Paper is better than plastic, right? Actually, when it comes to milk, it’s complicated.

Many consumers buy cardboard cartons of milk because they believe they are better for the environment. They’re operating under the assumption that a milk carton is the more sustainable option when compared to plastic jugs.

But is this actually true?

To determine sustainability, it’s important to get a wide picture. The materials used to make a milk container are important to consider. Consumers are aware that some materials are more sustainable than others. For example, plastic doesn’t biodegrade, so sustainably-minded consumers think it best to limit its presence in their lives. But materials are only one part of the puzzle.

It’s also important to think about where these materials come from, how they’re used, and where they go once the product is ready to dispose of.

By looking at the full life of a milk carton, it’s possible to see how sustainable a paper carton actually is.

Paper milk cartons are just as recyclable as plastic cartons

One of the main advantages of paper cartons, many people believe, is that they’re more recyclable. Paper is usually much easier to recycle than plastic. A natural conclusion to draw is that the same would be true for milk packaging.

The trouble with milk cartons is that they aren’t actually made with 100% paper. There’s a thin layer of plastic on the inside of the carton to keep the milk fresh, and to keep it from seeping through the cardboard. In aseptic milk cartons, they are also made with a small amount of aluminum to preserve the milk’s freshness.

Consumers sometimes assume that because of the layers of plastic parts, milk cartons aren't recyclable at all. But, depending on the way in which the consumer is looking to recycle their product, this generally isn’t true.

Recycling does become complicated when unique local recycling rules come into play. These rules are different everywhere: something that could be recycled curbside in one city might need to be delivered to a recycling facility in another.

62% of US communities can recycle paper milk cartons curbside. If a milk carton can’t be recycled curbside, it can often be mailed in to recycle.

Because of the mix of materials, milk cartons usually need to be recycled with plastic. In other words, both cartons and plastic packaging are equally recyclable.

The most important judge of sustainability and recyclability for milk cartons is whether they are actually recycled or thrown away. The choice and effort of the consumer to recycle their milk container is the main indicator of sustainability for the product.

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Milk cartons made of virgin materials

Neither paper nor plastic milk containers can be recycled into new milk containers. Instead, they’re often “downcycled” into other products.

After this, milk cartons can turn into paper (for example, paper towels) or building products (like construction boards).

This also means that when plastic milk jugs or paper milk cartons are made, they’re both made from new or “virgin” materials—not recycled materials. This usage of new materials makes them less sustainable.

When comparing options for recyclable milk containers, it turns out that the most recyclable option is glass bottles. Glass can melt down and turn into new glass products, including new glass milk bottles. In this respect, they are more sustainable than plastic or paper milk containers.

Yet glass has several other disadvantages in other realms of sustainability beyond the material.

For one thing, it’s heavy, much heavier than paper or plastic. When we think about transportation and the carbon emissions that come along with transporting hundreds of heavy objects, plastic and paper take the lead once again.

Waste is a key factor of sustainability

What happens when the pros and cons of plastic and paper milk cartons are even?

One study suggests examining sustainability from another angle. What happens when the material used to make a product is not the most important indicator of environmental friendliness?

The study poses the idea that the bigger threat to sustainability is not in the type of packaging chosen, but in the amount of milk waste.

Paper and plastic packaging both have advantages and disadvantages. Some types of packaging, like plastic, might seem unsustainable across the board. But they do have sustainable advantages in certain scenarios.

In this research, both paper and plastic turned out to be equally sustainable when considering a range of factors like:

  • Size
  • Weight
  • Cooled or ambient storage
  • Expiration dates
  • Milk waste

Waste can come in the form of milk that goes unfinished in the consumer’s home and gets poured down the drain. It can also look like containers damaged in transit, causing milk to spill or leak and become otherwise unsellable.

Taking into account other parts of the milk delivery system is perhaps not the first way one would think to judge sustainability. But every part of a milk container’s journey has an impact on the world.

Choices made about what to do with milk containers from production to consumption to disposal contribute greatly to whether the product is sustainable.

Sustainability is an intricate question

When thinking about sustainability, it’s crucial to think about the full life of a product.

If only one aspect, like the material a product is made from, is taken into account, it can be easy to overlook other more impactful parts of the question.

Reusing packaging as much as possible and ensuring cartons are recycled are the main choices individual consumers can make to reduce their environmental impact and live more sustainably.