Hair strands reveal the century-long payoff of the leaded-gas ban

A University of Utah study analyzed hair samples from Utah residents spanning roughly 1916–2024 and found lead levels rose to about 100 ppm by the mid-20th century and then fell sharply after the EPA began phasing out lead in gasoline and closing smelting plants, reaching under 1 ppm by 2024. The roughly 100-fold decrease provides strong evidence that environmental regulations effectively reduced lead exposure, a timely reminder amid ongoing debates about regulatory rollbacks. The research, published in PNAS, used hair as a proxy for environmental exposure and underscores historical lessons about policy impact.