What Are The Effects Of Radiation On Humans? What Is Radiation Poisoning?

 Contrasting media reports abound regarding the dangers occurring at the Fukushima nuclear facility in Japan. The reports have triggered uncertainty, concern and even panic among members of the general public in Japan and around the world.

Workers in Japan have been bravely battling to save the facility from a disastrous meltdown, exposing their bodies to potentially dangerous and lethal doses of radiation. In this text, we attempt to explain what impact radiation may have on the human body.

Radiation takes place when the atomic nucleus of an unstable atom decays and starts releasing ionizing particles, known as ionizing radiation. When these particles come into contact with organic material, such as human tissue, they will damage them if levels are high enough, causing burns and cancer. Ionizing radiation can be fatal for humans.

REM (roentgen equivalent in man) - this is a unit we use to measure radiation dosage. We use this measurement to determine what levels of radiation are safe or dangerous for human tissue. It is the product of the absorbed dose in rads and a weighting factor (W_R), which accounts for how effective the radiation is in causing biological damage.

A sudden, short dose of up to 50 rem will probably cause no problems, except for some blood changes. From 50 to 200 rem there may be illness, but fatalities are highly unlikely. A dose of between 200 and 1,000 will most likely cause serious illness - the nearer the 1,000 it is, the poorer the outlook for the human will be. Any dose over 1,000 will typically cause death.

When an atomic bomb explodes, as in Hiroshima and Nagasaki during WWII, people receive two doses of radiation: one during the explosion, and another from fallout. Fallout refers to the radioactive particles that float in the air after an explosion; they rise and then gradually descend to the ground. A dose of 100 rems will have probably cause some initial signs of radiation sickness, such as loss of white blood cells, nausea, vomiting, and headache. With a 300 rem dose you may lose hair temporarily - your nerve cells and those that line the digestive tract will be damaged. As the dose rises and more white blood cells are lost, the human's immune system becomes seriously weakened - their ability to fight off infections is considerably reduced.

Exposure to radiation makes our bodies produce fewer blood clotting agents, called blood platelets, increasing our risk of internal bleeding. Any cut on the skin will take much longer to stop bleeding.

Experts say that approximately 50% of humans exposed to 450 rems will die, and 800 rems will kill virtually anyone. Death is inevitable and will occur from between two days to a couple of weeks.

Millisieverts per hour (mSv) - this is a measure used more commonly by the International Commission on Radiological Protection. For example:

• A gastrointestinal series X-ray investigation exposes the human to 14 mSv
• Recommended limit for volunteers averting a major nuclear escalation - 500 mSv (according to the International commission on Radiological Protection)
• Recommended limit for volunteers rescuing lives or preventing serious injuries - 1000 mSv (according to the International commission on Radiological Protection)

Below is a list of signs and symptoms likely to occur when a human is exposed to acute radiation (within one day), in mSv:

• 0 to 250 mSv - no damage
• 250 to 1,000 mSv. Some individuals may lose their appetites, experience nausea, and have some damage to the spleen, bone marrow and lymph nodes.
• 1000 to 3000 mSv - nausea is mild to severe, no appetite, considerably higher susceptibility to infections. Injury to the following will be more severe - spleen, lymph node and bone marrow. The patient will most likely recover, but this is not guaranteed.
• 3,000 to 6,000 mSv - nausea much more severe, loss of appetite, serious risk of infections, diarrhea, skin peels, sterility. If left untreated the person will die. There will also be hemorrhaging.
• 6,000 to 10,000 mSv - Same symptoms as above. Central nervous system becomes severely damaged. The person is not expected to survive.
• 10,000+ mSv - Incapacitation. Death. Those who do survive higher radiation doses have a considerably higher risk of developing some cancers, such as lung cancer, thyroid cancer, breast cancer, leukemia, and cancer of several organs.

Radiation at and around the Fukushima Daiichi nuclear power facility - March 2011

Levels of radiation outside the plant have now fallen from 1,000 mSv an hour to 600-800 (18 March 2011).

Levels of Alert

Alert levels range from 0 to a maximum of 7.

In Japan on March 18th, 2011 the alert level was raised from four to five, the same as the 1979 Three Mile Island alert level.

In 1986, Chernovyl, on the other hand reached an alert level of seven.

The Japanese government initially thought the problem was just a local one, but today they announced it may have "wider consequences" They raised the severity grade because of core damage to reactors 2 and 3.

Reducing the effects on the body

Oral potassium iodide, or KI should be taken immediately following ingestion of radioactive iodine in the event of an accident or attack at a nuclear power plant, or the detonation of a nuclear bomb. KI would be useless after a dirty bomb, unless it contained radioactive iodine, and even then it would only help to prevent thyroid cancer.

Depending on the level of radiation exposure and how sick the patient becomes, doctors may use antibiotics, colony stimulating factors, blood products, and stem cell transplant.

Nuclear accidents that have occured

1952 - Chalk River, near Ottawa, Canad. Partial meltdown of the reactor's uranium fuel core. No injuries.

1957 - Windscale Pile No. 1, north of Liverpool, UK - 200 square miles became contaminated with radiation after a fire in a graphite-cooled reactor.

1957 - South Ural Mountains, Soviet Union - weapons factory exploded, releasing radioactive waste twelve miles from the town of Kyshtym. 10,000 people were evacuated. According to authorities, there were no injuries.

1976 - near Greifswald, East Germany - at the Libmin nuclear power plant; the radioactive core almost melted down. There had been a fire, safety systems failed.

1979 - Three Mile Island, near Harrisburg, Pa., USA - a reactor lost its coolant, causing overheating and partial meltdown of an uranium core. The worst accident in American history. Some radioactive gases and water were released.

1986 - Chernobyl, near Kiev, Ukraine, Soviet Union - a graphite core of one of four reactors caught fire and exploded. Radioactive material spread far, to other parts of the Soviet Union, Scandinavia, eastern Europe, and eventually western Europe. Although authorities claimed 31 dead, nobody is really sure what the true figure was. The worst nuclear accident on earth.

1987 - Goiânia, Brazil - a cesium-137 cancer-therapy machine was sold as scrap. 244 people became contaminated with radiation, four died.

1999 - Tokaimura, Japan - a uranium-processing nuclear fuel plant released high levels of radioactive gas into the atmosphere after an uncontrolled chain reaction. Two workers died, and one was seriously injured.

2004 - Mihama, Japan - steam (non-radioactive) leaked from a nuclear power station. Four workers died and seven other were severely burned.

2007 - Kashiwazaki, Japan - a 6.8 magnitude earthquake near Niigata caused a major fire, radiation leaks and burst pipes at a major nuclear power plant. The plant had been built right on top of an active seismic fault.

2011 - March 12, Fukushima Daiichi Nuclear Power Station, Japan - reactor number 1 exploded. One of the buildings collapsed completely. Shortly after a devastating earthquake and tsunami, the reactor's cooling system failed. Within three days two more explosions and a fire had everyone running around trying to keep the four reactors under control. The fire was contained, but some radiation leaked into the air.

Written by Christian Nordqvist
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