Amber teething necklaces sold online and across Canada pose a strangulation hazard and may be putting babies’ lives in danger, according to a new study that echoes previous warnings.

The study, presented Thursday at a Canadian Pediatric Society conference in Vancouver, tested 15 amber teething necklaces purchased from different retailers in Atlantic Canada to see if they would withstand the force required to release their clasps.

Using a suggested U.S. industry standard for children’s jewelry, the necklaces were tested using 15 pounds of force for 10 seconds. Eight out of 15 necklaces released when the force was applied and seven, or nearly half, remained intact.

Some of the necklaces had screw clasps and others had pop clasps. The ones that did not open during the test had screw clasps.

When the authors tested 10 necklaces with just 1.6 pounds of force, which studies have shown is enough to choke a child, only two of them released and eight remained intact.

Lucy Soudek, a Dalhousie University medical school student who co-authored the study with materials engineer Edward Moffatt and Dr. Robyn McLaughlin, a pediatrician at the IWK Children’s Hospital in Halifax, said the findings show that amber teething necklaces pose a serious risk to babies and children.

In a telephone interview with CTVNews.ca, Soudek also said there is no scientific evidence backing the purported healing properties of the amber teething necklaces.

Some manufacturers and retailers claim that the Baltic amber in the necklaces releases a pain-relieving substance that is absorbed by the baby’s skin.

“So not only is there no scientific evidence behind them, but (the necklaces) can actually result in severe harm to the child, including asphyxiation,” Soudek said.

The Canadian Pediatric Society advises parents not to use amber necklaces for teething pain because a baby can choke on the small beads or be strangled by the necklace. The society says teething rings should be used instead.

In 2010, Health Canada also issued a warning about teething necklaces, adding that all types of necklaces, strings, ribbons or chains should not be placed on a child under the age of three.