Describe what is meant by the linear hypothesis for nuclear radiation effects. W
ID: 2075617 • Letter: D
Question
Describe what is meant by the linear hypothesis for nuclear radiation effects. What does it say about a threshold? Is the linear hypothesis true for radiation illness? Why is there a debate about the linear hypothesis-can't the issues be answered scientifically? Give an example to show how the linear hypothesis affects public discussion of radioactivity. (See Chapter 4 of PFFP on D2L). What are the three types of radiation alpha-rays, beta-rays and gamma-rays really? What is ionizing radiation? Why is it dangerous? Which of the rays are ionizing radiation? Comment on the relative dangers of each to external exposure to the source of radiation or to internal (eating or breathing in) the source of radiation. Why does the United States Bureau of Alcohol, Tobacco and Firearms test wine, gin, whiskey and vodka for radioactivity; and if the test shows no radioactivity, the product can't be sold? What would be radioactive in these products anyway?Explanation / Answer
It is very difficult to measure the incidence of cancer and other ailments caused by low level radiation. This is because the rates are very much lower than incidence of cancer from other (more usual) causes. One way of estimating the incidence is to give animals high doses of radiation, count how many cancers occur and assume that the number at low doses is proportionately lower. This is called the no threshold linear hypothesis. There is no threshold and it is true for radiation illness.
The rival to the linear hypothesis is the threshold hypothesis. The body repairs damage to cells from ionizing radiation. According to the threshold hypothesis radiation results in cancer only when there is enough radiation to overwhelm the threshold mechanism.