Unglazed Ceramics May Be Dangerous for Food

The U.S. Food and Drug Administration has expressed concern about some clay pottery items sold to tourists that may pose health hazards if used to hold food.

Colorful pots and pitchers bought abroad can make colorful decorative items, but be careful about also using such ceramics for food service and storage. “Some of these products contain high levels of lead and cadmium which can be leached when the item has been poorly glazed and the colors aren’t properly sealed,” says Marvin Blumberg, a consumer safety officer for the FDA. Lead and cadmium are toxic metals.

Unfortunately, it’s impossible for the consumer to know, simply by looking at a ceramic piece, whether it has lead in the glaze and whether this glaze was manufactured by acceptable standards for food uses.

Many ceramic ware products are coated with glazes that contain lead and cadmium. The glaze is a thin, glassy coating fused onto a shaped body of clay in a kiln. The lead produces the shiny look, with the cadmium enhancing the colors.

Foods Containing Acids

But if the process of turning out these ceramics is improperly done, problems can occur when these products are used to store foods that are high in acid content. And the longer the foods are stored, the more the acids can work to release the metals from the finish.

There is no problem, of course, if you buy such items strictly for decorative purposes. But if you have food in mind for the products--be it preparing, storing or serving--Blumberg suggests that travelers beware of hand-painted items and products that have highly colored surfaces and appear poorly glazed. Similarly, be on the lookout for hand-painting that isn’t underneath the glaze.

Buying quality products from better stores is one safeguard, but even major manufacturers who try to be careful may have bad batches. There have been recalls of some ceramic products imported commercially into the United States from Italy and France.

A traveler may not necessarily recognize a manufacturer’s name. Nor is price always a consideration. “The potential danger can exist with any product that has to go through a kiln to seal the colors, and this can be items running from a small cup for 50 cents to a set of dishes costing hundreds of dollars,” Blumberg says.

Most items sold for functional food purposes are quite safe, with the glazes impervious to foods and beverages. But the story can be different if the glazes are badly handled. A glaze containing lead must be heated, or fired, at a high enough temperature and for a sufficient time to insure its safety. Both the temperature and the time vary according to the glaze formula used, the size of the piece and other factors.

Danger of Glazes

“The biggest danger with faulty glazes is when foods have a high acid content,” Blumberg says. “There’s always the possibility of the acid interacting chemically with the glaze’s components and eventually leaching out the lead and cadmium into the food.”

Some foods that may be vulnerable are apple sauce, pickle products and citrus fruits.

Toxins Drawn Out

“Let’s say someone stores orange juice in a mug with a poor glaze,” Blumberg says. “Over the course of time, perhaps just overnight, as the juice is left in a refrigerator the lead or cadmium might conceivably be drawn out.”

Another example might be a salad dressing. “Many food products have an acid base,” Blumberg says.

Whatever reaction you might have depends on the amount of leaching and your individual tolerance, Blumberg adds. Two examples of severe cases: A California family suffered acute lead poisoning from drinking orange juice stored in a pitcher bought in Mexico, and a Seattle couple were similarly afflicted from the use of terra cotta mugs acquired in Italy.

The FDA restricts its tests to commercially imported products, so the only way a traveler can be sure of an item is to have it tested at a private laboratory.

“If you have a real concern, the answer will probably be to take the item to a private lab,” Blumberg says. “It’s a difficult situation. People may have bought things on trips several years ago, and fears can be unfounded. If you notice colors starting to fade and becoming duller, this can be from general usage and being washed with detergents. But you’re guessing without a test.”

Comparable advice came from Gerita Hinkel, a spokeswoman for U.S. Customs. “If the item isn’t produced by a manufacturer for table use, don’t buy it unless it’s for decorative purposes. Look for a manufacturer’s mark.”

Hinkel also advises: “Don’t buy anything for food use that is unglazed. If it’s smooth to the touch and shiny, it’s been glazed. Rub your fingers over the item and if it feels chalky and not smooth and slick, then it hasn’t been glazed at all, or it’s been painted over the glaze and not reglazed.”

Insufficient Glaze

It’s possible, Hinkel says, for blank plates made by manufacturers that are intended to be decorated and then reglazed in another country to wind up with insufficient glazing for food use. “Entrepreneurs may just lightly glaze items to make them more attractive, but without enough glaze to make them safe for eating from.”

The bottom line, Hinkel stresses, is not to use any items for food storage unless you can see and feel the glaze.

The FDA has been setting limits on the amount of lead that can leach from ceramic ware since 1971. These “action levels” were tightened in 1980.

The FDA is reassesing its present limits to see whether they should be further reduced. About 60% of the ceramic food ware sold in the United States comes from foreign sources, according to the FDA.