When 19 British pre-schools stopped using glitter in art projects to save the oceans, it set off a frenzy that reached as far as New Zealand over glitter’s potential to harm marine life. The change at the Tops Day Nurseries, the chain’s directors say, is aimed at reducing plastic pollution entering the ocean, and it prompted Trisia Farrelly, an environmental anthropologist at Massey University in New Zealand, to call for a global ban.

“All glitter should be banned because it’s microplastic and all microplastics leak into the environment,” Farrelly says.

But what potential threat is posed by these sparkly bits of plastic that are ubiquitous in Christmas holiday season décor? It is hard to say.

Glitter is made from plastic sheets