Pizza Boxes Put in Garbage Cut Away Soiled Portions Any part of the pizza box soiled by food residue or grease is not recyclable and can contaminate other clean paper and cardboard. A clean pizza box can be recycled with cardboard, so cut away all soiled portions, or just recycle the top half. LunaseeStudios / Shutterstock.com Frozen Pizza Boxes Can’t Be Recycled Frozen pizza box aren’t recyclable because they have a wax coating that contaminates paper recycling. Find out more. Did You Know? The Cost of Recycling the Pizza Box Greasy pizza boxes contaminate clean recycling and are expensive for the recycling industry: it’s estimated that contamination costs recyclers $700 million per year, because of damaged machinery, the cost of disposing of non-recyclable materials and wasted time. What Came Before Pizza Boxes? Around two-thirds of all pizzas are delivered in pizza boxes. Pizzas first came in wax-lined paper bags just like pies. Between World War I and World War II, they started coming in boxes made from corrugated cardboard.