Study identifies adverse impact of bio-based materials on earthworms

Bio-based materials - which are used in textiles and products including clothing, wet wipes and period products - emit microfibres into the environment through the laundry cycle, the application of sewage sludge as fertilisers, or through wear and tear of textile products.

Despite increasing quantities of bio-based products being produced and sold globally, there has been little research to assess their potential impact on species and ecosystems.

Now, a study detailed in Environmental Science and Technology tested the effects of conventional polyester fibres and two bio-based fibres – viscose and lyocell – on earthworms, an important invertebrate that eats decaying plant material and creates healthy soils.

The study found that in high concentrations of fibres, 30 per cent of earthworms died after 72 hours when exposed to polyester, while those exposed to the bio-based fibres experienced mortality of up to 60 per cent for lyocell and 80 per cent for viscose.

A second experiment, using environmentally relevant concentrations of the fibres, indicated that earthworms housed in soils containing viscose fibres exhibited reduced reproduction compared to those exposed to polyester fibres. Earthworms in the soils containing lyocell fibres showed reduced growth and higher rates of burrowing within the soil compared to exposure to the other types of fibre.

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The researchers said the study highlights the complex nature of global efforts to reduce the threat of microplastic pollution, and the importance of testing new materials being advocated as alternatives to plastics before they are released on the open market.

The study was carried out as part of the BIO-PLASTIC-RISK project, led by researchers at the Universities of Plymouth and Bath, and supported with £2.6m funding by the Natural Environmental Research Council.

In a statement, Dr Winnie Courtene-Jones, lead author and lecturer in Marine Pollution at Bangor University, said: “Over 320,000 tonnes of bio-based and biodegradable fibres were produced globally in 2022 and research shows that substantial  quantities of that will end up in the environment. However, evidence of their ecological impacts has been lacking.

“Our study has shown that bio-based fibres have a range of adverse effects on earthworms – animals which are critical to the functioning of the environment. It highlights the importance of gathering further evidence before alternatives to conventional plastics are made available even more widely.”

The new study follows research published earlier in 2024 which highlighted that being exposed to the materials used in biodegradable teabags can result in earthworm populations experiencing up to 15 per cent greater mortality and have a detrimental effect on earthworm reproduction.