The Surprising Reason Why Pen Caps Have Tiny Holes at the Top

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iStock

If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

Lítla Dímun: The Smallest of the Faroe Islands Has Its Very Own Cloud

While some islands are known for their unusual geography or unique history, Lítla Dímun is notable for its weather. The island, which is the smallest of Denmark's Faroe Islands chain, is often capped by a lens-shaped cloud, making it resemble a scene from a fairytale.

According to Mental Floss's own Kerry Wolfe writing for Atlas Obscura, the cloud floating above Lítla Dímun is a lenticular cloud. This type of cloud forms when moist air flows over a protruding geological feature, like a mountain top. When the wind moving up the landmass hits the air current directly above it, a sort of wave is created on the downwind side of the mountain. The moist air falling down this wave evaporates and then condenses into a large, flying-saucer-shaped cloud atop the mountain peak as a result.

Another factor that makes Lítla Dímun distinct is that it's the only one of the 18 main Faroe Islands without human inhabitants. Visitors to the mystical location will instead find a thriving population of sheep. Originally, Lítla Dímun was home to a group of feral sheep likely dating back to the Neolithic era. But they were hunted to extinction in the 19th century. Domesticated sheep were introduced there around the same time, and today, farmers visit the island once a year to round up their flocks.

One of the few signs of human life are the ropes farmers use to scale the cliff faces bordering the island. Even if you have rock-climbing skills, Lítla Dímun may be dangerous to visit. A boat ride to the rocky shore is only possible when the surrounding sea is calm.

[h/t Atlas Obscura]

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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