According to a new study, childhood lead exposure in the United States is widespread and far more alarming than earlier estimates have shown.
Researchers discovered that more than 54% of Americans alive in 2015 had been exposed to harmful levels of lead as youngsters after combining data on leaded gas consumption from 1940 with data on blood-lead levels from the mid-1970s.
Because of the lead they breathed in, ingested, or absorbed as children, more than 170 million individuals are now at risk of neurological disease, mental illness, and cardiovascular problems.
There is no safe level of lead exposure at any point in a person's life, but this highly poisonous metal can be especially harmful to youngsters since it can hinder brain development, leading to lasting learning disabilities and behavioral concerns.
Overall, researchers believe that leaded gas has decreased the nation's IQ by 824 million points, or about three points per person.
And that is only the average. Those born in the 1960s and 1970s, when leaded gas usage was at its pinnacle, may have lost six to seven IQ points on average. The cohort's lead exposure was eight times higher than today's health standards.
Most people aren't aware of these effects, but some individuals with lower-than-average cognitive ability may be diagnosed with intellectual disability as a result.
"I frankly was shocked," sociologist Michael McFarland from Florida State University (FSU) said. "And when I look at the numbers, I'm still shocked even though I'm prepared for it."
Childhood lead exposure has significantly decreased since the U.S. government prohibited leaded gasoline for automobiles in 1996. Nonetheless, many Americans are still alive today who are suffering from the consequences of their upbringing.
Children born after 1996 had lower blood-lead levels than their parents and grandparents, but their lead exposure is still substantially higher when compared to generations before the preindustrial era.
Furthermore, hundreds of towns in the U.S., such as Flint, Michigan, continue to suffer from the nation's heritage of unrestricted lead usage, with racial disparities that are severe.
For example, Black individuals over the age of 45 were found to have much higher blood-lead levels than White adults, and this was true even for those born after 1996.
The study's authors are now looking into the long-term effects of that exposure and if they can explain racial disparities in health outcomes such as renal disease, coronary heart disease, and dementia.
The study was published in PNAS.
