Button cell batteries are found in everything from children’s toys to your remote control, watches, calculators, flashlights, singing greeting cards and much more. Increasingly, these coin-size batteries — less than 20-mm in diameter –pose significant ingestion risks to children. While the U.S. Consumer Product Safety Commission and industry have been exploring solutions, a Massachusetts team of researchers has developed a potentially viable solution for this growing hazard.
The American Academy of Pediatrics Journal estimates that there are an average of 3,289 battery-related emergency room visits each year, based on injury data from 1990-2009. The CPSC has tallied, from 1997-2010, an estimated 40,400 children under 13 years old treated in hospital emergency departments for battery-related injuries. Nearly three quarters of the injuries involved children aged under four-years old. The injuries can be severe enough to require a feeding tube for nutrition, a tracheostomy tube to relieve airway obstruction, vocal cord paralysis, mucosal burns to complete perforation, bronchial stenosis and even death. There have been 14 fatalities with the children ranging in from seven months to three-years-old.
Button-cell batteries wind up in the bodies of small children because the battery compartment in many of these items isn’t durable enough to hold the battery in through the wear and tear of the product. In addition, the batteries are accessible to children through the product packaging and during disposal. Imagine how many times a child opens and closes that greeting card just to hear the song one more time, or how quickly a gift and batteries are ripped open during the holidays, or how we may put them aside for a minute before disposing the expended batteries.
Recently, researchers at Harvard University, the Massachusetts Institute of Technology, Brigham and Women’s Hospital, and Massachusetts General Hospital have devised a new way to coat a button-cell battery with a special material called Quantum Tunneling Composite (QTC). Waterproof and pressure-sensitive, QTC acts like an insulator outside of the battery unit, preventing the battery from conducting electricity – the injury mechanism –after being swallowed, but allowing the battery to conduct electricity when compressed in the battery compartment. Jeffrey Karp, an associate professor of Medicine at Harvard Medical School said that the researchers’ interest was piqued by a New York Times article noting the rising number of emergency room visits caused by button-cell battery ingestions.
Karp, along with Robert Langer from the Harvard-MIT Division of Health Sciences and Technology and Bryan Laulicht, a postdoctoral associate, have published their research, Simple battery armor to protect against gastrointestinal injury from accidental ingestion, online at the Proceedings of the National Academies of Science.
“We began to immediately layout a path, and one of the things we noticed that any time you put a battery into a device you always kind of need to push on it so there is some force acting on a battery, whereas outside the device that force doesn’t exist. So, we started to think: what if we could develop a coating that could be an insulator that wasn’t in use but when the battery was in a device it could be converted into a conductor? “ Karp said. “The only way that could work would be if the forces exhibited by the body – esophagus or GI tract were not sufficient enough to convert from an insulator or conductor.” Laulicht had already performed extensive modeling on the forces exerted on pills, allowing the researchers to easily adapt them to coin cell batteries.
“[We] quickly realized that even with the strongest possible forces that the gut can produce on these batteries, which is called nutcracker esophagus, even the greatest forces would not be able to convert this coating form an insulator to a conductor,” Karp said. “We wanted this to be as simple as possible and get this out there as easily as possible. We wanted to think of all of the ways we could make a coating that was essentially a switch.”
The researchers tested the battery in a pig showing that the coating acted as an insulator in the animals’ stomach, but worked perfectly in a device like a laser pointer. Traditional batteries caused substantial tissue damage. They are now working on getting the coating as thin as possible with the goal of applying it to three-volt batteries and insuring that they work in standard housing such as AV equipment. The ultimate challenge is to work with industry to develop a manufacturing process for the 5 billion batteries manufactured every year. The trio also has sought guidance from the National Capitol Poison Control Center.
While there has been progress solving the packaging problem, Karp says, “kids can get to them at that phase or when the batteries are disposed of. There continues to be a lot of kids who accidentally ingest. We feel focusing this on the level of the battery is the most important step in making the battery safer.”
For years, safety advocates have been asking the industry to change the design of the battery compartment, or the battery itself to mitigate the harm to children. The Safety Institute hopes the CPSC and industry can work with this team to mitigate the hazard and take the next big step towards protecting our children.