I am a 21 year old female. I am concerned because I masturbated the other day after going to the grocery store and I don't believe I washed my hands prior (I am normally very good about this). Now I am concerned about what was on the shopping cart, etc. I am not worried so much about infection, however, I am worried about the possibility of STDs (if that's even possible). I am in a monogamous relationship and I don't cheat so there would be no way for me to contract a STD. Please help!!