Now that single-use plastic straws have been banned in the UK, many businesses have turned to cornstarch straws instead. In this article, we take you through the positives and negatives of using cornstarch straws for the environment and provide some alternatives.

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If you’ve been looking into eco-friendly alternatives to single-use plastic straws following their ban in the UK, it’s likely that you’ve stumbled across cornstarch straws. They’re made from compostable bioplastics, which have been praised by some as the answer to the world’s plastic problem. But is everything as it seems? How good are they really for the environment? 

What is cornstarch? 

Cornstarch is also known as PLA, or polylactic acid, and is a type of bioplastic. This means that 20% or more is made of cornstarch and kernels. To make PLA, cornstarch is mixed with acid or enzymes, heated and fermented. The result is a compostable material that looks and feels exactly like conventional plastic. PLA makes up a quarter of biodegradable plastics worldwide. 

What are the benefits of using cornstarch straws instead of plastic straws?

The main environmental benefit to using cornstarch straws instead of plastic straws is that they are compostable. In controlled composting environments, they take under 3 months to decompose. This is nothing compared with the hundreds of years that conventional plastics can persist in the environment after they’re finished with. What’s more, cornstarch straws are also biocompostable, which means that they don’t release any toxic gasses as they decompose and that they can break down so well that by the time they’re finished decomposing, they can’t be distinguished from the surrounding compost. 

Image source: Unsplash

Though the production of cornstarch straws actually emits more carbon than the production of plastic ones, it’s the end of their life cycle that really makes the difference. While the production of 1kg of polypropylene and PLA straws emits 1.6kg and 3kg of CO2 respectively, polypropylene straws emit a further 4.06kg when they go to landfill and 4.86kg when they are incinerated. The composting process of PLA emits far fewer greenhouse gasses and, crucially, doesn’t emit methane, which is 30 times more powerful than CO2 as a greenhouse gas. 

Type of strawCarbon emissions per kg throughout their life cycleEquivalent in miles driven
Polypropylene (plastic)5.6kg 17 miles
PLA 3kg9 miles

In terms of the experience of using cornstarch straws, they feel just like plastic, so they don’t affect the taste of the drink and their texture and shape shouldn’t change. They’re very durable and are well-suited to cold drinks — they can even go in the freezer if needed.

What are the disadvantages of using cornstarch straws? 

Cornstarch straws won’t effectively decompose in your compost bin at home or at work. They require industrial composting conditions, or consistent temperatures above 60 degrees Celsius. This means that they also won’t decompose quickly at landfills, where temperatures aren’t high enough and they are unlikely to receive much oxygen or light. There, they can take up to 1,000 years to decompose. If PLA ends up in marine ecosystems, it can pollute the water and air and enter the food chain. In effect, if PLA is not disposed of correctly and ends up at a landfill or in the environment, its impacts are similar to those of conventional plastics.

Cornstarch straws are not recyclable and shouldn’t be thrown in with your plastic recycling. PLA has a lower melting point than other plastics so it can cause problems at recycling centres. Separate disposal services should be organised for your PLA and conventional plastics.

Some people oppose the use of cornstarch straws because the corn used to make it is usually genetically modified. More nitrogen fertiliser, herbicides and insecticides, all of which can lead to soil erosion and water pollution, are used on genetically modified corn than any other crop. Genetically modified corn can also disrupt other crops and contaminate ecosystems.

Though cornstarch straws are great in cold drinks, they shouldn’t be used in hot drinks above 45 degrees Celsius and might even warp or melt in extremely hot weather. 

Are there any more eco-friendly alternatives to cornstarch straws?

The most eco-friendly alternative to cornstarch straws is giving up straws completely. For your personal use, though, reusable stainless steel or glass straws are the best options. As for single-use straws, rice straws could be the answer. They’re fully biodegradable, compostable and even edible! They also maintain their shape for 3 to 4 hours in cold drinks and 30 to 60 minutes in hot ones, and don’t affect the taste of drinks. In the future, seaweed straws, which are edible, compostable at the same rate as food, and degradable in the sea, will also become a great option.

Image source: Unsplash

Where can I buy cornstarch straws? 

You can buy cornstarch straws from these retailers: 

Don’t let the potential negative effects of cornstarch straws on the environment put you off them completely. As long as you dispose of them correctly by ensuring that they don’t end up in your recycling or at the landfill, they are far better for the environment than plastic straws. If you’re not convinced but still need single-use straws in your business, look into rice straws instead.

Sophie Comninos
Author: Sophie Comninos

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