Plastic is not something that we can just use and then forget about. What happens to our plastic waste is a problem for our environment on a scale that we cannot ignore. Plastic waste affects Earth's ecosystems and has a profound negative impact on the environment, wildlife, and people.
One of the direct ways that plastic ends up in our waterways and oceans is through littering, with approximately 80% of the litter in the seas coming from the land5. Sadly, many people picnic and enjoy time outdoors without following countryside codes. When they return home, they leave lots of plastic water bottles, bags, and containers.
Whether you leave plastic packaging and other items behind on a beach, beside a river, or in other environments, much of that litter will ultimately blow into the waterways and make its way into the oceans. And become what we know as ocean plastic.
Both in the seas and oceans and while it is on land, plastic litter significantly impacts wildlife. Wildlife gets entangled in larger pieces of plastic, which can kill or injure them. Many creatures also eat plastics – causing internal injury and even death. We can also implicate floating plastics in the spread of invasive marine species, pathogens, toxic chemicals, and bacteria, which disrupt ocean ecosystems.
Read more: Effect of plastic waste on marine life
But it is when the plastic litter begins to break down into ever smaller and smaller pieces that the most pervasive and worrying problems arise. Microplastics enter food chains and cause substantial environmental disruption and a huge range of health problems in animals. Including (potentially) people, though we do not yet fully understand the health effects of micro-plastic ingestion.
Most plastic waste we litter ends up as microplastics in oceans, but it does not just stay there. We can now find it in every ecosystem on Earth, from the Arctic to the Antarctic and even the human body. It leaves the oceans through food chains, and bubble burst ejection, cast back onto land in sea sprays.
We are yet to determine all the adverse effects of microplastic from land-derived litter. However, it is evident that leaving even one piece of plastic debris behind can have profoundly harmful impacts.
Another primary pollution source is the plastic we flush down the drain. Many people (often unknowingly) send plastic down the drain. Wet wipes and other larger plastic pieces contribute to the creation of 'fatbergs' that block sewage systems.
While other plastics like the plastic sticks from Q-tips cotton buds pass straight through treatment plant filters and end up in our oceans and on our beaches, the microplastics are the most insidious of all. Synthetic clothing releases microplastics every time we wash them (as well as when we wear them).
Sometimes, the slurry from sewage treatment plants is used as a fertilizer on farm fields. But recent exposés have proposed that this slurry contains all sorts of harmful contaminants, including microplastics. And often, regulation in this area leaves a lot to be desired, meaning consumers of agricultural produce are often unaware of the fact that plastic waste could contaminate the food they eat.
Throwing plastic in general waste for collection can be just as harmful as littering or flushing plastic waste down the drain. Where plastic waste ends up (if the system does not separate it from other waste streams) will depend on where you live and the practices in your area.
The problem is that there is usually little transparency regarding waste management. It can be challenging to determine exactly where the household waste you generate ends up.
A high proportion of general waste globally ends up in a landfill. The landfill may be in your own country or abroad for some developed countries. Of course, when countries ship plastic waste abroad, there will be carbon costs and pollutants associated with transportation to contend with.
Landfill sites should contain waste and prevent it from entering wider environments. Unfortunately, poor management (especially in developing nations where much waste from the developed world ends up) means plastic waste often blows away. Or the wind sweeps it off landfill sites and pollutes the wider environment.
However, even well-managed landfill sites have negative environmental impacts. When plastic waste ends up in a landfill, it can contribute to leachate. Where plastics are not handled correctly, certain types of plastic— such as polyvinyl chloride; and PVC— can leach toxic chemicals such as additives and plasticizer compounds into the surrounding land and waters.
Related read: Environmental Impact of Landfills.
Another common practice is incinerating or burning waste plastic, which produces CO2 and other greenhouse gases that contribute to our climate emergency. However, we sometimes use the energy from burning plastics to heat and power homes and businesses.
Whether or not this waste-to-energy solution can result in a net reduction in greenhouse gas emissions depends on several factors, including the efficiency of the incineration process and the mix of the energy sources it replaces.
Where the energy mix contains a high proportion of fossil fuel sources, burning plastic for energy can reduce emissions4. But in many countries — most across Europe, for example — where incineration efficiency is low and the energy mix is lower-carbon, this results in higher greenhouse gas emissions.
Even where incineration does lead to a net reduction in carbon dioxide (CO2) emissions, it is far from an ideal solution because incineration of plastic waste worsens air pollution and can release a range of harmful particulates into the air3.
