When considering the qualities of glazed ceramic mugs, you're likely to first think of their craftsmanship and appearance. Lots of people like earthenware products made by local hobbyists or amateurs because they are unique, and glazed ceramics such as porcelain, or china, are attractive and durable. You may not realize, however, that the glazes that cover these products may make you sick by releasing lead into foods and beverages.
In many ways, lead glazes are appealing to both manufacturers and consumers. They make for visually appealing mugs, are durable and reliable, and are easy to control. The danger they present lies in how they are produced. When they are formulated according to tight specifications and fired at sufficiently hot temperatures, the lead is sealed within the glaze and cannot leach into anything the china comes into contact with. When manufacturers fail to see that these conditions are met, however, lead can seep out of the glaze and into the beverage in your mug. This is particularly true with more acidic beverages, such as tomato juice or coffee.
The Health Risks of Lead
Lead is an element that, like mercury and copper, is classified as a heavy metal, and can cause severe damage to the central nervous system. This makes lead exposure in young children and pregnant women an especially serious concern. In the young, elevated levels of lead can result in behavioral disturbances, learning disabilities and poor coordination. Lead intoxication can be insidious, but powerful; high lead levels in blood have been associated with lower standardized test scores, with lead exposure an even more powerful predictor of student performance than class size. Several factors compound the problem: Children's bodies absorb and retain lead more easily than do those of adults, and lead poisoning often goes unsuspected when a child encounters developmental delays or difficulties. In higher levels, lead can also damage the kidneys and liver, along with the reproductive, cardiovascular, immune and gastrointestinal systems.
What to Watch For
The FDA requires makers of ceramics that contain a certain level of lead to put warning labels on those products to keep people from storing food in them. The FDA, however, cannot control what china manufacturers in other countries do, and notes that Chinese and Mexican manufacturers should be looked at with extra caution when it comes to ceramic mugs. Similarly, avoid serving beverages in antiques or collectible mugs, and be careful of those made by individuals or small ceramics operations. It is a good idea to stay away from mugs that are heavily decorated on the inside.
What You Can Do
Your best strategy for keeping lead out of your and your loved ones' bodies is to look for labels such as "Not for Food Use--May Poison Food" and limit your ceramic wares to products you know were made in the U.S. by larger manufacturers. Critically, understand that once lead is already inside a glaze, no amount of washing, boiling or scraping can eliminate it. You can, however, purchase test kits at a hardware store, or have your mug tested at an appropriate laboratory, such as a local university.