MADISON, Wis., – As more than two billion people worldwide still lack access to safely managed drinking water, new research from the La Follette School of Public Affairs investigates the effects of early-life exposure to citywide water filtration on longevity in the early 20th-century.
A series of 20th-century policy shifts in American cities to public health infrastructure, including drinking water filtration and purification, contributed to substantial improvements in drinking water quality in the early 20th-century and later decades. Citywide filtration systems alone may have increased old-age male mortality by as much as 3.2 months in the United States. This is according to research conducted by Jason Fletcher of the La Follette School and recently published in the American Journal of Health Economics.
Fletcher and his co-author, Hamid Noghanibehambari from Austin Peay State University, used data from the Death Master Files (DMF) of Social Security Administration death records, covering deaths that occurred among male individuals born between 1975 and 2005. With this information, they merged individuals’ year and city of birth/childhood with the water filtration data to identify how early-life exposure impacted longevity.
“While water quality has improved in many areas, this study shows the real impacts to communities without access to safe water, both in the U.S. and globally,” Fletcher says. “With about one in four people globally lacking safely managed drinking water at home, the consequences on human health are significant.”
Additional analyses using 1950–70 censuses also suggest that a portion of the long-term links can be explained by improvements in education and income due to early-life exposure to water filtration. Fletcher and Noghanibehambari also find that water filtration may have played a role in increased height and cognitive scores during early adulthood.
This new paper is part of a larger research agenda that connects early life conditions and mortality. Fletcher was awarded the prestigious 2023 Guggenheim Fellowship to further this work, and he and Noghanibehambari have investigated the effects of dozens of 20th-century phenomena. Another recent study of theirs examined the long-term effects of the hookworm eradication campaign begun in the American South in the 1910s, finding an increase of approximately 1.3 months in longevity for residents exposed to the campaign.
Fletcher’s new website, The American Mortality Project, documents more than two dozen studies in this broader research agenda investigating the conditions that impact longevity in the United States. The website organizes the research into themes shaping life expectancy: family factors, historical events, public health policies, laws, and practices, and race, racism, and globalization. The site’s research collection potentially provides the most comprehensive collection of modern phenomena and their impact on the American lifespan.
