Let’s use this week’s post to speculate a little bit. Let’s think about a world in which cancer is no longer feared. This is not necessarily a world without cancer – but at least one in which cancer is routinely prevented or treated, so that it is more like pneumonia or (at worst) diabetes. This is one possibility suggested by Dade Moeller in a lecture during the 2008 meeting of the National Council on Radiation Protection and Measurements (NCRP), and Dade’s talk inspired some interesting questions and speculation. From my standpoint as a health physicist, it raises one question in particular: what would radiation safety look like in a world where cancer is only a nuisance?
Most of radiation safety falls into the category of regulatory compliance, and the majority of our regulations either directly or indirectly are aimed at minimizing the chance that a person will develop a radiogenic cancer. Virtually all of our radiation dose limits are largely aimed at minimizing the chance that someone might develop cancer as a result of avoidable radiation exposure. If cancer were to be either defeated completely or become manageable (such as hypertension or diabetes, for example), many of these limits may no longer be as important.
Although there is a great debate over low-dose radiation effects, this debate may become moot in a post-cancer world. If cancer is preventable or treatable, the presence or absence of a threshold dose for carcinogenesis will be of scientific interest, but we may be able to worry less about radiation exposure below thte threshold for causing deterministic effects – skin burns, acute radiation sickness, and so forth. Thus, radiation safety practices may return to those of an earlier era – preventing burns and excessive organ dose.
Other things may change, too. How much would we worry about medical radiation exposure in a world without cancer? Would the public be more accepting of nuclear energy, or would concerns of global warming become even more pressing? Would radon remain an issue of concern to us if lung cancer were no longer so frequently fatal? Would we continue to worry about radiation dose to the environment? And how would we practice ALARA (the philosophy that radiation exposures should be kept As Low As Reasonably Achievable)?
This last question, in particular, is interesting to consider. Although I’ve heard a few comments to the effect that ALARA may become a meaningless concept if there is a threshold radiation dose, I disagree. To me, the key word in ALARA has always been “reasonable” – we should do what we can to keep radiation dose as low as reasonably achievable. If we are no longer concerned about developing cancer, then it may not be reasonable to try to maintain exposure at very low levels – there are thresholds for deterministic effects (skin burns and radiation sickness, for example, that occur at high doses), and what would be reasonable would be to ensure that we do not exceed these levels (with a comfortable safety margin, of course). ALARA would remain in place as a concept, just at a higher level to reflect the higher radiation doses needed to cause deterministic effects.
Of course, we can’t necessarily assume that a world in which cancer has been beaten is the same as a world without cancer at all – it could be a world in which cancer can be treated and managed; a world in which cancer still occurs, but is manageable. In this case, we might treat cancer like diabetes – more than a nuisance, but less than a likely death sentence. In this case, we would still want to avoid cancer, if only to avoid the treatments needed to keep it in check. On the other hand, the allowable dose might be increased – if the risk of death per rem (or Sv) is substantially reduced, then perhaps we could accept a higher dose in order to gain additional benefits such as the ability to perform more “hot” work, to receive a higher level of medical diagnosis, and so forth. Dose limits would not go away; but they could be relaxed to avoid the nuisance and expense of cancer, as opposed to fear of death from cancer.
Having said all of this, if a successful cancer treatment were announced tomorrow, I’m not sure that I would expect to see new radiation dose limits announced the next day. Probably not even the next year. For one thing, it would take time for the public to understand that cancer is no longer to be as feared, and it will take even longer to realize the implications of this for radiation safety regulations and practices. Old habits do not change immediately. It is also reasonable to assume that concerns for the environment (and radiation dose to the environment) will remain, notwithstanding the fact that cancer is not widely seen in wild creatures. And, finally, changing radiation dose limits to reflect the new facts of cancer treatment may not be a high priority for either the regulators, nor for the elected and appointed officials who may find it difficult to explain why they feel they should allow a higher radiation dose to their constituents. Gaining enough information to satisfy ourselves that cancer truly is manageable (or even beaten) will take time; changing decades-old opinions will take even longer – but I would like to be there when it happens.