Bite, swallow… and the battery burns a hole in the esophagus

About five years ago, a child of one and a half years old was brought in because she was found in a pool of blood. She was taken to the OR while she was being resuscitated, says Tjark Ebels, professor of cardio-thoracic surgery at the UMCG in Groningen, who then worked at the Amsterdam UMC. “It was thought to be a stomach bleeding, but it turned out not to be. Then I opened the chest, it turned out there was a hole in the aorta and a hole in the esophagus. I closed both of those, but the child didn’t make it.”

The injuries were caused by a button cell battery that the girl had swallowed unseen. “Everyone involved was totally upset and emotional. Understandable, of course,” says Ebels. It wasn’t Ebels’ first patient with serious battery injuries. “In response to some of these serious cases, I and my colleague Freek Dikkers contacted Marnix Wagemaker, professor of battery technology at TU Delft.” Button cell batteries must become safer for children, the professors believed.

In Delft, the researchers have now found two ways to make button cell batteries child-friendly: a fuse that interrupts the current after swallowing, and a mechanism that ensures that the battery discharges internally in one fell swoop.

Watery and salty

Small children like to put things in their mouths. Breadsticks, but also toys, pebbles and sidewalk chalk. A small, round, smooth and shiny battery is also very attractive to a child. Once swallowed, the batteries can quickly cause a lot of damage. The number of children who die or experience serious complications each year is estimated at 2,000 worldwide. And that number is rising. With a multiple, the battery is removed before serious damage occurs.

Button cell batteries are used in LED candles, bicycle lights, remote controls and many children’s toys. They are cheap and widely available. In children’s toys, the batteries must be firmly attached, behind a cover with a screw. In many other applications, the battery is less firmly seated in its housing. Danger also lurks when a battery is empty, is being replaced and may be on the table for a while.

Especially the batteries with a diameter of 2 centimeters are dangerous because they get stuck in the esophagus. These button cells can be recognized by the number 2032, 2022 or similar, where 20 stands for the diameter (20 millimetres) and 32 or 22 for the thickness (3.2 or 2.2 millimetres). “They slide easily through the first part of the esophagus, but they come to a stop at the bottom,” says Ebels. “There the esophagus makes a caliber jump, it becomes narrower. The button cell cannot go any further.”

The pH value is raised to such an extent that the tissue of the esophagus dissolves

The mucus in the esophagus, which is watery and salty, causes an alkaline reaction to occur. “Thanks to the salt, there are free ions in the mucus, which make it conductive. If the two sides of the battery come into contact with the slime, a current will flow,” says Professor of Battery Technology Marnix Wagemaker of TU Delft. “A battery likes to lose electrons at the minus pole and receive electrons at the plus pole, the conductive slime allows that. The reactions that arise at the poles are harmful, the pH value is raised to such an extent that the tissue of the esophagus dissolves.”

In videos on YouTube showing a button cell battery in a sausage or between slices of ham has stopped can be seen what happens: after about two hours the meat starts to turn black and after a while holes appear. “The meat from those films does not contain the mucus that is in the esophagus, but the damage looks about the same,” says Ebels.

“This does not just happen, the voltage must be high enough,” says Wagemaker. “That is exactly the case with the lithium-ion batteries that have been widely used in recent years, which have a voltage of 3 volts. Previously, button cells were nickel-metal hybrids, with 1.2 or 1.3 volts, then this problem was much smaller.”

The capacity of the batteries has also increased in recent years, so that the reaction in the esophagus lasts longer. This also applies if a battery seems empty. “A battery is never really empty when you take it out of a device,” says Wagemaker. “That also has to do with the voltage. LED lights, for example, require a threshold voltage, somewhere between 2 and 3 volts. When a battery is in use for a while, the voltage decreases. At a certain point you fall below that threshold value and then the light no longer works. But then there is often still 20 or 30 percent energy in the battery.”

