchers estimated.
A sign on a vintage gasoline pump advises that the gas contains lead at an antique shop in Nashville on Sept. 3, 2019.
Robert Alexander / Getty Images file
March 7, 2022,
By Elizabeth Chuck
Exposure to leaded gasoline lowered the IQ of about half the population of the United States, a new study estimates.
The peer-reviewed study, published Monday in the journal Proceedings of the National Academy of Sciences, focuses on people born before 1996 — the year the U.S. banned gas containing lead.
Overall, the researchers from Florida State University and Duke University found, childhood lead exposure cost America an estimated 824 million points, or 2.6 points per person on average.
Certain cohorts were more affected than others. For people born in the 1960s and the 1970s, when leaded gas consumption was skyrocketing, the IQ loss was estimated to be up to 6 points and for some, more than 7 points. Exposure to it came primarily from inhaling auto exhaust.
The team behind the study used gas consumption data, population estimates and other data to calculate that as of 2015, more than 170 million Americans had had blood lead levels above 5 micrograms per deciliter in their early childhood years.
Lead is a neurotoxin, and no amount of it is safe. Currently, 3.5 micrograms per deciliter is the reference value for blood lead levels to be considered high; the acceptable amount was once higher.
Principal study author Michael McFarland, an associate professor of sociology at Florida State University and a faculty member of the university’s Center for Demography and Population Health, called the number of people affected by lead exposure “staggering.”
“This is important because we often think about lead as an issue for children, and of course it is,” he said. “But what we really wanted to know is what happens to those children who were exposed?”
In many cases, McFarland said, a 2 to 3 point IQ difference is nominal, unless an individual is on the lower side of IQ distribution.
“If you’re more toward cognitive impairment, a couple points can mean a lot,” he said.
But on a population basis, shifting the average IQ down even a small amount could have large consequences, said Sung Kyun Park, an associate professor of epidemiology and environmental health sciences at the University of Michigan School of Public Health. The entire bell curve shifts, he explained, with more of the population at what was once the extreme low end of IQ scores.
Lead used to be added to gasoline to help engines run more smoothly until other, safer additives replaced it. In addition to being linked to lower IQs, it has also been associated with heart and kidney disease.
Flint Children Tested For Lead JAN. 27, 2016 01:08
March 7, 2022,
By Elizabeth Chuck
Exposure to leaded gasoline lowered the IQ of about half the population of the United States, a new study estimates.
The peer-reviewed study, published Monday in the journal Proceedings of the National Academy of Sciences, focuses on people born before 1996 — the year the U.S. banned gas containing lead.
Overall, the researchers from Florida State University and Duke University found, childhood lead exposure cost America an estimated 824 million points, or 2.6 points per person on average.
Certain cohorts were more affected than others. For people born in the 1960s and the 1970s, when leaded gas consumption was skyrocketing, the IQ loss was estimated to be up to 6 points and for some, more than 7 points. Exposure to it came primarily from inhaling auto exhaust.
The team behind the study used gas consumption data, population estimates and other data to calculate that as of 2015, more than 170 million Americans had had blood lead levels above 5 micrograms per deciliter in their early childhood years.
Lead is a neurotoxin, and no amount of it is safe. Currently, 3.5 micrograms per deciliter is the reference value for blood lead levels to be considered high; the acceptable amount was once higher.
Principal study author Michael McFarland, an associate professor of sociology at Florida State University and a faculty member of the university’s Center for Demography and Population Health, called the number of people affected by lead exposure “staggering.”
“This is important because we often think about lead as an issue for children, and of course it is,” he said. “But what we really wanted to know is what happens to those children who were exposed?”
In many cases, McFarland said, a 2 to 3 point IQ difference is nominal, unless an individual is on the lower side of IQ distribution.
“If you’re more toward cognitive impairment, a couple points can mean a lot,” he said.
But on a population basis, shifting the average IQ down even a small amount could have large consequences, said Sung Kyun Park, an associate professor of epidemiology and environmental health sciences at the University of Michigan School of Public Health. The entire bell curve shifts, he explained, with more of the population at what was once the extreme low end of IQ scores.
Lead used to be added to gasoline to help engines run more smoothly until other, safer additives replaced it. In addition to being linked to lower IQs, it has also been associated with heart and kidney disease.
Flint Children Tested For Lead JAN. 27, 2016 01:08
Lead can be inhaled or ingested, with children particularly susceptible to its poisonous effects. Children’s blood lead levels have been dramatically lowered in the U.S. in recent decades, but lead exposure still happens, and Black children are exposed more often than white children. Monday’s study, too, estimated that most Black adults under age 45 experienced “considerably higher” levels of blood lead levels in early life than their white counterparts.
The racial disparities are generally due to environmental contamination and infrastructure issues that affect drinking water in low-income and minority neighborhoods, with the water crisis in Flint, Michigan, one of the most egregious examples in recent years.
And while children are the most vulnerable to getting very ill from lead, the toxin’s damage can show up years later, Park said. Lead exposure is believed to put people at risk for chronic and age-related diseases, including cardiovascular disease and dementia.
“Lead is a never-ending story,” he said.
There are medical interventions available for children who have recently been exposed to high amounts of lead, but those wouldn’t work for adults born before 1996. Still, the study findings should not be a major cause for concern, McFarland said.
“There are a host of things that go into IQ,” he said. “This is one that is obviously negative, but if you also have a nurturing home environment, that helped your IQ.”
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