Anatoly Andreyevich Sitnikov was ordered to look over the roof's edge to see what the fire looked like down in the core of reactor 4. Tolya (Anatoly's nickname) reportedly saw the blue glow of the Cherenkov radiation. Tolya called others over to see it, including Vladimir. Vladimir's brown eyes were blue when he returned to the firetruck.
There are many situations where radiation is intriguingly beautiful. The bright sunshine of a spring morning that sends a radiometer's vanes aspin or the infrared glow emanating from the fading embers of a bonfire for example. I have seen Cherenkov radiation in a reactor pool back in the early 1980s (just a few years before Tolya saw it), but that was through several meters of water. There are few living people who have witnessed Cherenkov radiation in open air. Tolya would die on the 30th of May 1986.
The radiation dose the firefighters received on the roof was estimated to be around 300 sieverts per hour. Most of the men had visibly reddened skin when they retreated from the roof. They retreated because they were becoming incapable of manipulating the hoses. They were vomiting. On the ride back from the plant the headaches became unbearable. Several men could not stand. They leaked diarrhea uncontrollably. There was un-clotted blood in the fluids oozing from the men's bodies.
Their skin itched all over, but it itched worse where it was exposed or covered only lightly. Unlike a typical sunburn, where the skin is cooked by ultraviolet radiation from the outside, this burn was caused by highly penetrating gamma radiation; there was almost as much damage under the top layer of skin as on the surface. When the blistering began it would boil off layers of flesh and hair. Autopsy would reveal blisters on many of the internal organs of the firefighters. One man had a heavily blistered heart. The blisters would evolve into ulcers.
Much of what happened on the roof is inferred from the rambling partial statements that were compiled from these men whose brains had also blistered. Speech was slurred and difficult to understand, even when what was said was believed to be a response to a question. Movement was difficult, and when it did occur was jerky and uncontrolled. Their eyes moved about in their sockets in uncontrolled tremors.
Some of the men who did not go up on the roof avoided being haunting by the image of Cherenkov radiation, but there was other cool stuff for them to see. All over the ground were these funny gray-black bricks. Some of the men picked up a couple; they were light. The funny black brick fragments were the graphite blocks from the core of reactor 4. The graphite debris was giving off doses in the 100-200 sievert per hour range. The guys who were playing with the core fragments received a much lower dose than those on the roof.
The grounds crew began vomiting shortly after the firefighters who went up on the roof. Their uncontrollable diarrhea took a little longer to express itself also; as did the headache. The vomiting tapered off after they left the site, so did the diarrhea. Though they had lost much of their electrolytes intravenous replacement appeared to help. It was their headache transitioning to body racking fever that appeared to send them into semiconscious shock. Many would never fully regain consciousness.
There are very few places where one can receive a radiation at dose rates over 100 sievers per hour. With doses that high the organs of the body race to be the first to mortally fail. There is no time for the insidious effects of radiation to become manifest. It is like the body was hit by a bus, but the bus passed right through the body, and it takes the body a couple of days to figure out that is is dead.
At lover acute doses of radiation (like between 1 and 100 sieverts) the symptoms can be much less severe. Though there is often intense vomiting and diarrhea, there might also only be a seriously upset stomach. The incapacitating cognitive disruption might only be severe dizziness. With the headache, a little blood in the liquid stool, and the elevated heart-rate; the initial symptoms could be dismissed as “stomach flu” by most folksy medical practitioners. A doctor who did not measure the plummeting white-cell count and change in urine chemistry might miss the opportunity to provide the medical care needed to allow these lesser exposed individuals to survive long enough to experience the secondary symptoms of acute radiation exposure.
If the body makes it through the “hit by bus” phase it is left highly damaged. There are dead and dying cells peppered throughout the body. The damage is concentrated nearer the outer margin of the body. Lymphatic fluid pours into the cell spaces to dilute the toxic leakings of dying cells. The body swells, and puts enhanced pressure on the kidneys. The heart races to keep up. When the fluid homeostasis is upset too far the body either continues to swell to the point where clothing does not fit, or starts to shrivel.
The retreating of the fluid tide reveals a limp body covered in angry purple blotches. Sub-dermal capillaries and veins riddled with micro-punctures leak blood into surrounding tissue. The bodies clotting system is overwhelmed, and stops working effectively. The external hemorrhaging often starts with nosebleeds.
Every hair on the body falls out. The skin may take on a blotchy pattern of permanent pigmentation. The boiling blisters and ulcerations may take weeks to fully scar over.
The injured but living exposure victims have damaged blood in their veins. Their circulating immune system has crashed, and is almost completely incompetent in fighting infections. They lie in bed perched on a knife's edge of survival. Tubes and luck are all that anchor them to life. With enough concentrated competent medical care nearly half of these less-exposed people should live long enough to experience the tertiary effects of radiation exposure.
