A recently released study conducted by Atlanta-based paper company WestRock CP, LLC investigated several aspects of the recycling of post-consumer pizza boxes. The study points out that approximately 3 billion pizza boxes are used each year in the U.S.; however, grease and cheese contamination of the boxes has been thought to impact their viability for recycling. Ultimately, the study concludes that the typical grease and cheese levels found on post-consumer pizza boxes have a minimal impact on the strength of finished articles made using the typical level of less than 3% post-consumer pizza boxes. Other notable findings of the study include:

• Post-consumer pizza boxes are estimated to contain 1-2% grease;

• Cheese is hydrophilic, does not hinder hydrogen inter-fiber bonding of fibers, and tends to be screened out as solids during the recycled pulping process;

• At inclusion rates approaching 20%, grease from post-consumer pizza boxes does interfere with inter-fiber bonding and results in significant (~5%) paper strength loss.

The study supports that “there is no significant technical reason to prohibit post-consumer pizza boxes from the recycle stream.” The findings of the study are intended to inform the use of post-consumer pizza boxes and educate consumers about the levels of grease and cheese contamination that is acceptable for such pizza boxes. Based on the study, the American Forest & Paper Association (AF&PA) is encouraging communities to update their residential recycling programs guidelines to explicitly accept pizza boxes that are free of food.