By now, parents are trying not to trip over the new toys their kids got for the holidays. But a twisted ankle is not the only hazard lurking among the new playthings. Some of them may contain tiny, powerful magnets that can easily be ingested by children, leading to serious and potentially fatal injuries.

After a new generation of high-powered neodymium [nee-oh-DIM-ium] magnets became commercially available in 2009, the number of children being treated at emergency rooms after ingesting them soared. That led the Consumer Products Safety Commission in 2012 to limit the sales before banning the sales altogether in 2014. However, a court reversed that decision in 2016. The magnets reentered the market, and emergency room visits rose again.

These magnets, five to 10 times more powerful than traditional magnets, are used in a variety of toys such as building sets and jewelry kits. They’re also used in cordless tools, hard disk drives and vehicles.

Their small size makes them easy to swallow. Ingesting multiple magnets, or a magnet with a metal object, can result in a bowel obstruction, perforation, even death when they attach to each other through bowel walls.

A recent study published in JAMA Network reviewed 1,400 cases of children who had being taken to emergency rooms after swallowing magnets. The researchers examined trends before and after the sale of the magnets was stopped then reinstated and documented that the number of emergency room visits climbed when the magnets returned to the market.

Their takeaway: industry standards should be revisited considering that these injuries, and potential deaths, among children are preventable.