Lead pollution today compared to 100 years ago has dramatically declined—by 100-fold over the last century—according to new research.
Lead is a dangerous neurotoxin that accumulates in human tissues and is linked to developmental deficits in children. Due to the health risks, the United States and other countries start phasing out lead in the 1970s, with the US achieving total elimination for on-road vehicles by 1996.
The UK followed, banning general sale of leaded auto fuel by early 2000—and the last country, Algeria, stopped sales in July 2021.
Researchers examined hair samples from local residents going back a century to document how banning lead in gasoline has been a major success in reducing environmental pollution.
Before the 1970 establishment of the EPA, the Environmental Protection Agency, Americans lived in communities awash with lead from industrial smokestacks, paint, water pipes, and—most significantly—exhaust emissions.
The analysis of hair samples conducted by scientists at the University of Utah show “precipitous” reductions in lead levels since 1916.
“We were able to show through our hair samples what the lead concentrations were before and after the establishment of regulations by the EPA,” said University of Utah Professor Ken Smith.
“Back when the regulations were absent, the lead levels were about 100 times higher than they were after the regulations.”
The study showed that after the Nixon administration banned lead in gasoline in the 1970s, even as fuel consumption escalated in the US, the concentrations of lead in the hair samples plummeted, from as high as 100 parts per million (ppm) to 10 ppm by 1990.
And in 2024, the level was less than one part per million.
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He says the findings, published in the journal Proceedings of the National Academy of Sciences (PNAS), underline the vital role of environmental regulations in protecting public health.
The study notes that US lead laws are now being weakened by a White House administration moving to ease environmental protections.
“The lesson is: those regulations have been very important,” said study co-author Professor Thure Cerling.
“Sometimes they seem onerous and mean that industry can’t do exactly what they’d like to do when they want to do it, but it’s had really, really positive effects.”
Lead is the heaviest of heavy metals and, like mercury and arsenic, accumulate in living tissue, and are toxic at even low levels. By the 1970s its toxicity became well established and EPA regulations began phasing it out of paint, pipes, gasoline and other consumer products.
The researchers acquired multiple hair samples from 48 participants—both recent and when they were younger—which offered a window into lead levels along Utah’s ‘Wasatch Front’, which historically experienced heavy lead emissions from industrial sources.
Some participants were even able to find ancestors’ hair preserved in family scrapbooks dating as far back as a century.
“The Utah part of this is so interesting because of the way people keep track of their family history,” said Prof. Smith.
“I don’t know that you could do this in New York or Florida.”
He explained that this particular Utah region supported a vibrant metal smelting industry through most of the 20th Century. Most of Utah’s smelters were shut down by the 1970s, after the EPA clamped down on the use of lead in consumer products.
The research team ran the hair samples through mass spectrometry equipment and says the surface of the hair is special.
“Lead is not lost over time,” said research team member Professor Diego Fernandez. “It is concentrated and accumulated in the surface. It tells you about that overall environmental exposure.”
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Before the 1970s, gasoline contained around two grams of lead per gallon, which added up to nearly two pounds of lead per person a year released into the environment.
“It’s in the air for a number of days and it absorbs into your hair. You breathe it and it goes into your lungs,” explained Prof. Cerling.
But, thanks to federal regulations, the median blood lead level today in children, aged 1–5 years, fell from over 15 in the late 1970s to just 0.6 in 2020.
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