How do plastics impact waste? The answer might surprise you

ShutterstockVikentiy Elizarov

Have you ever stopped to ask, why do we use so much plastic, especially in packaging? The answer depends on the type of packaging, but one overriding answer is that plastic is more resource-efficient than its competing materials. In other words, it takes less energy and materials to do the job. Less energy means less money, and less money means that it is often the desired choice for a given package or consumer good.

I remember as a kid getting potato chips in a box, with a bag inside, and getting deodorant in a steel spray can. Now, I get both in plastic. We used to get our milk exclusively in glass and our motor oil in a steel-and-paperboard canister. Now, we get milk in plastic or plastic-coated paperboard and motor oil in plastic bottles. With this plastic and other materials, we get waste. Some of it we recycle and most of it we don’t, or can’t. Regardless of the waste we create we could all do a better job of recycling. But with all the new plastic we use, are we creating more waste?

If you are like most people, you missed the publication in the journal Waste Management of a peer-reviewed article titled "Role of plastics in decoupling municipal solid waste and economic growth in the U.S." This article, by researchers from City College of New York’s Chemical Engineering Department, explored the historic drivers of municipal solid waste (MSW) and the links to the materials that make up the waste.

Typically, we would expect that waste would track with population and economic growth. As the economy grows, people buy more goods and services which economists express as personal consumption expenditure (PCE). This takes population growth out of the picture, which seems fair. As we buy more, you would expect we would throw more away. The U.S. Environmental Protection Agency tracks MSW by material and categories and determines what we recycle, what we incinerate for energy and what we landfill.

Weight watchers

It turns out that as plastic consumption grew, the percentage of waste that is paper, metals and glass and glass is reduced. As many of these other materials are recycled at a higher current rate than plastics, you might think this is bad. In fact, the researchers determined there would be 30 percent more waste if we didn’t have plastic. They write: "The correlation with PCE demonstrates that since the late 1990s there has been a decoupling of MSW generation rates with PCE or economic growth. Plastics play a role in the decoupling due to materials substitution that reduce the overall weight of MSW and down-gauging that reduces the amount of material needed."

This may seem sort of boring, but it is also important. As we consider banning plastic materials, we need to think about what we are replacing it with. If we replace the plastic items with heavier, more resource-inefficient materials, we will cause an increase in energy use which correlates to greenhouse gases and climate change.

The Waste Management article cites research where plastic reduced waste across six categories of products: caps and closures; beverage containers; stretch and shrink; carrier bags; other flexible; and other rigid packaging. Thus, for example, beverage containers that normally would be glass were replaced with plastic, and caps and closures that would be metal were replaced with plastic. The environmental impact in the United States, where the total material weight replaced was 109 million pounds over the six categories, resulted in an 80 percent energy reduction and a 130 percent reduced potential global warming impact. This same study also notes that while replacement reduces weight and resource use, plastics continue to be source-reduced after they replace another material such as metals or glass. Between 2000 and 2014, they averaged a 3 percent per year reduction in weight.

Back to the future?

Another way to look at this is to consider the consequences of shifting back to non-plastic materials. A 2016 Trucost study (PDF) for the American Chemistry Council estimated that moving back to alternatives globally, away from plastics in consumer products and packaging would increase environmental costs by 3.8 times — from $139 billion to $533 billion.

In today’s world of knee-jerk reactions, banning plastic packaging items altogether requires careful thinking, especially as it relates to climate impacts. As with most sustainability questions, the simplest answer is often incorrect, environmentally speaking. The correct answer will depend (as it always does) on a number of factors — do we need to use the item in the first place, are there ways to use less of it, and are the alternatives really better?

My conclusion from the studies referenced above is that we need to think deeper before jumping to conclusions. Plastics have contributed to a significant reduction and decoupling of waste generation. As we look at switching back to alternatives such as glass, metals and paperboard, we all need to ask, "Will the alternative require more energy to make and process, and thus contribute more to global warming than the plastic item it is replacing?"

We also need to insist that the waste we do create is managed properly, which means we need to recycle, compost, recover the energy or landfill everything. Nothing should end up being littered or in our oceans.

Sitting here in hot and burning California right now, I vote to reduce global warming and manage all my waste properly.

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