Dear Recyclebank,

I live in a neighborhood in New York City that is participating in the Department of Sanitation’s curbside compost collection pilot program. The program collects many materials not taken by other composting programs. In addition to fruit and vegetable waste, they collect animal products and soiled paper products. I understand that animal products will break down, but my concern is about soiled paper.

We were told that they will take soiled napkins, paper towels (as long as they are not contaminated with chemicals such as cleaners), and any other food-contaminated paper products like pizza boxes, food containers, and paper bags. When I add soiled paper products — or small paper fragments as suggested in your article “Because You Asked: Is There a Minimum Size for Paper to Be Recycled?” — to the compost collection bin, is the resulting compost produced safe even though the paper may contains non-organic inks and dyes, solvents, and other chemicals like bleach, formaldehyde, and dioxin?

-Marc R., New York City, NY

Dear Marc,

If you were talking about composting at home, you'd be right to be concerned about chemical contaminants from paper. But because the New York City’s organics collection pilot program sends materials to industrial composters, the rules are a bit different. As you noted, the program accepts materials not typically accepted by other composting programs. “Since we process food scraps, food-soiled paper, and yard waste at industrial scale compost facilities, or through anaerobic digesters, we are able to accept meat, bones, dairy, and fats, which are not acceptable for backyard composting or at food waste drop-off sites,” says Mary Most, the public information and outreach specialist for the New York City Department of Sanitation (DSNY).

These industrial compost facilities and anaerobic digesters are also excellent at breaking down the contaminants found in paper products, such as the dyes and chemicals you mentioned. It's worth noting that much of the paper collected by this program was previously in contact with your food (pizza boxes, coffee filters, and napkins, for example) and is already generally free from harmful chemicals. Either way, the facilities maintain the high heat, aeration, moisture, and chemical balance needed to break down and decontaminate the collected materials. Remember that all other recyclable paper should be recycled rather than composted.

If that doesn’t assuage your worries, Most notes that compost produced from the organics collection program is certified with the Seal of Testing Assurance by the U.S. Composting Council. That means the compost is regularly tested according to the U.S. Composting Council’s parameters, as well as applicable state and federal regulations “to assure public health/safety and environmental protection.”

With all that being said, composters acknowledge that the best way to minimize unwanted or risky materials is to control the feedstock (the raw materials accepted into the facility). You can do your part by strictly following your compost collector’s list of acceptable materials. Clean recyclable paper still belongs with the paper recycling, and recycling it rather than composting it minimizes the already remote possibility of the contamination that you are concerned about.