How long does it take wool to degrade in the ocean?

This is the question Crown research institutes AgResearch and Scion hope to answer as they embark on a study of how woollen clothing and carpet biodegrades in seawater.

This research which may boost the appeal of the natural fibre as concern grows about synthetic microfibres entering the food chain.

The study comes out of AgResearch's core funding, initially running for 90 days, and goes to the CRI's mandate to demonstrate the sustainability of products that come from the farm, spokesman Jarrod Booker said.

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The first target is to establish a benchmark, with a detailed study beyond that, he said.

Finding new reasons for consumers to choose wool come amid evidence microfibres of synthetics such as polyester and nylon are a significant contributor to microplastics entering waterways and the oceans, being taken up by marine life and ultimately consumed by humans.

The Florida Microplastic Awareness Project, an offshoot of the University of Florida, says a synthetic garment can shed more than 1,900 fibres per wash which are too small to be filtered out by wastewater treatment plants and end up in the ocean. It advocates cotton, hemp and linen as alternatives that do break down.

AgResearch senior scientist Steve Ranford said there is only limited data on the behaviour of wool but that suggests that as a natural protein fibre it breaks down in seawater in a way pretroleum-based synthetics don't.

"To test that, we will be working with Scion in an experiment that tests how samples from both woollen clothing and carpets biodegrade in controlled salt water conditions, compared to samples from the synthetic alternatives," Ranford said.

"The aim is provide the public with objective information as they make choices about what they buy, as well as inform manufacturers and retailers of the performance of goods like clothing and carpet."

Wool contributed 26 percent of the total value of exports, but by 2011 wool's contribution to the value of exports had fallen to 1.6 percent, according to Stats NZ.