Your Coffee Mug May Be Leaching Lead and Cadmium

Your favorite coffee mug may be leaching cadmium and lead into your drink. A study on ceramic mugs found that both new and second-hand mugs release these heavy metals, especially from the exterior lip area you put in your mouth.

What the Study Measured

Published in a peer-reviewed study, researchers tested the migration kinetics of cadmium (Cd) and lead (Pb) from ceramic mugs. They tested both the interior surface (which contacts the liquid) and the exterior surface at the lip area (which contacts your mouth).

Both new mugs and second-hand mugs released heavy metals. The exterior lip area was a notable source, where glaze degrades over time with use and washing. Hot beverages accelerate migration. A mug that passes a room-temperature test may still leach at coffee or tea drinking temperatures.

The Glaze Problem

Lead and cadmium are used as colorants and stabilizers in ceramic glazes. Bright reds, oranges, and yellows often contain cadmium. Older glaze formulations used lead as a flux. Even some modern glazes can contain these metals if the manufacturer cuts costs.

There's no way to tell by looking at a ceramic mug whether it's safe. The colors don't reveal what's in the glaze.

Lead-free, food-safe glazes exist. The safest option is borosilicate glass or stainless steel mugs, which contain no glaze and don't leach metals. Browse non-toxic kitchen alternatives for safe mug options.

Also see glass food containers for safer alternatives.

Source: Migration kinetics of cadmium and lead from ceramic mugs (2025).