New research finds lead pollution dropped 100-fold over last century

By Stephen Beech

Lead pollution has dropped 100-fold over the last century, reveals new research.

Analysis of human hair samples from today compared to 100 years ago showed a dramatic decline in potentially deadly environmental lead levels.

Lead is a dangerous neurotoxin that accumulates in human tissues and is linked to developmental deficits in children.

The United States and other countries start phasing out lead due to health risks in the 1970s, with the US achieving total elimination for on-road vehicles by 1996.

The UK banned general sale of leaded petrol by early 2000, and the last country, Algeria, stopped sales in July 2021.

Researchers in Utah examined samples of local residents' hair going back a century to document how banning lead in petrol has been a major success in reducing environmental pollution.

Before the establishment of the Environmental Protection Agency (EPA) in 1970, Americans lived in communities awash with lead from industrial sources, paint, water supply pipes and, most significantly, exhaust emissions.

The analysis of hair samples conducted by University of Utah scientists show "precipitous "reductions in lead levels since 1916.

University of Utah Professor Ken Smith said: “We were able to show through our hair samples what the lead concentrations are before and after the establishment of regulations by the EPA.

“We have hair samples spanning about 100 years.

"And back when the regulations were absent, the lead levels were about 100 times higher than they are after the regulations.”

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 lead rules are now being weakened by the Trump administration in a wide-ranging move to ease environmental protections.

Study co-author Professor Thure Cerling said: “We should not forget the lessons of history.

"And the lesson is those regulations have been very important.

“Sometimes they seem onerous and mean that industry can't do exactly what they'd like to do when they want to do it or as quickly as they want to do it.

"But it's had really, really positive effects.”

Lead is the heaviest of heavy metals that, like mercury and arsenic, accumulate in living tissue and are toxic at even low levels.

Lead was added to paint to improve durability, speed up drying, and produce vibrant colours with greater coverage.

Lead also improved the performance of automobile engines by preventing pistons from “knocking.”

By the 1970s its toxicity became well established and EPA regulations began phasing it out of paint, pipes, gasoline and other consumer products.

The research team asked people to provide hair samples, both contemporary and from when they were young.

Some were able to find ancestors’ hair preserved in family scrapbooks dating as far back as a century.

The researchers acquired hair samples from 48 people, offering a window into lead levels along Utah’s Wasatch Front, which historically experienced heavy lead emissions from industrial sources.

Smith said: “The Utah part of this is so interesting because of the way people keep track of their family history.

"I don't know that you could do this in New York or Florida."

He explained that the Utah region supported a vibrant smelting industry through most of the 20th Century.

Most of Utah’s smelters were shut down by the 1970s, around the same time the EPA clamped down on the use of lead in consumer products.

The research team ran the hair samples through mass spectrometry equipment.

Research team member Professor Diego Fernandez said: “The surface of the hair is special.

"We can tell that some elements get concentrated and accumulated in the surface. Lead is one of those.

"That makes it easier because lead is not lost over time."

He added: “Because mass spectrometry is very sensitive, we can do it with one hair strand, though we cannot tell where the lead is in the hair.

"It's probably in the surface mostly, but it could be also coming from the blood if that hair was synthesised when there was high lead in the blood.”

Cerling said: “It doesn't really record that internal blood concentration that your brain is seeing, but it tells you about that overall environmental exposure.

“One of the things that we found is that hair records that original value, but then the longer the hair has been exposed to the environment, the higher the lead concentrations are.”

The team’s findings regarding lead in hair run parallel to the reductions of lead in petrol following the EPA’s establishment by President Richard Nixon.

For example, before 1970 gasolines contained around two grams of lead per gallon.

Considering the billions of gallons of fuel American cars burn each year, it added up to nearly two pounds of lead released into the environment per person a year.

Cerling added: "It's an enormous amount of lead that's being put into the environment and quite locally.

“It's just coming out of the tailpipe, goes up in the air and then it comes down.

"It's in the air for a number of days, especially during the inversions that we have and it absorbs into your hair, you breathe it and it goes into your lungs.”

But the study showed that after 1970s, even as fuel consumption escalated in the United States, the concentrations of lead in the hair samples plummeted, from as high as 100 parts per million (ppm) to 10 ppm by 1990. In 2024, the level was less than one ppm.