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 the Columbia University Mailman School of Public Health. The results of this study document substantial regional differences in exposure and provide some of the strongest evidence to date that household drinking water contributes significantly to lithium levels measured in the body. The result is Nature: A Journal of Exposure Science and Environmental Epidemiology.
Researchers measured lithium in household tap water collected between 2022 and 2024 and compared the results to urinary lithium levels collected from the same participants over a 15-year period. The researchers found that in Arizona and North/South Dakota, lithium in drinking water frequently exceeded the U.S. Geological Survey’s non-legally enforceable health-based screening levels, that urinary lithium concentrations were remarkably stable over time, and that household drinking water accounted for a significant portion of the variation in urinary lithium concentrations.
“Our findings improve community lithium exposure estimates from the Strong Heart Family Study and highlight the need for continued environmental monitoring and risk assessment, especially as lithium extraction and processing accelerates to meet growing energy demands,” said lead author Ellen Bannon, MPH, a doctoral student in environmental health sciences at the Columbia Mailman School of Public Health.
Demand for lithium is expected to increase more than six times by 2050, as it is an essential component of rechargeable batteries used in electric vehicles and renewable energy storage. At the same time, lithium production and processing is rapidly expanding across the United States, including on or near tribal lands.
Lithium occurs naturally in groundwater and surface waters, but releases to the environment from mining and industrial activities are raising new questions about potential human exposure. In 2022, the U.S. Environmental Protection Agency added lithium to its Fifth List of Contaminant Candidates to evaluate whether national drinking water standards should be developed. Despite growing concern, population-level exposure to lithium remains poorly understood.
To address this gap, researchers analyzed tap water samples from 673 homes and urine samples from 613 Strong Heart Families Study participants living in tribal communities in Arizona, Oklahoma, and North/South Dakota. The research team examined changes in urinary lithium over time, assessed the relationship between household water and urinary lithium concentrations, and assessed whether urinary lithium could serve as a biomarker of environmental exposure.
The study found that the median concentration of lithium in household drinking water was 35.6 micrograms per liter. All household water samples collected in Arizona exceeded the U.S. Geological Survey’s health-based screening level of 10 micrograms per liter, as did 93 percent of the Dakota samples and 35 percent of the Oklahoma samples. Overall, nearly three-quarters of household water samples exceeded screening levels.
Urinary lithium concentrations were highly stable over the 15-year study period. Median urinary lithium concentrations measured from 2006 to 2009 were similar to those measured from 2022 to 2024, indicating that study participants had sustained exposure over time.
Researchers found a strong relationship between lithium in household drinking water and lithium measured in urine. At both study visits, water lithium was strongly correlated with urinary lithium, with household drinking water accounting for approximately 29% of the variation in urinary lithium levels. Participants living in areas with high drinking water lithium concentrations consistently had higher urinary lithium concentrations, supporting urinary lithium as a reliable biomarker of environmental exposure.
“We also found that study location remained one of the strongest predictors of exposure, even though bottled water use was associated with lower urinary lithium concentrations, even before geographic differences were taken into account,” Bannon said. Participants in Arizona and North/South Dakota had consistently higher lithium concentrations in their drinking water and urine than those in Oklahoma, suggesting that local geology and other environmental factors continue to influence exposure patterns.
“The health effects of long-term, low-level lithium exposure remain uncertain,” said lead author Kathryn Schilling, Ph.D., M.A., assistant professor of environmental health sciences at the Columbia Mailman School of Public Health. “Although lithium has been used safely for decades as a treatment for bipolar disorder at doses well above environmental exposure levels, less is known about the potential health effects of chronic exposure through drinking water.” Lithium is currently not regulated under the Safe Drinking Water Act, and few water treatment technologies effectively remove lithium when it is present in drinking water.
“By combining individually collated household drinking water measurements with biomonitoring data collected over a decade, our study establishes an important baseline for understanding environmental lithium exposure in U.S. communities,” said co-author Ana Navas Asien, MD, chair of the Department of Environmental Health Sciences at Columbia Mailman School. “The results of this study highlight the value of combining environmental sampling and biomonitoring to characterize long-term exposure patterns and provide evidence supporting the use of urinary lithium as a biomarker of environmental exposure.”
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Columbia University Postman School of Public Health
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DOI: 10.1038/s41370-026-00947-7
