Radiation Dosages

Although the International System of Units (SI) defines the Sievert (Sv) as the unit of equivalent dose, chronic radiation levels and standards are still often given in units of Millirems (mRem), where 1 mRem equals 1/1,000 of a Rem and 1 rem equals 0.01 Sv. Light radiation sickness begins at about 50–100 Rad (0.5–1 Gray (Gy), 0.5–1 Sv, 50–100 Rem, 50,000–100,000 mRem).

Absorbed Dosages (D)

Total Absorbed Dosages +Total Absorbed Dosage Levels (D)Dosage LevelDescription250 mGyLowest dose to cause clinically observable blood changes260 mGyPeak natural background dose after one year in Ramsar, Iran2 GyLocal dose for onset of erythema in humans2.5 GyThis dose is lethal to 1% of humans (LD1).5 GyThis dose is lethal to 50% of humans (LD50).8 GyThis dose is lethal to 99% of humans (LD99).48.5 Gy (4.85 krad)Roughly calculated from the estimated 4,500 + 350 rad dose for fatality of Russian experimenter on June 17, 1997, at Sarov.100 Gy (10 krad)Estimated fatality at the United Nuclear Fuels Recovery Plant on July 24, 1964.2 kGyOne second of the estimated dose applied to the inner wall in ITER10 kGy (1 Mrad)Typical tolerance of radiation-hardened microchips10 MGy (1 Grad)The maximum radiation dosage of the most hardened electronics.

Effective Dosages (E)

The following table includes some dosages for comparison purposes, using millisieverts (mSv) (one thousandth of a sievert).

Note that 100 mSv is considered twice in the table below – once as received over a 5-year period, and once as an acute dose, received over a short period of time, with differing predicted effects. The table describes doses and their official limits, rather than effects.

