# Orders of magnitude (radiation)
## Radiation Dosages

Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning. Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, 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).
The following table includes some dosages for comparison purposes, using millisieverts (mSv) (one thousandth of a sievert). The concept of radiation hormesis is relevant to this table – radiation hormesis is a hypothesis stating that the effects of a given acute dose may differ from the effects of an equal fractionated dose. Thus 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.

### Absorbed Dosages (D)
#### Total Absorbed Dosages

Total Absorbed Dosage Levels (D) :
| Dosage Level | Description |
| 250 mGy | Lowest dose to cause clinically observable blood changes |
| 260 mGy | Peak natural background dose after one year in Ramsar, Iran |
| 2 Gy | Local dose for onset of erythema in humans |
| 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 kGy | One second of the estimated dose applied to the inner wall in ITER |
| 10 kGy (1 Mrad) | Typical tolerance of radiation-hardened microchips |
| 10 MGy (1 Grad) | The maximum radiation dosage of the most hardened electronics. |

### Effective Dosages (E)

| Level (mSv) | Level in standard form (mSv) | Duration | Hourly equivalent (μSv/hour) | Description |
| 0.001 | 1×10^$^{−3}$ | 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 | 1×10^$^{−2}$ | Daily | 0.4 | Natural background radiation, including radon |
| 0.06 | 6×10^$^{−2}$ | Acute | - | Chest X-ray (AP+Lat) |
| 0.07 | 7×10^$^{−2}$ | Acute | - | Transatlantic airplane flight. |
| 0.09 | 9×10^$^{−2}$ | Acute | - | Dental X-ray (Panoramic) |
| 0.1 | 1×10^$^{−1}$ | Annual | 0.011 | Average USA dose from consumer products |
| 0.15 | 1.5×10^$^{−1}$ | Annual | 0.017 | USA EPA cleanup standard |
| 0.25 | 2.5×10^$^{−1}$ | Annual | 0.028 | USA NRC cleanup standard for individual sites/sources |
| 0.27 | 2.7×10^$^{−1}$ | Annual | 0.031 | Yearly dose from natural cosmic radiation at sea level (0.5 in Denver due to altitude) |
| 0.28 | 2.8×10^$^{−1}$ | Annual | 0.032 | USA yearly dose from natural terrestrial radiation (0.16-0.63 depending on soil composition) |
| 0.46 | 4.6×10^$^{−1}$ | Acute | - | Estimated largest off-site dose possible from March 28, 1979 Three Mile Island accident |
| 0.48 | 4.8×10^$^{−1}$ | Day | 20 | USA NRC public area exposure limit |
| 0.66 | 6.6×10^$^{−1}$ | Annual | 0.075 | Average USA dose from human-made sources |
| 0.7 | 7×10^$^{−1}$ | Acute | - | Mammogram |
| 1 | 1×10^$^0$ | 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 Canada |
| 1.1 | 1.1×10^$^0$ | Annual | 0.13 | Average USA radiation worker occupational dose in 1980 |
| 1.2 | 1.2×10^$^0$ | Acute | - | Abdominal X-ray |
| 2 | 2×10^$^0$ | Annual | 0.23 | USA average medical and natural background Human internal radiation due to radon, varies with radon levels |
| 2 | 2×10^$^0$ | Acute | - | Head CT |
| 3 | 3×10^$^0$ | Annual | 0.34 | USA average dose from all natural sources |
| 3.66 | 3.66×10^$^0$ | Annual | 0.42 | USA average from all sources, including medical diagnostic radiation doses |
| 4 | 4×10^$^0$ | Duration of the pregnancy | 0.6 | Canada CNSC maximum occupational dose to a pregnant woman who is a designated Nuclear Energy Worker. |
| 5 | 5×10^$^0$ | Annual | 0.57 | USA NRC occupational limit for minors (10% of adult limit) USA NRC limit for visitors |
