5. What could be consequences of Nuclear or Radiological Accident?

The main adverse consequences of nuclear or radiological accidents are the following:

  • Consequences for health: deterministic and stochastic effects
  • Psychological consequences
  • Environmental consequences
  • Social and Economic consequences.

Consequences for health.

There are basically two types of physical health effect related to radiation exposure:

  • Deterministic effect

Deterministic effects are the result of acute exposure, which is exposure to a large, single dose of radiation, or a series of doses, over a short period of time. In most cases, large acute exposure to radiation can cause both immediate and delayed effects. For humans and other mammals, acute exposure, if large enough, can cause rapid development of acute radiation sickness (ARS), evidenced by gastrointestinal disorders, bacterial infections, haemorrhaging, anaemia and other issues. Immediate effects occur relatively soon (within days to weeks) after exposure to a high dose at a high dose rate. Essentially, the damage to the tissue from the radiation is so extensive that the body does not have time to regenerate new tissue, and so the effect becomes visible with many of the features of thermal burning, but it is usually much deeper and longer lasting. Deterministic effects often appear localised on the body depending on the radiation exposure pattern and the level of penetration of the radiation. Extremely high levels of acute radiation exposure can result in death within a few hours, days or weeks. Delayed biological effects can include cataracts, temporary sterility, cancer and genetic effects. 

  • Stochastic effect

A second type of health effect that can be caused by radiation is a so-called stochastic effect, such as cancer or hereditary effects in any future offspring. These types of effects are characterised by their late appearance after exposure (several years, possibly up to decades) and, critically, by the fact that their occurrence is not certain. The radiation may cause some damage to the cells of the body which is not visible but changes the functioning of those cells. These changes may manifest themselves at a much later date, as a cancer for example. Notice that we say ‘may’ manifest themselves, as there is no certainty of occurrence. For stochastic effects, we find that the chance or probability of an effect increases as the radiation dose increases. So at low doses there is a very low chance of cancer developing – at very high doses, there is a higher chance of cancer. However, it appears that there is no “safe” dose, or dose threshold below which cancers do not occur. Also it appears that it is the cumulative dose that influences the chance of cancer development and not the dose rate (at least not strongly). 
But nuclear and radiological accidents also have consequences other than direct physical effects on humans:

Psychological health effects will always accompany a nuclear or radiological accident whether or not it has resulted in persons receiving significant radiation exposure. Some protective actions taken during Chernobyl to reduce the radiological health risks, such as relocation and resettlement, did more harm than good in some cases because of the resulting psychological health effects brought on by stress and anxiety. 

Environmental consequences

When land, water or air becomes contaminated with radioactive material, there is concern about the environmental effects. Normally, radiation does not affect the ecosystem unless the levels are very high, although it can damage individual plants and animals. More problematic is the impact of countermeasures on the environment – countermeasures that were taken to protect humans. Moreover, when the environment becomes contaminated with radioactive material, even if the levels are very small, there is concern among the population continuing to live there. Finally environmental processes, such as wind movement and rivers can transport radioactive material from one place to another, which raises further concerns. 

Social and Economic consequences

Any countermeasures taken to address the health or environmental impact will have associated costs, whether the direct cost of the countermeasure itself or the lost economic output from formerly productive areas. 
Combining the health and environmental impact with the social consequences associated with the accident and any countermeasures employed, it is clear that the consequences are often more than just the direct health consequences alone.