Potential biological effects depend on how much and how fast a radiation dose is received. Radiation doses can be grouped into two categories, acute and chronic dose.
4.2.1 Acute dose
An acute radiation dose is defined as a large dose (10 rad or greater, to the whole body) delivered during a short period of time (on the order of a few days at the most). If large enough, it may result in effects which are observable within a period of hours to weeks.
Acute doses can cause a pattern of clearly identifiable symptoms (syndromes). These conditions are referred to in general as Acute Radiation Syndrome. Radiation sickness symptoms are apparent following acute doses >100 rad. Acute whole body doses of >450 rad may result in a statistical expectation that 50% of the population exposed will die within 60 days without medical attention.
As in most illnesses, the specific symptoms, the therapy that a doctor might prescribe, and the prospects for recovery vary from one person to another and are generally dependent on the age and general health of the individual.
Blood-forming organ (Bone marrow) syndrome (>100 rad) is characterized by damage to cells that divide at the most rapid pace (such as bone marrow, the spleen and lymphatic tissue). Symptoms include internal bleeding, fatigue, bacterial infections, and fever.
Gastrointestinal tract syndrome (>1000 rad) is characterized by damage to cells that divide less rapidly (such as the linings of the stomach and intestines). Symptoms include nausea, vomiting, diarrhea, dehydration, electrolytic imbalance, loss of digestion ability, bleeding ulcers, and the symptoms of blood-forming organ syndrome.
Central nervous system syndrome (>5000 rad) is characterized by damage to cells that do not reproduce such as nerve cells. Symptoms include loss of coordination, confusion, coma, convulsions, shock, and the symptoms of the blood forming organ and gastrointestinal tract syndromes. Scientists now have evidence that death under these conditions is not caused by actual radiation damage to the nervous system, but rather from complications caused by internal bleeding, and fluid and pressure build-up on the brain
Other effects from an acute dose include:
- 200 to 300 rad to the skin can result in the reddening of the skin (erythema), similar to a mild sunburn and may result in hair loss due to damage to hair follicles.
- 125 to 200 rad to the ovaries can result in prolonged or permanent suppression of menstruation in about fifty percent (50%) of women.
- 600 rad to the ovaries or testicles can result in permanent sterilization.
- 50 rad to the thyroid gland can result in benign (non cancerous) tumors.
As a group, the effects caused by acute doses are called deterministic. Broadly speaking, this means that severity of the effect is determined by the amount of dose received. Deterministic effects usually have some threshold level - below which, the effect will probably not occur, but above which the effect is expected. When the dose is above the threshold, the severity of the effect increases as the dose increases.
Another perspective on the effects of radiation is from Bruce Beach and is excerpted from his page Radiation and Detectors:
The following is interpreted from attached "official" and other "expert" sources. These sources often provide a 'range' for effects, but I have simplified this to a single number to make the table easier to memorize - and you should memorize it. You can then 'extrapolate' for your self the relative severity of effects of a number between a higher and lower number.
- 600R -- means 100% chance of fatality is expected.
Some much earlier - but last within two weeks.
- 400R -- means 50% will die within one to three weeks.
Those that don't die are going to be VERY sick and wish that they would. After a few days some may feel better but will often then turn, sicken and die in a few weeks.
- 200R -- lots of sickness, and radiation sickness is pretty terrible.
(Think of cancer treatment without pain killers.) Lots of vomiting - hair falling out - and all that. Not nice
- 50R -- No fatalities at this level.
There is a difference of opinion, as to whether the sickness at this level is physical. Some thin that at this level the sickness is psychosomatic. Whatever its cause it is very general.
- 30R -- Most everyone will feel some sickness.
- maybe just "punky" and it may be "just" psychosomatic but it certainly would not be beneficial for children and pregnant mothers. Even this level is a thousand times higher than the maximum general population exposure permitted under peacetime standards.
In the final analysis, fatality is probabilistic, somewhat like car accident fatalities. There have been cases of people getting very much higher radiation and surviving, and others with much lower who have not. Cause and effect become clouded when working with probability issues. There are many impinging factors, such as age, health, medical care, or lack of medical care.