Incomplete combustion of Polyethylene (PE), Polypropylene (PP), and Polystyrene (PS) can release carbon monoxide (CO) and noxious emissions, while polyvinyl chloride (PVC) can produce dioxins.
Modern facilities for incineration in the developed world have largely managed to introduce regulations and filtration to catch pollutants.
But in developing nations, open incineration is still common and causes huge pollution problems. Containment for even modern facilities is still sometimes a contentious area and one of concern.
That said, incineration is sometimes better than landfills in our fight against global warming. And is the best currently available solution to deal with non-recyclable plastics on a large scale.
And interestingly, certain studies have found that when we consider all factors, it can be a more environmentally friendly solution than some forms of recycling. This highlights the complexities of the issues of plastic waste and shows that we must take everything into account.
Where possible, it is, of course, generally best to try to recycle plastic waste whenever we can. But it is important to recognize that recycling waste plastic alone is insufficient. Or even better, refuse, reduce, reuse, and recycle.
Unfortunately, we cannot recycle some of the plastic waste we generate each year globally at all. And even when we can recycle plastic waste, it is not always actually recycled at all, even when placed in recycling bins.
For guides to some common types of plastic waste recycling, click:
Often, recycling simply isn't economically viable for authorities and businesses. When oil prices are low, it can be cheaper for the plastic industry to make new raw plastic products (e.g., plastic bags and packaging) than to recycle, which poses a major problem economically.
Another problem is that consumers do not always clean their mixed plastics and sort them as they should. This can also lead to reduced recycling rates – even when consumers believe they are doing the right thing.
The environmental benefits of recycling plastics are clear. For example, recycled PET plastic production reduces emissions compared to virgin production by 32%. And recent examples have shown that results can be even better.
But the issue is not always as clear-cut as some people believe. Researchers have also made many assumptions. Based on the idea that each tonne of recycled plastic can replace one ton of raw, virgin material.
But this is not always possible. Recycling processes cannot consistently deliver a like-for-like product. It very much depends on the types of plastic waste generation we are talking about and which recycling methods regions use.
Read up on our home recycling tips for more info on maximizing your home recycling rate.
Most plastics go through a mechanical recycling process.
Unfortunately, we can only recycle these plastics mechanically once or twice before they are down-cycled. This means that the recycling plant demotes them to lesser-valued materials. Those things are then often not recyclable at the end of their useful lives.
This often means that recycling does not prevent plastic waste from ending up in landfills or incinerated – it only delays it.
Chemical recycling involves breaking plastic polymers down into their crude components. This, in theory, means that we can recycle certain plastics endlessly rather than being downgraded.
We can utilize state-of-the-art techniques such as chemolysis, pyrolysis, fluid catalytic cracking, hydrogen techniques, and gasification—all to break down plastics to make fuels for reuse2.
But chemical recycling does not necessarily bring environmental benefits. Though chemical processes are more tolerant of contamination1 and yield polymers identical to the originals, eliminating downcycling, they can often pollute and produce higher greenhouse gas emissions.
How environmentally friendly the process is will depend on the exact processes used, energy efficiency, and the type of energy used.
It is clear that of all the options currently commercially available, chemical recycling is usually the best option. But to solve the problem of plastic waste and reduce pollution, refusing, reducing, and reusing must also be critical parts of the picture. To tackle plastic pollution, we need to find ways to break our reliance on the product once and for all.
|C&EN, 2019: Plastic has a problem; is chemical recycling the solution?|
|Kim Ragaert, Laurens Delva, Kevin Van Geem, Mechanical and chemical recycling of solid plastic waste, Waste Management, Volume 69, 2017, Pages 24-58, ISSN 0956-053X, https://doi.org/10.1016/j.wasman.2017.07.044|
|Rinku Verma, K.S. Vinoda, M. Papireddy, A.N.S. Gowda, Toxic Pollutants from Plastic Waste- A Review, Procedia Environmental Sciences, Volume 35, 2016, Pages 701-708, ISSN 1878-0296, https://doi.org/10.1016/j.proenv.2016.07.069|
|Ola, E., Göran, F. (2009). Plastic waste as a fuel - CO2-neutral or not? https://doi.org/10.1039/B908135F|
|European Commission (Environment): Our Oceans, Seas and Coasts. Descriptor 10: Marine Litter|
Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.
Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.