Can a person sitting in a bath dehydrate?

05 September 2013

Question

If one went without consuming water for three or four days but was submerged in fresh water for all that time, would you still dehydrate?

thanks,
Ahmed

Answer

Ginny - The short answer is, no. Your skin is pretty waterproof. That's why we can go out in the rain and we don't get all soggy. Well, our clothes might, but our skin is actually pretty waterproof. Although, if you were in somewhere very, very hot, sitting in water might actually help stop you from dehydrating, just because it would keep you cool, so you'd sweat less. But you wouldn't actually be able to absorb it through your skin. Now, there's a group of researchers in Denmark who actually decided to test this, but rather than using water, they thought it would be a bit more fun to do it with vodka. So, they sat with their feet in a bath of vodka for a while and they tested their blood alcohol levels and they found that they didn't get drunk at all. So, that just shows that you're not absorbing things through your skin like that.

Chris - We did interview them on this programme, Ginny and they did say that although they didn't absorb any alcohol according to the blood test, they did all start talking very loudly and telling rather raucous jokes. So, it had a psychological effect if not a physiological one.

Ginny - Well, I wouldn't have been surprised if they'd inhaled some alcohol fumes and got drunk that way. I'd be quite interested to know though if their feet went wrinkly because we all know that our fingers and toes go wrinkly in the bath. People used to think that that was because you're absorbing water through your skin. But actually, some recent research at Newcastle suggests that it's evolved to help us grip objects when our hands are wet. They think it's actually down to your nerves because if you've got nerve damage, it doesn't happen. So, they found that people were much better at picking up marbles underwater when their hands had been in water for a while, so their fingers had gone wrinkly. So, it works a bit like the tread on tyres, but it's actually controlled by your nerves, not by you absorbing water through your skin.

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