Microplastics have been found almost everywhere: in blood, placentas, lungs – even the human brain. One study estimated our cerebral organs alone may contain 5g of the stuff, or roughly a teaspoon. If true, plastic isn’t just wrapped around our food or woven into our clothes: it is lodged deep inside us.

Microplastics are shed from packaging, clothes, paints, cosmetics, car tyres and other items. Some are tiny enough to slip through the linings of our lungs and guts into our blood and internal organs – even into our cells. What happens next is still largely unknown.

"Designing a definitive experiment is hard, because we’re constantly being exposed to these particles,” says Dr Jaime Ross, a neuroscientist at the University of Rhode Island in the US. “But we know microplastics are in almost every tissue that has been looked at, and recent studies suggest we’re accumulating far more plastic now than 20 years ago.”