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     Living dangerously -- Standard radiation safety limits used around
     the world may have to be revised to protect the young and old
     by Rob Edwards

     New Scientist magazine, 28 February 1998


     YOUNG children and old people around the world could be exposed to
     damaging doses of radiation from nuclear plants and other sources
     because the database that is used to set safe limits is flawed. A
     new analysis by a leading British epidemiologist suggests that the
     young and old are more sensitive to radiation damage than was
     previously thought.

     The international system of radiation safety limits is mostly
     based on epidemiological studies of 76,000 people from Hiroshima
     and Nagasaki who were still alive five years after their cities
     were obliterated by American atom bombs in 1945. The rates at
     which they have contracted cancers compared with people from other
     Japanese cities are used by regulatory agencies to estimate the
     risks of exposing people to radiation from nuclear plants, bomb
     tests and fallout from accidents such as that at Chernobyl in
     1986.

     But Alice Stewart, famous for her work in the 1950s revealing the
     dangers of X-raying pregnant women, argues that the atom bomb
     survivors are not a normal, homogeneous population. She says her
     analysis shows that children and old people are more vulnerable to
     radiation, and that a high proportion of them died between 1945
     and 1950 before studies of the Hiroshima and Nagasaki residents
     began. The young and old are therefore under-represented among the
     survivors. "The atom bomb data are no good as a basis for
     radiation safety regulations," she says.

     Aged 91, Stewart is an honorary professor at the University of
     Birmingham School of Medicine. Her study, which is due to be
     published by the Scientific and Technological Options Assessment
     unit of the European Parliament in the next few weeks, compares
     2601 survivors who suffered from acute radiation injuries with
     63,072 survivors who did not. Stewart found that of those with
     acute injuries, children who were under 10 when the bombs exploded
     were a thousand times as likely to die of cancer as people aged
     between 10 and 55.

     People over 55 at the time of the explosions were twice as likely
     to die of cancer as those aged between 10 and 55, the study shows.
     Among those who did not suffer acute injuries, children under 10
     at the time of the explosions were three times as likely to die of
     cancer as other age groups.

     Stewart says her results show that the very young and very old are
     particularly sensitive to radiation. She suggests that the immune
     systems of the young and old are more easily harmed because they
     are either still developing or are breaking down. A damaged immune
     system makes people more vulnerable to cancers and infections, she
     says.

     The National Radiological Protection Board, which advises the
     British government, accepts that the Japanese database is not
     perfect because it lacks information on the first five years of
     exposure. But the board's spokesman, Mike Clark, points out that
     safety limits are also derived from other databases-including
     Stewart's earlier work on X-rays.