http://www.newscientist.com/dailynews/news.jsp?id=ns9999289
Cold war, hot secret
Radioactive tags were used to track dissidents behind the Berlin Wall
East German dissidents probably didn't spot the plain-clothes agent with the
vibrating armpit. But agents could track suspected political opponents
without even seeing them. They just followed a trail of radioactivity shed by
their unwitting quarry.
In the 1970s and 1980s, the German Democratic Republic's secret police - the
Stasi - frequently labelled suspected dissidents with highly radioactive
chemicals so that agents wearing concealed Geiger counters could keep tabs on
them, according to a paper by Klaus Becker, a leading radiation protection
expert.
So that targets would not hear the clicking of the counter at close range,
Stasi agents wore the detector strapped under one arm, while a vibrating
alarm was slung under the other arm. Bizarrely, this 30-year-old invention
mirrors the vibrating "silent ringers" on today's pagers and cellphones.
Evidence of the radioactive tracking exercise was found in the vast Stasi
archives by officials of the Berlin-based Gauck Commission, a government
agency investigating the former secret police. "It is a remarkable story.
It's the first well-documented case of such a thing," says Becker.
Cancer deaths
It has long been suspected that the Stasi used radiation as a weapon. Becker
reports that "unusual non-medical X-ray machines" in former political prisons
could have been used for covertly irradiating inmates.
Large doses of X-rays are thought to be behind the deaths from cancer of a
number of prominent dissidents. "I wouldn't be surprised if it was true, but
I suspect it will never be officially proved," says Becker.
But no one knew about tracking people with radionuclides. "It really is the
stuff of James Bond movies," comments Barrie Lambert, a radiobiologist at St
Bartholomew's Hospital in London. "It's an unpleasant thing to do. The risk
is not limited to the person being tagged. You'd be exposing other people,
such as a spouse."
Spray and decay
The Stasi files reveal that dissidents were labelled with radioactive
substances in a number of ways. If people could not be sprayed with a
radioactive solution the spies would label their cars, documents or paper
money, Becker reports.
A favourite radio-nuclide was the beta and gamma emitter scandium-46. If
floors in dissident meeting rooms were treated, he says, the Stasi could
follow anybody who attended. And the Stasi also developed an airgun that
could fire radio-labelled silver wire into a car tyre from 25 metres away.
While victims received radiation doses of around 150 millisieverts per
action, the Stasi looked after its own, ensuring that its agents were not
exposed to any more than the internationally recommended maximum - 1 mSv per
week at the time.
But Michael Clark, spokesman for Britain's National Radiological Protection
Board, says that there would be "inherent uncertainty" in any dose
calculation and that actual doses could have been anywhere between 50 and 500
mSv.
Tainted money
Becker left East Germany in 1951, aged 18. He later became head of radiation
dosimetry at the Jülich Nuclear Research Establishment in West Germany.
He says that while doses were usually below what would seriously harm or
kill, there were mishaps. "The Stasi marked West German deutschmarks with
large amounts of scandium to see how they circulated, to whom and for what
purpose. While they expected to retrieve them, they didn't and the notes
disappeared without trace," he says.
The Stasi later calculated that if more than one note was in a man's pocket,
the effect on his fertility "came close to castration," Becker says. More at:
StrahlenschutzPraxis (vol 3, p 25)
Correspondence about this story should be directed to
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1900 GMT, 3 January 2001
