Radiation dosage is measured in sieverts and millisieverts, replacing the old unit called the rem. Dosage is assessed in terms of relative damage to different parts of the human body, some being more sensitive to damage than others. Acceptable dose limits are recommended by the International Commission on Radiological Protection (ICRP) and should be observed by all countries involved, though there is no guarantee of that. The following is taken from the World Nuclear Association website (www.world-nuclear.org), which is believed to be compatible with ICRP advice.
100 millisievert/year...lowest level at which any increase in cancer is evident. Above this exposure probability of cancer increases with dose.
1000 millisievert cumulative...would probably cause a fatal cancer many years later in 5 percent of persons exposed.
1000 millisievert single dose...would cause temporary sickness such as nausea and decreased white cell count, but not death (but see above for long term effect)
5000 millisievert single dose... would cause death within one month of half those receiving it
10,000 millisievert single dose... fatal in a few weeks.
Against the above which are all large doses, the average dose to US nuclear industry employees is quoted as 2.4 millisievert/year. so for a 40 year working life this amounts to 96 millisieverts cumulative.
The current limit for nuclear industry employees is 20 millisieverts/year. (Not clear if this is in the US or world-wide, but it is presumably ICRP recommended).
About 500 to 1000 RADS is enough to kill a human. it takes between 1-5 days for the radiation to kill all the cells in a human body. About 50,00 to 100,000 RADS causes death within minutes or hours. We're talking end-of-raiders-of-the-lost-ark radiation levels!
An equivalent radiation dosage of two to six sieverts will result in a fatality rate of up to 50%, even with medical care. Over eight sieverts will result in a near 100% fatality rate within a week. Thirty sieverts will kill any human within two days.
Lethal radiation dose varies, depending on physical condition and care given after receipt of dose. There is a grey area (no pun intended) between 6 and 8 Grays (a unit of ionizing radiation), equivalent to about 600 to 800 rads (in the old nomenclature), where 95% to 100% of those untreated will die, and 50% to 100% of those treated will die. Above 8 Grays, 800 rads, 100% will die.
For gamma radiation, one Gray is approximately equal to one Sievert, which is a unit of dose equivalent for biological tissue, so these numbers are comparable, i.e. 8 Sieverts or 800 rem.
anything at and above 1 Sievert (100 Microsieverts)
This is the equivalent to LD50
LD50 means that there is a 50% chance you could become irradiated or contract cancer.
sodium and chlorida
100 rem
Immersed in cold water
True, a vector quantity has direction, and a scalar quantity does not.
The alara principle stands for As Low As Reasonably Acheivable. This describes the evaluation which medics have to conduct before supplying an x-ray, or another procedure which emmits radiation. Medics have to consider whether or not the advantages outweigh the risks of inflicting radiation upon a person.
A safe reactor don't emit a significant or dangerous quantity of any radiation. But in the core of the reactor all the types of nuclear radiations are emitted.
When sick people are treated with radiation, that does not make them radioactive. Radiation is dangerous, but radiation patients are not.
Any electromagnetic radiation can be dangerous. Alpha waves are higher on the radiation scale than x-rays so yes, they are dangerous.
It's not dangerous to people on earth, because the atmosphere shields us from the radiation.
EXTREMLY
In massive quantity yes, but know more dangerous than tobacco, but in moderation it varies from person to person, for some it may have no effect, for others it gives of a mellow high and occasionally light dizziness.
It is potentially dangerous. The radiation level found in granite is enough to suppress the immune system, cause birth defects, and cause cancer. There are granite composite options which are not containing the level of radiation that is dangerous.
alpha radiation
Yes they very are
Other than Japan most countries haven't been majorly affected by radiation at dangerous levels.
Radiation therapists have a potentially dangerous job since they work with radioactive materials, however, there are numerous safety procedures, and if followed correctly, the job is not particularly dangerous. The median yearly salary for a radiation therapist in the U.S. is $74,813.
The most dangerous type of radiation is Nuclear radiation which is the one that should be most worried about.