Household Drinking Water Identified as Major Source of Long-Term Lithium Exposure in Western U.S. Tribal Communities
Key Insights
A Columbia University study found that household tap water is a significant and persistent source of lithium exposure in Tribal communities across Arizona, Oklahoma, and the Dakotas.
Nearly three-quarters of household water samples exceeded the U.S. Geological Survey (search) health-based screening level of 10 µg/L, with 100% of Arizona samples surpassing the threshold.
Urinary lithium levels remained remarkably stable over a 15-year period, and household drinking water explained approximately 29% of the variation in urinary lithium concentrations.
Household drinking water is a widespread and persistent source of human lithium exposure across Tribal communities in the Western United States, according to a new study from Columbia University Mailman School of Public Health (search). Published in the Journal of Exposure Science & Environmental Epidemiology, the research provides some of the strongest evidence to date that tap water is a major contributor to lithium levels measured in the body, with nearly three-quarters of all household water samples exceeding the U.S. Geological Survey (search)'s non-enforceable health-based screening level of 10 micrograms per liter.
The study 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. Researchers compared water lithium concentrations with urinary lithium levels collected over a 15-year period, spanning from 2006–2009 to 2022–2024.
"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 of the study.
Striking Geographic Variation in Exposure
The study documented substantial regional variation in lithium exposure. Every household water sample collected in Arizona exceeded the U.S. Geological Survey (search) health-based screening level of 10 µg/L, as did 93% of samples in North Dakota/South Dakota and 35% of samples in Oklahoma. The median lithium concentration across all household drinking water samples was 35.6 µg/L.
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. "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.
Urinary Lithium as a Reliable Biomarker
A key finding was the remarkable stability of urinary lithium levels over time. 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. Water lithium was strongly correlated with urinary lithium at both study visits, and household drinking water accounted for approximately 29% of the variation in urinary lithium levels.
"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."
Uncertain Health Implications Amid Rising Demand
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. In 2022, the U.S. Environmental Protection Agency (search) added lithium to its Fifth Contaminant Candidate List to evaluate whether a national drinking water standard should be developed.
"The health effects of long-term, low-level lithium exposure remain uncertain," said 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 (search) 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. Unlike many other drinking water contaminants, only reverse osmosis consistently removes lithium ions from water.
Epidemiologic studies of environmental lithium concentrations have reported mixed findings, with some evidence linking lithium in drinking water to thyroid dysfunction, impaired fetal development, and altered reproductive outcomes, while other studies have suggested potential benefits, including lower suicide rates and reduced risks of neuropsychiatric and neurodegenerative outcomes. The researchers emphasized that their work focused on characterizing exposure rather than evaluating health effects, establishing a critical foundation for future investigations.
Future Research Priorities
The study highlights several priorities for future research, including evaluating whether long-term environmental lithium exposure is associated with health outcomes—particularly related to lithium's primary target organs: the kidney, thyroid, and brain. Additional research is needed to investigate exposure sources beyond household tap water, including diet, bottled water, and occupational or environmental exposures. Expanding environmental monitoring and biomonitoring to other regions will also help researchers better understand how lithium exposure varies geographically and identify populations that may experience higher exposure levels.
The research was supported by grants from the National Heart, Lung, and Blood Institute, the National Institute of Environmental Health Sciences, the National Institute of Diabetes and Digestive and Kidney Disease, and the National Institute on Minority Health and Health Disparities.