Meredith DelPrete, 10, was at school one day and did something that she said is popular among kids her age: She pretended to have a pierced tongue. The Fairfax County fifth-grader took two magnetic balls from her pocket and placed one on top of her tongue and the other on the underside. The magnets, the size of a BB, are extremely powerful. They made it look like she had a stud. She opened her mouth to show a friend.

That’s when the silver orbs rolled off.

“I could feel them in the back of my throat. I tried to get them out, but I couldn’t. So I just swallowed them,” she said in an interview this week.

That accidental swallowing led to five days at Inova Fairfax Hospital, at least 10 X-rays, three CT scans and an endoscopy. Finally, on Jan. 20, a surgeon used a metal instrument to manipulate the magnets into her appendix, avoiding major surgery. He then removed her appendix, and the magnets, doctors said.

Doctors and consumer-product safety officials say the growing popularity of small, ball-bearing magnets pose a unique health hazard. Not only are they in toys, but they can also be found in jewelry and are marketed as desktop toys for adults. The magnets that Meredith received as a gift are a popular brand known as Buckyballs, which are 5mm in diameter. The labels warn to keep them away from children and not to put them in the nose or mouth; they say that if swallowed, magnets can cause serious injury or death.

Another 10-year-old was hospitalized at Inova Fairfax at the same time as Meredith: a boy who had swallowed three ball-bearing magnets. He passed them without incident, doctors said. On Wednesday, a third child, a 9-year-old boy, was taken to the hospital and transferred to Georgetown University Hospital, a doctor said. The boy’s condition could not be immediately determined.

Neither Meredith nor the other 10-year-old suffered serious injury, doctors said.

When two or more magnets are swallowed, they can attract each other internally, resulting in serious injuries, such as small holes in the stomach and intestines, intestinal blockage, blood poisoning and even death, according to safety and health officials.

In November, the Consumer Product Safety Commission issued its first product-wide warning about ball-bearing magnets in adult products in a news release with manufacturers. The commission had received 22 reports of incidents involving the magnets from 2009 through October, it said.

The actual number is likely higher, doctors said. Inova Fairfax alone had three cases in less than a week.

Although parents of younger children are generally warned about the hazards of small toys, there is less awareness among adults — and even medical professionals — about the risk of magnets, especially when older children use them to emulate tongue or lip piercings, according to parents, doctors and safety officials.

“The potential for serious injury and death if multiple magnets are swallowed demands that parents and medical professionals be aware of this hidden hazard,” said commission Chairman Inez Tenenbaum. “This is not a children’s product and should be kept away from children.”

Three doctors who treated Meredith said they did not know children were using magnets to mimic piercings.

“I had not heard about it until that evening,” said Sharon Day, an emergency-room doctor on duty when Meredith and the other 10-year-old were hospitalized. Day, who lives in Montgomery County, quizzed her two high-school-age children. “I said to my kids, ‘Are you guys doing this?’ . . . They weren’t, but they had heard about it.”

Voluntary recalls

Marsha Kay, who chairs the pediatric gastroenterology department at the Cleveland Clinic Children’s Hospital, said magnet ingestion among children has been reported increasingly in recent years.

“They’re very popular and perceived to be safe,” she said of the magnets.

Reports first began appearing in the United States in 2005. That year, a 20-month-old boy died after swallowing nine cylindrical magnets from an older sibling’s toy building set, according to the Centers for Disease Control and Prevention. The magnets had joined across two loops of intestine, causing a twisting of the bowel that led to a fatal bloodstream infection.

Since 2008, the Consumer Product Safety Commission has received more than 200 reports of children swallowing all kinds of magnets; at least 18 children required emergency surgery to remove them.

And at least two major toy manufacturers have issued voluntary recalls of toys with magnets since 2006. In 2010, the maker of Buckyballs and the commission issued a voluntary recall of Buckyballs magnet sets to update the labeling.

The recent reports may be linked to the holiday season. Kay said she received a call this week from a doctor elsewhere in the country about an accidental ingestion by a school-age child.

Stephen Kim, the Annandale pediatric surgeon who removed the magnets from Meredith, said he and two other doctors in the practice have recently received more inquiries from pediatricians and gastroenterologists. As a result, they are aiming to come up with a treatment protocol.

“We’re trying to discuss a unified response to anyone who consults us,” he said.

“This is a big, big problem,” said Ben Enav, the pediatric gastroenterologist who treated Meredith and the 10-year-old boy. In the past year, he had a third case, another school-age child who swallowed the same type of magnets and needed surgery because of a perforated intestine.

“I can see how an innocent bystander can think this seems all very benign and nothing to worry about, but if these things get separated and are floating through your intestine,” they can cause serious injury, he said.

Even urgent-care and emergency-room clinicians have assumed — incorrectly — that they can send a child who has swallowed magnets home. “They are not aware of how serious a problem this is,” Enav said.

Craig Zucker, chief executive for Maxfield & Oberton, the manufacturer of Buckyballs, said the company puts warning labels in five places, inside and outside the boxes. The company works with the safety commission to spread the message that the magnets should be kept from children.

“We don’t sell to stores that sell exclusively children’s products or toy stores,” he said. “We are doing everything we can to make sure it’s not getting to children.”

Brookstone, one of many retailers that carry the magnets, says they are a popular item. A boxed set of 125 Buckyball magnets sells for $24.99. A company spokeswoman said new product training includes warnings that they are for adults only.

‘My favorite’ gift

Meredith said she likes Buckyballs because “you can use them for fake piercings on your ear, your nose, lip or tongue.” On braces, too. The magnets are also very strong, she said, “so you can make different stuff out of them.”

Many friends had them, so she was excited to get a set for Christmas. Her siblings, 11 and 13, also each got a box.

She didn’t read the warnings about not putting the magnets in her nose, mouth or ears.

“I just opened it,” she said.

“It was probably my favorite of everything I got until I swallowed it,” she said of the magnets.

On Jan. 17, a Tuesday, she was in the library at Oak View Elementary School, checking out a book with a friend. The two magnets were in her pocket.

After she swallowed them, Meredith, at her friend’s urging, told the school nurse. The nurse sent Meredith back to class, but as a courtesy, notified Meredith’s mother, Helen DelPrete.

DelPrete called her pediatrician, Gary Bergman, as a precaution and was told to take Meredith to the emergency room immediately.

Luckily for Meredith, the two magnets had connected in her esophagus, making the situation less dangerous, doctors said. For four days, doctors monitored the movement of the magnets in Meredith’s body. She was not allowed to eat. They maneuvered the magnets to her appendix after they became embedded in her large intestine.

Helen DelPrete said her husband bought the magnets for the children and didn’t notice the warning labels. She said she wasn’t aware of the concerns until after Meredith was hospitalized.

“It’s etched on the plastic container [holding the magnets], but you can’t even read it — it’s the same color as the plastic container,” she said.

So far, Meredith’s hospital charges are about $22,000, DelPrete said, but when the individual doctors’ charges are added, the total cost could be twice that figure.

She has confiscated the magnets from her children. Meredith says she still wants to play with them but wouldn’t put them near her nose or mouth.