Radioactive isotopes ingestion

Two forms of gold provide medical treatments. The radioactive isotope Au-198, with a short half-life of 2.7 days, is used to treat cancer and is produced by subjecting pure gold to neutrons within a nuclear reactor. A gold salt, a solution called sodium thiosulfate (AuNa O Cl ), is injected as an internal treatment for rheumatoid arthritis. However, since gold and some of its compounds are toxic when ingested, this treatment may cause complications such as skin rashes and kidney failure. It is a less popular treatment, particularly with the development of newer and more effective medications. 

While adequate Intestinal absorption Is clearly required to maintain zinc sufficiency, a number of different methods are presently used for Its measurement. Intestinal absorption has been measured by clinical balance studies, tracers (using both stable and radioactive Isotopes) and serum levels after Ingestion of pharmacologic doses of stable zinc compounds. Each can be useful, but each also has limitations and It Is Important to note that different methods. In reality, measure different aspects of absorption. While results are often reported as absorption, specific nomenclature has been developed to specify the results from each method of measurement(13,14). 

Radioactive isotopes react chemically just like the nonradioactive isotopes of the same element. Because of this, physicians can add a little radioactive isotope to a sample of an element, which is then ingested or injected into the body. They can then determine the element s location in the body by detecting the particles that the radioactive isotope emits. The radioactive isotope is called a tracer, and this technique is used extensively in medicine and other fields (Section 21.1). 

Its inherent toxicity and that of its compounds resembles that of calcium. The state of calcium nutrition of exposed individuals is a major determinant of toxicity. The radioactive isotope, when ingested or inhaled, is processed by the body and resides in bones. Strontium ionizes molecules in the body by the emission of beta particles. It increases the risk of cancer. 

The UBT is based on HP urease activity. The carbon (nonradioac-tive isotope) and " carbon (radioactive isotope) tests require that the patient ingest radiolabeled urea, which is then hydrolyzed by HP (if present in the stomach) to ammonia and radiolabeled bicarbonate. The radiolabeled bicarbonate is absorbed in the blood and excreted in the breath. A mass spectrometer is used to detect carbon, whereas " carbon is measured using a scintillation counter. The stool antigen test is approved by the Food and Drug Administration (FDA), but availability in the United States is limited. It is less expensive and easier to perform than the UBT, and may be useful in children. Although comparable to the UBT in the initial detection of HP, the stool antigen test is less accurate when used to confirm HP eradication posttreatment. Salivary and urine antibody tests are under investigation. ... 

Radioactive isotopes of strontium were produced by the explosion of nuclear weapons. They were considered serious health hazards because they were incorporated into the bones of animals that ingested them. Explain why strontium would be likely to be deposited in bones. 

Radioactive isotopes of an element have similar environmental and toxicological behavior to the non-radioactive isotopes. If they are introduced into the body by inhalation ingestion, the chemical properties of the element will determine its ultimate destination in the body. For example, it is well known that strontium and radium are chemically similar to Ca and tend to deposit on bone surfaces and bone marrow with that element tritium ( H) becomes incorporated into water molecules and is distributed throughout the body. The main difference between radioactive and nonradioactive isotopes is that the radionuclides emit one or more types of radiation as they decay to more stable forms. The type and energy level of the emitted radiation is nuclide-specific. 

External radioactive contamination occurs when a radioactive isotope (e.g. debris from a nuclear explosion) is deposited on the skin and clothing. Such debris is usually in the form of a dust. This contamination can be removed by surface cleaning with soap and water (as for chemical contamination). Care must be taken during external decontamination to avoid accidental ingestion and subsequent internal contamination. 

Fig. 17. Biological model recommended for describing the uptake and retention of cerium by humans after inhalation or ingestion. Numbers in parentheses give the fractions of the material in the originating compartments which are cleared to the indicated sites of deposition. Clearance from the pulmonary region results from competition between mechanical clearances to the lymph nodes and gastrointestinal tract and absorption of soluble material into the systemic circulation. The fractions included in parentheses by the pulmonary compartment indicate the distribution of material subject to the two clearance rates however, these amounts will not be cleared in this manner if the material is previously absorbed into blood. Transfer rate constants or functions, S(t), are given in fractions per unit time. Dashed lines indicate clearance pathways which exist but occur at such slow rates as to be considered insignificant compared to radioactive decay of the cerium isotopes.

As with other metals, the transition metals and many of their compounds are toxic, and their powdered or gaseous forms should not be ingested or inhaled. In addition, all but one of the isotopes of scandium are radioactive and should be handled by experienced personnel. 

The transfer factor Fm from feed to milk is defined in equation (2.11) as the activity per litre expressed as a fraction of the activity ingested daily by the cow. Numerous measurements of Fm have been made by dosing cows with iodine isotopes or by comparing radioactive or stable iodine in milk and in the herbage eaten by the cows. Table 3.6 shows a selection of the results. Fm depends on the yield of milk and on seasonal factors (Gamer, 1971), but it does not appear to depend on the chemical form of the iodine (Bretthauer et al., 1972). Gamer (1971) recommended Fm = 5 x 10 3 d l-1 for UK conditions, but noted that US results tended towards a higher value. 

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