The Consumer Council said on Mondaythat some teethers currently on sale in Hong Kong could make babies sick, cause cancer or suffocate them.
In its latest report, the consumer watchdog said it tested 20 teethers, designed for babies to bite on when their teeth emerge through their gums.
The most expensive model, produced by “Nuvita” on the mainland and priced at HK$139, contained N-nitrosatable substances which could cause cancer.
The substances detected in the teether came to about 0.94 mg/kg, while the European Union sets a limit for these substances at 0.1mg/kg.
A baby teether of another brand "Skip Hop" also contained the cancer-causing substances.
A spokeswoman of the council, Professor Nora Tam, said the products are "dangerous" to babies.
The consumer watchdog also found that a banana-shaped product produced by “Edison mama” in South Korea could pose choking risks to babies as part of it is too small.
The customs has urged parents to immediately stop letting their babies use the product.
Meanwhile, the watchdog found a teether was filled with seriously contaminated liquid.
It found the aerobic microbial count in the “Clippasafe” model was 340,000 units, far exceeding the European Union limit of 100 units.
It also contains bacteria which could cause gastroenteritis and fever in babies, the council said.