[attach id=245670 size="medium"]Swallowing a single magnet is generally innocuous, much like swallowing any other inert foreign body. [/attach]

Magnets small enough to swallow pose an increasing threat to young children, scientists have warned.

When the objects stick to each other it can cause life-threatening problems such as perforations of the bowel, say experts.

Doctors writing in the Canadian Medical Association Journal called for parents to be made more aware of the problem.

The pointed out that magnet ingestion, once thought to be rare, was becoming more common. Magnets today were also 10 to 20 times more powerful than they used to be, and able to adhere to one another through the wall of the stomach or intestines.

A case study outlined in the article involved a three-year-old boy who had swallowed several magnets. Examination showed that three of them had come together in his bowel, causing abdominal pain.

The authors, led by Daniel Rosenfield, from the Hospital for Sick Children in Toronto, also quoted data showing that between 1993 and 2007 a total of 178 Canadian children under the age of 14 were admitted to hospital because of injury caused by swallowing magnets.

They wrote: “Swallowing a single magnet is generally innocuous, much like swallowing any other inert foreign body. 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.

“Although healthcare providers can play an important role in disseminating information on the risks of magnet ingestion, further targeted campaigns are needed to inform parents of the risks.”