Also in this week's column:

• Why doesn't a hangover occur the night before?
• What issues are there for women in space?
• Why do babies always seem to have a runny nose?

Can you die from testing a 9V battery on your tongue?

Asked by Liam Johnson of Frankfurt, Germany

Here's Liam's question in full:

First the simple question: Can you die from testing a 9V battery on your tongue? I have read newspaper reports (around 1990) of a woman dying after her boyfriend used a 9V battery as sexual stimulation.

A brief look on the internet brings up a number of comments.

1. Apparently there was a US sailor being trained as an electrician who killed himself by sticking the probes of an Ohmmeter through his skin to measure his internal resistance.
2. There are also claims of eight people a year dying in Australia (why just Australia?) from testing batteries.

Now, the explanation I have heard as to why this is, is that in certain freak cases, the battery can make an almost direct connection to the nervous system where the nerves are close to the surface and the skin is wet, thus ionising the nerves so that they will not work correctly. Result is death.

The detractors who attempt to answer this question invariably end up quoting figures for levels of current which kill then stating that a batter cannot generate these levels of current. This basically just dodges the issue since we have a fairly specific set of circumstances and it is not claimed that the current actually kills, rather the effect of a DC potential connected directly to the nervous system.

Besides, the figures quoted are guidelines for safety and not intended to be an absolute guarantee of safety. It is also my understanding, having spoken to a number of older electrical engineers, that there were different figures quoted for lethality for DC voltages and AC voltages, with the level of DC being significantly lower than for AC. Hope you can find some information on this issue! Thank you very much for your time!

Dr Xheng Hu of the School of Electrical and Information Engineering at the University of Sydney confirms that a 9V battery does not have enough voltage to kill a person by testing it on the tongue.

He adds: "It cannot be entirely excluded however. If a person is very ill, for example, has heart problems, or has a heart pacemaker that could be disrupted, and so on, they could possibly die from testing the battery in this way. But normally it wouldn't happen."

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

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