Unit 1.7 Flashcards
List the late effects of radiation on the biological system.
Somatic effects include life shortening (due to accelerated aging), Leukemia, and other cancers.
Define a doubling dose and what is the dose that meets that criteria?
The dose that doubles the likelihood of a mutation. It is approximately 100Rem.
Why is it that while radiation increases spontaneous mutations, it does not cause genetic (aka heritable/preserved) mutations?
Likely because mutations in reproductive cells produce changes that cannot undergo viable embryogenesis and are aborted during fertilization. it does increase the likelihood that mutations that are already possible will occur - aka if the risk is 1/1000 that someone will have a Trisomy 21, that may increase slightly due to radiation exposure.
What effects on birth weight, infant mortality, major congenital abnormalities, still births, or sex ratio have been noted in the lineage of radiation survivors?
None. There has been no evidence that these have been increased over the general population.
Define Mutation.
A relatively stable change in the DNA of the cell nucleus, which, when in the germ cells lead to inherited effects and when in somatic cells may lead to dysplasia/cancer.
List the stages of fetal development.
Pre-implantation (0-9 days) - rad likely results in death.
Organogenesis (9d - 6 weeks) - rad likely results in malformations (**Most sensitive)
Fetal (6 weeks - term) - less likely to affect fetus.
At what threshold is there a low likelihood of embryonic death in humans?
Intl. Commission on Radiological Protection says doses < 10 rads will produce very infrequent death in humans.
What are the most likely effects of radiation on a fetus in the organogenesis stage?
Microcephaly and general growth retardation. Other congenital malformation, Mental Retardation, and increased Cancer risk are also found in high doses.
At what threshold of ionizing radiation are IQ changes and malformations unlikely to happen?
No adverse-effect for malformations: 20 rem
No increased risk of IQ decrease; < 10 rem.
