When Eric Nelson looks back on his years as a waste reduction manager at the University of Kansas, what stands out are the pizza boxes. "One year, there was a first-week event for all the clubs and organizations," he told me on a phone call from Lawrence. "I think Pizza Hut sent over like 500 medium one-topping pizzas." That was great for the hungry college students, not so much for Nelson, who spent the evening schlepping 500 pizza boxes to the dumpster "because we couldn't recycle pizza boxes."

It's advice from the dawn of curbside recycling: Don't put your pizza box in the blue bin because the greasy cardboard and cheese scraps make it unrecyclable. For years, conscientious recyclers followed this advice, and tens of billions of pizza boxes were sent to landfills and incinerators. The intentions were good, but it turns out that the advice wasn't. New research reveals that, so long as you remove all the pizza, the cardboard container that held your Veggie Supreme can be readily recycled into something new.  

That’s good news, because all those pizza boxes add up. A single dorm floor at the University of Kansas, says Nelson, might go through 20 to 30 boxes during a single party. According to new research from WestRock, one of the world's largest paper and packaging companies, 3 billion pizza boxes are sold in the United States annually. Altogether, they weigh 600,000 tons—the equivalent of 53 Eiffel Towers. If they were all recycled, they would account for 2.6 percent of the recyclable cardboard generated in the US annually.

Pizza boxes have not been deemed recyclable in the past because grease and cheese, when added to a pile of cardboard ready for recycling, are not exactly quality enhancers. A stack of clean, broken down Amazon boxes can be recycled into new boxes that meet the strength and color specifications of, say, a large e-commerce company. The fear was that cardboard infused with mozzarella or marinara could weaken or discolor the paper or cardboard into which it's being recycled. Consequently, some paper mills refused to accept pizza boxes, and recycling programs that service those mills—such as the one at the University of Kansas—prohibited them too.

It turns out, however, that such prohibitions are far from universal. In fact, they are relatively rare. According to WestRock, 73 percent of the US population has access to recycling programs that accept pizza boxes. And a recent survey of companies that belong to the American Forest & Paper Association found that pizza-box acceptance is now almost universal among companies that manufacture from recycled cardboard. 

That’s because, as WestRock’s study found, cheese and grease "at typical levels" do not impact the quality of paper and cardboard manufactured at mills using recycled materials. Technology gets some of the credit: Over the years, paper mills have become more adept at screening out chunks of cheese during the pulping process. Meanwhile, it turns out that it's the very rare mill that receives pizza boxes in a volume large enough to impact its end products. As a result, the AFPA just responded with new industry guidance: Pizza boxes are recyclable. Consumers need only make sure that they empty the boxes of stray slices and crust, plus any chicken wings, sauce containers, pizza savers, and anything else that might be left inside. (Pizza savers, those little three-legged plastic tables that keep the cheese from sticking to the top of the box, are sadly too small to be recycled.) There is no longer any excuse to hold onto this oldest, and most common, of recycling myths. 

This is major news for recycling advocates. Pizza boxes aren't the biggest slice of the American recycling pie, but they're an under-utilized resource, and dispelling the myths around their disposability will boost sustainability efforts from college campuses to anywhere hunger strikes. 

For Eric Nelson, now president of the Kansas Organization of Recyclers and a man who has trashed more pizza boxes than most, the news is personal. "I'm a trash nerd," he proclaimed. "And this is the most exciting thing to happen in my field in years."