Lithium Levels in Drinking Water Associated With a Rare Heart Rhythm Condition in Children

Wolff-Parkinson-White (WPW) syndrome is a cardiac condition involving an additional electrical pathway between the upper and lower chambers of the heart. This pathway can allow electrical signals to bypass the heart's normal conduction system and trigger episodes of an unusually rapid heartbeat. Some children with WPW syndrome have no symptoms and are diagnosed incidentally during an electrocardiogram. Others may experience palpitations, dizziness, fainting, chest discomfort, or episodes of rapid heart rate. Rarely, the condition can be associated with serious arrhythmias that require urgent medical care. The research reported on 14 October 2026 examined whether environmental lithium exposure might be associated with the diagnosis of WPW syndrome in children. Researchers analyzed health records from more than 2.3 million children in California and reported higher adjusted odds of the condition among children living in counties with higher lithium concentrations in water sources. A separate New York analysis supported an association at a lower concentration threshold. Lithium occurs naturally in some geological formations and may enter groundwater. Lithium is also used as a prescribed medicine for certain psychiatric conditions, but environmental exposure through drinking water is a different exposure pathway and should not be equated with therapeutic dosing. The study raises questions about whether environmental exposures could influence the development of cardiac electrical pathways before birth. Nevertheless, county-level water measurements cannot establish exactly how much lithium each child consumed, and observational research cannot rule out all alternative explanations. Researchers would need further studies to confirm the association, investigate possible biological mechanisms, assess individual exposure levels, and determine whether the observed relationship is causal. Medical significance: The findings are preliminary and do not establish a new drinking-water hazard or justify changing a child's water source without reliable local evidence. Children experiencing fainting, unexplained rapid heartbeats, or recurrent dizziness should receive appropriate medical evaluation.