Ceramic ware is much safer than it used to be (Fiesta ware hasn’t coated its plates in uranium since 1973), but according to NPR, not all new ceramics are free of dangerous chemicals. If you own a mug, bowl, plate, or other ceramic kitchen item baked in an older kiln, it may contain trace amounts of harmful lead.

Earthenware is often coated with a shiny, ceramic glaze. Historically, lead has been used in glazes to give pottery a glossy finish and brighten colors like orange, yellow, and red. The chemical is avoided by potters today, but it can still show up in handmade dishware baked in older kilns that contain lead residue. Antique products from the era when lead was a common crafting material may also be unsafe to eat or drink from. This is especially true when consuming something acidic, like coffee, which can cause any lead hiding in the glaze to leach out.

Sometimes the amount of lead in a product is minuscule, but even trace amounts can contaminate whatever you're eating or drinking. Over time, exposure to lead in small doses can lead to heightened blood pressure, lowered kidney function, and reproductive issues. Lead can cause even more serious problems in kids, including slowed physical and mental development.

As the dangers of even small amounts of lead have become more widely known, the ceramics industry has gradually eliminated the additive from its products. Most of the big-name commercial ceramic brands, like Crock-Pot and Fiesta ware, have cut it out all together. Independent artisans have also moved away from working with the ingredient, but there are still some manufacturers, especially abroad, that use it. Luckily, the FDA keeps a list of the ceramic ware it tests that has been shown to contain lead.

If you’re not ready to retire your hand-crafted ceramic plates, the FDA offers one possible solution: Purchase a home lead testing kit and analyze the items yourself. If the tests come back negative, your homemade dishware can keep its spot on your dinner table.

[h/t NPR]

This piece was updated to clarify that while lead may be present in antique ceramics and old kilns, it's no longer a common ingredient in ceramic glazes.