Some children’s slime toys contain potentially unsafe levels of a chemical which can cause vomiting and impair fertility, according to Which ?.
An investigation by the consumer group into 11 popular gunk products find eight contained higher than recommended levels of a chemical called boron.
One product had more than four times the EU safety limit, the tests found.
Which? is advising mothers to “approach slime with caution” and said retailers and the government must do more.
It also urged parents to be careful when choosing to build “homemade slime”, adding that some ingredients used to construct slime – such as some contact lens solutions – contain borax, which is made up of boron.