Lithium in Water Linked to Heart Rhythm Disorder
A UCSF study found higher naturally occurring lithium levels in California drinking water were associated with Wolff-Parkinson-White diagnoses in children.
Updated on Nov. 7, 2026 in Heart Disease
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Researchers at UCSF reported in The Journal of Clinical Investigation on 13 October 2026 that children in California counties with higher naturally occurring lithium levels in drinking water had greater odds of a Wolff-Parkinson-White diagnosis. The study analyzed health and water-quality data for more than 2.3 million children in California.
Why it matters
Lithium in drinking water is not currently regulated in the United States, so the findings raise questions about whether a common environmental exposure could contribute to a heart rhythm condition. The researchers noted that lithium's medicinal use during pregnancy has been linked to congenital heart defects, which helped motivate the investigation.
The analysis used health records alongside county-level water-quality data, with exposure estimated by county of residence rather than individual intake. The researchers have not determined whether lithium is causally responsible, and exposure during pregnancy has not yet been measured directly.
The players
University of California, San Francisco (UCSF)
A public research university whose researchers led the study linking lithium levels in drinking water to Wolff-Parkinson-White diagnoses in children.
U.S. Environmental Protection Agency
The federal agency that requires monitoring of lithium through its unregulated contaminants program, though lithium in drinking water is not currently regulated.
The details
The team reviewed health and water-quality data and tested its main finding in a replication analysis of nearly 2 million children in New York, where children in areas with lithium above 10 parts per billion also showed greater odds of WPW. In California, higher lithium levels were additionally associated with palpitations, fainting, and supraventricular tachycardia. Accessory pathways that cause WPW usually occur in people with no family history of the condition, which suggests environmental exposures during fetal development may play a role.
Timeline
13 October 2026: Study published in The Journal of Clinical Investigation.
Roadmap
The study points to a gap between monitoring and regulation: the EPA tracks lithium through its unregulated contaminants program, yet no federal standard currently limits it in drinking water. Whether the association reflects a causal effect will depend on follow-up studies in other populations and research that measures exposure during pregnancy more precisely.
For most readers, this study does not change current care, since the findings are preliminary and exposure was estimated at the county level. Parents of children with palpitations or fainting may wish to discuss those symptoms with a clinician, while follow-up research determines whether lithium in water plays any causal role.
The takeaway
The study identifies a possible environmental link to a heart rhythm condition, but it remains an association rather than proof of cause. Readers should watch for follow-up research before drawing conclusions about their own water supply.
Further reading
For related context, see the Heart Disease section on how environmental exposures are studied in relation to cardiac conditions.
Source note: This article includes information reported by SciTechDaily.
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