Chernobyl effect of radiation on leaf mutation. Recognize any?
At the photo below burns from radiation of a fireman at Chernobyl.
At the photo below burns from radiation of a fireman at Chernobyl.
Is any amount of radiation safe?There is no firm basis for setting a "safe" level of exposure above background for stochastic effects. Many sources emit radiation that is well below natural background levels. This makes it extremely difficult to isolate its stochastic effects. In setting limits, EPA makes the conservative (cautious) assumption that any increase in radiation exposure is accompanied by an increased risk of stochastic effects.
Some scientists assert that low levels of radiation are beneficial to health (this idea is known as hormesis).
However, there do appear to be threshold exposures for the various non-stochastic effects. (Please note that the acute affects in the following table are cumulative. For example, a dose that produces damage to bone marrow will have produced changes in blood chemistry and be accompanied by nausea.)
Exposure
(rem) Health Effect Time to Onset(without treatment)
5-10 changes in blood chemistry
50 nauseahours
55 fatigue
70 vomiting
75 hair loss2-3 weeks
90 diarrhea
100 hemorrhage
400 possible deathwithin 2 months
1,000 destruction of intestinal lining internal bleeding and death1-2 weeks
2,000 damage to central nervous system loss of consciousness;minutes and deathhours to days
rem [rem] roentgen equivalent man; the amount of any ionizing radiation which has the same biological effect as 1 rad of x-rays; 1 rem = 1 rad RBE (relative biological effectiveness). 1 shievert = 100rem
Radiation Dose Equivalent
Different radiations do different amounts of biological damage
Dose Equivalent = Dose X QF
QF = Quality factor
Betas, Gamma: QF = 1; Alpha: QF = 20
Units
Rem (1 mrem = 0.001 rem)
Sievert (Sv) [1 Sv = 100 rem)]
Dose = Energy absorbed per mass
Units:
Rad
Gray (Gy) [1 Gy = 100 rad)
A rad is defined as a dose of 100 ergs of energy per gram of the given material.
The SI unit for absorbed dose is the gray (Gy), which is defined as a dose of one joule per kilogram. Since one joule equals 107ergs, and since one kilogram equals 1000 grams, 1 Gray equals 100 rads.
Some scientists assert that low levels of radiation are beneficial to health (this idea is known as hormesis).
However, there do appear to be threshold exposures for the various non-stochastic effects. (Please note that the acute affects in the following table are cumulative. For example, a dose that produces damage to bone marrow will have produced changes in blood chemistry and be accompanied by nausea.)
Exposure
(rem) Health Effect Time to Onset(without treatment)
5-10 changes in blood chemistry
50 nauseahours
55 fatigue
70 vomiting
75 hair loss2-3 weeks
90 diarrhea
100 hemorrhage
400 possible deathwithin 2 months
1,000 destruction of intestinal lining internal bleeding and death1-2 weeks
2,000 damage to central nervous system loss of consciousness;minutes and deathhours to days
rem [rem] roentgen equivalent man; the amount of any ionizing radiation which has the same biological effect as 1 rad of x-rays; 1 rem = 1 rad RBE (relative biological effectiveness). 1 shievert = 100rem
Radiation Dose Equivalent
Different radiations do different amounts of biological damage
Dose Equivalent = Dose X QF
QF = Quality factor
Betas, Gamma: QF = 1; Alpha: QF = 20
Units
Rem (1 mrem = 0.001 rem)
Sievert (Sv) [1 Sv = 100 rem)]
Dose = Energy absorbed per mass
Units:
Rad
Gray (Gy) [1 Gy = 100 rad)
A rad is defined as a dose of 100 ergs of energy per gram of the given material.
The SI unit for absorbed dose is the gray (Gy), which is defined as a dose of one joule per kilogram. Since one joule equals 107ergs, and since one kilogram equals 1000 grams, 1 Gray equals 100 rads.