Overview: Mass Radiation Exposure

Richard Denton, MD

Radiation is an invisible, odourless emission of energy as electromagnetic waves or moving subatomic particles that cause ionization—for an atom or molecule to become charged positively or negatively or to break apart molecules. It is this ionization that causes radiation to become lethal.

This energy comes in various forms; alpha (a subatomic particle the size of a helium nucleus that can kill quickly—it killed Alexander Litvinenko from alpha radiation from polonium 210 in 23 days—or by inducing cancers over a long period of time, years, when taken internally); beta, (an electron), gamma, and X rays (that can kill acutely).

While radioactive particles can be localized, they often travel by wind in the air to the point of circling the globe in the higher atmosphere and in water, or are taken up by living organisms. Their concentration increases as one goes higher up the food chain. People vary in their susceptibility to radiation, with fetuses, babies, children, and women being the most susceptible. There is no threshold below which radiation is safe; the “linear no threshold theory” is baseless. Radiation effects are also cumulative, so that small amounts over a period of time, (chronic) can mount up to become lethal.

Human acute effects are dependent on the dose or amount of exposure to the radiation. With 50-100 mSv (milliSieverts), come changes in blood chemistry. At 500 mSv, one develops nausea, and then fatigue, followed by vomiting at 700 mSv., followed by hair loss and then diarrhoea over the following 2-3 weeks, as the most rapidly dividing cells are affected first. At 1000 mSv., you start bleeding. At 4,000 mSv, there may be death in two or three months. At 10,000 mSv., there is death within one or two weeks, with destruction of the intestinal system and bleeding. At 20,000 mSv., the neurologic system is affected, resulting in loss of consciousness, and death within hours to a few days.

Human chronic effects can be; miscarriages; mutagenic (changes the genetic material, usually DNA but also RNA leading to mutations such as Down’s syndrome), teratogenic (which disturbs the development of a fetus, resulting in congenital malformations that can be passed down to future generations); cancers such as leukaemia, thyroid, breast, brain, pancreas; hardening of the arteries, leading to strokes and heart attacks; cataracts to kidney damage and acceleration of the overall ageing process.

When we look at a crisis that can destroy our civilization, radiation is one possibility. It can occur from atomic bombs (see nuclear war) or from a disaster at a nuclear power plant that has melted down (Chernobyl or Fukushima) or from sabotage by terrorists attacking stored radioactive material such as depleted uranium, or a dirty bomb (a conventional bomb with radioactive material in it) or from accidents at nuclear plants that are being used for military purposes. We also shoot radioactive material, depleted uranium, to destroy tanks and as bunker busting bombs; then children play in these areas. People affected by radiation are called Hibakusha and can be victims of the exposures noted above or from the testing of nuclear weapons.

The International Nuclear Event Scale (INES) rates the severity of accidents on a logarithmic scale from 1 to 7 with 7 being the worst; a major accident; (Chernobyl April 1986, and Fukushima March 2011). A level 6 serious accident was the Kyshtym disaster at the Mayak Chemical Combine in the Soviet Union in September 1957 at a nuclear waste reprocessing plant. Level 5, accidents with wider consequences, include Windscale fire at Sellafield on October 1957 in the United Kingdom that caused a fire with graphite and uranium in a military air cooled reactor, Three Mile Island on March 1979 nuclear power plant, Chalk River December 1952 when the reactor core was damaged, and the Goiania accident in Brazil in 1987 when a caesium chloride radiation source was taken from an abandoned hospital.