Why Are Plastic Salad Containers Often Not Recyclable?

Written by Leigh Matthews, BA Hons, H.Dip. NT


Leigh Matthews, BA Hons, H.Dip. NT

Sustainability Expert

Leigh Matthews is a sustainability expert and long time vegan. Her work on solar policy has been published in Canada's National Observer.


It’s good to eat your greens, but what if your only source of fresh salad leaves is a plastic container that can’t easily be recycled? A good alternative is to grow your own microgreens on a sunny window ledge at home. But about that plastic clamshell container… why are plastic salad containers often not recyclable and what can we do to get cities to recycle these common items?

Table of Contents
  1. Why can’t I recycle plastic salad containers?
  2. How big is the problem?
  3. What you can do
  4. What companies are doing
  5. The best approach to plastic salad containers

Many recycling centers accept a variety of rigid plastic containers and packaging, as well as overwrap and plastic bags, but look a little closer at the small print on those recycling guides and chances are you can’t recycle plastic salad containers. Why?

Why can’t I recycle plastic salad containers?

The short answer is, you can! But the process is a little more complicated than for other plastics.

Salad clamshells are labeled with the same Number 1 and chasing arrows symbol as everything else you just threw in your plastics recycling bin, so you’d think they’d be treated just the same. However, the difference with salad containers is that these have undergone a molding process that makes the plastic more brittle, harder to reuse, and less valuable as a raw material.

Clamshells are made with polyethylene thermoplastic (PET) using a process called thermoforming. Most plastic bottles and jugs are also made with PET but undergo blow molding instead of thermoforming. The different processes result in different grades of PET, so staff at recycling centers have to manually separate these types of plastic containers.

PET that has undergone thermoforming is typically considered a contaminant, with little, if any, market value and good only for landfill or incineration. This is why most recycling centers won’t accept the containers in the first place: to avoid contamination, increased labor, and increased costs.

A handful of places do accept these plastic containers, however, despite them having little to no value. The low-grade plastic is collected and may be shipped offshore to be recycled where costs are lower.

One extra snag, though, is that the lids for these containers can wreak havoc on recycling technology. Because of their shape and size, plastic lids for the plastic tubs are often mistaken by machinery for paper or cardboard. As such, even recycling centers that accept the salad tubs often won’t accept the lids!

How big is the problem?

Plastic clamshell containers are often used for salad mixes and fresh fruit, as well as snacks such as dried fruit and nuts. These containers often have labels that are hard to remove thanks to strong adhesives, which can complicate recycling. The containers also have different bulk density and more fine particles when processed, compared to plastic jugs and bottles.

Some 79% of plastic worldwide is not recycled and the small amount that is recycled is far from guaranteed. This is because several countries (such as China) that previously imported plastics for recycling are now banning such imports. This means that the plastic is often incinerated instead.

Incineration is actually the most effective way to reduce the volume of residual organic materials, rather than having plastics sit in landfill, while also recovering some embedded energy. However, incinerating PET and other polymers releases airborne toxic substances such as dioxins, toxic carbon, and oxygen-based free radicals.

The good news is that because PET is technically recyclable whatever its grade, there are some programs that do accept plastic clamshells. One report found that in 2018 more than 100 million pounds of PET thermoform material was recycled in the U.S. This is still just a fraction of the amount produced for packaging each year though.

What you can do

The first thing to do is to check your local recycling guidelines. If they say to keep plastic clamshells out of recycling, please do. This will help avoid contamination of otherwise recyclable plastic and can increase the success of recycling programs overall.

Don’t throw out those clamshells though! If you are in the U.S., you can enter your ZIP code, city, or state into the Earth911 Recycling Search tool and search for #1 Plastic Clamshells to see if there are any nearby recycling facilities accepting this packaging. I tried this with Wyoming and found one program that currently accepts #1 Plastic Clamshells: The City of Cheyenne Curbside Recycling Program. Good work, Cheyenne!

If there are no good options nearby,  but you have room to store this kind of plastic, consider doing that in case facilities come online soon or in case you take a trip to another area where you can drop off plastic recycling in bulk. Or, consider purchasing the TerraCycle plastics recycling box (View on EarthHero), which you can fill and then ship back to TerraCycle, where staff sort the plastics and ensure they’re actually recycled.

What companies are doing

To combat plastic waste, some companies have tried switching the plastic to compostable bioplastics instead. But are these actually any better for the environment? Possibly not.

Polylactic acid (PLA) containers are made from materials such as corn, bamboo, and sugarcane and are technically biodegradable but, in practice, have to be processed at industrial facilities. As you might have already guessed, those facilities are about as lacking as facilities to recycle #1 plastic clamshells. A 2019 report from BioCycle found that of the roughly 4,000 composting facilities in the U.S., just 53 accepted BPI-certified compostable bioplastic products.

What’s more, the U.S. National Organics Program doesn’t allow compost created with compostable plates, bioplastic bags, cups, or cutlery to be sold as organic compost. This is partly because some compostable packaging is made with perfluoroalkyl substances (PFAS) or ‘forever chemicals’ that are highly toxic contaminants.

Even if salad containers made with PLA can be composted it’s not entirely clear that they’re more eco-friendly across their lifecycle compared to conventional plastics. A review of 18 years of lifecycle assessments conducted by the Oregon Department of Environmental Quality (DEQ) found a higher impact associated with the manufacture, use, and composting of compostable bioplastic materials, compared to non-compostable items and those that were recycled, incinerated, or went to landfill.

One primary reason for the arguably greater environmental impact of compostable packaging is the potentially higher burden associated with the production of raw materials used for these products. Composting is also, according to the report, “a relatively poor method of recovering nutrients or value embedded in human-made materials such as packaging”, especially when compared to recycling.

How is this possible? Well, when bioplastics break down in composting facilities, they often just turn into carbon dioxide and water. In essence, they disappear into air and water, producing very little in the way of actual compost.

The best approach to plastic salad containers

The best option for buying pre-packaged salad greens, then, may be to look for plastic containers made with recycled materials. Even if these can’t be recycled in turn, they are at least helping to reduce average energy consumption and carbon dioxide emissions associated with production.

Recycling a pound of plastic clamshell containers could save a pound of carbon dioxide emissions and 2.5 gallons of water, as well as around 3.35 kilowatt hours. This is according to figures included in a report called “Eco-profiles of the European Plastics Industry”, which you can download as a doc. here.

Assuming you eat salad most days, this would amount to a packaging production energy saving of around 174 kWh a year, a 52 lb. decrease in carbon emissions, plus a saving of 130 gallons of water annually.

Of course, the even better approach is to grow your own greens at home or to buy fresh greens locally at farmers markets. And remember to bring your own reusable bags and containers for the full zero-waste experience!

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  1. Great post, Leigh. Unfortunately, in Jackson, WY, the local recycling stations don’t accept any plastic salad containers despite the local grocery stores selling lots and lots of packaged greens. Major problem.

  2. Thanks for the very informative article. There is a recycling drop off facility that takes clamshell containers 13 miles from my house. I was all ready to take a bunch of containers there but then realized that I would produce more carbon dioxide by burning gas driving there than would be saved by recycling them. I will now wait to take them when I will be in that area for additional reasons instead of making a trip solely to recycle the clamshells.

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