THURSDAY, Oct. 15, 2026 (HealthDay News) — Kids could have a higher risk of a rare heart condition if their drinking water contains higher levels of lithium, a new study says.
Children living in California counties with the highest lithium water levels had 71% greater odds of being diagnosed with Wolff-Parkinson-White (WPW) syndrome, a heart defect that can cause a dangerously fast heartbeat, researchers said.
The findings were published Oct. 13 in the Journal of Clinical Investigation.
WPW occurs when children are born with an extra strand of heart muscle that creates an abnormal electrical connection in the heart.
Most people with the syndrome don’t have a family history, suggesting that exposures to environmental factors like lithium during fetal development could play a role, researchers said.
“We’ve known about these pathways for decades, and we know how to treat them, but we haven’t known why people develop them,” senior researcher Dr. Gregory Marcus, an endowed professor in atrial fibrillation at the University of California San Francisco, said in a news release.
“This is an exciting step because it points to a potential environmental factor that may be modifiable, but we need more research to determine whether lithium is actually contributing to their development,” Marcus said.
WPW is associated with a small increased risk of sudden death from cardiac arrest, researchers said in background notes. The condition is treated with ablation, a procedure that uses electricity to destroy the heart tissue causing the abnormal connections.
Previous research has linked medicinal doses of lithium taken during pregnancy with an increased risk of heart birth defects, researchers said.
This led the research team to focus on whether lithium in drinking water might have the same effect. Lithium is a naturally occurring element in groundwater.
For the study, researchers compared local water quality data to health records for more than 2.3 million children in California and nearly 2 million kids in New York.
Results showed that the top quarter of California counties with the highest lithium levels had significantly greater odds of WPW. Similar results were found in New York.
Lithium in drinking water is not currently regulated in the United States, although federal regulators require monitoring of drinking water levels. The U.S. Geological Survey also measures lithium in groundwater.
Researchers noted that the study cannot prove that lithium directly causes WPW, but only established a potential link. Other environmental or genetic factors might help explain the association.
The team also cautioned that people should not be alarmed about the safety of drinking water, including pregnant women. WPW is rare, with just 686 out of the more than 2.3 million California kids having a documented diagnosis.
“The next step is to determine whether lithium itself is contributing to the development of these pathways and, if so, how much exposure matters and when during development it matters most,” Marcus said. “That will require studies that can measure exposure much more precisely.”
More information
The U.S. Environmental Protection Agency has more on lithium contamination of drinking water.
SOURCE: University of California San Francisco, news release, Oct. 13, 2026
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