acute radiation in the news

["Michael C. Baker" <mcbaker@lanl.gov>]

Effects of acute radation are long lasting - study

UK: May 4, 2000

LONDON - Exposure to acute, high doses of radiation
can cause genetic changes that are passed on to
future generations, researchers in Britain said on
Wednesday.

A pilot study of mice reported in the science journal Nature
showed that the grandchildren of animals exposed to short
but extreme levels of radiation had a six-fold increase in the
frequency of genetic mutations.

Yuri Dubrova, of the University of Leicester, and scientists
at the Medical Research Council Radiation and Genome
Stability Unit in Harwell said their results could have
implications for humans, even though people are more often
exposed to chronic radiation - small doses over a long
period of time.

"We don't know whether chronic exposure can induce this
sort of thing," Dubrova said in a telephone interview. "There
is no way, currently, of extrapolating this data to humans
because of the very nature of exposure. Human exposure is
mostly chronic. In our experiments we used acute
exposure."

But Dubrova said the study raises the issue of delayed
genetic risk.

The researchers exposed male mice to fission neutrons and
mated them with unexposed females. Their offspring were
mated with other normal mice.

"When we profiled the grandchildren of the exposed males
we found a six-fold increase in the frequency of mutation,"
according to Dubrova.

The first generation of mice carried differences in their
germline cells, sperm or ova, that they passed on to their
children. The differences cause instabilities in the repeated
sequences of DNA in the offspring.

The mice were exposed to extremely high levels of radiation
- similar to those that would be caused by accidents at
nuclear processing plants like the disaster at Chernobyl in
1986, when Dubrova said about 100 people were exposed
to acute radiation.

The explosion of the reactor in the Ukraine killed 31 people
and sent a radioactive cloud across parts of the Ukraine,
Russia, Belarus and parts of Western Europe. Emergency
workers sent to clean up the site were among the most
serious victims.

Humans normally receive much smaller doses of radiation
over longer periods of time.

"Chronic exposure would increase the mutation rate in the
exposed parents but we don't know what will happen to
their offspring if you remove the radiation," Dubrova, who is
also affiliated with The Russian Academy of Sciences in
Moscow, added.

Story by Patricia Reaney
REUTERS NEWS SERVICE 

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