Yes! In 1996, research was done using pre-1950s US-made ceramic tableware obtained from antique stores and flea markets. They discovered dangerous lead concentrations (>3 microg/ml) in microwave leachates from dishes with uranium-containing glazes, copper-containing glazes, and flowery over-the-glaze decorations. This study implies that using such plates to microwave popular foods might result in unacceptably high levels of lead intake. See - Sheets, R W et al. “Effect of microwave heating on leaching of lead from old ceramic dinnerware.” The Science of the total environment