Do You Know Where Recycled Plastic Bags Go After You Drop them Off?

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For years, many US consumers have gathered and dropped off accumulated plastic bags in dedicated bins at their local grocery store to be recycled. But are these plastics being recycled? In March 2024, a team of researchers published a clever study where electronic trackers (Apple AirTags and Android Tiles) were placed in plastic bags/film, placed in plastic film drop-off bins at grocery stores throughout the US, and tracked the plastic to their final destination. The study concluded there is “…no evidence that…[plastic] packaging is being widely recycled.” However, my analysis paints a very different picture, where most plastic bundles made their way to an established manufacturer with a documented history of using recycled plastic in their products. My conclusion from the study is that while the recycling system isn’t perfect, the results show that dropped-off plastics were effectively sent for recycling. Still, the authors’ work highlights a vital takeaway: we need checks on and transparency in corporate environmental claims on products and packaging to maintain trust and continue pushing toward the best possible environmental outcome.

Why are Plastic Films Collected Differently Than Other Recyclables Like Cardboard, Aluminum Cans, etc.?

The short story is because plastic bags physically differ from other typical "Curbside” recyclables (i.e., those typically picked up at your home) that are primarily rigid materials like glass, metal, and cardboard. Material Recovery Facilities (MRFs) - the term of art in the recycling industry for a place that sorts all incoming recyclables into their component parts - have historically been designed to target the largest quantity and most valuable stuff. Because film plastic is flexible and lightweight, MRFs are not an ideal destination for plastic bags and films, and in fact most MRFs will try to sort out films early in the recycling process to avoid clogging or damaging separation equipment.

Thus, dedicated drop-off bins for plastic film recycling sprang up at hundreds of locations, such as grocery stores and retailers, to give consumers an outlet to drop off plastic bags and films. This system allows plastic bags and films to be recycled while avoiding aforementioned problems at the MRF.

A New Era of Transparency and Accountability for the Waste and Recycling Industry

OK, so we’ve described a couple common pieces of the recycling system, namely MRFs and the separate collection systems for plastic films. But how well is this system working? Although recycling has been a familiar and conscious activity for many worldwide for decades, the last decade has seen a reckoning and far more attention being paid to the details of the recycling and waste system than ever before. Why? One of the most influential factors stems from a seminal paper published in 2015 by my friend and colleague, Prof. Jenna Jambeck, who along with her co-authors estimated that as much as 13 million tons of plastic enter the world’s waterways every year. In the decade since, I’ve seen unprecedented attention paid by researchers, technologists, investors, and others to understanding the following:

1. How much plastic and other wastes are entering the environment, why, and working to reduce it.

2. The amount of valuable discarded materials burned or disposed of rather than reused or recycled.

3. The fate of materials sent for recycling to ensure they are recycled, or identifying the “highest and best use” for recycled materials.

The rest of this post focuses on a recently released study relating to item (3) above. Recycling systems are complex and require multiple parts of sometimes complex supply chains to align so that the system “works” (i.e., stuff you recycle actually gets recycled). The study asked the question, “What happens to plastic films and bags after you drop them off in a dedicated recycling bin?”

Who Did the Plastic Film Recycling Study, What Did They Do, and What Were Their Conclusions?

Two non-profit organizations, the US PIRG Education Fund and the Environment America Research and Policy Center, designed a study that included the following steps carried out by the research team and volunteers:

1. Gathered plastic packaging, including bubble wrap mailers, plastic bags, and air pillows. [Note: the study focused on plastic packaging associated with Amazon deliveries, but the results are generalizable to other film plastics with confirmed recycling outlets].

2. The plastic was bundled, an Apple AirTag or an Android Tile was affixed to the bundle, and 93 different bundles were dropped off at grocery store film plastic drop-off bins over an 11-month period at different locations throughout the US.

3. Periodically tracking of the location of each plastic bundle and reported on each bundle’s final location and classifying the final destination type. If one of the trackers stopped communicating for one week, the authors marked the location as “final”.

The authors concluded the following:

However, a closer examination of the results tells a different story. I reviewed the study’s reported details for all 93 plastic bundles, analyzed the final destination, and created simple plots to understand better what happened. Here are some of my findings:

1. Only forty-three of the 93 bundles had a “confirmed destination”. Of these, 57% went to Trex, 31% went to Landfill, 10% went to a MRF, and 5% went to a waste-to-energy facility. For those unfamiliar, Trex manufactures composite decking and related construction material using (in part) recycled plastic as a raw material.  

