Some ceramic glazes and decorations contain lead or cadmium. If a glaze is poorly formulated or under-fired, small amounts can migrate into food, especially acidic food. Many markets limit how much tableware may release. Ask suppliers what their glazes are made to meet, and ask to see the documentation.
We choose our food carefully. We read labels and ask where ingredients come from. Very few of us ask what the plate is made of, even though it touches every bite.
Why these metals appear in glazes
Lead has long been used in glazes because it helps them melt at lower temperatures and gives a bright, glossy finish. Cadmium has been used to produce vivid reds, oranges and yellows.
Both are toxic. The World Health Organization notes there is no known level of lead exposure without harmful effects. Cadmium accumulates in the body over time.
When a glaze can release metals
A well-formulated, properly fired glaze locks its ingredients into a stable glass. Problems are more likely when:
- The glaze formulation is poor, or the piece is under-fired.
- Food is acidic: tomatoes, citrus, vinegar, pickles, wine, fruit juices.
- Food is hot, or stored in the dish for long periods.
- The glaze is worn, chipped or crazed with fine cracks.
- Decoration sits on top of the glaze in areas that touch food.
You can’t see, smell or taste whether a glaze is releasing metal. The only way to know is testing.
How markets regulate it
Many markets, including the EU and the US, set limits on how much lead and cadmium ceramic tableware may release under standardised test conditions. The limits and test methods vary by country and by type of item.
Five questions to ask any supplier
- Are your glazes made to meet lead and cadmium release limits for my market?
- Can I see the test documentation, and which method and laboratory were used?
- Does the documentation cover the specific pieces and glazes I’m buying?
- Is any decoration applied on top of the glaze in food-contact areas?
- What temperature are the pieces fired at?
Where VITRO stands
VITRO porcelain is fired at approximately 1,250°C, and our glazes are made to meet international food-contact requirements for lead and cadmium release. We’d rather you ask us how than take our word for it. Ask about documentation for your market.
At home
Retire pieces with chipped or crazed glaze from everyday use, particularly for acidic food. Be cautious with decorative or antique ceramics of unknown origin that were never meant for food.
