One of the more common effects of ionising radia­tions, which were apparent from the wartime exposures in Japan and also from the effects of radiotherapy, is a reddening of the skin (erythema) often referred to as ‘radiation burns’. This is often associated with hair loss. Erythema degenerates to desquamation (skin loss) which is termed moist or dry according to the degree of severity and can be directly related to cell ‘death’ (and impaired blood flow). Erythema first ap­pears at skin doses of about 4 Sv, as previously mentioned.

Of course, in real cases of massive exposures, a combination of the above syndromes would appear depending on the dose received. Rapid death from CNS damage would only occur after the most massive doses.

Treatment of acute exposures

There are several types of treatment that increase the chances of survival if the acute dose is not too high. Death from CNS damage appears inevitable after very high doses but the other syndromes can be treated. Infection and fluid imbalance can be treated with broad spectrum antibiotics and fluid replacement.

Haemorrhage can be treated with blood transfu­sions and, with much greater difficulty, by bone mar­row transplants. Even in tissues which have been severely damaged, normal recovery is possible. A few viable cells may be left in the damaged tissue and, provided the individual survives, these cells multiply to repopulate the damaged tissue.

Some permanent damage may be produced which is not life threatening. The skin may suffer permanent loss of hair or sweat glands or, after high doses and resultant ulceration, a permanent scar may be formed. Cataracts do not exhibit repair and are a late effect of acute exposures. Other effects such as cancer (sto­chastic effects) may only become apparent after many years.

Acute exposures may be continuous or intermittent. Both cell loss and repopulation take place at the same time. If repair lags behind damage then the cell po­pulation of sensitive tissues gradually declines. If, however, repair keeps up with damage the tissue may appear normal. Continual tissue damage may give rise to late effects such as cancer.

If an individual receives a dose of radiation over only part of the body the biological response will be largely restricted to that part and the prognosis will be better than for a whole-body irradiation. The effect on the individual will depend very much on whether or not the most important tissues were included in the radiation field. Thus І0 Sv to the abdomen may produce death by GI syndrome but the same dose confined to the feet or hands will produce only lo­calised damage.

Radiation which does not penetrate deeply may pro­duce a similarly muted response. If radioactive ma­terial finds its way into the body via ingestion “or inhalation it may also provide partial-body irradiation if it is concentrated in specific organs, e. g., iodine in the thyroid, strontium and other materials in the bone.