No, seriously -- if there is a lining in it, and the higher temperatures caused by dry-boil have caused it to crack up, you can end up with PCBs in your tea, not good for you. This is a danger with TEFLON linings in frying pans which have been scratched up by steel implements, for example. It is significantly different than a plain metal kettle. I would inspect it carefully inside and if it is cracked up, toss it.

A