Doctors, nurses, technicians - despite the precautions taken, are they more likely to eventually suffer from cancer? Does length of career or type of work make any difference?
Mrs. Geek used to be a nuclear medicine technologist, so most of my knowledge of this comes from her.
Your question is a bit controversial There are some experts who think that any increased exposure to radiation causes harm. There are other experts who say that the exposure limits for most of these folks too low to be significant. The debate between the two groups is somewhat heated at times.
A lot of nuclear medicine folks (at least in the area where Mrs. Geek used to work) noticed what seemed to them to be rather high incidences of thyroid problems among workers, though at the time they were told that statistically this wasn’t true throughout the industry.
If there is a significant increased risk, the longer your career in the field, the greater your overall exposure would be, and hence the greater the risk would be.
To build on this point: This is the debate between the cumulative and the threshold schools of thought. (I don’t know if that’s the official terms for them, it’s just what I used while I was doing rad control work while in the Navy, and got involved in the various debates and evidence.)
The key difference is that while both schools agree that there are self-correcting and healing mechanisms for exposure, the threshold school claims that below some threshold the exposure won’t have any long-term effect. The cumulative school holds that all exposure has the potential to affect long term health on the exposed person.
The evidence for either school, at the time I was reading up on this, was still pretty iffy. The largest study I am aware of for the long-term effects of low-level radiation exposure is the mid nineties study by Brigham Young University, which was simply following people who had gotten occupational dose working on US Navy nuclear plants. The study found that, excepting a higher-than normal lung cancer (esp. mesothioloma) rate*, the incidence of cancer in the studied group was lower than among the general population from the same time frames.
Even at the time the study was roundly criticized by the various anti-nuke groups. Their claim that any study showing radiation exposure to be beneficial had to be flawed. I think that’s a misrepresentation of what the study showed. Considering that the studied population had to meet physical and health standards that the general population doesn’t, it makes sense to me for the general cancer rate to be below that observed in the population at large. Either way the study remained controversial the whole time I was involved in the industry, and paying attention to the literature.
At any rate, what I believe both sides are agreeing on is that if there is an increase in the cancer rate, it’s a very small variation in the data compared to other environmental factors, and will be difficult to isolate out statistically.
*The lung cancer rate was expected to be higher than the general population, since most of those plants also were using asbestos insulation on the piping - which had already been recognized as the cause of continuing health problems for many exposed personnel.