Health risks, radioactive isotopes

Because exposure to radiation is a health risk, the administration of radioactive isotopes must be monitored and controlled carefully. Isotopes that emit alpha or beta particles are not used for Imaging, because these radiations cause substantial tissue damage. Specificity for a target organ is essential so that the amount of radioactive material can be kept as low as possible. In addition, an Isotope for medical Imaging must have a decay rate that is slow enough to allow time to make and administer the tracer compound, yet fast enough rid the body of radioactivity in as short a time as possible. 

Although the uptake of by the thyroid gland was a health risk after the Chernobyl disaster (Box 2.2), controlled uptake has medical applications. If a patient ingests l (e.g. as a solution of l-labelled Nal), the isotope is quickly absorbed by the th5Toid gland and the size and state of the gland can be detected by monitoring the radioactivity emitted. For l, ri 8 days, and the dose administered soon decays. 

There are a number of iodine isotopes that are radioactive, with some being more hazardous than others. From a radiological perspective, the radioisotope is the most harmful and poses the greatest health risk. emits multiple beta particles and photons that contribute to the radiation dose. The most important beta particle, which predominantly delivers radiation dose to local tissues, has a mean energy of 192 keV. 

Indoor air pollutants, including radon gas, can pose significant health risks. Radon is a radioactive gas found in the soils and rocks of Earth s crust. It finds its way into homes through cracks in the foundation or basement, and sometimes through the water supply. Radon is invisible and odorless, and becomes a health hazard when it is allowed to build up inside the home. The isotope of radon commonly found in homes is radon-222, a product of the uranium-238 decay chain, formed by the a decay of radium-226. Radon-222, in turn, decays by a emission. 

The method of choice for exact quantitative determination of key flavorrelevant constituents in foods is currently IDA, isotope dilution analysis (stable isotope dilution assay or SIDA), in which the isotope-labeled analog used as the internal standard undergoes the same losses during workup as does the analyte. Either radioactive or stable isotopes can be used for the isotope dilution method. The latter are simpler and can be handled without health risks. For this reason, only stable isotopes are used in flavor analysis. 

---