杏吧原创

AS THE alcoholic excesses of yuletide draw near, a scientist in Sweden has
unveiled a test which can show whether you鈥檝e been drinking heavily the night
before鈥攅ven if little of the ethanol you consumed remains in your body. If
driving with a hangover ever becomes an offence, the test could earn the same
legal status as today鈥檚 Breathalyser.

People who drive the morning after a night鈥檚 heavy drinking often have blood
alcohol levels below the legal limit
(This Week, 25 January, p 8). Yet there is
plenty of evidence that hangovers impair concentration and the ability to
perform skilled tasks, including driving.

Wayne Jones, head of Sweden鈥檚 National Laboratory of Forensic Toxicology at
Link枚ping University Hospital, has developed a test based on two 鈥渕arker鈥�
substances which reach peak levels in urine hours after most of the ethanol has
gone. 鈥淭hese could provide objective evidence of a recent drinking binge,鈥� he
says.

One of the markers is methanol, which occurs naturally in the body when
bacteria break down sugars and polysaccharides in the gut. Methanol is also
found in small quantities in drinks such as whisky, cognac and red wine.

Ethanol and methanol are both broken down by the same enzymes in the liver,
but ethanol breakdown always takes priority. After a heavy drinking session,
methanol breakdown is on hold, so natural 鈥渂ackground鈥� levels in the blood rise.
Indeed, methanol is thought to cause many of the symptoms associated with a
hangover.

Jones鈥檚 test also looks at compounds formed by the breakdown of the brain鈥檚
neurotransmitters. Ethanol disrupts the natural balance between two breakdown
products鈥攃alled 5-hydroxyindoleacetic acid (5HIAA) and 5-hydroxytryptophol
(5HTOL). Normally, concentrations of 5HIAA exceed those of 5HTOL by 1000 times,
but the disparity narrows after drinking, because the removal of 5HTOL from the
body slows while ethanol is being broken down.

To test the usefulness of the markers, Jones and 19 other volunteers drank 50
or 80 grams of alcohol, in the form of white wine and strong lager, in an
evening session. They gave urine samples at three-hour intervals throughout the
night and the following day.

Levels of methanol and the relative concentrations of 5HTOL were highest when
the volunteers emptied their bladders at 8.00 am. By this time, almost all the
ethanol was gone. But the markers stayed above baseline levels until well into
the afternoon.

As a first step towards validating the tests, Jones will examine 80 samples
of urine taken at the postmortems of Swedes who died in accidents at work. He
wants to see if the victims had high levels of the markers even though pathology
reports recorded only low levels of ethanol.

Roger Vincent, a spokesman for the Royal Society for the Prevention of
Accidents in Birmingham, says the big test will be to show that people with high
levels of methanol and 5HTOL in their urine have poor coordination.

A spokesman for Britain鈥檚 Department of the Environment, Transport and the
Regions, which launches its Christmas campaign to curb drink-driving next week,
says that there are no immediate plans to target hungover drivers. 鈥淏ut there鈥檚
no reason why those developing the test shouldn鈥檛 bring it to our attention,鈥� he
says.