Continued everyday use could cause even greater harm, it found.
"However, someone who wears a product of this kind for a prolonged period [a year, 24 hours a day[ could expose themselves to a level of radiation that exceeds the stringent limit for skin exposure that applies in the Netherlands," the body said.
"To avoid any risk, the ANVS calls on owners of such items not to wear them from now on."
Although 5G technologies are considered safe, conspiracy theorists have incorrectly linked the technology to adverse health effects, like cancer, decreased immune function and even the Covid-19 pandemic. The wireless technology network has been developed to provide ultra high internet download and upload speeds, with the function to allow for more users and bigger network capacity.
On Twitter, social media users have commented and made light of the irony.
"Look, it's very easy to mock the fact that 'Anti-5G' necklaces worn by conspiracy 'theorists' have turned out to be radioactive … So knock yourself out!" joked one user.
"An almost unimprovable story," wrote another.
"Omg the irony, it burns. It burns. Anti-5G necklaces found to be radioactive."
When it comes to dispelling myths around 5G, health authorities, government bodies and even the World Health Organisation have long denounced links between 5G and adverse heath effects.
As the WHO clearly states on its website, research on wireless technologies from across the entire radio spectrum – which include 5G products – have shown "no adverse health effects".
"Tissue heating is the main mechanism of interaction between radiofrequency fields and the human body," the WHO states.
"Radiofrequency exposure levels from current technologies result in negligible temperature rise in the human body.
"Provided that the overall exposure remains below international guidelines, no consequences for public health are anticipated."