Acute Radiation Syndrome

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As we are discussing stability of the power grid and possible consequences of an unstable power grid it may be worthwhile to review some of what is known about radiation sickness. The Armed Forces Radiobiology Research Institute and The Defense Nuclear Agency have written the "Medical Consequences of Nuclear War". Chapter two concerns Acute Radiation Syndrome (ARS) or radiation sickness.

In brief there is a spectrum from subclinical to lethal effects with a dose dependent relationship. While dose rate, radiation quality, medical condition, etc. effect this relationship usually any exposure over 3.5 Gray (Gy, 100 Rads or 1 joule/kg) is fatal. In animal studies, mortality rate vs Lethal Dose (LD) plots an S-shaped curve with, LD 95%/LD 5% equal to about 2. The fatal exposures may be divided into three syndromes based on increasing dose, hematopoetic, gastrointestinal and neurovascular. Each syndrome is characterized by four phases, prodromal, latent, manifest illness and possibly recovery. The prodromal phase of the hematopoetic syndrome consists of nauseau, vomiting, anorexia and diarrhea, this is followed by about three weeks of latency, "a brief reprieve from symptoms, when the patient may have appeared to recover", or may show "significant fatigue and weakness". "The clinical symptoms of manifest illness appear 21-30 days after exposure and may last up to two weeks. Severe hemorrhage from platlet loss and infection associated with pancytopenia from bone marrow suppresion are the lethal factors in the hematopoetic subsyndrome." The other syndromes are similar but more rapid in onset and course with effects manifest on the relatively more radiation resistent gastrointestinal and neurovascular cells respectively. Interventions such as fluids, antibiotics and platlet transfusions increased, in one animal study, the LD 50 by a factor of 1.5. Concomitant injuries such as burns or trauma lower the LD 50. While bone marrow transfusion or sterile environment might further improve survival such procedures are labor intensive. I have not had the opportunity to read up on KI, but I would doubt it has any effect except in the subclinical range of exposure as a protectent against sequestering radioactive idoine in the thyroid. wonder if NaI or iodized salt does the same. Hope this helps. Keep praying.

-- Anonymous, June 26, 1999

Answers

To clarify LD 50 is lethal dose 50% or the dose of radiation which was lethal in 50% of subjects, similarly LD 95 is the dose which was lethal in 95% of subjects

-- Anonymous, June 26, 1999

>usually any exposure over 3.5 Gray (Gy, 100 Rads or 1 joule/kg) is fatal

3.5 Gy = 350 Rads. The DoE handbook, Operational Health Physics Training (pub. Argonne National Lab, 1988) says that the prognosis for a dose of 100 rads (1 Gy) is "excellent" and rates the incidence of death at "none." In the range 200-600 rad, the prognosis is "good" and the incidence of death is "0%-80% (variable)" From 600-1000 rad (6-10 Gy), the prognosis is "guarded" and the incidence of death is "80-100%."

Something to note about dose rates in this range: those who died of acute radiation syndrome at Chernobyl were the reactor operators, and the firefighters who literally looked down into the glowing core (from what remained of the roof). There was also a doctor, a pediatrician IIRC, who also was physically present at the reactor -- he came in to help treat burns and other injuries.

In other words, to get acute radiation syndrome, mild or severe, you have to BE THERE. You could very well pick up what Paul refers to as "subclinical" doses -- anything under 100 rad -- which will NOT kill you but will variably increase your risk of cancer (variably, because in the range of 10-70 rad -- 0.1-0.7 Gray -- the risk of leukemia increases, but the risk of breast cancer actually decreases). If all the nuke plants in the USA blow up like Chernobyl, you are not going to be at risk for ACUTE radiation syndrome unless you personally go into the remains of a confinement building and try to watch the core melt.

Radiation behaves like light -- its intensity drops off as the SQUARE of the distance from the source. If the radiation field is 10,000 R (100 Gy, nearly instantly fatal) at 50 feet from the core, it will be 2500 R at 100 feet:

feet from source dose in Rads dose in Grays

50 10,000 100 100 2500 25 200 625 6.25 400 156.25 1.56 501 99.60 1.00 800 39.06 .39 1600 9.77 .10 3200 2.44 .02 5280 (one mile) 0.90 .01 6400 0.61

That's distance from the *core*, not from the reactor building, not from the power plant site. And that is assuming *no* shielding left by remaining walls of concrete, or anything. Note that at just over 500 feet from such a core, you'd already be down into the "subclinical" range (the Occu. HP Training handbook mentioned above lists 0% risk of death at this range -- cancer risk being not included when talking about ACUTE radiation syndrome. But don't *stay* there and accumulate a dose!!)

