You will hear people say that due to pollination, air pollution, or the intervention of the Alien Overlords (OK. I made that last one up. But people get a little extremist at times) there is no such thing as organic food any more.
Yes, any government official can be impeached - Presidents, Legislators & Judges, etc. But you can't impeach people for doing a bad job. Impeachment is necessarily dependent upon a charge of criminal or significant unethical behavior to warrant removal. Yes, Granholm is awful, but we're stuck with her for 4 more years.
Two Presidents have been impeached in the US House of Representatives:   (1) Andrew Johnson in 1868 centering on abuse of power related to dismissal and reappointment of his Secretary of War. (2) William Clinton in 1998 centering on abuse of power related to charges of perjury and obstruction of justice.