Coated paper and the quest for its bin

Image by Mircea Ploscar from Pixabay (bin added)

This story begins not so long ago with a milk carton and my willingness to follow rules, or in this case, the guidelines for our local garbage collection service. The guidelines said to place coated paper food packaging, including milk cartons, in the compost bin. I thought I was being clever by using these cartons to collect food scraps that I didn't want in my home compost pile. Something seemed off, though: Coated paper, cartons or otherwise, typically has a thin layer of plastic, so placing this material in the compost bin seemed wrong. I reached out to the collection service for clarification, concerned that the plastic coating would break down to create microplastics. I'll come back to the conversations that ensued later. But first, let's peel back the layers of coated paper.

A confounding array of products and coatings

Coated paper includes not just cartons for milk and other beverages, but also butter cartons, ice cream and other frozen food cartons, take-out cartons, pizza boxes, cereal boxes, bakery boxes, deli paper, parchment paper, and waxed/wax paper, plus paper plates, bowls, and cups. It shows up in your mailbox in the form of catalogs, flyers, magazines, and mailers. It covered the book I was reading last night. The coating lends superpowers to these items, making them smoother, shinier, more durable, impervious to liquids, and protecting their contents against leakage and spoilage. That superpower coating is a thin polymer layer—sometimes imperceptible—that is usually a synthetic petroleum-based plastic, but it can also be silicone or plant based. Plant-based coatings, or biopolymers, may or may not include additional synthetic polymers. All these variants make it difficult to determine whether an item should be recycled, composted, or trashed. Without consistency across materials, labeling, collection, and processing, we're often left to our best guesses.

Different materials require different processing

Proper disposal starts with knowing what items can be processed by your local recycling and composting facilities: Just because an item is suitable for recycling or composting, doesn't mean that the facility is equipped to process it. Gable top cartons, commonly used for milk, juice, and other refrigerated liquids, can be recycled only at facilities that can identify the unique shape and separate the layers. Recently I learned that there are four different methods used for commercial composting, and each method can process only a subset of items deemed "commercially compostable." This limitation is because different materials require different conditions for them to fully degrade.

Coatings add confusion to composting

Compostability largely depends on the type of coating. As a general rule, petroleum-based coatings are not compostable, silicon-based coatings are sometimes compostable, and plant-based coatings are compostable only if they don't contain synthetic additives. The coatings aren't easy to identify, and package labeling is often missing or misleading, featuring terms like "biodegradable" or "earth-friendly" on items that aren't compostable. Oatly brand oat milk cartons state, "The plant based coatings of this carton package support sustainable sugarcane production." The labeling implies compostability, but when I asked Oatly for confirmation, their convoluted response was effectively "no, not compostable":

"As with many industrial materials, polymers from sugar cane require specific additives to secure functional performance. These additives might not be from renewable resources – nevertheless, they are a very small part of the plant-based polymer composition. We can say these polymers are plant-based, or a renewable material. However, we cannot claim they are 100% plant-based or 100% renewable."

PFAS contamination is an ongoing concern

In response to the proliferation of toxic PFAS (forever chemicals), about 20% of U.S. states have adopted legislation that bans intentionally added PFAS from food packaging. In February of 2024, the FDA announced that PFAS used in grease-proofing agents for food packaging were no longer being sold in the U.S. Yet the following month, a study found 61 unauthorized PFAS chemicals in food packaging. While it's virtually impossible to identify food packaging that contains these chemicals, it's important to keep them out of compost so they don't further contaminate our food sources and the environment. The best course of action is to look for PFAS-free labeling, contact manufacturers, and do your own research. A good resource is the consumer activist website Mamavation.com, as they've done PFAS testing on a range of products and published the results on their product investigations page. (Note that some tests are a few years old and manufacturers may have since made changes given recent bans.)

Composting certifications are helpful, but not universal

Unlike the chasing arrows symbol, which has become effectively meaningless, composting certifications are meaningful in that they identify items that are compostable, either at home or at a commercial facility. The caveat: Certification doesn't mean an item is universally accepted at all facilities. Note that "BPI Compostable" certification also means that the item is PFAS-free. This standard doesn't apply to other certifications, though. For example, Hefty ECOSAVE Paper Straws are CMA Composter Approved, even though the Hefty website calls out that they have added PFAS. (My disdain for straws has been heightened.)

Certifications for compostable packaging

Tips for choosing the right bin

Outlined below are guidelines and resources that can help increase your odds of choosing the right bin for coated paper products. Above all else, always check the guidelines for your local facilities.

Coated paper mailings and similar items

• Recycle: If you can easily tear the paper, the paper isn't soiled, and it doesn't contain glitter, put it in the recycling.

• Trash: Everything else.

Coated paper food packaging in general

• Recycle: For items that aren't soiled and are free from any food residue, like cereal boxes, you can likely follow the same recycling guidelines for coated paper mailings—excluding waxed paper and parchment paper, which I'll cover separately. Recycle other items according to your local guidelines.

• Compost: Check for one of the composting certifications above, or search for items in the Compost Manufacturing Alliance database. That link is filtered to show items universally accepted at all facilities. If you know the composting method used by your local facility, choose it from the Accepted Products > Accepted Lists menu at the top of the page.

• Trash: Everything else.

Gable top cartons

Note that coated paper cartons are separate from shelf-stable aseptic containers, which have an additional layer of aluminum.

