What is the effect of gamma rays on the human body?

Answer 1

A gamma ray is the shortest wavelength and highest energy electromagnetic radiation on the spectrum; it's at the very top. A gamma ray begins moving the instant it is created. And it moves at the speed of light (for the medium in which it is traveling). It continues this way until it "runs into something" and "bounces off" in an event we call scattering. The gamma ray may or may not lose energy in this scattering event. There are different ways it can scatter, but there is also the possibility that this ray, if it has sufficient energy and passes close to an atomic nucleus, will experience what is called pair production. A large chunk of the energy is converted directly in mass to create an electron and a positron (the anti-particle of the electron or antimatter). Another idea is that when the gamma ray passes through any matter, it can give energy to that matter. What happens is dependent on the energy of the ray and what atoms or molecules are present. You probably guessed there would be variables, huh. Atoms can be ionized (the electrons are kicked out of their orbits), or chemical bonds broken by the ionizing radiation. This is a particularly nasty possibility that presents itself because of the extreme energy of the gamma ray. And covalent bonds, the low-energy kind of chemical bond that is so commonly present in living material, can take a beating from gamma rays. That's what makes them so dangerous. Eventually, the gamma ray scatters and loses enough energy to become something less penetrating and harmful. But some matter had to "pay the freight" on the scattering and energy reduction events. You'll find a link below for more information.

Answer 2

This section of the Wikipedia entry for Gamma Rays gives some information, you may like to read the whole entry, and look at the references. The following website may also be of interest:

http://www.world-nuclear.org/info/inf05.html

Gamma rays are the most dangerous form of radiation emitted by a nuclear explosion because of the difficulty in shielding them. This is because gamma rays have the shortest wavelength of all waves in the electromagnetic spectrum, and therefore have the greatest ability to penetrate through any gap, even a subatomic one, in what might otherwise be an effective shield. Gamma-rays are not stopped by the skin. They can induce DNA alteration by interfering with the genetic material of the cell. DNA double-strand breaks are generally accepted to be the most biologically significant lesion by which ionizing radiation causes cancer and hereditary disease. A study done on Russian nuclear workers exposed to external whole-body gamma radiation at high cumulative doses shows the link between radiation exposure and death from leukemia, lung, liver, skeletal and other solid cancers. Alongside radiation, gamma-rays also produce thermal burn injuries and induce an immunosuppressive effect. After gamma-irradiation, and the breaking of DNA double-strands, a cell can repair the damaged genetic material to the limit of its capability[citation needed]. However, a study of Rothkamm and Lobrich has shown that the repairing process works well after high-dose exposure but is much slower in the case of a low-dose exposure. This could mean that a chronic low-dose exposure cannot be fought by the body[citation needed]. The probability of detecting small alterations or of a detectable defect occurring is most likely small enough that the cell would replicate before initiating a full repair[citation needed]. Some cells can not detect their own genetic defects

Answer 3

A gamma ray is highly energetic form of electromagnetic radiation, and gamma ray photons result from changes in atomic nuclei. This type of radiation is ionizing radiation, and it is highly penetrating. Additionally, it will easily break chemical bonds in organic (and other) compounds. This results in tissue damage. Should the damage occur to the DNA within a cell, the cell has a much more difficult time repairing that, and it could die or mutate. Large doses of gamma radiation can cause an individual to suffer radiation sickness, and a sufficiently large dose can kill an individual.