2. The researchers classified the remaining 50 plastic bundles with one of the following fates: (i) never left the drop-off location, (ii) delivered to an intermediate destination, or (iii) the tracking tag “died in transit”. Therefore, no conclusions can be made about the fate of more than half of the plastic bundles tracked by the researchers.

2. The claim that the plastics are not being recycled is primarily one of semantics. Twenty-four of the 43 plastic bundles with a confirmed fate went to Trex. The authors contend this is not recycling because Trex isn’t making new plastic bags and films from the plastic bags and films it receives. I think this is too narrow of an interpretation of recycling, as the intent of recycling is to (in part) reduce or eliminate the use of natural resources in production processes. Further, Trex commissioned independent analyses characterizing the environmental performance of its materials compared to traditional, virgin resources (i.e., treated lumber - see here, p. 29), which showed favorable results across several environmental dimensions like total greenhouse gas emissions, air pollutant production, and more.

3. The authors suggest Trex does not want to accept dropped-off film plastics and that Trex products are not recyclable when removed from service, but these claims are not supported by Trex’s sustainability disclosures. The report suggests that Trex does not desire dropped-off flexible film, citing, for example, “...it is unclear how much Trex uses the post-consumer plastic film collected from drop-off bins in stores” [p. 10]. However, Trex’s most recent Annual Environmental, Social, and Governance report (2022, p. 19) cites post-consumer film plastic as one of three key material feedstocks for their products. Further, Trex highlighted progress on research and development efforts around reverse logistics and reprocessing of Trex material taken out of service for recycling into new products [p. 21].

4. Some factual errors in the study may need to be clarified for an already-confused public about which recyclables should go where. Page 8 of the study highlights how four plastic bundles were delivered to MRFs and implies those were the only bundles reaching the correct destination. For reasons I stated at the beginning of this post, MRFs are not an ideal destination for film plastic owing to its lightness and tendency to clog MRF equipment mainly designed for larger, heavier, more rigid items.

5. Some of the Plastic Bundles May Have Been Delivered to a Disposal Location Because of Contamination, Including the Presence of the Electronic Tracker Itself. Using trackers to understand the journey of the dropped-off plastics was a clever but imperfect way for the researchers to assess the fate of materials in this study. First, a device with a battery and other electronic components is decidedly not “film plastic,” so it is unclear how many materials that ended up at a landfill or a waste-to-energy facility did so because the tracker was identified and the bundle separated during the journey. Most recycling processes (MRFs and otherwise) have physical and mechanical processes to ensure only desirable materials continue going down the recycling supply chain. Further, other contaminants may have been placed in the drop-off bins before or after the tracked bundles were placed, resulting in the load being sent to disposal rather than the contaminated materials continuing down the recycling supply chain. For example, page 10 of the study states: “...many of our volunteers reported that they saw food scraps in the collection bins they used for this investigation”. It’s not clear how many “many” is, but it appears clear that contaminants likely played a role in some of the bundles not being routed for recycling.  

6. Plastic Bundles Going to Trex Had Longer Journeys Compared to Other Destinations. I converted the reported start and end point for each bundle into a latitude and longitude and analyzed the “as the crow flies” travel distance for each bundle, and the results are shown below. I’m not surprised by this result, given that there are far more waste handling and disposal facilities than recycling facilities. 

9. There Appears to be Little Relationship Between the Store Where Plastic Bundles Were Dropped Off and the Reported Fate. The messy figure I made below shows the reported fate across the couple dozen grocery retailers where the plastic bundles were dropped off. All but three of the retailers had 5 or fewer plastic bundles that were tracked, making meaningful statistical conclusions a bit out of reach.

What Can We Conclude from All of This?

My read is that the plastics tracked here with a confirmed final destination essentially went to a place (Trex) where they were likely recycled into new products. Calling composite lumber made from recovered plastics “not recyclable” is a primarily unhelpful game of semantics. Environmental claims should constantly be scrutinized, and the “receipts” as they were should always be made available by those making the claims to ensure credibility and to maintain public trust, not only for recycling claims but other sustainability-related claims. In this case, I think Trex does a good job of reporting on their progress while acknowledging continued investment and analysis in doing better (in this case, reducing the overall environmental burden of their products and trying to create systems to take back and reprocess their manufactured materials when they reach the end of their useful life). Although the study examined here contained some inaccuracies and misleading statements, studies like this can serve as essential checks on corporate environmental claims and may help contribute to greater transparency and, ideally, better environmental outcomes.

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