Hormesis U.: A Review

Before leaving dear old Hormesis U., here is a short review to see if you've got a handle on the curriculum. You should know...

• Elements are identified by the number of protons in the nucleus (atomic number).
• Isotopes of elements have different numbers of neutrons (n + p = atomic weight).
• Atoms of some isotopes are stable, while others are radioactive and, over time, will disintegrate (decay) into other elements of a lower atomic number.
• Alpha and beta particles have a short range (a few inches and a few feet respectively).
• Gamma rays and X-rays can penetrate several inches of steel or feet of concrete.
• The half-life of a radioactive isotope is the time it takes half of the original amount to decay; after thirty half-lives the original amount is considered to be gone.
• The longer the half-life, the lower the activity of an isotope.
• A curie is 37 billion becquerels.
• A pCi is a picocurie and is equal to one-trillionth (10^-12) of a curie.
• Absorbed doses of radiation are measured in rads or grays; 100 rads equal 1 gray.
• Biological doses are measured in rems or sieverts; 100 rems equal 1 sievert.
• The absorbed dose and the biological dose are the same for gamma and X-rays. 
• A fatal acute dose is about 4 sieverts or 400 rems (50% fatalities in thirty days) when received in a relatively short time (a few days or less).
• Radiation sickness occurs at about 1 sievert or 100 rems (50% of those exposed over a short time). 
• Doses below 1 sievert or 100 rems (100,000 millirems) have no immediate biologic effects but are generally thought to increase the risk of cancer in the future.

Thanks for your attendance at Hormesis U. No doubt you'll find the rest of the information on radiation hormesis much more understandable now than when you were a mere freshman. Oh, and be sure to send in your contribution to the Alumni Fund.

Acute Radiation Syndrome

Table 8 – Acute Radiation Syndrome
Subclinical Range 0 – 100 rads		Therapeutic Range 100 – 500 rads			Lethal Range 500+ rads
		100 – 200	200 – 300	300 – 500	500 – 2000	2000+
Appropriate Action	None	Clinical surveillance	Therapy effective	Therapy promising	Therapy palliative (comfort patient only)
Incidence of Vomiting	None	100 rads: 5% 200 rads: 50%	75%	75%	100%	100%
Delay Time	n/a	3 hours	2 hours	1 hour	3 min.	3 min.
Main Organs Affected	None	Blood Forming Tissue			Gastro-intestinal Tract	Central Nervous System
Characteristic Signs	None	White Blood Cell Decrease	Fatigue, infection, erythema, sterilization, loss of hair above 300 rads, hemorrhage		Diarrhea, fever, electrolyte imbalance, bleeding	Convulsion, coma, loss of muscle control, lethargy, tremors
Critical Period	n/a	n/a	4 – 6 weeks		5 – 14 days	1 – 48 hours
Post-exposure Therapy	Assure of Safety	Blood analysis; assure of safety	Blood transfusion; anti-biotics	Possible bone marrow transplant	Maintain electrolyte balance	Sedatives
Outlook	Excellent	Excellent	Good	Guarded	Hopeless	Hopeless
Convalescent Period	None	Several weeks	1 – 2 months	Long	n/a	n/a
Death Rate	None	None	0% - 40%	40% - 100%	90% - 100%	100%
Death Within	n/a	n/a	2 – 4 weeks		2 weeks	2 days
Cause of Death	n/a	n/a	Hemorrhage, infection		Dehydration	Respiratory failure; heart attack

Table 8 Source: "Terrorism With Ionizing Radiation General Guidance: Pocket Guide," produced by the Employee Education System for the Office of Public Health and Environmental Hazards, Department of Veterans Affairs.

Some may think that certain data are emphasized in this and other chapters in an attempt to minimize the dangers of exposure to radiation. This is not at all true. I am trying to put the dangers in perspective and eliminate the Pavlovian negative response to even the very mention of the subject. Table 8 shows the accepted syndrome from short-term exposures. Please note that this table is in rems (not millirems) and can be mentally converted to centisieverts (cSvs) of the same numerical value. Radiation can obviously be very dangerous. But so can an unreasonable fear of radiation.