Newer, more powerful magnets are putting children at greater risk for life-threatening health problems, says a new Canadian case study, which also found that incidents of kids swallowing magnets is more common than previously believed.

The study, published Monday in the Canadian Medical Association Journal, found that children often swallow more than one magnet. And because newer magnets -- neodymium-iron-boron magnets, or rare-earth magnets -- are between 10 and 20 times stronger than older magnets, they can stick together through loops of the bowel.

Magnets that attract each other from different points in the intestinal tract can lead to serious health consequences for the child, as tissue that is stuck together dies off and becomes infected, the study’s authors write.

"Swallowing a single magnet is generally innocuous, much like swallowing any other inert foreign body,” write the authors, led by Dr. Daniel Rosenfield of Toronto’s Hospital for Sick Children.

“However, multiple magnets, especially when swallowed at different times, can attract each other through loops of the gastrointestinal tract. The force created through the bowel or stomach wall may result in pressure necrosis and eventual perforation."

In the past, a child who swallowed a magnet was monitored until it passed through the digestive tract, often without any health consequences. But the authors write that incidents of children swallowing magnets are more common than previously thought, and related emergency department visits have skyrocketed over the past decade.

At Sick Kids, doctors have had to remove magnets from more than a dozen children over a one-year period, with four needing surgery.

If an X-ray shows more than one magnet in the child’s digestive tract, they may have to be removed by endoscopy, a laxative or surgery. They are so powerful the body cannot expel them on its own.

The child featured in the case study was three years old when he swallowed toy magnets that looked to him like candy.

Joseph Bender, now five, was taken to hospital, where doctors found magnets that had been swallowed separately had adhered to one another as they moved through his digestive tract. Bowel tissue was stuck in between.

“There is tissue trapped between the magnets,” Rosenfield told CTV News. “There is tissue dying.”

The magnets in Bender’s digestive tract had to be removed via emergency surgery, during which doctors had to repair four holes in his colon.

The authors say they felt they had to publish their paper because the increasing prevalence of rare-earth magnets has led to an increase in the number of kids needing medical attention after swallowing them.

“We’ve shown without fail that even though they have big warnings on them that these are not toys, these are not for children, we’re not able to keep them out of the hands of children,” Rosenfield said.

In a statement to CTV News, a spokesperson for Health Canada said the department “welcomes” the study, “which draws attention to the dangers of ingesting small, powerful magnets.”

Health Canada “has worked, and continues to work towards educating Canadians on the safe handling practices for magnets,” the statement went on, noting that the agency will look at what more it can do to deal with the issue.

The case study’s authors say that one of the keys to lowering the risks for children is getting doctors to discuss the issue with parents.

“Media exposure on the topic and information in primary care offices are needed,” the authors write. “The 18-month well-baby visit may be an appropriate time to discuss magnet safety in the context of safe toys."