Although I have supplied over a thousand words to the description of acute radiation exposure it is not acute radiation exposure that renders radioactive contamination such a pernicious threat. What I have ham-handedly dubbed the “tertiary” effects of radiation exposure are more properly described as the level of exposure where radiation leads to other diseases. At a dose of less than 1 sievert the exposed individual is more likely to be hospitalized because of a disease caused by radiation exposure than symptoms primarily caused by the radiation exposure itself. This “tertiary” phase reads almost like a list of every possible cancer, with notations indicating that some are more likely than others.
Into this phase we also see the largest number of potentially exposed individuals. In addition to the irradiated people there are all those who have come in contact with radioactive contamination. These are people who inhaled the wrong particle of dust, or who ingested the wrong contaminated tomato, or who took the wrong shower. These are the people who lived their lives unaware of some cloud of radioactivity passing over their home.
Dosage and exposure take on new contextual meanings. Ingested or inhaled radioactivity is not moderated by the small but effective shielding which prevents alpha rays from causing significant damage. With a Q factor as much as twenty times that used in the calculation of external exposures the exposure rates for internal exposure are orders of magnitude greater than what an external exposure would be for the same amount of radioactive material.
Then there are the biological concentration factors.
Most radioactive material appears like useless, even toxic, material to the body. This material passes right through the digestive system. We can calculate the exposure simply by multiplying the number of hours it takes the radioactive material to pass through the body by the amount of radiation it gives off per hour.
There are some places where radiation can get lodged on the body. Radioactive material can look like ash. Like ash it can get stuck under the fingernails, in the hair, between the teeth, or in the lungs. If the radioactive particle is not removed it will continue to irradiate the surrounding tissue until it completely decays. Complete decay of even very tiny radioactive particles can take longer than the lifespan of a healthy individual. A person with radioactive ash coating their lungs does not usually remain a healthy individual for long.
Some radioactive material is not seen as toxic, or may be caught in the same biological machinery used to harvest nutrients from the environment. Radioactive calcium and phosphorus can be concentrated in the bones. Some heavy metals can contaminate the iron-uptake mechanisms, and be found in the bone marrow and liver. Bone cancers and leukemia can result.
In the initial contamination the types and concentration of radioisotopes can give significant information regarding the areas of potential biological concentration. One of the highly radioactive byproducts of primary fission is iodine-131. In the first ten days of the Chernobyl indecent this was a major component of the radioactive plume. Since the Soviets were too busy minimizing the impact of the radioactive fallout from the disaster they were not able to inform people about the extent and composition of the radioactive material. In people, small children especially, there is a very active mechanism for transporting ingested iodine into the thyroid. Thousands of people died of thyroid cancer after the Chernobyl indecent.
It is important to point out that some uptake mechanisms can be overwhelmed. People taking huge doses of non-radioactive iodine can block the uptake of iodine-131. If all the pathways for uptake of micro-nutrients could safely be overwhelmed it might be possible to take a pill that minimized the internal dosage caused by the initial contamination event. This is, however, not possible. There are only a few, like iodine and calcium, that can be safely overwhelmed. Even attempting to overwhelm some systems, like the iron uptake system, can result in extreme toxicity and death.
The rest of the environment does not block the uptake of radiation. Many radioisotopes become sequestered in the tissues of other living systems. When they are internalized into something like plant tissue the radioactivity no longer appears at all like a toxic material. There is a second (and potentially third fourth, fifth...) wave of potential exposures from contaminated foodstuff. The contamination from food can be actively incorporated into a person's tissue where it can reside till the radioactivity decays.
A radioactive carbon-14 atom can become part of a person's DNA just like any other atom of carbon. When it decays it releases a beta ray. The beta ray shoots off breaking up other parts of the DNA. Where the carbon-14 atom used to be there is now a nitrogen-14 atom (or more likely a hole) which causes disruption of the DNA. What has occurred is a mutation. If the mutation is in the wrong gene it may cause a cancer. If it is in the wrong cell it can cause a congenitally-transmissible mutant trait. Most likely the mutaion is repaired.
I chose carbon-14 as an example because, with a half-life of 5,700 years, it will have enough time to become widely distributed in the food chain. Carbon-14 from other nuclear events is found in most food on the planet. Our bodies constantly deal with the effects of carbon-14 decay. Increasing the amount of carbon-14 in the body increases the rate of carbon-14 decay-caused disease in the body. It is impossible to attribute a particular disease to a particular isotope that came from a particular source. All that can be noted is an an overall increase in unattributable diseases.
How much radioactive material becomes inhaled, ingested, or incorporated contamination depends on what and how much radioactive material is released. Where and how potentially exposed individuals can respond depends on what the component isotopes of that radioactive material is. It is not a exaggeration to state that rapid wide-scale dissemination of specific information about the number of curies released, and detailed breakdown of the isotopes contributing to that bulk measure of radiation, can save lives for years after a nuclear disaster. I have yet to see that information coming out of the ongoing Dai-ichi incident.