Online doctor portal

It is clear that the injuries become more serious with age from research of US pediatricians in 2019. In 2003, approximately 0.32 percent of the total number of recorded ingestion cases in the US had a very serious or fatal outcome, in 2016 it was approximately 0.63 percent, while the recorded number of swallowed batteries in total in those years is fairly stable between 10 and 12 per million inhabitants.

These figures also include ingestion cases involving smaller batteries. Batteries with smaller diameters usually cause less damage, because they pass through the gastrointestinal tract and come out again. “Such a battery in the stomach is not good either, but it is less harmful because it is short-lived and there is a larger volume of fluid and tissue to absorb the current,” says Wagemaker.

The top three intended uses for the batteries removed from children in the US between 2014 and 2016 are remote controls, flashlights, and LED tea lights.

In the Netherlands, figures on accidents involving button cell batteries are not kept centrally, but in previous coverage a doctor from Erasmus MC stated that in her hospital there are 5 to 10 cases of ingestion per year. The National Poisons Information Center keeps track of how often doctors request information about button cells. There were 86 concrete cases in 2020, 63 cases in 2021 and 64 cases in 2022. In addition, an online doctor’s portal is consulted 140 times a year. Incidents where the doctor already knows what to do are therefore not included.

“When Tjark and Freek invited us to the hospital, I was soon impressed by what they said about their young patients,” says Wagemaker. “Of course we will look into this, I immediately thought.”

Deflate very quickly

The first idea the researchers in Delft had was to build in a fuse. Just like in the fuse box at home, something breaks when overloaded, causing the current to be interrupted. “This approach only works if there is a peak current as soon as the battery is stuck in the esophagus, because the battery must work during normal use in a device,” says Wagemaker. “So the first thing we did was mimic the esophagus.”

It turned out that there was indeed a peak current, an extra strong current, when the battery gets stuck in the slimy esophagus. A button cell battery consists of many stacked layers, the fuse is an extra layer of which the conductive part melts away when there is a peak current. “Making a fuse is not difficult,” says Wagemaker. “The difficulty is getting it very flat, and cheap. We’re still working on that. It has to fit into the existing manufacturing process.”

The second concept that the researchers in Delft came up with ensures that the battery drains very quickly without passing a current through the body. “It is a kind of short circuit, but within the battery,” says Wagemaker. “The electrons then go from positive to negative in one fell swoop. It does get warm, but we have calculated how much heat is released and it does not leave a burn in the esophagus. We think that this solution can become even cheaper and smaller than the fuse.”

The batteries may become safer, but the question is whether this will happen soon

The American study mentions another approach: a coating that ensures that the current can only flow when pressure is applied. That pressure is there in the housing in the device where the battery has to do its job, but not in the esophagus.

So there are possibilities to make the batteries safer. Whether it will happen in practice is another matter. “We approached battery manufacturers with our ideas,” says Wagemaker. “They are very interested in themselves, but a bag of money is not forthcoming. That surprised me.” TU Delft and the UMCG have recently jointly applied for an international patent on the two concepts, which is still pending.

“Policy work needs to be done before the batteries really become safer,” says Ebels. “The batteries are so cheap, every addition makes them more expensive. Producers must be forced to do this, it does not happen automatically.”

Extremely bitter taste

That’s what most doctors think. In early June, a group of European pediatricians sent a letter to Stella Kyriakides, European Commissioner for Health and Food Safety. In it, they ask her to help establish regulations in the field of safe battery packaging and stricter safety requirements for battery compartments in appliances, as is already common practice in children’s toys. “Some producers are already doing this, which shows that it is technically and economically feasible. But so far they do so on a voluntary basis,” they write.

Indeed, there are safer batteries for sale. Duracell sells the button cells with a diameter of 2 centimeters in packages that require scissors to open. It says ‘baby secure’ on it. And as early as 2020, Duracell announced that their button cells were coated with an extremely bitter taste, which made children immediately spit them out.

But yeah. Duracell’s 2032 button cell batteries cost 2.10 to 3.29 euros per two, depending on where you buy them. The 2032 batteries of the A-Force brand, for sale at Action, cost 99 cents – for 6 pieces.