Should we even recycle plastics?

Probably, but the system needs work

Plastics are a real problem. Unless you’ve been living under a rock, you’re likely aware of the issues. Actually, you’ve probably got microplastics and/or PFAS under your rock too, so there’s really no excuse.

The crux of the problem is, we can’t cancel plastics. We need them for the critical services they provide. Plastics are now at the very base of Maslow’s Hierarchy of Needs, underpinning modern healthcare, shelter, food, clothing, and even the mattresses we sleep on. They’re fundamental to future energy systems. We might not need a plastic straw in every drink, but we don’t know how to make a wind turbine without plastics.

And yet, the current system is fundamentally unsustainable. Plastics were designed for a linear economy, made to be used and thrown away. Only 9% of plastic around the world is recycled (OECD 2022). In some regions, more than half of plastic waste is mismanaged, ending up as pollution in the environment. The very characteristics that make plastics essential—strength, durability, light weight—make them an environmental nightmare.

As if that’s not enough of a problem, plastics are made mostly from fossil fuels. As we move towards Net Zero, the use of fossil fuels for chemicals, including plastics, has got to stop. According to the Nova Institute’s Renewable Carbon Initiative, by 2050 we should be getting 20% of our carbon from bio-based sources, 25% directly from CO2, 50% from recycling of those renewable sources, and 5% from recycling of fossil feedstocks. There’s no space in this scenario for virgin fossil fuel plastics.

So, great, let’s recycle plastics! Get everyone to toss their bottles in the recycling bin, improve the efficiency of recycling methods, we’ll be all set. Right?

Ah, no.

There’s a major problem with the fundamental concept of plastics recycling: we don’t know what’s in recycled plastics. We don’t even really know what’s in virgin plastics, since the supply chain is so opaque. When you buy a plastic toy, you’re not told what the main polymer is, much less anything about additives or contaminants. When you buy recycled plastic, which may have come from a variety of virgin sources and been processed through multiple facilities and multiple methods, the problem is compounded.

A new paper from the University of Gothenburg puts this problem under the spotlight. The team analysed 28 samples of recycled HDPE pellets, and managed to quantify 491 organic chemical compounds. Since there are currently 13,000 chemicals known to be used in plastics production, that’s not surprising. Furthermore, I am a chemist, so I don’t view the presence of chemicals as inherently alarming. However, a full third of the chemicals detected were pesticides and biocides. Another 18% were pharmaceuticals, 13% were industrial chemicals, and less than 10% were the expected plastic additives.

Now that is alarming. The highest concentrations found were for deliberate additives, rather than accidental biocides, but it serves as a warning of the problem with the plastics supply chain. I don’t much mind if my recycling bin has some pharmaceuticals sprinkled throughout (as long as they don’t leach into the environment), but I would very much object to them in a baby’s teething toy.

As more data like this comes out, it is becoming clearer to everyone that the whole system needs to be redesigned. Even academic chemists, who tend to focus on chemistry-powered solutions, are recognising that developing some clever catalysts isn’t going to cut it.

We need:

• reduction of plastic usage

• renewable feedstocks

• polymer chemistry designed for recycling

• redesign or removal of additives

• comprehensive waste management systems

• improved recycling methods

• safe degradation at end of life

• supply chain transparency

And probably more things that I haven’t thought of. None of these are easy, and what’s more, we need to ensure equal access to safe and sustainable plastics. We’re currently in a world where the toxicological burden of plastics (and chemicals) falls on the most vulnerable populations. Environmental justice means that everyone can buy safe toys for their children, and you don’t need a Ph.D. in chemistry to figure out what’s okay to put on your skin.

As with most problems in sustainable chemistry, this one seems overwhelming. Most humans want to hide in their closets rather than work on a problem this big. Even for those passionately working towards greener plastics, it can get exhausting explaining that yes, it’s proven biodegradable, but no, that doesn’t mean it breaks down in the ocean.

My trick for this, as always, is optimism. Wouldn’t it be cool to live in a world where plastics did their jobs and caused no harm? Becky Chambers’ Monk and Robot series paints a vivid picture of such a world. When you need something made of plastic, you go to your local print shop, and the fabricator advises on the plethora of bio-based options available. The rigidity can be tailored as needed, and everything’s durable, yet biodegradable (presumably under any environmental conditions, since this is, after all, fiction). If you want to go even further, Octavia Butler’s Xenogenesis trilogy features the last surviving humans being rescued by aliens who are natural genetic engineers, and are horrified at the very concept of plastic, since they grow everything they need from engineered plants. That’s not terribly helpful, but it is a very good read!

Perhaps more helpful is the Scientists’ Coalition for an Effective Plastics Treaty, which shares materials developed by a variety of experts on the plastics problem.

Anybody else have inspirational reading to share?