1. There are all kinds of deeply wretched germs crawling under your fingernails. Tap to play or pause GIF Tap to play or pause GIF Bravo / beamlyus.tumblr.com Fingertips are hives of nastiness, and are home to various types of bacteria, fungus, and YEAST (eww). One particularly prevalent germ found under nails is Staphlococcus aureus, which can cause a load of crazy skin infections like boils and abscesses. Mmmm, oral boils. 2. When you suck and chew on your fingernails, they become an even greater bacterial paradise. Tap to play or pause GIF Tap to play or pause GIF britneyspearsgifs.tumblr.com Back in 2007, Turkish scientists tested 59 people to see whether nail biting had any real effect on transporting bacteria to the mouth. They swabbed each person’s mouth for saliva to check for diarrhoea and vomiting bacteria such as Escherichia coli and many other nasties starting with E. And guess what? Seventy-six per cent of those who bit their nails tested positive, compared to just 26.5% of non-biters. So if you don’t want to spend half your life shitting for Britain, you might want to take your fingers out of your mouth, now. 3. If you bite your nails, chances are that you’re already causing dental damage. View this photo on Instagram instagram.com Who knew that a little innocent nibble could cause such havoc on the old gnashers? In real hardcore cases, nail biting has resulted in tooth fractures, tooth loss, and crazy, displaced jaws. 4. You're more likely to grind your molars into dust at night. View this photo on Instagram instagram.com Nail biting can be a nervous reaction, so the likelihood is that if you’re chewing up your fingers on the reg, you’re also susceptible to grinding your teeth at night. "Those who bite their teeth are often stressed", said Dr Adam Roberts, senior lecturer at UCL’s department of microbial diseases, "so may have other factors that affect their teeth such as grinding."If you already have weak teeth, continually tearing off bits of nail with your front teeth could lead to dental chipping. And if you can't see from this delightful picture, grinding can also LEAD TO TEETH FALLING OUT. 5. Brace-wearing biters run the risk of causing unprecedented damage to their chompers. Tap to play or pause GIF Tap to play or pause GIF Netflix / orangeitnblack.tumblr.com Dr Ansa Akram, a clinical lecturer in orthodontics at the University of Bristol, told BuzzFeed that nail-chewing brace wearers are treading particularly risky water. Not only does the habit put the brace at risk from breaking, but it can also cause or increase root resorption in teeth undergoing orthodontic treatment, which IRL means that your body's own cells start to EAT AWAY AT THEMSELVES and dissolve tooth structure. 6. Nail biting can make you prone to grim gums... Tap to play or pause GIF Tap to play or pause GIF Warner Bros. Pictures / Via mavieserasibelle.tumblr.com Chowing down on your fingertips can cause a load of accidental trauma – that's right, TRAUMA – to your gums. One particularly horrendous case study mentioned in a report by Dr Carlene B. Krejci mentioned a kid who suffered from gingival (gum) swelling under one of his teeth after years of sticking his craggy, half-eaten fingernails under the gum tissue of his tooth. Turned out, there were SIX FINGERNAIL FRAGMENTS STUCK UNDER HIS TOOTH. 7. It can also help cultivate skunk breath. Tap to play or pause GIF Tap to play or pause GIF Universal-International / Via rhetthammersmithhorror.tumblr.com The same unpleasant report also found that nail biters were prone to halitosis, aka highly disgusting breath. There's plenty of bacteria living in your mouth and most of it is meant to be there, but if you keep sticking your fingers in your mouth you're going to introduce a ton of gross germs too. 8. Your fingertips can soon turn into a pus bath. commons.wikimedia.org Nail biting and picking at the skin around the nail often go hand-in-hand. And while that might feel like a great way to while away the time, having acute infective paronychia isn't. It's caused by Staphylococcus aureus bacteria getting into small, open sores, and results in pools of pus forming around the nail. Basically, it's like finger herpes, which is actually caused by the cold sore virus. It can be cured by pills, but sometimes it has to be surgically drained. :O 9. Nail biting can even lead to ORAL STIs. NO JOKE. commons.wikimedia.org So it turns out that this horrible habit can even GIVE YOU HERPES. It's pretty rare but there have been occasions where STIs have resulted in oral lesions (lip blisters) thanks to a transference of bacteria from finger to mouth. Stay woke. 10. Nail varnish is essentially poison and should not be chewed. View this photo on Instagram instagram.com Plenty of nail varnishes contain formaldehyde – as in the stuff they use to embalm dead bodies. A Yale study led by Dr David Katz took swabs from under the nails of different students, and after three days, those wearing varnish had the least amount of bacteria growth. So sure, it’s useful in reducing how many E-something bugs you’re carrying under your nails, but you shouldn't really be chewing on it. 11. And finally, those nails might NEVER GROW BACK. Tap to reveal Click to reveal en.wikipedia.org Chronic nail biting can damage the nail bed, which, when exposed, leads to the irreversible shortening of nails. In other words, biting far enough down the nail bed means that no nail can latch on in future and so nails remain as stumps FOREVER. 11 Slightly Horrifying Things You Never Knew About Belly Buttons buzzfeed.com Like BuzzFeed UK on Facebook.