Touching your tongue to frozen metal must be a rite of passage if you’re a five-year-old boy from a cold place. It’s possibly more irresistible than hopping in mud puddles or sampling a newly frosted cake. But it is dangerous?

Anders Hagen Jarmund knows all about this particular temptation. Yes, he’s gotten his tongue stuck.

“I’m from a small place called Hattfjelldal, which is quite cold in the winter,” he said. “I don’t remember if it was a signpost or a lamppost behind the school, but I remember licking it and my tongue got stuck.”

Turns out he wasn’t alone.

“This was an experience that my friends had also had, actually, and then we were wondering if it was actually dangerous, getting your tongue stuck to a lamppost or railing,” he said.

In fact, in Norway, at least, the government was concerned enough about the problem to pass regulations in 1998 prohibiting bare metal in playground equipment.

So he and a group of friends who were also researchers decided to find the answer to their question: is getting your tongue frozen to cold metal dangerous?

The short answer is that most of the time, licking a piece of frozen metal is probably not going to result in serious harm.

You’ll want to warm the metal where the tongue is stuck to loosen it, maybe by breathing on the metal or using a little warm water.

Whatever you do, however, do not yank the tongue off, Jarmund says.

“Try not to panic,” he said. “I remember the panic, you’re standing there and your tongue is stuck to metal. But above all else: Don’t pull your tongue off too fast.”

This is not just idyll speculation. Jarmund and his friends have recently published two academic articles about the problem in peer-reviewed medical journals. And one way they found their answers involved pig tongues.

To understand what happened next, you need to know a little bit about Jarmund.

He’s just finished his medical degree at the Norwegian University of Science and Technology (NTNU) and is finishing his PhD dissertation on preeclampsia right now. He also works on the side with data analysis for an NTNU research project on using ultrasound to measure blood flow in infant brains.

Thus, it shouldn’t surprise you that he and his friends – his brother Ståle, Sofie Eline Tollefsen and Cristoffer Sakshaug, thought doing a little research project in their spare time would be fun.

They’d already done a thorough assessment of healthcare-related social media memes which they published in an academic journal. So why not tackle this question?

As best they could tell, there was nothing in the medical literature that assessed the true danger of actually freezing your tongue to frigidly cold metal.

So, in the spirit of true scientific explorers, they decided to fill this particular knowledge gap. Their quest would involve two important tools, one conventional, one less so: a literature review, and the aforementioned pig tongues.

First, Jarmund and his colleagues conducted a thorough review of Scandinavian newspapers since 1748 for stories of people freezing their tongues to cold metal. They found the first report in 1845.

60 per cent of the victims – though to be fair they could equally be called perpetrators – were boys.

They combed through more than 17000 search hits and identified 856 reports. A number were so newsworthy that they merited coverage in more than one newspaper. That left 113 individual cases.

And they found a scientific study that gave the experience a name: Tundra tongue.

The name was a fun find, but more importantly they had enough cases to identify trends.

Here’s the biggest: the prime age for getting your tongue stuck to frozen metal is five. And 60 per cent of the victims – though to be fair they could equally be called perpetrators – were boys.

“I’m not surprised the majority were boys,” Jarmund said. “The thing is, I’ve had my own little freezing experience.”

In the end, what the researchers found was that most cases of tundra tongue had no or mild consequences.

But fully 18 per cent of the cases they found resulted in visits to a doctor or hospital to deal with problems like avulsion. That’s the clinical way to describe a piece of your tongue getting torn off, such as when yanking it off a frozen piece of metal.

Once having uncovered this sticky outcome, Jarmund and his research partners decided they needed to do more.

“We were curious, of course, and no one has studied this,” he said. “We wanted to do something systematically. That’s what research is about. It was also a little bit for us to learn how to do this type of research.”

Although his colleagues were all researchers, none of them had actually conducted an experimental study like this, where they would answer questions such as:

• How do we study freezing tongues to metal objects without having to use our own tongues?
• How do we measure how much force it takes to remove a tongue that is frozen stuck to metal?
• And where do we get enough volunteer tongues to ensure we could have statistically significant results?

They also managed to pull together a very interdisciplinary team: an associate professor in mechanical engineering and professors in pathology and biophysics pitched in to help.

About this time, Jarmund’s brother, Ståle, was on the lookout for a good master’s project. Not to be too tongue-in-cheek, but this project seemed like a perfect solution, served up on a platter.

That meant they were able to line up the equipment - multiple sensors, an infrared camera, and a setup that required no small amount of tinkering to get everything synced up.

Among the key pieces of equipment was something called a force sensor, which is about what it sounds like, and they did donate saliva to lubricate the tongues.

But they didn’t want to volunteer their own tongues to the project, and they didn’t want to recruit volunteers either.

“We doubted any ethical committee would approve human volunteers for this,” Jarmund said.

After a debate about which animal species might have a tongue that was closest to human tongues, they settled on pig tongues. Eighty-four tongues, to be exact.

A licensed slaughterhouse north of Trondheim willingly supplied them.

“And they were quite cheap,” Jarmund said. “But I’m not sure there’s a huge market for pig tongues.

While Jarmund spent three months on a research exchange in warm, sunny California, the rest of the team spent days in the lab, warming the tongues, cooling metal and putting the two together.

They found, not surprisingly, if you apply pig tongues to a frozen section of a metal lamppost, they will stick, and quite well.

In fact, in 54 per cent of the experiments, parts of the tongue were torn. The harder they pulled, the greater the likelihood that a piece of the tongue would get torn off.

The greatest risk of having a piece of your tongue torn off, their experiments showed, was when temperatures were between -5 and -15 °C.

There was a surprise, however: when they tested the pig tongues on very cold metal, there was less chance of avulsion.

They don’t know exactly why, but they think it’s because the tongue freezes hard enough so it can resist being torn when yanked free from the icy grip of frozen metal.

So, what exactly should you do when your five-year-old boy decides that he is unable to resist… and licks a light post when it’s -7.5C?”

The science is clear: Take a deep breath, don't panic – and don't yank your tongue off too fast.