Thousands of “harmful” tiny plastic particles could be lurking in vegetable roots, experts warn.
Researchers at the University of Plymouth found that particles found in the soil can be absorbed into the edible parts of crops during the growing process.
Nanoplastics measuring as little as one millionth of a centimetre in diameter were found in radishes. And for the first time, experts found that these plastics can enter through the roots and spread through the plant as they are so small.
Lecturer in physiology Dr Nathaniel Clark said: “Plants have a layer within their roots called a Casparian strip, which should act as a form of filter against particles, many of which can be harmful.”
But he warned that nanoplastic particles can get beyond that barrier and be passed on to humans when the vegetable is consumed.
“There is no reason to believe this is unique to this vegetable, with the clear possibility that nanoplastics are being absorbed into various types of produce being grown all over the world,” Dr Clark added.
In the study, published in the journal Environmental Research, researchers grew the radishes in a lab with the roots submerged in a solution that contained plastic particles.
After five days, they examined how far into the plant the plastic particles had penetrated. They found nearly 5 per cent of particles originally in the solution had been retained by the root system, amounting to millions of nanoplastics entering the crop.
Of those particles, around a quarter had made their way into the edible fleshy roots, while 10 per cent had accumulated in the leaves.
“To some extent, these findings shouldn’t be a surprise – after all, in our previous work we have found microplastic pollution everywhere we have looked for it,” Professor Richard Thompson, director of the Marine Institute, said.
Researchers at the university have studied microplastics for more than 20 years, showing the presence of plastic particles from the deepest parts of the global ocean to the slopes of Mount Everest.
It has identified some of the main sources of microplastic pollution – from tyre wear to the laundry cycle and flaking paint, and the degradation of larger items in the environment.
Previous research has also shown nanoparticles in molluscs and fish, suggesting these particles can move and build up throughout the food chain.
“This study provides clear evidence that particles in the environment can accumulate not only in seafood but also in vegetables,” Professor Thompson added.
But scientists are concerned plastic pollution has contaminated Britain’s entire food chain, meaning it is not just a marine issue and has become almost impossible to avoid.
Scientists at Sussex and Exeter universities found microplastics in slugs, beetles, snails and earthworms.
The study published in May suggested polyester, most likely from clothes, was the most common type of plastic found in the invertebrates tested.
Researchers suspected these plastic fibres came from dried human sewage sludge, which is used as fertiliser by some farmers and can contain fibres from washing machines.
