Effects and Doses: How Can We Protect Ourselves from Radioactivity?
Editorial review 2026
Fear of radiation dates back to the beginning of the 20th century, when the first radiologists became its victims. At the time, radioactivity generated great enthusiasm, but gradually it became apparent that, at sufficiently high doses, these radiations could be harmful. Much later, in 1945, the use of atomic weapons in Hiroshima and Nagasaki demonstrated the deadly dangers of nuclear explosions. More recently, the Chernobyl accident in 1986 and the Fukushima accident in 2011 left a lasting impression on public opinion.
The mysterious and insidious nature often attributed to radiation contributes to this fear. Radiation is not painful. Leukemias and cancers that may be triggered by exposure to radiation can take years to appear. Except in the case of very high doses, it is not possible to attribute the appearance of a cancer to a past irradiation event.
Fears are often amplified by a profound lack of knowledge about the effects of radiation. The subject is not commonly taught in schools. The consequences of this lack of understanding can be dramatic. After the Fukushima accident, anxiety about contamination, fear of cancer, and the trauma associated with evacuations caused a number of deaths far greater than those expected from the effects of radiation itself. « Fukushima: Is Fear of Radiation the Real Killer? » was the title of an interesting BBC report on the subject.
The vast majority of exposures fall within the range of low doses. In this domain, the effects are small, but many uncertainties remain. The main uncertainty concerns the relationship between the received dose and the associated risk. Is there a threshold below which radioactivity has no effect? The effects depend on how the dose is distributed over time, the organs exposed, the individual concerned, their age, and probably their genetic background.
Doses “for living organisms” are defined to represent the sensitivity of the entire human body (effective dose) or of a particular organ or tissue (absorbed dose, equivalent dose).
Radiation protection is the science of studying these risks and protecting against them. The precautionary principle assumes that the risk is never zero (an assumption that is probably pessimistic). Regulations are designed to reduce exposures resulting from human activities to levels that are as low as reasonably achievable.
Internal and External Exposure
Exposure to radiation through ingestion or inhalation of radioactive atoms, or through exposure to a radiation source
© CEA.
SUMMARY OF THE TOPICS COVERED
– Effects of Radiation on Living Organisms: Biological effects, relationships between exposure and effects, effects of low doses, radiological toxicity.
– Radiation Doses: Activity doses and becquerels, energy deposition and grays. Effective and equivalent doses, millisieverts.
– Modes of Exposure: Internal, external, and contact exposure.
– Principles and Techniques of Radiation Protection: Regulatory bodies and oversight organizations, legal limits.
– Dosimetry: Dose measurement and exposure monitoring.