Microplastics have infiltrated every part of the planet, from Antarctic sea ice to the deepest ocean trenches. Now they are turning up in the food we eat, with European farmland becoming the biggest global reservoir of these tiny plastic fragments, according to a study by researchers at Cardiff University.
The study found that between 31,000 and 42,000 tonnes of microplastics, or 86 trillion to 710 trillion particles, contaminate European farmland each year. This contamination comes from sewage sludge, the byproduct of wastewater treatment, which is commonly used as organic fertiliser in the US and Europe. In the UK, between 500 and 1,000 microplastic particles are spread on each hectare of farmland annually, among the highest concentrations in Europe.
The microplastics persist for decades. A study by Philipps-University Marburg found microplastics up to 90cm below the surface on agricultural fields where sewage sludge had last been applied 34 years ago. Ploughing also spreads the plastic into areas where sludge was not applied.
Eventually, the microplastics are washed into waterways. A study in Ontario, Canada, found that 99% of microplastics were transported away from where sludge was dumped into aquatic environments. “The major source of contamination in our rivers and oceans is from runoff,” said James Lofty, lead author of the Cardiff study.
Microplastics also leach toxic chemicals such as PFAS, or “forever chemicals”, into the soil. The Environmental Working Group found that sewage sludge has contaminated nearly 20 million acres of US cropland with PFAS, which do not break down under normal conditions and can enter the food chain.
