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Some plastic straws degrade faster than others

In a recent study, scientists from Woods Hole Oceanographic Institution (WHOI) examined the degradation rates of different types of straws in the ocean. 

The research, conducted in collaboration with Eastman, a bioplastic manufacturing company, aimed to identify sustainable alternatives to conventional plastic straws.

Focus of the study

The team suspended various types of straws in a tank of continuously flowing seawater from Martha’s Vineyard Sound, Massachusetts, to mimic natural marine conditions. 

The types tested included straws made of cellulose diacetate (CDA), polyhydroxyalkanoates (PHA), paper, polylactic acid (PLA), and polypropylene (PP). 

Key insights

Over 16 weeks, the researchers observed that the CDA, PHA, and paper straws degraded by up to 50%, with an estimated environmental lifetime of 10-20 months in the coastal ocean. In contrast, PLA and PP straws showed no measurable signs of degradation.

“We lack a firm understanding of how long plastics last in the ocean, so we’ve been designing methods to measure how fast these materials degrade,” said Collin Ward, a WHOI scientist. “It turns out, in this case, there are some bioplastic straws that actually degrade fairly quickly, which is good news.”

Foam straws

The study also compared two CDA straws provided by Eastman, one solid and the other a foam variant. The foam CDA straw, a prototype designed to increase surface area and accelerate degradation, was found to degrade 184% faster than the solid straw, indicating a shorter projected environmental lifetime than even the paper straws.

“The unique aspects of this foam straw are that it’s able to have a shorter expected lifetime than the paper straws but retain the properties that you enjoy of a plastic or a bioplastic straw,” explained Bryan James, a WHOI scientist.

Study significance 

Jeff Carbeck, Eastman’s Vice President of Corporate Innovation, emphasized the significance of the study for straw manufacturers. 

“This study can be immensely valuable for straw manufacturers by providing informed and transparent data when selecting a material for straws. Even more, it provides reassurance that CDA-based straws won’t add to the persistent plastic pollution, while also demonstrating straw manufacturers’ commitment to offering a sustainable product that reduces risk to marine life.”

The findings highlight the importance of developing new materials that are sustainably sourced and degrade more effectively in the environment, thus reducing the impact of plastic pollution.

Plastic straws and the environment 

Plastic straws have become a significant environmental concern due to their impact on ecosystems, particularly marine life. 

Most plastic straws are made from polypropylene or polystyrene, which are not biodegradable. This means they can persist in the environment for hundreds of years.

Ocean pollution

Many plastic straws end up in the ocean, contributing to the vast amount of plastic waste there. They can harm marine life through ingestion or entanglement.

Wildlife harm

Marine animals, including fish, turtles, and seabirds, can mistake plastic straws for food. This can lead to injury or death. Straws can also block airways or digestive tracts.

Microplastics generation

Over time, plastic straws break down into smaller pieces, known as microplastics. These microplastics are difficult to clean up and can be ingested by marine life, entering the food chain.

Resource intensive

The production of plastic straws involves the use of petroleum, a non-renewable resource, and also results in the emission of greenhouse gases.

Challenges in recycling

Plastic straws are often not recycled due to their small size and lightweight nature, which makes them difficult to process in standard recycling equipment.

The study is published in the journal ACS Sustainable Chemistry & Engineering.

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