Where can i find a lab coat?
Answers: Go to a pet store, and ask to borrow a labrador retriever's jacket! ;)
Seriously, though, considering that the Metro DC area is chock full of hospitals, I can't envisage that you'd have any trouble finding any type of medical dress, even if that's not your profession or intended use (hmmm . . . make me wonder . . .!).
You could buy an oversized men's shirt!
Look at the links, below, or look in the wan pages below "Medical Supplies", or just call for the nearest hospital and ask!
In a lab.
More Questions and Answers ...