If your wallet/bag/kitchen table looks anything like most people’s, it’ll be stuffed full to the brim with receipts. Little wonder, given that UK retailers dish out 11.2 billion of them every year, according to a study. But at what cost to the environment?

Most receipts are made from a special paper that is thermally sensitive, explains Simona Maccarrone from Matmatch, a platform that helps product designers and engineers source and evaluate materials. “So you don’t print with ink, rather you warm the paper up and it makes that area black and change colour with heat,” 

That means that many receipts can’t be recycled, because they’re made from more than one material, which makes it practically impossible to separate.  

Around half of thermal paper receipts – usually the shiny ones – are coated with potentially harmful substances called bisphenol A (BPA) and bisphenol B (BPS), according to an article in Wired. Because of these substances, they could contaminate other materials headed for recycling.

So what should you do with your receipts? Current advice is that they should be chucked in the bin rather than recycled. However an increasing number of retailers now offer digital receipts as an alternative, so opt for this if you’re concerned. (Although that does mean giving them your email address.)

Receipts are among many items in the UK that can’t currently be recycled because they’re made from more than one material. Coffee cups, for example, are difficult to recycle at regular plants because they are made of an outer paper shell with an inner lining that can’t be easily separated.