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Saturday, March 1, 2008

Myth of cockroach’s immunity to nuclear

Cockroaches survived much more than humans

Fruit flies, flour beetles tougher than cockroaches

Last year, the Myth Buster TV team from the Discovery Channel
announced that they would find out experimentally whether
cockroaches would be the only living
form to survive a nuclear war (The Hindu, November, 1, 2007). On
January 30, this year (Episode number 97), the team busted the
myth which was in their priority list from day one.

The announcement that the myth buster team will conduct an
experiment received wide media coverage; surprisingly, the media
virtually ignored the results of the experiment.

The experiment

The staff of the Pacific Northwest National Laboratory at Hanford
site (U.S.) assisted the team to expose three groups of German
cockroaches (50 each) to 1,000, 10,000 and 100,000 rads
of gamma radiation using an irradiator located in the basement of a
building at Hanford. The fourth group of 50 cockroaches served as
control... (Rad is a unit of radiation dose; a dose of 450 rads may kill
50 per cent of the persons exposed) They exposed similar groups of
50 flour beetles and 100 fruit flies which represented other living forms
to similar doses. Many bugs initially survived after receiving 1,000 rads
and 10,000 rads . However, only some flour beetles survived after
receiving a dose of 100,000 rads. Fruit flies and flour beetles are found
to be tougher than cockroaches. For instance, on the second day after
receiving 100,000 rads, all the cockroaches died; 40 per cent
of the fruit flies and 90 per cent of the flour beetles survived. The
survivors will be infertile.

“While cockroaches survived much more than the humans would,
the other two test subjects did better than the cockroach,” the TV
channel declared. They concluded that they busted the myth since,
more life forms than cockroaches survived!

The spectators’ reactions to the TV programme, revealed how
differently the common man understands radiation related concepts.
Is it safe to go into the room after cobalt irradiated the bugs? A viewer
wanted to know. The questioner wrongly felt that irradiation with
cobalt will leave the room radioactive!

One viewer objected to the use of cobalt radiation to irradiate
the bug. “Consideringthat the myth was “will cockroaches survive
a nuclear blast” shouldn’t they have used uranium-238?” he
queried. “I believe that this is the substance used in modern day
nuclear weapons,” he argued. (Obviously he did not understand
the difference between radiation from a nuclear weapon and that
from uranium-238).

It was equally wrong on the part of the TV channel to claim that
they are exposing the insects to a nuclear blast when they actually
exposed the bugs to gamma radiation from a cobalt source. The
survivability of cockroaches in a nuclear war has been a topic of
interest for several years.

Based on the work of Hassett and Jenkins (Nucleonics, 1952),
Professor John Moulder, Professor of Radiation Biology, Medical
College of Wisconsin, noted that about900-1,000 Gys are needed
to kill a cockroach (one Gy= 100rads); more dose is
required if the dose is delivered at a slower rate. The claim that
not enough scientific data are available is not true.

Strong evidence

In 1957, Drs Wharton and Wharton found that 1,000 rad can
interfere with the fertility of cockroach. In 1963, Drs Ross and
Cochran found that a low dose of 6,400 rad would kill 93 per cent
of immature German cockroaches.

Inspite of such unimpeachable evidence on its
radiation-vulnerability, the myths about this unlovable creature
may survive, not withstanding the fame and popularity of the
‘Myth Busters.’