Polypropylene is a plastic which you probably use everyday. But how sustainable is it?
A sustainable material is one that is environmentally friendly and doesn’t put great pressure on the environment or on our health from its production until its disposal. When evaluating how sustainable a material is, a number of elements need to be taken into consideration throughout its whole life cycle:
- Production – Does its manufacturing process emit greenhouse gasses?
- Disposal – Is it biodegradable and/or recyclable?
- Use – Can it damage human health during or after use?
With this in mind, we’ll assess the sustainability of polypropylene and provide you with some alternative materials which have fewer long-term impacts on the environment.
What is polypropylene?
Polypropylene (PP), sometimes called polypropene, is one of the cheapest plastics available. It’s also one of the most commonly used plastics, exceeded in use only by polyethylene. In 2020, over 80 million tons of polypropylene were produced. China is the world’s leader in polypropylene production — in 2016, it produced 27% of the world’s polypropylene.
What is polypropylene used for?
The durability of polypropylene means that it is used in a huge variety of everyday items. Its principal use is in plastic packaging, particularly in food containers. Most bottle caps, lids, thin-wall containers like yoghurt pots, tupperware and microwave covers are made from polypropylene. This is because it doesn’t absorb water, has a high melting point and is unlikely to leach any chemicals into the food that it contains unless exposed to extremely high temperatures.
It’s also used in car batteries and indoor hinges, as it is resistant to cracking and daily wear and tear. In the medical world, it is used in syringes and pill containers.
What is the carbon footprint of polypropylene production?
Because of the diversity in the way that different companies produce polypropylene, it is impossible to work out the exact carbon footprint of its production. However, it’s likely that the production of 1kg of polypropylene emits between roughly 1.95kg and 3.5kg CO2.
The production of polypropylene has a lighter carbon footprint than the production of many other types of plastic. For example, the production of polyethylene and polycarbonate, which are both used in many everyday items like food packaging, generates up to triple the carbon emissions of polypropylene!
| Material – 1KG | CO2 emissions per kg | Equivalent in miles driven |
|---|---|---|
| Polypropylene | 1.95kg – 3.5kg | 5.85 miles – 10.4 miles |
| Polyethylene | 6kg | 18 miles |
| Polycarbonate | 6kg | 18 miles |
| Bamboo | 1.4kg | 4.3 miles |
| Paper | 950g | 2.9miles |
| PLA | 500g | 1.5 miles |
| Bagasse | 36g | 0.1 miles |
Is polypropylene biodegradable?
Not really, but it takes a much shorter time to degrade than other types of plastic. While some plastics, like polyethylene and polystyrene, can take over 500 years to degrade, the degradation of polypropylene only takes around 20 to 30 years. This doesn’t mean that you can stop worrying about what will happen if your polypropylene ends up at the landfill or in the natural environment, though. As it degrades, polypropylene may release cadmium, which is a carcinogen and is toxic to both plants and animals.
Is polypropylene recyclable?
Yes, polypropylene is fully recyclable and doesn’t release any toxic chemicals in the recycling process. Though recycling polypropylene is undoubtedly the best option once it’s finished with, only around 1% worldwide is recycled, with the vast majority of the rest going to landfill. To make sure that polypropylene is recycled in your area, you should check with your local authority.
How does polypropylene affect our health?
Compared with other types of plastic, like polycarbonate, polypropylene has very few damaging impacts on human health. Its high heat tolerance makes it unlikely to leach toxins and chemicals into any food that it contains. It’s also free from BPA, which is a chemical that, if released into food and water supplies, can potentially lead to issues with immune function, learning abilities, brain development and more. However, when heated to extremely high temperatures, it has been linked with occupational asthma.
Are there any more sustainable alternatives to polypropylene?
Though you won’t be able to find more sustainable substitutes to polypropylene for all of its uses, there are plenty of options for food containers made from more eco-friendly materials.
1. Paper
Paper is a more sustainable material than plastic and is probably its most accessible alternative. It isn’t microwaveable but it makes for a sturdy food container.
2. Bioplastics
Bioplastics are made from 20% or more renewable materials. PLA, for example, is made principally from corn kernels. Bioplastics are safe as food packaging materials, though they aren’t microwaveable.
3. Bagasse
Bagasse is the plant fibre left behind in the sugar extraction process from sugarcane. It’s microwaveable and is used to make plates, bowls, food containers, takeaway boxes and cups.
4. Bamboo
You can find bamboo alternatives to tupperware and food containers, but some aren’t microwaveable.
So, is polypropylene sustainable? Not completely, but it is much more sustainable than other types of plastic, as it is more quickly biodegradable, has a lighter carbon footprint and isn’t threatening to our health.
Because polypropylene is used in such a wide variety of everyday items, it might not be possible to completely eliminate it from your home or workplace. If you’d like to limit your use of polypropylene, start by swapping your polypropylene food containers for ones made from paper, bioplastics, bagasse or bamboo.
