Early-Life Lead Exposure and Old-Age Longevity
In the early decades of the twentieth century, many American cities installed municipal water systems. A wide range of materials were used for pipes, but lead was a common choice due to its durability, ease of installation, and relatively low incidence of leaks. In Toxified to the Bone: Early-Life and Childhood Exposure to Lead and Men’s Old-Age Mortality (NBER Working Paper 31957), Jason Fletcher and Hamid Noghanibehambari show that the use of lead pipes in these systems had detrimental effects on long-term health among residents of affected cities.
The study examines the impact of early-life exposure to these lead pipes on longevity at older ages. It combines Social Security Administration death records from 1975 to 2005 for men in the 1880 to 1930 birth cohorts with information on the installation of water systems in 761 cities.
The researchers compare longevity for cohorts exposed to lead pipes in their local water systems, either in utero or during early childhood, to longevity for earlier birth cohorts who were not. They account for potential confounding effects of adopting a new water system by comparing cities that installed new water systems with lead pipes to a control group of cities that also installed new water systems but chose other pipe material, such as cast iron or galvanized steel.
Because most lead is stored in bones and most bone development takes place in early childhood, the researchers hypothesize that lead exposure at ages below 11 has a larger impact on longevity than exposure at later ages. They find that on average, exposure before age 11 reduces longevity by 2.7 months, with the largest effects for those who were exposed during prenatal development. Impacts are concentrated among groups with lower socioeconomic status. Exposure to lead pipes prior to age 11 decreases longevity for non-Whites by 9.6 months.
The researchers note that lead from pipes is more likely to leach into drinking water when the water is relatively acidic or alkaline, and they find larger effects on longevity — a 15.6-month decline — for children in communities that used lead pipes to supply relatively acidic or alkaline water.
In other datasets, the researchers explore possible mechanisms for reduced longevity. Using Census data, they demonstrate that lead exposure during childhood is associated with lower educational attainment, which could affect subsequent health status. In World War II enlistment data, they show that lead exposure during childhood causes lower height-for-age, an indicator of worse health.
In recent years, the replacement of lead pipes has substantially reduced lead exposure in the United States. This may result in increased longevity for the affected cohorts.
— Robin McKnight
The researchers acknowledge financial support from the National Institute on Aging (grants R01AG060109 and R01AG076830).
