July 24, 2026-- Lithium in drinking water is a widespread and persistent source of human exposure across Tribal communities in the Western United States, according to a new study from Columbia University Mailman School of Public Health. The findings document substantial regional variation in exposure and provide some of the strongest evidence to date that household drinking water is a major contributor to lithium levels measured in the body.
The results are published in Nature: Journal of Exposure Science & Environmental Epidemiology.
The researchers measured lithium in household tap water collected between 2022 and 2024 and compared those findings with urinary lithium levels collected from the same participants over a 15-year period. They found that: drinking water lithium frequently exceeded the U.S. Geological Survey's non-enforceable health-based screening level in Arizona and North Dakota/South Dakota, urinary lithium levels remained remarkably stable over time, and household drinking water explained a substantial proportion of the variation in urinary lithium concentrations.
"Our findings improve lithium exposure estimates among the Strong Heart Family Study communities and highlight the need for continued environmental monitoring and risk evaluation, particularly as lithium extraction and processing accelerate to meet growing energy demands," said Ellen Bannon, MPH, PhD student of Environmental Health Sciences at Columbia Mailman School of Public Health, and first author.
Lithium demand is projected to increase more than six-fold by 2050 because it is an essential component of rechargeable batteries used in electric vehicles and renewable energy storage. At the same time, lithium production and processing are rapidly expanding across the United States, including in regions on or near Tribal lands.
While lithium occurs naturally in groundwater and surface water, environmental releases associated with mining and industrial activities have raised new questions about potential human exposure. In 2022, the U.S. Environmental Protection Agency added lithium to its Fifth Contaminant Candidate List to evaluate whether a national drinking water standard should be developed. Despite growing concern, population-level exposure to lithium has remained poorly illustrated.
To address this gap, researchers analyzed household tap water samples from 673 homes and paired urine samples from 613 Strong Heart Family Study participants living in Tribal communities in Arizona, Oklahoma, and North Dakota/South Dakota. The team examined changes in urinary lithium over time, evaluated the relationship between household water and urinary lithium levels, and assessed whether urinary lithium could serve as a biomarker of environmental exposure.
The study found a median lithium concentration of 35.6 micrograms per liter in household drinking water. Every household water sample collected in Arizona exceeded the U.S. Geological Survey health-based screening level of 10 micrograms per liter, as did 93 percent of samples in the Dakotas and 35 percent of samples in Oklahoma. Overall, nearly three-quarters of household water samples exceeded the screening level.
Urinary lithium levels were highly consistent over the 15-year study period. Median urinary lithium concentrations measured in 2006–2009 were nearly identical to those measured in 2022–2024, indicating long-term, persistent exposure among study participants.
Researchers found a strong relationship between lithium in household drinking water and lithium measured in urine. Water lithium was strongly correlated with urinary lithium at both study visits, and household drinking water accounted for approximately 29 percent of the variation in urinary lithium levels. Participants living in areas with higher drinking water lithium consistently had higher urinary lithium concentrations, supporting urinary lithium as a reliable biomarker of environmental exposure.
"We also uncovered that although bottled water use was associated with lower urinary lithium levels before accounting for geographic differences, study location remained one of the strongest predictors of exposure," noted Bannon. Participants in Arizona and North Dakota/South Dakota consistently had higher lithium concentrations in both drinking water and urine than participants in Oklahoma, suggesting that regional geology and other environmental factors continue to influence exposure patterns.
"The health effects of long-term, low-level lithium exposure remain uncertain," according to senior author Kathrin Schilling, PhD, MSc, assistant professor of Environmental Health Sciences at Columbia Mailman School of Public Health. "While lithium has been used safely for decades as a medication to treat bipolar disorder at doses far higher than environmental exposure levels, less is known about the potential health implications of chronic exposure through drinking water." Lithium is not currently regulated under the Safe Drinking Water Act, and few water treatment technologies effectively remove it once it is present in drinking water.
"By linking individually matched household drinking water measurements with biomonitoring data collected over more than a decade, our study establishes an important baseline for understanding environmental lithium exposure in U.S. communities," said Ana Navas-Acien, MD, PhD, chair of the Department of Environmental Health Sciences at Columbia Mailman School and a co-author. "The findings underscore the value of combining environmental sampling with biomonitoring to characterize long-term exposure patterns and provide evidence supporting the use of urinary lithium as a biomarker of environmental exposure."
A full list of co-authors can be found in the paper.
The study was supported by the National Heart, Lung, and Blood Institute 75N92019D00027, 75N92019D00028, 75N92019D00029, and 75N92019D00030; R01HL090863, R01HL109315, R01HL109301, R01HL109284, R01HL109282, and R01HL109319; cooperative agreements U01HL41642, U01HL41652, U01HL41654, U01HL65520, and U01HL65521; by National Institute of Environmental Health Sciences grants R01ES021367, R01ES025216, R01ES032638, R01ES035219, P42ES033719, and P30ES009089; the National Institute of Diabetes and Digestive and Kidney Disease R01DK138542; and by the National Institute on Minority Health and Health Disparities, U19MD020537.
The authors have no competing financial interests.
Columbia University Mailman School of Public Health
