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The results of the evaluation help to assess possible hazards to the safety and health of workers and to define protective measures. Since electromagnetic fields may influence passive or active implants of workers, it is essential to consider the exposure at their workplaces separately in the risk assessment. [10]
Radiation damage is the effect of ionizing radiation on physical objects including non-living structural materials. It can be either detrimental or beneficial for materials. Radiobiology is the study of the action of ionizing radiation on living things, including the health effects of radiation in humans.
Gamma rays are better absorbed by materials with high atomic numbers and high density, although neither effect is important compared to the total mass per area in the path of the gamma ray. Ultraviolet (UV) radiation is ionizing in its shortest wavelengths but is not penetrating, so it can be shielded by thin opaque layers such as sunscreen ...
For an exposure of 1 roentgen by gamma rays with an energy of 1 MeV, the dose in air will be 0.877 rad, the dose in water will be 0.975 rad, the dose in silicon will be 0.877 rad, and the dose in averaged human tissue will be 1 rad. [10] "rad" stands for radiation absorbed dose. [4]
The exposure to 4.5 Gray of penetrating gamma rays has many effects that occur at different times: In 24 hours: [10] vomiting; diarrhea; These will usually abate after 6–7 days. Within 3–4 weeks there is a period of extreme illness. [10] severe bloody diarrhea, indicating intestinal disorders causing fluid imbalance; extensive internal bleeding
Gamma radiation is eventually absorbed as it penetrates a dense material. Lead is good at absorbing gamma radiation, due to its density. The hazard from contamination is the emission of ionizing radiation. The principal radiations which will be encountered are alpha, beta and gamma, but these have quite different characteristics.
An emitted gamma ray from any type of excited state may transfer its energy directly to any electrons, but most probably to one of the K shell electrons of the atom, causing it to be ejected from that atom, in a process generally termed the photoelectric effect (external gamma rays and ultraviolet rays may also cause this effect).
In most locations, the levels remained well below the levels required to damage human health, as the recommended annual maximum limit is well below the level that would affect human health. [188] [189] [190] Natural exposure varies from place to place but delivers a dose equivalent in the vicinity of 2.4 mSv/year, or about 0.3 μSv/h.