Before the Environmental Protection Agency (EPA) was established in 1970, Americans were exposed to high levels of lead from various sources, including industrial emissions, paint, water pipes, and most notably, vehicle exhaust. Lead, a neurotoxin that accumulates in human tissues, is linked to developmental issues in children. Since the introduction of EPA regulations, environmental lead levels have significantly decreased, as has human exposure.
The evidence of this decline can be found in our hair. Researchers at the University of Utah have conducted an analysis of hair samples, revealing a dramatic reduction in lead levels since 1916. “We were able to show through our hair samples what the lead concentrations are before and after the establishment of regulations by the EPA,” stated Ken Smith, a distinguished professor emeritus of family and consumer studies. “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.”
The Role of Environmental Regulations
The study, published in the Proceedings of the National Academy of Sciences (PNAS), highlights the crucial role of environmental regulations in safeguarding public health. However, the study also notes that recent policy shifts under the Trump administration have weakened these protections. “We should not forget the lessons of history. And the lesson is those regulations have been very important,” said co-author Thure Cerling, a distinguished professor of geology and biology. “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, while useful in various applications, such as pipes and paint, is toxic even at low levels. By the 1970s, its dangers were well-documented, prompting the EPA to phase out lead in consumer products, including gasoline.
Utah’s Unique Contribution to Lead Research
To assess the effectiveness of these regulatory measures, Smith collaborated with geologist Diego Fernandez and Cerling, who had developed methods to analyze chemical compositions in hair and teeth. Their research builds on a prior study funded by the university’s Center on Aging and the National Institutes of Health, which involved Utahns providing blood samples and family health histories.
For the new study, participants were asked to provide hair samples, both recent and historical. Many were able to locate ancestors’ hair preserved in family scrapbooks dating back a century. In total, the team acquired hair samples from 48 individuals, offering a comprehensive view of lead levels along Utah’s Wasatch Front, a region historically affected by industrial emissions.
“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,” noted Smith, who directed the U’s Pedigree and Population Program at the Huntsman Cancer Center during these studies.
Mass Spectrometry and Hair Analysis
The research team utilized mass spectrometry equipment, overseen by Fernandez, to analyze the hair samples. “The surface of the hair is special. We can tell that some elements get concentrated and accumulated on the surface. Lead is one of those,” explained Fernandez. “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 on the surface mostly, but it could also be coming from the blood if that hair was synthesized when there was high lead in the blood.”
While blood provides a more precise exposure assessment, hair is easier to collect and preserve. It also offers insights into past exposures, even for individuals who have since grown up or passed away. “It doesn’t really record that internal blood concentration that your brain is seeing, but it tells you about that overall environmental exposure,” Cerling noted. “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.”
Impact of EPA Regulations on Lead Levels
The research findings align with the reduction of lead in gasoline following the EPA’s inception by President Richard Nixon. Before 1970, gasoline contained about 2 grams of lead per gallon. Although this may not seem substantial, it resulted in nearly 2 pounds of lead being released into the environment per person annually. “It’s an enormous amount of lead that’s being put into the environment and quite locally,” Cerling stated. “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.”
Despite increased gasoline consumption in the United States post-1970s, lead concentrations in hair samples have plummeted, dropping from 100 parts per million (ppm) to 10 ppm by 1990, and less than 1 ppm by 2024.
The study, titled “Lead in archived hair documents decline in human lead (Pb) exposure since establishment of the US Environmental Protection Agency,” was published Feb. 2 in PNAS, with support from the Huntsman Cancer Foundation and the National Cancer Institute through a grant to the Utah Population Database and the University of Utah.
This research underscores the profound impact of environmental regulations on public health and highlights the importance of maintaining such protections to continue safeguarding future generations.
