EPA regulations cut lead exposure shown by Utah family hair samples

Family hair samples trace lead exposure

Hair kept in family scrapbooks over the last century has demonstrated how effectively the US Environmental Protection Agency (EPA) has reduced lead pollution since the 1970s.

Measures that removed lead from goods including paint, pipes and petrol have sharply lowered people's exposure to this neurotoxin within only a few decades.

Researchers at the University of Utah have now documented this public-health achievement using locks of hair handed down between generations.

For thousands of years, human contact with lead rose before its health harms were understood. Lead accumulating in the body increases the likelihood of cardiovascular disease and heart disease, while also endangering mental health and children's IQ.

Reducing contact with lead is one challenge; proving that the body is absorbing less requires biological samples collected from people across a broad area over extended periods.

Although hair retains lead, very few people preserve locks for decades.

Utah family records and preserved locks

Because many Utah residents take a keen interest in family history – particularly people within the state's substantial Mormon population – they are more inclined to retain ancestral keepsakes, including treasured locks of hair.

"The practice of keeping a journal or 'book of remembrance' has been a long-standing tradition in the Church of Jesus Christ of Latter-Day Saints. In this spirit, childhood hair and teeth are often maintained as part of honoring their families," the researchers explain.

Community members provided 48 hair samples from relatives, with some specimens dating to 1916.

The team used mass spectrometry to measure lead concentrations, creating a limited but reliable record of individual lead exposure across the Wasatch Front in north-central Utah. This heavily populated region had formerly faced substantial lead contamination from the smelting industry.

EPA regulations cut lead levels in Utah hair samples

Before 1970, the year the EPA was established and started regulating industry, petrol generally held about 2 grams of lead per gallon. Exhaust from this leaded fuel emerged from the tailpipes of America's much-loved cars and entered the lungs – and hair – of nearby people. Utah's smelters would likewise have contributed to lead exposure.

Although US petrol use kept increasing after 1970, the new EPA rules restricted lead levels. Utah hair samples show a matching fall at about that point, dropping from 50 parts per million (ppm) to 10 ppm during the 1990s. Samples collected after 2020 contained an average of under 1 ppm of lead.

"We should not forget the lessons of history. And the lesson is those regulations have been very important," says lead author Thure Cerling, a geologist and biologist from the University of Utah.

"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."

The research appeared in the Proceedings of the National Academy of Sciences.