Scientists at the University of Utah have analyzed nearly a century's worth of human hair samples and found that lead concentrations dropped 100-fold after the EPA began cracking down on leaded gasoline and other lead-based products in the 1970s. The findings, published in the Proceedings of the National Academy of Sciences, drew on hair collected from Utah residents -- some preserved in family scrapbooks going back generations. Lead levels peaked between 1916 and 1969 at around 100 parts per million, fell to 10 ppm by 1990, and dropped below 1 ppm by 2024. The decline largely tracks the phase-out of leaded gasoline after President Nixon established the EPA in 1970; before the agency acted, most gasolines contained about 2 grams of lead per gallon, releasing nearly 2 pounds of lead per person into the environment each year. The study arrives amid the Trump administration's broader push to scale back the EPA. Lead regulations have not yet been targeted, but the authors note concerns about loosened enforcement of the 2024 Lead and Copper rule on replacing old lead pipes.

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