Hello and welcome to ‘the chronicle flask’, a blog of interesting chemical bits and pieces. Jumping right in, we begin with a tale of jellyfish, wee and wittertainment. Here goes…
Last week I was listening to the Kermode and Mayo ‘wittertainment‘ film podcast in which the esteemed film critic Mark Kermode was discussing the film The Paperboy. There’s a scene in this film in which Nicole Kidman’s character wees (urinates, for the benefit of any non-Brits) on Zac Efron‘s jellyfish sting. It’s an idea that’s been used before, famously in an episode of Friends, and the question arose: does this actually work? For those that aren’t aware, Simon Mayo is also an author of the rather wonderful Itch series of books, which hinge around a character with an interest in chemistry, and he wanted to know what the chemical equation might be for the wee + jellyfish venom reaction. So, being a chemist and a big fan of the show, I fired off an email on this very subject. Here it is:
First of all a quick reminder of the pH scale: it goes from 0-14 where 0 is very, very acidic (think battery acid) and 14 is very, very alkaline (think drain cleaner), and 7 is neutral (think water).
I mention this because acids neutralise alkalis, and vice versa. If you mix exactly the right amount of acid with the right amount of alkali you get just water and salts.
Since you asked for an equation the general one is:
acid + alkali –> salt + water
Human urine is, actually, about pH 7, i.e. the same as plain water. People often think it’s alkaline because they have the idea there’s ammonia in it, but there isn’t and it’s not (well not usually). It varies a bit from 4.6-8, and if anything it tends to be a tiny bit acidic. If you have a urinary infection it can become more acidic, but we’ll assume for our purposes that Nicole Kidman didn’t.
Jellyfish venom not surprisingly varies by species. I’m relying on the internet here as I’m not a zoologist, and it seems that there are lots of different varieties of jellyfish in Florida, so the sting could be anything. But as far as I can work out, they tend to be alkaline (greater than 7).
So if jellyfish venom is slightly alkaline, and human urine is slightly acidic, one MIGHT neutralise the other, and this is probably what lies behind this. Obviously TV shows and films like this endlessly perpetrate the idea, so it sticks. In truth this ‘remedy’ is unlikely to do anything much though.
In fact it might actually make it worse. The proper, official medical advice is to rinse the area with salty seawater, because that apparently deactivates the stinging cells whereas plain water (and urine is closer to plain water than seawater) makes it worse – I imagine this is to do with osmosis, but that’s a lesson for another day – try and remove the stinging cells by scraping the skin with a credit card and, obviously, seek medical attention.
Whatever you do don’t try battery acid. That’d be really bad.
I was then contacted by the editor of the show, and they actually invited me on to explain this as a special guest. This, as you might imagine, made my week – I don’t think they’ve ever had a non-film guest on the show before. If you’d like to hear it, you can download it here. The shows used to only be available for about a week but they now seem to be hanging around a bit longer (hurrah!).
Now since this is supposed to be a chemistry blog, I have a few more musings on the topic of animal stings. Jellyfish aren’t the only creatures to have this sort of defence mechanism of course, and probably more familiar to us here in the UK are the humble bee and wasp. Bee stings are acidic, whereas wasp stings are alkaline. So can you treat them with household acids or alkalis? I think, to my shame, that I may even have suggested vinegar as a treatment for wasp stings myself in the past.
Now that I actually think about this for more than 30 seconds I realise that this is very unlikely to be effective. First of all, wasp venom is complicated stuff. After all it’s not as if the wasp is injecting a few drops of pure alkali into your arm. No, wasp venom contains, amongst other things, enzymes which help to break down cell membranes and a chemical to reduce blood flow called norepinephrine, which is why the sting hurts for ages and doesn’t immediately get flushed away by your bloodstream. The sting itself is a tiny amount of fluid, and only a minute amount of acid would be required to neutralise any alkali present. So will sloshing an unknown quantity of an unknown concentration of acetic acid (the acid in vinegar, also known as ethanoic acid) actually achieve anything? Especially considering that the sting is injected under the skin, whereas you’re dribbling the contents of your kitchen cupboard on the surface? Very unlikely. Chances are you’ll just irritate your skin even more.
Of course there is the placebo effect to consider. Doing something, anything, rather than just dancing around yelping in pain will probably make you feel better. And rubbing your skin usually makes minor injuries hurt a bit less. But chemically? Nah.
So in short, if you get stung it’s probably more effective to reach for the paracetamol rather than the condiments.