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Parents are being warned about potentially toxic levels of chemicals in slime toys popular with children.

The consumer group Which? tested 11 of the most popular products on the market and found eight of them had above the recommended levels of boron.

The chemical is found in borax, a common ingredient in slime that helps to create its stickiness.

Exposure to excessive levels of boron can cause irritation, diarrhoea, vomiting and cramps.

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

It said there needed to be better regulation of the market, as many slimes had minimal safety labelling or information on ingredients.

'Peace of mind'

Which? director of research Nikki Stopford 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".

The products found with above the recommended 300mg/kg level of boron were:

Jupiter Juice (pink) by Toysmith

Fluffy Slime (pink) by CCINEE

Crystal Slime Magic Clay (pink) by Cosoro Dodolu

Mini Bucket Putty (green) by Baker Ross

Slime Toy (purple) by iBase Toy

Fluffy Slime (blue) by LOYO

Brezeh Free Slime Toy (orange) by Brezeh

My Fluffy Slime (green) by Virtuotrade

All of them were sold by Amazon.

The company told Which? it had removed the products that had failed the tests from sale.

Amazon was unable to provide a comment to the BBC.

Which? said people who had bought the products should be entitled to a refund and should stop using the product.

And the group warned parents whose children were making "homemade" slime that they should also be careful.

This is because some ingredients listed for slime, such as contact lens solution, contain borax and often slime recipes do not list the quantities that need to be added.