As a former Radiation Safety Officer I am very aware of the ALARA principle as applied to ionising radiation, which means that doses should be kept As Low As Reasonably Achievable. The key is the word "reasonably".

The stochastic risk (the chance that some ionising event will occur) increases with increasing time, activity and type of radiation exposure. It's a bit like saying that spending more time driving in heavy traffic increases the risk of having some form of accident.

However, not all such events will have a measurably deleterious effect, just as most car accidents are merely fender-benders, not catastrophic or fatal. For example, a beta particle will be stopped by the epidermis, which is dead, and will be very unlikely to cause any negative effect at all unless one happens to inhale a source. The same applies to alpha particles. On the other hand, high-energy neutrons can do a lot of damage, although most of them are going to pass straight through a body doing no harm at all and the same applies to gamma. The chance of actual harm occurring during an ionising event is the "deterministic risk". To use the driving analogy, this is the chance that an accident will cause an injury and we take steps, such as seatbelts, airbags,crumple zones, to reduce that risk, as well as speed limits, signage, road rules, driver training to reduce the stochastic risk, with the result that an intrinsically hazardous activity is now so safe that we do it with our kids routinely.

Radiation workers are allowed about 50 times the annual dose of the general public and this is monitored using film badges. It is so much higher because they are few in number - raising the stochastic risk in a a small number of people is not going to lead to an explosion of cases of radiation-induced illness/injury. In the same way, we allow emergency workers to ignore speed limits, provided they do so in certain ways that limit risk to others. This is where the "reasonable" part comes in. [cont]

We reasonably recognise that the job of being a radiation worker or an emergency worker entails some unavoidable added risk from the work itself and we do what we can to ensure that they are reasonably safe. We don't say "no risk is acceptable", because that would mean society would not enjoy the benefits that such work produces. Instead, we give those workers the tools to minimise their exposure to avoidable risk and expect them to accept the unavoidable ones as part of the job.

The problem we face is that there is very poor understanding of genuine risk management principles among the public and even among those professionals who are in the safety management business. Instead, we have allowed a silly "zero tolerance"/zero-thought approach, in which any risk, whether stochastic or deterministic is seen as unacceptable and so truck drivers are not allowed to climb on trays, forklift drivers have to beep their horn every time they turn a corner, men are not allowed to sit next to children on planes, the list goes on and on and it's a depressing story about our society and the problem of managerialism as it is playing out in the risk-management industry.

Let's face it, cancer treatment using radiation would never have been developed if the risk-managers of today had to approve the experiments that lead to it.

Shadow Minister is simply wrong. A number of reputable scientific bodies have studied high AND LOW dose radiation effects on animals. Among these were the research of Clinton Laboratories (later Oak Ridge National Laboratory) on hundreds of thousands of mice, and on beagles at the University of California. For ethical reasons, such studies are supposedly not done on humans, (but in fact have been done - results kept secret, by US military).
More recently, reputable studies by the University of California, and Oxford University (UK) have shown increased leukaemia in children exposed to three or more X rays,
USA Department of Energy is now funding very small tinpot studies on small numbers of mice to try to show that low dose radiation is harmless.

Noel,

At least you admit that the studies you mentioned have no comparison for low level radiation.

I have read the Oxford study and I note that they very carefully said that they found a modest "association" (not a causal link) for the very reason that the reasons people needed >3 x rays could be linked to why the leukemia developed. They also commented on another similar study that found no association, and finally "Given the lack of precision in the exposure estimates, the results of this study should be interpreted with caution, but they warrant further investigation"

If you have anything that is substantial I would be glad to see it.