Balloons containing up to six times the legal limit of carcinogens are available to UK consumers through leading online marketplaces, according to an investigation.

Which? found that AliExpress, Debenhams, eBay, The Range and Shein have continued to sell carcinogenic balloons on their platforms despite more than 100 brands being recalled or flagged in official product safety alerts over the last 10 years.

Which? bought 21 packs of latex balloons from seven online marketplaces and put them through British standard tests to find out about the levels of carcinogenic chemicals they contained.

Eight out of the 21 balloons contained concentrations of potentially carcinogenic chemicals significantly above the UK’s permitted limit – meaning that they were being sold illegally.

Tests revealed that one balloon from AliExpress contained more than six times the legally permitted level of nitrosamines – chemicals that are probable carcinogens.

An eBay balloon and one from The Range – also available at Wilko – were found to contain more than four times the safe level of nitrosamines.

Wilko said it independently tested these products in June 2025 and found them to be safe.

“But, as customer safety remains our top priority, we have recalled the balloons from our stores and website as a precautionary measure while we undertake further testing.”

A balloon bought from Debenhams contained more than twice the legal amount of nitrosatable substances – chemicals that can turn into nitrosamines when they mix with saliva.

Which? said testimonies from consumers suggest that its investigation could only be the “tip of the iceberg” for dangerous balloons sold on online marketplaces.

The watchdog said Trevor and Lucille Mathers bought balloons from Amazon Marketplace in March 2024 for their child’s birthday.

A full year later, Amazon sent a notification warning to Trevor and Lucille that the balloons they bought could cause cancer, saying the product contained at least 25 times the legal limit of potentially carcinogenic chemicals, the consumer group said.

The alert stated that substances in the balloons may cause cancer through ingestion or dermal exposure and a child could be exposed when touching or putting them in their mouth.

Mr Mathers told Which?: “It wasn’t easy to read when you know your kids have been doing exactly that, months after Amazon knew the balloons were loaded with carcinogens but didn’t tell us.”

Amazon said it removed the balloons from sale immediately when notified. Later, when it received a request to contact customers, this happened immediately.

Natalie Hitchins, who works for Which?, said she bought two packs of balloons from Shein for her son’s birthday.

She said: “The strong chemical smell from a pack of superhero-themed balloons was really noticeable. As I blew them up my lips went numb, all I could taste were chemicals and I became dizzy. At that point my partner came into the room and was shocked by the chemical smell.”

Which? tested the same balloons that Ms Hitchens bought and found them to contain more than twice the legally permitted level of nitrosamines.

One seller on the Shein store reported 99,000 sales for balloons which had more than twice the legal limit of nitrosamines, the consumer group said.

Another seller of carcinogenic balloons on eBay had 277 listings and claimed to have sold more than 300,000 – however, Which? confirmed it had not tested the remainder of the listings beyond those specified.

Which? head of consumer protection policy Sue Davies said: “Allowing children to be exposed to high concentrations of carcinogens is outrageous – especially given the repeated official safety warnings for balloons over the last 10 years.

“Seemingly innocent items like party balloons can have serious health consequences if there aren’t proper checks to make sure they comply with safety laws.

“The government must urgently prioritise secondary regulations for the Product Regulation and Metrology Act to impose a clear legal duty on online marketplaces for ensuring the safety of products sold through their third party sellers, with tough enforcement for those that fall short.”

An AliExpress spokeswoman said: “We take product safety very seriously and we have strict rules and policies in place to ensure a safe online shopping environment. Third-party sellers who list items for sale on our marketplace must comply with the applicable law as well as our platform rules and policies.

“The listings of the products that failed the test have been removed from the site. Our platform will inform consumers who have purchased the products directly about the risks, unsuitability for use and support consumers’ refund request.”

A Debenhams spokeswoman said: “The product in question was listed by a third-party seller through our marketplace. As soon as we were made aware of a potential safety issue, we immediately removed this product and all similar listings under the same brand from our website.

“We have contacted the customer who purchased this product to inform them of the issue and provide support. While the product was sold by an independent third-party seller, we are liaising with them to understand how this occurred.”

An eBay spokeswoman said: “The two listings identified by Which? have been removed and the sellers have been informed.

“We’re reviewing the wider marketplace to remove any listings offering identical products and automatically notifying buyers of any safety issues.”

Shein said: “Upon learning of these claims, we immediately removed the items from our site as a precaution while we investigate.”

A Wilko spokesman said: “We independently tested these products in June 2025 and found them to be safe.

“But, as customer safety remains our top priority, we have recalled the balloons from our stores and website as a precautionary measure while we undertake further testing to verify the suitability of these items.

“Any customers who have purchased these balloons are able to obtain a full refund by returning the product to us.”

The Range has removed the balloons from its site.