Canadian Water Quality Guidelines for the Protection of Aquatic Life - Thallium

hallium (Tl) is an inorganic element found in the earth’s crust at concentrations ranging from 0.3 to 0.6 mg⋅kg (NRCC 1982). Thallium is rarely present as large ore deposits, but can be recovered from sulphide ores of lead, copper, and zinc and may also be associated with cadmium, iron, and potassium minerals such as feldspars and micas. Thallium minerals such as crookesite, hutchinsonite, lorandite, and avicennite occur naturally but are rare. Most of the thallium used in Canada is imported from the United States and is used in alloys, electrodes, low-melting and highly refractive glass, cardiac imaging, electroplating, and as a high-temperature super-conducting compound (ATSDR 1991; Gregotti et al. 1992; Sager 1992). Thallium compounds are also used in photocells, infrared detectors, catalysts, dyes, imitation jewellery, electrical equipment, photographic and ceramic formulations, ozone measurement, and pyrotechnical applications (McNeely et al. 1979; Chandler and Scott 1986; ATSDR 1991). The estimated yearly world production of thallium was 30 t for 1985 (Emsley 1991).