A break in a dish isn't always a big, obvious crack. Sometimes it's just a small chip out of one corner or a tiny fracture. No matter how minuscule the imperfection is though, you'll want to avoid eating off that dish. Beyond the obvious risks of cutting yourself or swallowing a stray chip, broken dishes can harbor bacteria and increase your exposure to lead.
Cracks and crevices in dishes are ideal breeding grounds for bacteria that can contaminate your food, making you very sick. Foodborne illness most commonly causes gastrointestinal problems -- cramping, diarrhea, nausea and vomiting -- that are unpleasant for healthy adults and dangerous for kids, older adults and pregnant women.
Ceramic plates, glasses and bakeware have a nice smooth finish over them -- it's not just for aesthetics. That coating also protects you from ingesting the lead that may be present in some dishes. Dish manufacturers continue using lead because it makes their products durable; if you chip your plate with a steak knife or somehow crack it, you could ingest lead while eating. While it isn't likely that you'll consume dangerous amounts of lead from your dishes, lead is linked with chronic health problems like high blood pressure, chronic pain, gastrointestinal complications and neurological issues -- and you'll want to keep it away from kids.