Researchers analysing health and water‑quality records for more than 2.3 million children reported an association between elevated lithium concentrations in drinking water and a higher likelihood of Wolff‑Parkinson‑White (WPW) syndrome, a rare congenital heart disorder that causes an abnormally fast heartbeat.

WPW syndrome affects roughly one to three individuals per 1,000 worldwide and is characterised by an extra electrical pathway that can trigger rapid heart rates, dizziness, palpitations or fainting.

Children residing in counties where lithium levels fell in the top quartile had 71 % higher odds of being diagnosed with WPW syndrome compared with peers in lower‑exposure counties.

The association was also observed in a separate dataset from New York, reinforcing the need for further investigation into environmental lithium exposure.

The study cautioned that the findings do not establish causality; lithium occurs naturally in groundwater and concentrations vary widely across locations.

Only 686 of the more than 2.3 million children in the California dataset had a documented WPW diagnosis, underscoring the condition’s rarity despite the observed statistical link.

Researchers highlighted limitations, including reliance on county‑level lithium measurements rather than individual exposure data and the inability to fully account for other genetic or environmental factors.

The authors called for future studies that directly measure lithium intake, especially during pregnancy, and that replicate the analysis in other populations to determine whether the association holds elsewhere.