Estimating Risks to Children of Parents Exposed to Ionizing Radiation
Naturally-occurring genetic ( i . e ., hereditary ) diseases arise as a result of alterations ( mutations ) occurring in the genetic material ( DNA ) contained in the germ cells ( sperm and eggs ) and are heritable ( i . e ., they can be transmitted to the offspring and subsequent generations ). The concern over whether exposure to ionizing radiation would cause an increase in the frequencies of genetic diseases launched extensive research programs to examine the adverse genetic effects of radiation in the children of A-bomb survivors and other studies focusing on mammals that could be bred in the laboratory , primarily the mouse . Studies of 30,000 children of exposed A-bomb survivors show a lack of significant adverse genetic effects . During the past 10 years , major advances have occurred in our understanding of the molecular nature and mechanisms underlying naturally occurring genetic diseases and radiation-induced mutations in experimental organisms including the mouse .
The risk estimates presented in this report have incorporated all these advances . They show that , at low or chronic doses of low-LET irradiation , the genetic risks are very small compared to the baseline frequencies of genetic diseases in the population .
Given BEIR VII estimates , one would not expect to see an excess in adverse hereditary effects in a sample of about 30,000 children ( the number of children evaluated in Hiroshima and Nagasaki ). One reason that genetic risks are low is that only those genetic changes compatible with embryonic development and viability will be recovered in live births .
Research Needs
Continued research is needed to further increase our understanding of the health risks of low levels of ionizing radiation . BEIR VII identifies the following top research needs :
• Determination of the level of various molecular markers of DNA damage as a function of low dose ionizing radiation
• Determination of DNA repair fidelity , especially double and multiple strand breaks at low doses , and whether repair capacity is independent of dose .
• Evaluation of the relevance of adaptation , low-dose hypersensitivity , bystander effect , hormesis , and genomic instability for radiation carcinogenesis .
• Identification of molecular mechanisms for postulated hormetic effects at low doses .
• Reduction of current uncertainties on the specific role of radiation in how tumors form .
• Studies on the genetic factors that influence radiation response and cancer risk .
• Studies on the heritable genetic effects of radiation .
• Continued medical radiation and occupational radiation studies .
• Continued follow-up health studies of the Japanese atomic-bomb survivors , 45 % of whom were still alive in 2000 .
• Epidemiologic studies to supplement studies of atomic-bomb survivors , for example studies of nuclear industry workers and persons exposed in countries of the former Soviet Union .
Committee to Assess the Health Risks from Exposure to Low Levels of Ionizing Radiation : Richard R . Monson ( Chairman ), Harvard School of Public Health ; James E . Cleaver ( Vice Chairman ), University of California , San Francisco ; Herbert L . Abrams , Stanford University ; Eula Bingham , University of Cincinnati ; Patricia A . Buffler , University of California , Berkeley ; Elisabeth Cardis , International Agency for Research on Cancer , Lyon , France ; Roger Cox , National Radiological Protection Board , UK ; Scott Davis , University of Washington and Fred Hutchinson Cancer Research Center , Seattle , WA ; William C . Dewey , University of California , San Francisco ; Ethel S . Gilbert , National Cancer Institute ; Albrecht M . Kellerer , Ludwig-Maximilians-Universität , München , Germany ; Daniel Krewski , University of Ottawa , Ontario , Canada ; Tomas R . Lindahl , Cancer Research UK London Research Institute ; Katherine E . Rowan , George Mason University ; K . Sankaranarayanan , Leiden University Medical Centre , Leiden , The Netherlands ; Daniel W . Schafer , Oregon State University ( from May 2002 ); Leonard A . Stefanski , North Carolina State University , ( through May 2002 ); Robert L . Ullrich , Colorado State University , Rick Jostes ( Study Director ), National Research Council .
This brief was prepared by the National Research Council based on the committee ’ s report . For more information , contact the Nuclear and Radiation Studies Board at 202-334-3066 . BEIR VII : Health Risks from Exposure to Low Levels of Ionizing Radiation is available from the National Academies Press , 500 Fifth Street , NW , Washington , DC 20001 ; 800-624-6242 ; www . nap . edu . This report is sponsored by the U . S . Department of Defense , U . S . Department of Energy , U . S . Nuclear Regulatory Commission , U . S . Environmental Protection Agency , and U . S . Department of Homeland Security .