A remarkable new century-long analysis shows that banning leaded gasoline and other lead sources has had a huge positive impact on human health. Researchers from the University of Utah examined archived hair samples stretching back as far as 1916, and found that lead concentrations in people’s hair have dropped by about 100-fold over the past century. This dramatic decline parallels the phase-out of leaded gasoline and other environmental regulations spearheaded by the U.S. Environmental Protection Agency.

Lead — a heavy metal once ubiquitous in paint, pipes, and fuel — is a neurotoxin that accumulates in the body and can cause developmental problems, particularly in children. By the 1970s, health studies had firmly established these dangers, leading regulators to progressively eliminate lead from gasoline, consumer products, and industrial emissions. As a result, hair lead levels plummeted from as high as 100 parts per million in the early 20th century to under 1 part per million by 2024.

The study, published in the Proceedings of the National Academy of Sciences, highlights how environmental policy can meaningfully reduce harmful exposures and improve public health. By literally measuring the evidence in people’s hair, it offers compelling proof that strong regulations can make communities cleaner and safer — an inspiring example of science and policy working together to protect people