There are calls for toy slime to be removed from sale ahead of Christmas.
Consumer group Which? found almost half of them, in high street shops and online, failed EU safety limits for the potentially dangerous chemical boron.
The consumer watchdog says it's informed manufacturers and retailers.
Boron is found in borax, the ingredient commonly used in slime to give the product its stickiness, and can cause convulsions and illness.
It comes as many children have slime on their santa list this Christmas.
