Potentially unsafe levels of chemical widespread in certain children’s slime products

Serious concerns over the safety of some children’s slime products have been raised following an investigation by Which?.

Following the craze that has led to millions of YouTube views and Instagram hashtags, the consumer champion tested 11 popular slime products for boron. Boron is found in borax – a common ingredient in slime that helps to create its stickiness.

Exposure to excessive levels of the element can cause irritation, diarrhea, vomiting and cramps in the short term. According to the European Commission, exposure to very high levels of boron may also impair fertility and could cause harm to an unborn child in pregnant women.

Eight out of 11 toy slime products tested exceeded the EU safety limit of 300mg/kg.

The worst product, Toysmith Jupiter Juice, had more than four times the permitted level of boron. This was followed by CCINEE Pink Fluffy Slime, which contains 1000mg/kg, and Cosoro Dodolu Crystal Slime Magic Clay, which contains 980mg/kg.

All eight products that failed were purchased on Amazon.  Just one product purchased from Amazon, Hulk Green Halloween Slime, met the standard.

Following the results, Which? is advising parents to approach all slime with caution, as many slimes have minimal safety labelling or information on ingredients.  Some of the slimes Which? tested even self-certified the packaging with a CE mark, suggesting the product is safe, despite the fact that the boron levels were too high when they were tested.

However, two high street retailers, The Works and Smyths, both sell slime that was found to be within the safety limit when tested.

Which? has passed its findings to the Office for Product Safety and Standards (OPSS). Anyone who owns one of the slimes that failed Which?’s testing should be able to return it to the retailer and get a refund.

Although Amazon has now removed the potentially unsafe products from sale, the results raise concerns about the safety of some products sold through online platforms.

The consumer champion believes more must be done by retailers and the Government to proactively identify potentially unsafe products and stop them from reaching people’s homes.

Parents need to be confident that the products they purchase will not harm them or their children, and if retailers cannot guarantee the safety of the products they stock, they have a duty of care to remove them from sale.

Producing ‘homemade’ slime is also a popular alternative, but parents should be careful when considering this option too. This is because some ingredients listed for slime (such as some contact lens solutions) contain borax, and often slime recipes don’t list the quantities that need to be added.

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”.


  1. Testing results (images available on request)
Retailer Supplier Sample name (colour of sample tested) Level (mg/kg)
Amazon Toysmith Jupiter Juice (Pink) 1400
Amazon CCINEE Fluffy slime (Pink) 1000
Amazon Cosoro Dodolu Crystal Slime Magic Clay (Pink) 980
Amazon Baker Ross Mini Bucket Putty (Green) 930
Amazon iBase Toy Slime Toy (Purple) 860
Amazon LOYO Fluffy slime (Blue) 730
Amazon Brezeh Brezeh Free Slime Toy (Orange) 560
Amazon Virtuotrade My Fluffy Slime (Green) 560
The Works HGL Goopy Slime (Green) 280
Amazon Planet Slime Shop Hulk Green Halloween Slime 220
Smyths Glam Goo Glam Goo Deluxe Pack (Clear) 75
  • Red indicates that the slime product exceeded the EU safety limit of 300mg/kg.
  • Where the colour is mentioned in brackets, only that colour in the slime was tested.
  • The other metals and phthalates tests conducted for all products were within permitted limits
  • Slimes that had over the safe limit of boron but also had a CE mark: CCINEE Pink Fluffy Slime, Baker Ross Putty, Cosoro Dodolu Crystal Slime Magic Clay
  • Slimes were selected according to a series of criteria, including:
    • The most common and popular slimes available at major children’s toy retailers
    • Highly recommend slimes on Instagram and YouTube
    • Popularity rankings on Amazon Prime
    • Price
  1. Italian consumer group Altroconsumo tested slime toys given away free with newsstand magazines. They found a third of products tested contained Boron above permitted limits. They reported their findings to the Italian Ministry of Health.
  2. In response Amazon said: “All Marketplace sellers must follow our selling guidelines and those who don’t will be subject to action including potential removal of their account. The products in question are no longer available.”
  3. Baker Ross, supplier for Mini Bucket Putty, claimed that its product should officially be declared putty, not a slime, and was therefore within the safety limited for Boron. Our expert laboratory confirmed that it should be classed as a slime because of it’s texture and substance. Pending further investigation, Baker Ross told Which? that it has taken Mini Bucket Putty off sale.

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