+Effective Dosage Levels (E) Level (mSv) Level in standard form (mSv) Duration Hourly equivalent (μSv/hour) Description 0.001 Hourly 1 Cosmic ray dose rate on commercial flights varies from 1 to 10 μSv/hour, depending on altitude, position and solar sunspot phase. 0.01 Daily 0.4 Natural background radiation, including radonOak Ridge National Laboratory (http://www.ornl.gov/sci/env_rpt/aser95/tb-a-2.pdf ) 0.06 Acute - Chest X-ray (AP+Lat)Health Physics Society (http://www.hps.org/documents/meddiagimaging.pdf) 0.07 Acute - Transatlantic airplane flight. 0.09 Acute - Dental X-ray (Panoramic) 0.1 Annual 0.011 Average USA dose from consumer productsOak Ridge National Laboratory (http://www.ornl.gov/sci/env_rpt/aser95/appa.htm ) 0.15 Annual 0.017 USA EPA cleanup standard 0.25 Annual 0.028 USA NRC cleanup standard for individual sites/sources 0.27 Annual 0.031 Yearly dose from natural cosmic radiation at sea level (0.5 in Denver due to altitude) 0.28 Annual 0.032 USA yearly dose from natural terrestrial radiation (0.16-0.63 depending on soil composition) 0.46 Acute - Estimated largest off-site dose possible from March 28, 1979 Three Mile Island accident 0.48 Day 20 USA NRC public area exposure limit 0.66 Annual 0.075 Average USA dose from human-made sources 0.7 Acute - Mammogram 1 Annual 0.11 Limit of dose from man-made sources to a member of the public who is not a radiation worker in the US and CanadaRadiation Protection Regulations, Canada 1.1 Annual 0.13 Average USA radiation worker occupational dose in 1980 1.2 Acute - Abdominal X-ray 2 Annual 0.23 USA average medical and natural background Human internal radiation due to radon, varies with radon levels 2 Acute - Head CT 3 Annual 0.34 USA average dose from all natural sources 3.66 Annual 0.42 USA average from all sources, including medical diagnostic radiation doses 4 Duration of the pregnancy 0.6 Canada CNSC maximum occupational dose to a pregnant woman who is a designated Nuclear Energy Worker. 5 Annual 0.57 USA NRC occupational limit for minors (10% of adult limit)USA NRC limit for visitors 5 Pregnancy 0.77 USA NRC occupational limit for pregnant women 6.4 Annual 0.73 High Background Radiation Area (HBRA) of Yangjiang, China 7.6 Annual 0.87 Fountainhead Rock Place, Santa Fe, NM natural 8 Acute - Chest CT 10 Acute - Lower dose level for public calculated from the 1 to 5 rem range for which USA EPA guidelines mandate emergency action when resulting from a nuclear accidentAbdominal CT 14Acute-18F FDG PET scan, Whole Body 50 Annual 5.7 USA NRC/ Canada CNSC occupational limit for designated Nuclear Energy Workers 100 5 years 2.3 Canada CNSC occupational limit over a 5-year dosimetry period for designated Nuclear Energy Workers 100 Acute - USA EPA acute dose level estimated to increase cancer risk 0.8% 120 30 years 0.46 Exposure, long duration, Ural Mountains, lower limit, lower cancer mortality rate 150 Annual 17 USA NRC occupational eye lens exposure limit 170 Acute Average dose for 187,000 Chernobyl recovery operation workers in 1986 175 Annual 20 Guarapari, Brazil natural radiation sources 250 2 hours 125,000 (125 mSv/hour) Whole body dose exclusion zone criteria for US nuclear reactor siting10 CFR Part 100.11 Section 1 (converted from 25 rem) 250 Acute - USA EPA voluntary maximum dose for emergency non-life-saving work 400–900 4– Annual 46–103 Unshielded in interplanetary space. 500 Annual 57 USA NRC occupational whole skin, limb skin, or single organ exposure limit 500 Acute - Canada CNSC occupational limit for designated Nuclear Energy Workers carrying out urgent and necessary work during an emergency.Low-level radiation sickness due to short-term exposureCenters for Disease Control and Prevention (https://emergency.cdc.gov/radiation/ars.asp) 750 Acute - USA EPA voluntary maximum dose for emergency life-saving work 1,000 Hourly 1,000,000 Level reported during Fukushima I nuclear accidents, in immediate vicinity of reactor 3,000 Acute - Thyroid dose (due to iodine absorption) exclusion zone criteria for US nuclear reactor siting (converted from 300 rem) 4,800 Acute - (actually LD50/60) in humans from radiation poisoning with medical treatment estimated from 480 to 540 rem.Biological Effects of Ionizing Radiation 5,000 Acute - Calculated from the estimated 510 rem dose fatally received by Harry Daghlian on August 21, 1945, at Los Alamos and lower estimate for fatality of Russian specialist on April 5, 1968, at Chelyabinsk-70. 5,000 . Most commercial electronics can survive this radiation level.ieee.org - Radiation Hardening 101: How To Protect Nuclear Reactor Electronics 16,000 Acute Highest estimated dose to Chernobyl emergency worker diagnosed with acute radiation syndrome 20,000 Acute Interplanetary exposure to solar particle event (SPE) of October 1989. Acute - Calculated from the estimated 2,100 rem dose fatally received by Louis Slotin on May 21, 1946, at Los Alamos and lower estimate for fatality of Russian specialist on April 5, 1968 Chelyabinsk-70. Acute - Roughly calculated from the estimated 4,500 + 350 rad dose for fatality of Russian experimenter on June 17, 1997, at Sarov. Acute - Roughly calculated from the estimated 6,000 rem doses for several Russian fatalities from 1958 onwards, such as on May 26, 1971, at the Kurchatov Institute. Lower estimate for fatality of Cecil Kelley at Los Alamos on December 30, 1958. Acute - Roughly calculated from the estimated 10,000 rad dose for fatality at the United Nuclear Fuels Recovery Plant on July 24, 1964.30,000,0003,600,000Radiation tolerated by Thermococcus gammatolerans, a microbe extremely resistant to radiation. Hourly 70,000,000,000,000 Estimated dose rate for the inner wall in ITER (2 kGy/s with an approximate weighting factor of 10)Henri Weisen: ITER Diagnostics, page 13. Accessed August 28, 2017

See also Mars Radiation Environment Experiment (MARIE)

External links unh.edu: The Carrington event: Possible doses to crews in space from a comparable event, received in 2004 and concludes an interplanetary dose for a Carrington event at 34 - 45 Gy depending on type of flare spectrum and using a 1 gram/cm2 aluminium shield (3.7 mm thick). Dose can be decreased down to 3 Gy through the use of a 10 gram/cm2 aluminium shield (3.7 cm thick).

References