Slime has been growing in popularity online, with videos of the sticky toy going viral on social media.
The toy may seem like harmless fun, but U.K.-based consumer group Which? is warning that it often contains a potentially toxic ingredient.
The chemical in question is boron (also known as borax or boric acid), which is a key ingredient, giving slime its sticky texture.
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The consumer group revealed that it tested 11 popular slime brands being sold on Amazon, and found that eight contained “excessive levels” of the chemical.
It then contacted Amazon, which said it had removed the products that did not meet European Union safety regulations.
Which? issued the warning to parents, saying they should still remain vigilant when buying slime for children, as there are countless brands selling the product.
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Not all the companies label the product’s ingredients, either.
Making slime at home can help, but the group said caution should be exercised in this matter as well.
“Some ingredients listed for slime, such as some contact lens solutions, contain borax. Often slime recipes don’t list the quantities you need to be adding,” the group’s post read.
Similar warnings have been issued about slime in the past, including by Health Canada.
In 2016, the health agency said Canadians should avoid using boron when making slime at home.
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The release explained that boron can cause developmental and reproductive health effects, and exposure should especially be limited for children and pregnant women.
There have been reported cases of slime recipes going wrong.
For example, the case of an 11-year-old from Rockland, Mass. who sustained third-degree burns after making slime from a viral do-it-yourself recipe found online.
Doctors said the burns were caused by boric acid.
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But it’s not just slime that contains the chemical, it’s also found in the environment.
People can be exposed to it naturally through food (like fruits and vegetables) and drinking water. It can also be found in cleaning products, cosmetics, swimming pool and spa chemicals, drugs and natural health products.
The U.S. National Pesticide Information Center, Oregon State University and the U.S. Environmental Protection Agency also say contact with boric acid can be corrosive to the eye and cause irritation to the skin.
Being in contact with extreme amounts (often by ingestion) can result in a red and blistering rash and skin loss.
— With files from Global News reporter Dani-Elle Dubé