杏吧原创

EAST German dissidents probably didn鈥檛 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鈥檚 secret
police鈥攖he Stasi鈥攆requently 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 鈥渟ilent ringers鈥� on today鈥檚 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. 鈥淚t is a remarkable story. It鈥檚 the
first well-documented case of such a thing,鈥� says Becker.

It has long been suspected that the Stasi used radiation as a weapon. Becker
reports that 鈥渦nusual non-medical X-ray machines鈥� 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.
鈥淚 wouldn鈥檛 be surprised if it was true, but I suspect it will never be
officially proved,鈥� says Becker.

But no one knew about tracking people with radionuclides. 鈥淚t really is the
stuff of James Bond movies,鈥� comments Barrie Lambert, a radiobiologist at St
Bartholomew鈥檚 Hospital in London. 鈥淚t鈥檚 an unpleasant thing to do. The risk is
not limited to the person being tagged. You鈥檇 be exposing other people, such as
a spouse.鈥�

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鈥�1 mSv per
week at the time.

But Michael Clark, spokesman for Britain鈥檚 National Radiological Protection
Board, says that there would be 鈥渋nherent uncertainty鈥� in any dose calculation
and that actual doses could have been anywhere between 50 and 500 mSv.

Becker left East Germany in 1951, aged 18. He later became head of radiation
dosimetry at the J眉lich Nuclear Research Establishment in West Germany.

He says that while doses were usually below what would seriously harm or
kill, there were mishaps. 鈥淭he 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鈥檛 and the notes disappeared
without trace,鈥� he says. The Stasi later calculated that if more than one note
was in a man鈥檚 pocket, the effect on his fertility 鈥渃ame close to castration,鈥�
Becker says.