Mercury Radioisotopes: Unstable isotopes of mercury that decay or disintegrate emitting radiation. Hg atoms with atomic weights 185-195, 197, 203, 205, and 206 are radioactive mercury isotopes.Mercury: A silver metallic element that exists as a liquid at room temperature. It has the atomic symbol Hg (from hydrargyrum, liquid silver), atomic number 80, and atomic weight 200.59. Mercury is used in many industrial applications and its salts have been employed therapeutically as purgatives, antisyphilitics, disinfectants, and astringents. It can be absorbed through the skin and mucous membranes which leads to MERCURY POISONING. Because of its toxicity, the clinical use of mercury and mercurials is diminishing.Mercury PoisoningRadioisotopes: Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Mercury Compounds: Inorganic compounds that contain mercury as an integral part of the molecule.Zinc Radioisotopes: Unstable isotopes of zinc that decay or disintegrate emitting radiation. Zn atoms with atomic weights 60-63, 65, 69, 71, and 72 are radioactive zinc isotopes.Mercury Poisoning, Nervous System: Neurologic disorders associated with exposure to inorganic and organic forms of MERCURY. Acute intoxication may be associated with gastrointestinal disturbances, mental status changes, and PARAPARESIS. Chronic exposure to inorganic mercury usually occurs in industrial workers, and manifests as mental confusion, prominent behavioral changes (including psychosis), DYSKINESIAS, and NEURITIS. Alkyl mercury poisoning may occur through ingestion of contaminated seafood or grain, and its characteristic features include POLYNEUROPATHY; ATAXIA; vision loss; NYSTAGMUS, PATHOLOGIC; and DEAFNESS. (From Joynt, Clinical Neurology, 1997, Ch20, pp10-15)Methylmercury Compounds: Organic compounds in which mercury is attached to a methyl group.Radioisotope Dilution Technique: Method for assessing flow through a system by injection of a known quantity of radionuclide into the system and monitoring its concentration over time at a specific point in the system. (From Dorland, 28th ed)Strontium Radioisotopes: Unstable isotopes of strontium that decay or disintegrate spontaneously emitting radiation. Sr 80-83, 85, and 89-95 are radioactive strontium isotopes.