The hugely popular Rainbow Loom craft kit has spawned many imitations, and there are questions whether these colourful bands - real and fake - are safe for children.
Spring Singapore is investigating feedback that several rubber band loom products contain a concentration of phthalates beyond the safety requirement of 0.1 per cent.
The chemical makes plastics more flexible and durable but it has also been associated with increased risk of cancer.
Spring, which oversees the safety of general consumer goods in Singapore, said it would stop the sale of products that do not meet minimum standards.
Tens of thousands of the original Rainbow Loom kit, which retails at $29.90 and is made in China, have been sold since it was launched in Singapore last November. It is distributed to more than 30 retailers.
The original kit, which has passed US safety tests, contains a plastic pegboard, a metal hook, C-shaped fasteners and about 600 small rubber bands in assorted colours for children to create bracelets and other accessories.
There are reports overseas of children breaking out in rashes while wearing creations made with imitation rubber band loom products, as well as claims that some fake charm accessories are toxic, with high levels of phthalates.
In Singapore, Sophie & Friends, the sole distributor of the original product which was created by an American migrant from Malaysia, said it received complaints almost every day in the first half of the year from those who bought similar products made by other companies. Some of the complaints were about children developing rashes.
Sherry Lim, 11, suffered rashes on her wrist from a bracelet made with the bands from a copy-cat kit. She has since switched to playing with the genuine kit.
Said her father Marcus Lim, who works in sales: "She has sensitive skin. I told her to put away all the imitation rubber bands to play it safe. There have not been any problems with the authentic ones."
Mr Lin Daoyang, 34, the managing director of Sophie & Friends, said the number of imitations has at least doubled since July.
The Consumers Association of Singapore has not received any complaints but has advised people to buy genuine products that have been vigorously tested by accredited labs.
Dr Lynn Teo of The Dermatology Practice said friction between the bands and skin caused by repeated actions, such as flicking, can result in dryness and itchiness.
High amounts of phthalates or prolonged contact with a toy that contains the chemical could also potentially irritate the skin.
Some parents are playing it safe.
Managing director Carlene Fong has bought seven different kits and hundreds of packs of bands for her 10-year-old daughter. "I told my daughter that from now on we will have to look for the genuine ones since we do not know what is safe and what is not. Better to be safe than sorry," she said.