The study results indicated a reduced cancer risk in areas where exposure to lithium in drinking groundwater was higher.

Lithium is a metal that is naturally found in rocks and minerals that can leach into groundwater used to supply public and private wells. Currently, there is no drinking water standard for lithium concentrations, however, the U.S. Environmental Protection Agency (EPA) recently began collecting data on lithium in drinking water.  Health organizations have connected low-level occurrences of natural lithium in drinking water with both positive and negative human health outcomes. 

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In 2024, USGS New England Water Science Center Research Hydrologist Melissa Lombard completed the first national estimates study of naturally-occurring lithium in public and private wells, or groundwater used for drinking. Estimates from that study were meant to support public health scientists looking to comprehensively evaluate how people’s health can be affected by exposure to lithium. 

“This new research linking lithium with cancer risk is an example of how USGS data and models of contaminant concentrations provide useful information to public health scientists,” Lombard explained. 

Public health scientist Jiajun Luo of the University of Chicago used Lombard’s data in a sensitivity analysis that verified his findings of a lower incidence of cancers being associated with higher estimates of lithium levels in drinking water. Luo evaluated the association between lithium in drinking groundwater and cancer risk by compiling a group of participants from the National Institutes of Health’s All of Us study cohort living for more than three years within areas where lithium concentrations were determined at 4,700 wells, according to a 2021 USGS dataset. Both Luo’s initial analysis with the 2021 data and the sensitivity analysis using the more comprehensive 2024 data found similar findings of an increase in lithium in the drinking groundwater being associated with a reduced risk of cancer. 

Additionally, Lombard and USGS Supervisory Hydrologist Joseph Ayotte provided subject matter expertise about groundwater geochemistry and the use of groundwater as drinking water to Luo. 

“Interdisciplinary collaborations between scientists who understand the contaminant occurrence and scientist who understand the human health data and implications are necessary for producing useful studies such as this,” says Lombard. 

The USGS New England Water Science Center investigates soil and groundwater contaminants throughout New England and the nation for environmental and public health research.