Slime toys could be harming children.
Parents are being warned that some slime products may contain up to four times the legal amount of a chemical which can cause convulsions and sickness.
Consumer group Which? tested 11 products, and found that eight of them breached EU regulations on the amount of boron they contain.
Boron is found in borax, the ingredient commonly used in slime manufacture to give the product its stickiness.
It comes as slime and slime products have become increasingly popular among children, with YouTube tutorials going viral.
Science journalist Sean Duke says parents should always supervise their children when making slime, products should be bought in high street retailers instead of online, and children should avoid eating it and getting large amounts on their skin: 'Some of these products, people just think they're safe, if you're getting borax from the chemist make sure not a lot of it goes into the mix'.