Look at the science – smoking and obesity are more harmful than radiation

The recent frenzy following the events in Japan suggests that the media are keen to feed our nuclear fears, by focusing on exposure to radiation that is extremely unlikely to result in a single death, compared with a natural catastrophe that has killed at least 20,000 people and displaced more than 100,000.

We are a successful species inhabiting a radioactive world and must have evolved protective mechanisms to deal with the effects of natural radiation. Let's inject some science into the nuclear debate to find out just how dangerous exposure to radiation might be, and apply it to our daily lives.

What can our experience of the atomic bombs and Chernobyl tell us about the health effects of radiation exposure? Radiation can be divided into two main types – highly penetrating such as X and gamma ray, and isotopic such as iodine-131, which needs to enter the body to have an effect. The radiation exposure in Hiroshima and Nagasaki was a short-lived, intense, exposure to relatively high doses of penetrating radiation. Following the Chernobyl accident, the radiation was prolonged and mainly isotopic. Exposure was therefore via ingestion and inhalation of radiostopes, mainly iodine-131 and caesium-137.

The majority of those who died following the atomic bombs in Hiroshima and Nagasaki died from flash burns or other injuries; 15-20% died as a result of acute radiation sickness. Long-term studies between 1950 and 1997 show that, of the 9,335 cancer deaths in the 86,572 population, only 440 (5%) of the solid cancers and 103 of 310 leukaemias were attributed to radiation exposure. A very small proportion (0.8%) of non-cancer related deaths were also associated with radiation. In addition, there are no inherited effects observed in the subsequent generation.

The decrease in average life expectancy is 2.6 years and 21 days respectively for those who received the highest and lowest doses. Since the majority of the population received low doses, the average loss of life expectancy is four months. The argument can be made that the full consequences will only be known when the last of the exposed generation have reached old age, but we can already ask the question, "does radiation exposure at this level, cause as many health problems as we thought?" I do not think so.

The only proven radiobiological effect has been an increase in thyroid cancer in those who were young at the time of the accident. The increase was rapid, and is still apparent today, although the level of thyroid cancer is back to what it was prior to the accident for those who were born from 1987 onwards – when the radioactive iodine disappeared from the environment.