Ruffian
434
There are still a lot things we don't know about radiation risk.
Nov 11, 2015,03:33 AM
Perhaps 'lead-time' was the wrong phrase. 'Latency period' is probably the correct term. Regardless, if you google 'radiation-induced osteosarcoma', you will see that most of these cancers (a bone cancer) developed 10 years after radiation.
You are right that the 'trigger level' or threshold is unknown. In fact, some scientists argue there is no threshold and others that there is one.
The problem with radiation risks (and the reason why clear information is so difficult to find) is that we have been extrapolating data from Japanese survivors of the atomic bombs dropped on Hiroshima and Nagasaki. These people were exposed to levels of radiation several magnitudes higher than what patients are exposed to say, in a CT scan (and, presumably from radium in watches). The problem with extrapolating is that our bodies may behave differently at lower levels of radiation. Indeed, some people believe a low level of radiation protects against cancer (by inducing DNA-repair mechanisms).
Consider this interesting fact: In some parts of Iran, the background radiation is 260 mSv (mainly due to radon gas). In the UK or USA, background radiation is 2-3 mSv. But, people in these parts of Iran do not have a higher rate of cancer than the rest of the world.
You are right that the risk is cumulative. That is, if you receive 1 mSv once a year x 10 years, it is equivalent to receiving a 10 mSv dose (which is typical of a CT scan).
This message has been edited by Ruffian on 2015-11-11 03:38:32 This message has been edited by Ruffian on 2015-11-11 03:39:56