Handbook of Radon.
5. Some basic facts about radiation: a perspective.
There is no disputing that ionising radiation (often just called radiation) can cause cancer. However, there are many causes of cancer, some not well understood. Radiation, including that from radon exposure, seems responsible for only a few per cent of cancers in the UK, perhaps about 3%.
Major causes of cancer include smoking and poor diet. Although the link with diet is not fully understood (or agreed) it is possible that as many as 35% of cancer cases may be linked in some way to food and drink.
Radon daughters are responsible for most of the ionising radiation to which most people are exposed. In 1987, the UK Government acted upon NRPB advice that householders whose homes were found to contain on average more than 400 Bq/m3 of radon should be advised to treat them in some way so as to reduce their radiation exposure. At that time, Sweden had an advisory level of 800 Bq/m3 and most other European countries had not formulated guidance.
In January 1990, the so-called ‘action level’ in the UK (400 Bq/m3 ) was reduced to 200, again on NRPB advice. This is not a danger level and it is not a safety level. It is (merely) an advisory threshold where the advice is "above this level consider taking some action in the longer term". In 1991, the EC set an action level of 400 Bq/m3 . Thus, as of 1992, the UK has one of the lowest ‘action levels’ for radon in homes.
At first sight, houses containing 400 Bq/m3 of radon and in which the occupants could receive annual doses as high as 20 mSv (see Section 6) might appear to be quite dangerous. 20 mSv is five to ten times the dose that most radiation workers receive. In fact, the risks are not all that great but it needs to be borne in mind that some houses in the UK have been found to contain 5000 Bq/m3 of radon. This still has to be kept in perspective, because in the United States and Eastern Europe people have lived for decades with 100,000 Bq/m3 of radon. One house has been reported in East Germany at 300,000 Bq/m3 .
At the other end of the radiation scale, are the minute personal doses to members of the public received routinely from nuclear reactors and reprocessing facilities. These are generally below 0.001 mSv, less even than the dose from cosmic radiation received during a short plane flight.
One illustration of nuclear perspectives is the story of Three Mile Island in the USA (see Section 40 also). A nuclear reactor came close to melt-down, and was severely damaged. Much of the internal cooling water was heavily contaminated with radionuclides (radioactive atoms). This water has long since been decontaminated and it is now so pure that it is less radioactive than the local river water. But it is still stored and has not been discharged to the river, for fear of public outcry. This is one example of the expenditure on minute risks that so characterises much of radiological protection.
Another example is the perhaps understandable overreaction to the accident at Chernobyl (see Section 45 also). In the surrounding countryside, people have been evacuated and compensated because of average annual doses of 5 mSv, and are being compensated for doses as low as 1 mSv. Yet the average radiation dose from natural causes in Cornwall is about 10 mSv per year!
KEY FACTS:
As with some aspects of nuclear power, radon has been taken out of perspective, especially by some public administrators in the United States. One encouraging sign is that both radon experts and health professionals have begun to question past excesses of policy.
Nevertheless, radon can represent a severe risk in the worst affected homes.