Bioplastics marketed as “biodegradable” are remaining in soils and ditches for longer than the two-year industry standard, a scientific study by Wageningen University in the Netherlands has found.
The study was commissioned by Dutch environmental charity Plastic Soup Foundation and conducted by researchers at Wageningen University in the Netherlands.
Researchers found 3,000 microplastics per gram of sediment in samples taken from ditches surrounding agricultural fields, which the study says is evidence that microplastics accumulate in the environment.
The main reason for the microplastic pollution in soils is the use of plastic mulch to warm up the soil and to prevent weed growth, the Plastic Soup Foundation says.
The study found high concentrations of microplastics derived from biodegradable plastic mulches that did not degrade in two years under field conditions. Plastic Soup Foundation says samples were taken at eight flower farms in the Netherlands in September 2022 and at eight coriander farms in Spain in November 2022.
Researchers found 48 different types of microplastics across the tested samples. 61% of the microplastics detected were found to be fossil fuel-based, while the remaining 39% were bio-based, the study found.
This study shows that these mulches risk contaminating the soils in which the food we eat is grown.
Commenting on the study, Maria Westerbos, director of Plastic Soup Foundation, said: “Biodegradable plastic mulches are increasingly used by farmers. Mulch is sold to farmers with the false promise of degradability within two years. ‘They can simply be left on the field and ploughed under’ producers claim under false promises.”
“This study shows that these mulches risk contaminating the soils in which the food we eat is grown. A wide body of evidence has linked microplastic pollution with serious health threats. Because of this, I urge the plastic manufacturers to urgently cease selling products to farmers with dubious claims of biodegradability.”
From 13 – 19 November 2023 the negotiations for a Global Plastic Treaty continue at the United Nations Environmental (UNEP) headquarters in Nairobi.
On behalf of the Plastic Health Council, the Plastic Soup Foundation says it will work with A Plastic Planet to “plea” with leading scientists for a “strong and comprehensive” treaty that tackles plastic pollution on a global scale.