Ceramics: Pretty, and Maybe Poisonous
Those brightly colored ceramic mugs you bought at the craft show certainly liven up your breakfast table. And that old pitcher from the yard sale is just the perfect size for orange juice.
It's hard to imagine that such attractive pieces of pottery could be dangerous to your health.
In truth, they may cause lead poisoning and some may leach cadmium into food and drink. The glaze that gives ceramics their shiny surfaces may release toxic levels of lead into your food. The U.S. Food and Drug Administration (FDA) has strict limits on the amount of lead that can leach from a ceramic piece. Cups, mugs and pitchers have the most stringent limits. That's because these pieces usually hold food longer, allowing more time for lead to leach.
As a part of the finishing process, clay objects are painted with glaze and fired at a high temperature in a kiln. The result is a shiny, glassy finish.
Glazes that contain lead must be fired at high temperatures to make sure that the lead in the glaze won't leach into food or beverages. When an improperly glazed object is used to store foods high in acid content, the chemical reaction can release the lead and cause problems.
Large manufacturers of pottery generally make products that are fired properly and are safe to use. The FDA requires that any decorative ceramicware that reaches high levels of lead be permanently labeled that it's not to be used with food.
The FDA says potential danger arises from products imported from Mexico, China and several other countries. These items may not be labeled, and there is no guarantee that these items have been fired correctly. The FDA tests imported ceramics for lead, but has no control over objects ordered overseas or brought back by tourists.
Likewise, the agency can't monitor your local amateur pottery buff to make sure that he or she is selling safe products. Small potters often can't control the firing of lead glazes as well as large commercial manufacturers, the FDA says, so their ceramics are more likely to leach illegal lead levels, although many do use lead-free glazes.
Antiques and collectibles may be suspect, as well. The FDA did not regulate lead levels in dinnerware until 1971. Other sources of lead and heavy metal contamination in food includes the use of pewter and lead crystal eating utensils and glassware.
High levels of lead can harm the kidneys and liver, as well as the nervous, reproductive, cardiovascular, immune and gastrointestinal systems. Low levels of lead in children may cause learning, behavioral and growth problems.
The FDA makes the following suggestions to avoid lead poisoning from ceramics:
Avoid storing food, especially acidic items like tomato juice, wine and vinegar, in ceramics.
High temperatures and increased time of contact with food also contribute to greater leaching of lead from the container to the food. If you use a piece often, you increase your exposure to lead.
Beware of products purchased in other countries. If you're unsure about safety standards, don't use them with food.
Don't serve food or beverages in antiques or collectibles.
Be careful of ceramics made by amateurs or hobbyists.
Avoid using cups, mugs or pitchers if the glaze develops a chalky gray residue after washing.
Do not store food or beverages in vessels that are highly decorated on the inside.
If you want to be completely sure that a piece of pottery is safe, the only way to find out is to have it tested. You can buy test kits for $20 to $30 at your local hardware store, or have the pottery tested by a lab.