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 US Presidents were impeached by the House of Representatives. Andrew Johnson, and Bill Clinton. It is the Sentate who votes on whether or not the impeachment charges warrant removal of the President from office. Both Andrew Johnson and Bill Clinton were tried and acquitted by the Senate.