No safe dose

At higher levels, cell death results. At extremely high doses, cells cannot be replaced quickly enough, and tissues fail to function; this can result in massive cell death, organ (particularly bone marrow and gut) damage and death to the individual.

Radiation effects are often categorised by when they appear.

The prompt effects include radiation sickness and radiation burns. High doses delivered to the whole body within short periods of time can produce effects such as blood component changes, fatigue, diarrhoea, nausea and death. These effects will develop within hours, days or weeks, depending on the size of the dose. The larger the dose, the sooner a given effect will occur.

When radiation effects are delayed, DNA abnormalities are passed on to subsequent generations of cells, where the abnormal coding can lead to tissue abnormalities, including cancers.

Cancer development is a multistage process, and is similar for radiation-associated cancers as for spontaneous cancers or those associated with exposure to other carcinogens.

Low dose radiation appears to act principally on the early stages of cancer initiation, whereas for higher doses, effects on later stages of cancer promotion and progression are also likely. Genetic disorders associated with deficiencies in the ability to repair DNA damage and in tumour-suppressor type genes (which normally suppress cancer development) increase the radiation cancer risk.

Mutational events at key points such as “proto-oncogene” or “suppressor gene” sites provide a credible mechanism for radiation-induced malignant (cancerous) transformation.

Such cancers will take many cell generations to develop, so it may be several decades before they are detected.

The delay enables polluters to avoid responsibility for the disease-promoting properties of radiation. This avoidance is amplified by the fact that leukemia and other cancers induced by radiation are indistinguishable from those that result from other causes.

Ionising radiation is also responsible for serious reproductive effects through prenatal exposure. Rapidly proliferating and differentiating tissues are most sensitive to radiation damage, so radiation exposure can produce developmental problems, particularly in the developing brain, when the fetus is exposed in the womb.

The developmental conditions most commonly associated with prenatal radiation exposure include low birth weight, microcephaly, mental retardation, and other neurological problems.

Long-term, inter-generational genetic effects are also possible if the damage to the DNA code occurs in a reproductive cell (egg or sperm) whereby the coding error may be passed on to offspring … resulting potentially in birth defects and cancers in the children.