What are the implications of "asher Yitma lo" in connection with both Sheretz and Adam? What is "Adam"?
Rashi: Both refer to the Shi'ur Tum'ah - a k'Adashah (the size of a lentil) by a Sheretz; and a k'Zayis by Adam - a Mes.
What does "l'Chol Tum'aso" come to include?
Rashi: It comes to include someone who touches a Zav, Zavah, Nidah or Yoledes,