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The source can be in the vicinity of the body or can be on the skin surface. The level of health risk is dependent on duration and the type and strength of irradiation. Penetrating radiation such as gamma rays, X-rays, neutrons or beta particles pose the greatest risk from an external source.
Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination. Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue.
Most X-rays occur during the third trimester of pregnancy. [8] There is sparse information on radiation exposure from the first trimester of pregnancy. [8] However, data suggests that the relative risk is 2.7. [8] Relative risk is a measure of probability of an outcome in one group versus the other.
In the "1951 Recommendations" the commission recommended a maximum permissible dose of 0.5 roentgen (0.0044 grays) in any 1 week in the case of whole-body exposure to X and gamma radiation at the surface, and 1.5 roentgen (0.013 grays) in any 1 week in the case of exposure of hands and forearms. [1]
Ultraviolet radiation of wavelengths shorter than 300 nm (actinic rays) can damage the corneal epithelium. This is most commonly the result of exposure to the sun at high altitude, and in areas where shorter wavelengths are readily reflected from bright surfaces, such as snow, water, and sand.
Diagnosis is typically made based on a history of significant radiation exposure and suitable clinical findings. [3] An absolute lymphocyte count can give a rough estimate of radiation exposure. [3] Time from exposure to vomiting can also give estimates of exposure levels if they are less than 10 Gy (1000 rad). [3]
Exposure to electromagnetic rays such as x-rays and gamma rays can, depending on the time exposed, cause sterility, genetic defects, premature ageing and death. [ 12 ] Non-ionising radiation is the terms used to describe the part of the electromagnetic spectrum covering 'Optical radiation', such as ultraviolet light and 'electromagnetic fields ...
The ICRP further states "For internal exposure, committed effective doses are generally determined from an assessment of the intakes of radionuclides from bioassay measurements or other quantities (e.g., activity retained in the body or in daily excreta). The radiation dose is determined from the intake using recommended dose coefficients". [5]