Lithium in drinking water found across western Tribal communities

A Columbia University study found lithium in drinking water across Tribal communities in parts of the western United States, adding evidence that household tap water can be a meaningful source of exposure. The findings matter as lithium production expands in the U.S. and regulators weigh whether the element needs a national drinking water limit.

The study, published in the Journal of Exposure Science & Environmental Epidemiology, compared lithium measured in home tap water from 2022 to 2024 with urine samples collected from the same Strong Heart Family Study participants over a 15-year span, according to Columbia University Mailman School of Public Health.

Researchers analyzed tap water from 673 homes and paired urine samples from 613 participants in Tribal communities in Arizona, Oklahoma and North Dakota/South Dakota, Columbia said. The work examined whether urine could show longer-term environmental exposure and how closely it tracked with household water levels.

What did the lithium in drinking water study find?

Columbia researchers reported a median lithium concentration of 35.6 micrograms per liter in household drinking water. Nearly three-quarters of the household samples were above the U.S. Geological Survey’s nonenforceable health-based screening level of 10 micrograms per liter, according to the study summary.

The exceedances varied sharply by location. Columbia said every Arizona household water sample tested above the screening level, compared with 93% of samples in North Dakota/South Dakota and 35% in Oklahoma.

Urine results showed a similar geographic pattern. Participants in Arizona and North Dakota/South Dakota had higher lithium levels in both drinking water and urine than participants in Oklahoma, which the researchers said points to regional geology and other environmental conditions as continuing drivers of exposure.

The urine measurements also changed little over time. Columbia said median urinary lithium concentrations from 2006–2009 were nearly the same as those from 2022–2024, indicating persistent exposure among the participants studied.

Household water levels were strongly associated with lithium measured in urine, according to Columbia. The research team found that tap water explained about 29% of the variation in urinary lithium concentrations, supporting the use of urinary lithium as a biomarker for environmental exposure.

Ellen Bannon, a Ph.D. student in environmental health sciences at Columbia Mailman and the study’s first author, said the findings improve exposure estimates for Strong Heart Family Study communities and show why continued monitoring is needed as lithium extraction and processing grow to meet energy demand.

Is lithium in drinking water regulated?

Lithium is not regulated under the Safe Drinking Water Act, according to Columbia. The Environmental Protection Agency added lithium in 2022 to its Fifth Contaminant Candidate List, a step used to assess whether a national drinking water standard should be considered.

Lithium occurs naturally in groundwater and surface water, Columbia said, while mining and industrial activity can also raise exposure concerns. Demand for lithium is projected to rise more than sixfold by 2050 because rechargeable batteries used in electric vehicles and renewable energy storage rely on it, according to the university.

Kathrin Schilling, an assistant professor at Columbia Mailman and senior author of the study, said the health effects of long-term, low-level lithium exposure remain uncertain. Columbia noted that lithium has long been used as a medication for bipolar disorder at doses far above environmental exposure levels, but less is known about chronic exposure through drinking water.

The university also said few water treatment technologies remove lithium effectively once it is in drinking water. Ana Navas-Acien, chair of Columbia Mailman’s Department of Environmental Health Sciences and a co-author, said combining home water testing with biomonitoring gives researchers a baseline for understanding long-term lithium exposure in U.S. communities.

This story draws on original reporting from Phys.org.