| 5 | 5×10^$^0$ | Pregnancy | 0.77 | USA NRC occupational limit for pregnant women |
| 6.4 | 6.4×10^$^0$ | Annual | 0.73 | High Background Radiation Area (HBRA) of Yangjiang, China |
| 7.6 | 7.6×10^$^0$ | Annual | 0.87 | Fountainhead Rock Place, Santa Fe, NM natural |
| 8 | 8×10^$^0$ | Acute | - | Chest CT |
| 10 | 1×10^$^1$ | 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 accident Abdominal CT |
| 14 | 1.4×10^$^1$ | Acute | - | $^{18}$F FDG PET scan, Whole Body |
| 50 | 5×10^$^1$ | Annual | 5.7 | USA NRC/ Canada CNSC occupational limit for designated Nuclear Energy Workers(10 CFR 20) |
| 100 | 1×10^$^2$ | 5 years | 2.3 | Canada CNSC occupational limit over a 5-year dosimetry period for designated Nuclear Energy Workers |
| 100 | 1×10^$^2$ | Acute | - | USA EPA acute dose level estimated to increase cancer risk 0.8% |
| 120 | 1.2×10^$^2$ | 30 years | 0.46 | Exposure, long duration, Ural Mountains, lower limit, lower cancer mortality rate |
| 150 | 1.5×10^$^2$ | Annual | 17 | USA NRC occupational eye lens exposure limit |
| 170 | 1.7×10^$^2$ | Acute | | Average dose for 187,000 Chernobyl recovery operation workers in 1986 |
| 175 | 1.75×10^$^2$ | Annual | 20 | Guarapari, Brazil natural radiation sources |
| 250 | 2.5×10^$^2$ | 2 hours | 125,000 | (125 mSv/hour) Whole body dose exclusion zone criteria for US nuclear reactor siting (converted from 25 rem) |
| 250 | 2.5×10^$^2$ | Acute | - | USA EPA voluntary maximum dose for emergency non-life-saving work |
| 400-900 | 4–9×10^$^2$ | Annual | 46-103 | Unshielded in interplanetary space. |
| 500 | 5×10^$^2$ | Annual | 57 | USA NRC occupational whole skin, limb skin, or single organ exposure limit |
| 500 | 5×10^$^2$ | 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 exposure |
| 750 | 7.5×10^$^2$ | Acute | - | USA EPA voluntary maximum dose for emergency life-saving work |
| 1,000 | 10×10^$^2$ | Hourly | 1,000,000 | Level reported during Fukushima I nuclear accidents, in immediate vicinity of reactor |
| 3,000 | 3×10^$^3$ | Acute | - | Thyroid dose (due to iodine absorption) exclusion zone criteria for US nuclear reactor siting (converted from 300 rem) |
| 4,800 | 4.8×10^$^3$ | Acute | - | LD$_{50}$ (actually LD$_{50/60}$) in humans from radiation poisoning with medical treatment estimated from 480 to 540 rem. |
| 5,000 | 5×10^$^3$ | 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 | 5×10^$^3$ | | | 5,000 - 10,000 mSv. Most commercial electronics can survive this radiation level. |
| 16,000 | 1.6×10^$^4$ | Acute | | Highest estimated dose to Chernobyl emergency worker diagnosed with acute radiation syndrome |
| 20,000 | 2×10^$^4$ | Acute | 2,114,536 | Interplanetary exposure to solar particle event (SPE) of October 1989. |
| 21,000 | 2.1×10^$^4$ | 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. |
| 48,500 | 4.85×10^$^4$ | Acute | - | Roughly calculated from the estimated 4,500 + 350 rad dose for fatality of Russian experimenter on June 17, 1997, at Sarov. |
| 60,000 | 6×10^$^4$ | 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. |
| 100,000 | 1×10^$^5$ | Acute | - | Roughly calculated from the estimated 10,000 rad dose for fatality at the United Nuclear Fuels Recovery Plant on July 24, 1964. |
| 30,000,000 | 3×10^$^7$ | | 3,600,000 | Radiation tolerated by Thermococcus gammatolerans, a microbe extremely resistant to radiation. |
| 70,000,000,000 | 7×10^$^{10}$ | 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) |