Radiation mutations passed to children - study
Date: 11-Feb-02
Country: USA
Author: Maggie Fox, Health and Science Correspondent
And the mutations faded out by the time grandchildren were born, which suggests test ban treaties are doing their job in protecting future generations, the researchers reported in Friday's issue of the journal Science.
Radiation is known to cause genetic mutation, and the rate of certain cancers goes up in areas exposed to nuclear fallout, such as Hiroshima and Nagasaki in Japan and the area around Ukraine's Chernobyl power plant.
Yuri Dubrova, a geneticist at the University of Leicester in Britain, knew people living around the Semipalatinsk nuclear weapons test site in Kazakhstan were exposed to nuclear fallout from the explosions of four nuclear bombs between 1949 and 1956.
"The first Soviet nuclear device was tested there," Dubrova said in a telephone interview last week.
Dubrova's team wanted to see if the genetic mutations caused by radiation from these bombs were passed on from parent to child, and to future generations.
Working with teams in Britain, Kazakhstan and Finland, they took blood from 40 three-generation families in the area and tested an area on the chromosomes prone to genetic mutation.
"We need to know to what extent exposure to radiation might affect the mutation rate in our germ cells and therefore cause an elevated mutation rate in the offspring of exposed people," Dubrova said. Germ cells are the egg and sperm.
All the grandparents were born before 1949, with succeeding generations born through the 1960s.
They got blood from people who lived in a similar but uncontaminated geographical area, and matched genetic samples by age, ethnicity, whether they smoked and so on.
HIGH MUTATION RATE IN GRANDPARENTS
As would be expected, the grandparents had a soaring mutation rate. "It went up twofold roughly or 100 percent if you compare with the controls," Dubrova said. "In the next generation, which was less exposed, it was 50 percent higher."
Some of the nuclear fallout was still in the environment when the oldest members of the second generation were born, so direct exposure to this radiation could have caused some of the mutation, Dubrova said.
There was even some radiation around when the first grandchildren were born, and Dubrova found that the younger the person his team tested, the fewer mutations he or she had.
"I was jumping from joy here. I was dancing, singing," he said. "It went down with the year of birth."
Dubrova said the tests do not show whether the people with the most mutation have a higher risk of cancer, because they are not the genes known to be involved in cancer when they are damaged.
