| Glazes and Decorations on Dishes Information |
Information from the Food and Drug Administration (FDA):
FDA has compiled the following information on toxicity of dinnerware for Public Health Service's (PHS) FDA Drug Bulletin (Sept.-Oct. 1977).
Glazes (compound glass coatings) are used to seal the surface of dinnerware to make it shiny and smooth, easier to clean, more resistant to wear, and less likely to absorb organic matter and entrap microorganisms on the surface. Decals containing heavy metals are often bonded over the glaze, by firing, as decorations. Some of these are more resistant than others and their rate of release of toxic metals in the presence of acidic foods varies greatly. When glazes and decals are properly formulated, applied, and fired, however, no hazard exists under normal use conditions in the absence of acidic foods.
According to FDA, the most prevalent problem arises from heavy metals in the decals and glazes, not only on inexpensive pottery and intermediate-priced earthenware, but also on expensive fine bone china. Under normal conditions of use no health hazard is present, but leaching of heavy metals (cadmium, lead) may occur when acidic foods (carbonated beverages; cider; foods containing vinegar; fruit juice, cooked fruits and other fruit products; sauerkraut; tomatoes; wines, etc.) are stored in dinnerware. Frequency of use, duration of storage, temperature, and location of decals influence the degree of toxicity produced. Decorative border decals on flat dinnerware obviously pose much less of a problem than decals on the inside bottom of a bowl in direct contact with foods.
In 1970, FDA initiated a testing program for imported dinnerware. In the early stages of the program well known brands including even fine bone china were found to be in violation of FDA guidelines.
In 1971, FDA began an inspection program to ensure the safety of domestic dinnerware as well. Fortunately, through government and industry cooperation the problem has greatly diminished. FDA does, however, maintain surveillance. If you purchase handmade pottery, ask what is in the decals and glazes; be cautious about using for acid foods listed above.
This article was written by Anne Field, Extension Specialist, Emeritus, with reference from the Food and Drug Administration newsletter.
MSU 2003
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