Carmarthenshire's Trading Standards are testing batches of loom bands they believe may contain harmful levels of toxic chemicals.
Whilst awaiting the results, they are warning parents to be careful when purchasing the bright coloured elastic bands and charms that have become popular with children all over the world.
Thousands of children have become hooked on the loom band craze, making bracelets, necklaces and trinkets out of small coloured elastic bands, either using their fingers or a plastic loom to twist and link them together.
Trading Standards have found that a number of bands and charms, particularly of cheap or low quality, that have been bought locally do not comply with the Toy Safety Regulations 2011, in terms of labelling and warnings.
A number have been sent for chemical analysis, with particular concern that they may contain toxic levels of phthalates – a substance which is used to make plastic safer and pliable, but is strictly controlled as they can migrate from plastic into the body if it comes into contact with saliva or sweat.
The legal limit of phthalates in plastic toys should not exceed 0.1 per cent, but tests carried out by other Trading Standards teams in the UK have found some loom bands and charms contain around 50 per cent.
Most of these have come to the UK from the Far East.
The findings have prompted safety fears, and Carmarthenshire’s Trading Standards team are urging parents to search for the CE mark and for a UK distributor's address before buying loom bands and charms for their children.
Cllr Jim Jones, Executive Board Member for Public Protection, said: “We do not want to spoil anybody’s fun, especially since this craze is encouraging wonderful creativity, but we also don’t want to see anyone come to any harm.
“All we’re asking is that parents carefully consider the quality of the bands and charms they are buying for their children – especially the cheaper bands that may have been imported and do not meet British safety standards.
“We are advising people to only buy loom bands from reputable sellers, and to look for a UK distributor's address on the packaging as well as a CE mark.
“For obvious reasons we’re also advising parents to ensure that children do not put these loom bands in their mouths.”
He added: “We are awaiting the outcome of chemical analysis and will make people aware of the outcome in due course.”