While you're getting into the habit of recycling, bear in mind there are some items that can't be recycled. These include: medical waste, shredded paper (because it's impossible for the people recycling it to know what kind of paper it was); takeout containers and pizza boxes with an oily or greasy residue as this poses a contamination risk; any plastic containers or wrappers that have the numbers 1 - 7 on them. For more info on what to recycle, check out the full article.