I did some reading up on this a while back. Sometimes you'll find a number stamped into the plastic telling exactly what material it's made of. If it's food safe, I feel better using it.
From a quick search, below is a quick reference. Anything not a 1 or 2 is known to leak one thing or another.
Cheap thin walled trash cans are generally made of (LDPE) Low-density polyethylene #4 , which is rated "ok" for food.
Thicker walled trash cans can be made of (HDPE) High density polyethylene #2, rated "good" for food.
If you can find something made of (PET or PETE) Polypropylene #1, you've found food grade plastic.