I don't wish to downplay the seriousness of a nuke plant meltdown. Worry about gaseous releases, worry about fallout getting on you or into your food. Worry very much about that lump you suddenly find in a special body part a few years later.

But as for dying directly of radiation (i.e., acutely), you have to be at ground zero. It is *very hard* to encounter *that* much radiation. 350 Rad (or 3.5 Gray) is a *lot* of energy -- and extremely energetic things are also extremely compact. Don't go sightseeing at the melting core, and you will avoid acute radiation syndrome.

Cancer is something else: >I have not had the opportunity to read up on KI, but I would doubt >it has any effect except in the subclinical range of exposure as a >protectent against sequestering radioactive idoine in the thyroid. >wonder if NaI or iodized salt does the same.

Paul is right, KI (potassium iodide) is for subclinical exposures. In fact, it is specifically to prevent *thyroid* cancer. KI will do NOTHING to protect any of your other organs; do NOT think that KI is some kind of magical anti-radiation umbrella!

One of the most volatile releases from any kind of nuclear explosion is iodine gas -- it travels fast & far, and unlike xenon or argon, iodine will react chemically very readily, especially with your thyroid which is *designed* to pick up iodine. When that iodine is radioactive, your risk of thyroid cancer leaps up. HOWEVER -- if your thyroid is already full of iodine, it won't pick up new stuff (like what just blew out of your friendly neighborhood nuke, or the latest bomb from China). That's why you take potassium iodide -- to give yourself an iodine-loaded thyroid. What happens to the radioactive iodine you inhaled, then? It's breathed back out; if you swallow it, it's flushed from the body in a few hours and is gone (unlike, say, strontium-90, which is one of the bone-seekers.)

The catch it, you can't live on KI in anticipation of a nuclear event. It's not recommended for any more than 10 days at most. But you can certainly load your diet with iodine-rich foods. Yes, iodized salt IS effective (don't know anything about the edibility of NaI), as is seafood, and seaweeds. The incidence of thyroid cancer after the Japanese bombings was nothing over normal; around Chernobyl, however, there has been a significant increase. This is because the Japanese diet is typically iodine-rich, and that in Ukraine is not.

Oh, if you live near a reactor, and one blows up, and you find chunks of strange metallic stuff crashing through your roof -- leave it alone and LEAVE. A chunk carried in your pocket could give you a nasty radiation burn (which seem very reluctant to heal); a chunk left in a kitchen drawer for weeks could give the family hematopoeic syndrome, without being dangerous enough to kill outright. There are reports of incidents like these, usually involving broken irradiators of the sort used for checking steel welds. The cumulative dose is what gets you.



-- Anonymous, June 28, 1999


Hmm, let's try that table again --

feet from source dose in rads dose in Grays 50 10,000 100 100 2500 25 200 625 6.25 400 156.25 1.56 501 99.60 1.0 800 39.06 .39 1600 9.77 .1 3200 2.44 .02 5280 0.89 .01

Hope this one works.

-- Anonymous, June 28, 1999


Not sure how to account for the differing radiation exposure dangers you bring up. I suspect that the numbers you are using assume standard Western medical care available to the patient. As noted, relatively simple medical interventions increase survivability by a factor of approxiately 1.5 which would put the two sets of numbers in the same ball park. I also read the memoirs of the California pediatrician (hematologist?) who treated many patients from Chernobyl. I can't recall the name of the book but agree that extraordinary exposures occured for ARS to set in and this was the exception rather than the rule for most exposures in that tragedy. Chernobyl, however, along with its devestating long term consequences, takes the potential for ARS from a nuclear accident out of the realm of the theoretical. It is heartening then to hear the detailed and well thought out discussions of competent specialists on this board regarding measures to prevent safety lapses from occuring secondary to Y2K.

I was not aware of the danger from radioactive iodine gas. Some collateral information, the thyroid gland, prompted by Thyroid Stimulating Hormone, released from the pituitary gland manufactures its two hormones, Triodothyronine (T3) and Thyroxine (T4). As their name implies these two molecules incorporate 3 or 4 molecules of exogenous iodide (first oxidized to iodine in the thyrdoid) into their structure. The levels of these circulating hormones then regulate a wide variety of metabolic processes as anyone with hypo or hyper thyroidism can attest. Interestingly, radioactive iodine, I131, is a common treatment for some forms of thyroid cancer. These patients stay in hospital approximately two days and are a blessing to over worked interns as no one can enter their rooms on rounds.

God Bless,

-- Anonymous, June 29, 1999


Thanks for catching my error on NaI not equaling iodized salt

-- Anonymous, June 29, 1999


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