Researchers from Scandinavia have warned that large quantities of plastic micro-beads could be ending up on agricultural land. The beads - tiny bits of plastic used in cosmetic products like face scrubs and toothpastes - could end up in agricultural soils and watercourses through applications of sewage sludge fertilisers.

At the beginning of the month, Defra secretary Andrea Leadsom announced plans to ban micro-beads, in response to growing concerns that the beads are building up in marine environments and risk harming fish and crustaceans. Now though, researchers from the Norwegian Institute for Water Research (NIVA) and the Swedish University of Agricultural Sciences have said these beads could also pose a threat to agricultural landscapes and freshwater ecosystems.

Reporting in the journal Nature this week, researchers from the two institutes called for in-depth research into the effects of micro-beads entering the farmed environment. Unlike the known effects the beads can have on sea-life, the researchers said not enough is know about the impacts on-land, even though the burden of micro-bead pollution could be greater here than at sea.  

The researchers said data from the Swedish Environmental Protection Agency suggests that that between 63,000 and 430,000 tonnes of micro-plastics could be being added annually to farmlands in Europe alone (44,000–300,000 in North America), compared to an estimated 93,000–236,000 tonnes in surface waters in the world’s oceans.

This isn’t the first time researchers have called for further investigation of sewage-based fertiliser use. Scientists from the University of Exeter’s Medical School warned in 2014 that residues of drugs prescribed for human use could be making their way into farm soils through a number of routes, including the use of sewage sludge as fertiliser and waste water for irrigation, and last year researchers from the Universities of Aberdeen and Nottingham published a study suggesting that grazing on land where sewage sludge fertilisers were used could affect fertility in sheep - and possibly humans.