I CALCULATE that there is a time lag of about 18 months these days between the human race finding something fun to do and it being branded hazardous to their health.

The latest fun to be "cold watered" is tongue piercing, that amusing fashion for people looking for a new part of the body to mutilate. It's the British Dental Association that has now given several very sensible reasons for why it is bad for you: infected piercings can lead to septicaemia. You can crack a tooth, you can have an allergic reaction and your tongue swells up. You can choke.

Not only tongues but other piercings are bad news - if not for your health then certainly for your vibes.

"The belly button is a point of where the acupuncture meridians meet so it can cause all kinds of upset," says Dr Robert Hempelman of the Brompton Dental Clinic. Likewise with rings way up the ears. "The metal in the ear could over-stimulate the liver and the kidneys because that's where their acupressure points are."

A friend agrees with this. "My au pair had her belly button pierced and it changed her completely. Before she was lively and cheerful. Afterwards she suffered from depression."

As so many of us have faith in acupuncture, we just accept that piercing - which is effectively permanent acupressure - could also have an effect.

The advice this week is not how to get a safe tongue/belly/nostril/ ear piercing but how to resist the temptation in the first place.

1. Find a new way to challenge your need to be different other than something that everyone else is doing. Plait armpit hair perhaps.

2. Visit Leicester Square. Seeing hoards of unattractive people having their lumpy ankles painted with henna will soon remove any desire for body decorations.

3. Think ahead. Piercing is 'over'. No one will do it in the zeroes.

'Menace in the Mouth' by Dr Robert Hempelman is out this month.