I used to work for a company that did spray foam insulation. There are 2 different chemicals that make up the spray foam. Long story short they cannot find companies to recycle the plastic barrels b/c of the chemical that was in them. The residual that is left in them pretty much either hardens into a thin film on the walls of the barrel which is harmless. Spray them out with some soap and water and you are good to go. I'm in NJ and every time I call to get a few barrels they BEG me to take all of them......like 200 empty barrels. So I in turn clean them out real quick and sell them for $15-20 a piece. I keep 3 or 4 for my use of course.........just an idea for you guys that have space to store them.