• Recycle: To see if coated paper beverage cartons (and aseptic cartons) are recycled in your area, go to the Carton Council Recycling Locator and enter your street address. Alternatively, you can mail cartons to a recycling center. When recycling cartons, follow these guidelines:

  • Don't flatten cartons in the U.S. and Canada, unless you're mailing them. The unique shape aids in sorting the cartons for recycling.

  • Reattach caps and push straws back into cartons before recycling them.

• Trash: Cartons not recycled.

Waxed paper, parchment paper, and butter wrappers

A common misconception is that the coating on these items is natural wax, but it's usually petroleum-based paraffin for waxed paper and butter wrappers, and silicone for parchment paper. Recycling isn't an option for these papers, since their water-resistant coatings resist the process used to break down paper fibers.

• Compost: You can compost these papers if they meet the following conditions:

  • The paper is unbleached. Residual bleach breaks down to create highly toxic dioxins that not only harm soil microbes but are also linked to reproductive and developmental problems, immune and hormone disruption, and cancer in humans.

  • The coating isn't petroleum based. Check for one of the composting certifications above or for labeling that specifies that the coating is vegetable based. Labeling is pretty good for waxed paper and parchment paper, but lacking for butter wrappers. I checked with 10 different brands and found that Trader Joe's was the only one with compostable butter wrappers. (Here's the list of brands I checked.)

  • The paper is PFAS-free. Mamavation.com tested parchment papers and butter wrappers to determine which brands were free from PFAS. I've not found a similar test for waxed paper, but the If You Care waxed paper might be safe, since the brand's parchment paper tested clean. Or maybe switch to parchment paper?

• Trash: Papers not suitable for compost.

Back to the conversations that ensued

As mentioned earlier, I had asked our collection service to confirm whether coated paper cartons were appropriate for the compost bin. The first rep wasn't sure if coated paper cartons were accepted or not. The second rep told me they were, assuring me that the composting process doesn't create microplastics but instead breaks down the plastic coating to its basic molecular structure. Not convinced, I dug deeper and found a 2011 study titled "Microplastics in Compost: The Environmental Hazards Inherent in the Composting of Plastic-Coated Paper Products." When I shared the study with the collection service, their response was, "We're just the collection service. You'll need to contact the composting facility."

Which of course I did. But first, I checked the composting facility's website and found the following statement: "If food papers have foil or plastic on them, we cannot accept them." When I asked the composting facility why coated paper was being collected for composting, they were surprised, thinking that collection of those items had stopped. They also asked me to provide the details showing that the collection service was accepting these items. I willingly obliged with a marked-up PDF file and screenshots from the online disposal guide. (Red flag: Why is the composting facility asking me, a customer, for details on what the collection service accepts?)

A few months later the online disposal guide was quietly updated, stating that coated paper cartons should go in the trash. I have no idea whether my actions played a role, and while I was thankful to see the change and glad to have closure, more questions remained: Why weren't customers notified of the updated guidelines, and more baffling, why was the composting facility unaware that the collection service was accepting coated paper items? For now, I'm waiting to see if the composting facility will respond to my question about whether they've tested their compost product for microplastic contamination.

A small victory. Left: The old guidelines to place cartons in the compost bin. Right: Updated guidelines to place cartons in the trash bin. (Similar changes were made for other coated paper items, too.)

Brands checked for compostability of butter wrappers

For this assessment, I started with the organic brands that tested clean for PFAS in the Mamavation study, expanded the options to include both salted and unsalted varieties, and added Tillamook and Violife brands. I didn't include non-organic butters based on my personal preference to avoid exposure to toxic pesticides and other hazardous chemicals where I can, particularly when it comes to meat and dairy products. Besides, organic is better for the environment.

Nature's Promise and O Organics tested clean in the Mamavation study but aren't represented below because they didn't respond to my requests

Brand	Style	Contains PFAS*	Compostable wrapper
365 Whole Foods	Organic salted and unsalted	No	No
Tillamook	Salted and unsalted	No	No
Horizon Organic	Organic salted and unsalted	No	No
Vital Farms	Salted and unsalted	No	No
Trader Joe's	Organic salted and unsalted	No	Yes
Clover Sonoma	Organic salted and unsalted	No	No
Kirkland	Organic salted and unsalted	No	No
Straus Family	Organic European style, salted and unsalted	No	No**
Violife (Upland)	Plant butter, salted and unsalted	No	No
Miyokos	Plant milk Euro butter, salted and unsalted	No***	No

*Based on the responses I received from brands, not based on the independent Mamavation study.

**Straus Family responded that their wrappers are compostable, but also informed me that the wrappers are coated in paraffin wax, which is not compostable.

***In the Mamavation study, detectable levels of PFAS were 12ppm (parts per million) for the first lot and non-detect for the second lot.

Sources

• Coated paper — Wikipedia (Mar 2024)

• Microplastics in Compost: The Environmental Hazards Inherent in the Composting of Plastic-Coated Paper Products — W. Brinton, C. Dietz, A. Bouyounan, D. Matsch. Woods End Laboratories Inc and Eco-Cycle ,  Academia.edu (originally published Apr 2011; updated May 2018)

• Can wax paper be recycled? Environmentally friendly alternatives — Treehugger (Jun 2022)

• Dioxins — World Health Organization (Nov 2023)