It's a small chance of passing an infection along, but non zero:
As I've pointed out before, this is the same reasoning used to calculate that particulates from coal burning power plants is killing people, and allowing them to regulate the emissions.
In reality, I'm unconcerned, use disposable plastic, reusable, or recyclable brown paper, whatever is convenient to you and the store selling the food. I've got bigger things to worry about.
Via Hot Air.