NOT so long since there was the clamour for those colourful loom bands; then it was fidget spinners and now children are eager to get their hands, literally, on slime.

Young viewers seem to be transfixed by social media screenings of fingers sinking into the stuff and the delightful slurping sounds it makes when worked between digits.

Many are eager to try and re-create their own slime at home, but after seeing some of the ingredients for some of the suggested recipes, it’s no surprise parents can be put off.

Interestingly, the consumer watchdog Which? has been investigating the safety of some children’s slime products and, according to the watchdog, some may contain higher than recommended levels of boron - found in borax - which can be used in eye drops, mild antiseptics and washing powders.

Apparently it is a common ingredient in slime that helps to create its “stickiness.”

A European Union safety directive sets out how liquid or sticky toys should contain no more than 300mg/kg of boron.

The consumer champion set out to investigate whether some children’s slime products contained the recommended safe levels. It found eight out of 11 toy slime products tested exceeded limit.

Which? said it has passed its findings to the Office for Product Safety and Standards.

It also warned that parents making homemade slime should be wary when considering this option.

Some reports have suggested that youngsters have sustained injuries after trying to replicate slime recipes found online.

Nikki Stopford, director of research and publishing at Which? said: “If you have school-age kids you’re probably very well aware of the latest slime craze sweeping the playgrounds. Kids love it.

“Parents buying slime for their children should have peace of mind that these toys are safe, so they will be shocked to find that the health of their children could be put at risk by these slimes.

“There must be fundamental changes to the product safety system.

“Manufacturers must stop making unsafe products and the Government and retailers simply have to do a far better job of getting anything identified as a risk off the shelves and out of people’s homes”.

A Department for Business, Energy and Industrial Strategy spokesman said: “The Government’s top priority is to keep people safe, which is why goods being sold in the UK must meet some of the strictest safety laws in the world.

“The evidence provided by Which? will be considered by the Office for Product Safety and Standards and [it can] take any appropriate action.”

Slime making sessions have proved popular at Hello Crafter in Shipley.

Kylie Henshaw who runs them believes the popularity stems from children watching how slime is made online.

Her tried and tested recipe has been well researched and her advice to those wanting to create their own is to do their research.

Dr Philip Drake, Material Chemist, Lecture in Chemistry, Chemistry and Biosciences within the Faculty of Life Sciences at the University of Bradford, explains: “The food we eat every day contains low levels of boron. The average adult consumes a few milligrams per day in their diet and boron is considered to have a low toxicity. What’s more, the boron we consume does not accumulate in our bodies; it is cleaned out every day when we urinate.”

However he says children with cuts, grazes, rashes or eczema should wear gloves due to potential skin irritation. “There has been reports of children suffering skin irritation or even burns from playing with slime, however, this may be caused by other components rather than boron,” says Dr Drake.

His advice is to buy slime from a reliable source and don’t eat it, like it or lick hands after playing with it in case of other metals that may exist.

“Slime is fun to play with and actually represents a pretty interesting material from a science perspective. Dr Nadeem Javid at Bradford University studies jelly and other slimy things in his research (hydrogels). We make boron slime in our undergraduate laboratory practical’s at Bradford University School of Chemistry and Biosciences, and base these on guideline given out by the Royal Society of Chemistry. In this class we use about 400mg of boron and our slime has about 4000mg/kg, higher than the EU safety limit (but we do not class it as a toy and we tell our students not to eat it…and they wear gloves!).”