Haematopoietic Syndrome
Occurs in lower amounts of exposure. It is the consequence of exposure to the medullary function, which halts the production of the blood cells and leads to pancytopenia. Lymphocytopenia is first produced after a dose as weak as .3 Gy. With doses of 4 or 5 Gy, granlocytopenia occurs, then thrombocytopenia, then after about 10 days, anaemia. After a week of aplasia, the regenerative phase appears to stop, involving all the cell lineages.
Gastro-Intestinal Syndrome
Occurs in doses of 6 or 7 Gy, and is the result of damage to the intestinal mucosa and the lesions on the small vessels the sub-mucosa. It has a short latency period, from several days, to one week. It starts with a large loss of liquid, which results from vomiting, diarrhea, and hemorrhaging. It is very serious, and almost always accompanied by irreversible medullary damage, and leads to death in 10 to 14 days.
Nervous Syndrome
Occurs from very high doses of exposures, which range between 20 and 30 Gy. The latency period is very short, from a few hours to three days. It is characterized by a continual deterioration of consciousness, by convulsions, terminating in a coma and death in a period from a few hours to a week after the exposure.
Skin Injuries
Pulmonary Syndrome
Acute pneumopathies are frequently observed after medical therapy for bone-marrow transplant.
Haematopoietic Tissues
The slowness with which stem cells regenerate explains the persistence, over many years, after a large exposure to radiation, of bleeding, with a lowered resistance to damage.
Gastro-Intestinal Tract
Occurs in one or two years after a radio-exposure, the abdominal pains, episodes of diarrhea and constipation, and difficulties in digesting fats, can be explained by injuries to the intestinal all, fibrated and oedemated, the shrinking of the intestinal lumen, and adherences. Theses are observed in 30% of all people after and exposure of 50 to 60 Gy.
Nervous System
A few weeks after an exposure of 50 Gy, produces acute myelopathies (reversible, in the month following the exposure), paraplegiae (rare, but irreversible, in the following months or years), and cerebral lesions (in about 5% of cases, in the following years).
Skin
These appear after 6 months to two years after exposure. Radiodermatitis occurs, and is characterized by cutaneous fragility and chronic ulcerations.
Pulmonary
After a year or two, the progressive acquisition of delayed pulmonary fibrosis, which is irreversible in most cases.
Ocular
Occurs after exposure to the eyes for a threshold of 2 Gy. The lens is the most radiosensitive part, and opacification occurs, and progresses rapidly with the increase of the absorbed dose. The are permanent for absorbed doses above 12 Gy. For anything higher than that, acute conjunctivitis occurs, which is less serious.
Hepatic
Occurs when the liver is exposed. After a long latency period (due to the slowness of hepatic cell turnover) a progressive alteration of its functions, owing to injuries of the centrolobulary veins. It leads to hepatitis, which can be fatal when exposure exceeds 35 Gy.
Thyroid
Occurs when the thyroid is exposed, and brings about a slow, progressive atrophy, from several years to several dozens of years after the exposure.
Radio-exposure has a harmful effect on the development of the fetus. The tissues that from the embryo have only a limited number of cells, so that the death of only a few of these can bring about irreparable damage.
Pre-Implantation Stage
This stage lasts from fecundation to he fifteenth day. The damaged cells, when in small numbers, are replaced by intact cells normally. Therefore, during this stage, exposure to radiation will have no effect, or if the dose is high, will prevent implantation, and the egg will be rejected.
Large Organogenesis
This stage lasts from the fifteenth to the fiftieth day, and by this time, a certain amount of cellular differentiation has emerged. Injured cells can no longer be replaced through the intact cells. Exposure will bring about anomalies of development, depending on the stage of morphogenesis. Radiosensitivity is at its maximum between the third and fourth week of gestation, and then decrease until the tenth week. Exposure even at low doses (.1 Gy), in this period, can cause congenital malformations.
A child who is appears to be healthy at birth is not necessarily free from damage. It can reveal pathological manifestations due t the retarded effects of exposure in utero.
List of Different Kinds of Defects