'\ , Chemistry 1 Applications, Toxicity 1 and Po·llution Potential of Thallium by v. Zitko FISHERIES AND MARINE SERVICE SER V ICE DES PECHES ET DES SCIENCES DE LA MER TECHNfCAl REPORT No. RAPPORT TECHNIQUE N° 518 197 5 Environment Ehviro nnement + Canada Canada Fisheries Service des peches and Marine et des sciences Service de la mer Technical Reports Technical Reports are research documents that are of sufficient importance to be preserved, but which for some reason are not appropriate for primary scientific publication. Inquiries concerning any particular Report should be directed to the issuing establishment. Rapports Techniques Les rapports techniques sont des documents de recherche qui revetent une assez grande importance pour etre conserves mais qui, pour une raison ou pour une autre, ne conviennent pas a une publication scientifique prioritaire. Pour toute demande de renseignements concernant un rapport particulier, il faut s'adresser au service responsable. Department of the Environment Ministere de l'Environnement • Fisheries and Marine Service Service des Peches et des Sciences de la mer Research and Development Directorate Direction de la Recherche et Developpement TECHNICAL REPORT No. 518 RAPPORT TECHNIQUE N° 518 (Numbers 1-456 in this series were issued (Les numeros 1-4';6 dans cette serie furent as Technical Reports of the Fisheries utilises comme Ra]Jports Techniques dE:, l' office Research Board of Canada. The series des recherches sur les pecheries du Canada. name was changed with report number 457) Le nom de la serie fut change avec le rapport numero 457) Chemistry, applications, toxicity, and pollution potential of thallium By V. ZITKO This is the seventy-eighth Ceci est le soixante-dix-huitieme Technical Report from the Rapport Technique de la Direction de la Research and Development Directorate Recherche et Developpement Biological Station Station Biologique St. Andrews, New Brunswick St-Andrews, N.-B. 1975 Zitko, V. 1975. Chemistry, applications, toxicity, and pollution potential of thallium. Fish. Mar. Servo Res. Dev. Tech. Rep. 518: 41 p. ABSTRACT The occurrence, production, properties, applications, determination, toxicity, and pollution potential of thallium are reviewed. Thallium is present at low levels in many rocks and ores and is recovered industrially from base-metal sulfide ores. Most thallium compounds are highly soluble in water and have little tendency to f orm complexes. Thallium is used in alloys, electronic devices, special glass, and catalysts f o r organic reactions. Many methods are available for the determination of traces o f thallium. Thallium is slightly more acutely toxic than mercury to mammals and as acutely toxic as copper to fish. Little is known about its chronic effects. The present industrial uses of thallium are too limited to generate pollution problems, but pollution may exist in the vicinity of mines and ore-processing plants. Thallium was detected in base-metal mining effluents. The conventional removal of heavy metals from waste water has little effect on thallium. ~ ~ RESUME Nous revoyons ici les caracteres suiva nts du thallium: incidence, production, proprietes, applications, dosage, toxicite et pouvoir polluant. On rencontre le thallium en faible concentration dans plusieurs types de roches et de minerais et, sa recuperation industrielle se fait a partir de minerais de metaux communs sulfures. La plupart des composes du thallium sont tres solubles dans l'eau et ne se complexent que tres rarement. On utilise le thallium dans les alliages, les dispositifs electroniques, les verres speciaux et dans les catalyseurs de reactions organiques. On dispose de plusieurs methodes de dosage du thallium a l'etat de traces. La toxicite du thallium pour les mammiferes est legerement plus prononcee que celle du mercure et sensiblement la meme que celle du cuivre, pour les poissons. Ses effets chroniques nous sont presque completement inconnus. A l'heure actuelle, l'utilisation industrielle du thallium est encore trop restreinte pour entrainer des problemes de pollution sauf, peut-etre, a proximite des mines et des usines de traitement du minerai. On a decele la presence de thallium dans les effluents produits par l'extraction miniere des metaux ordinaires. L'elimination classique des metaux lourds des eaux usees a peu d'effets sur le thallium. 2. INTRODUCTION Thallium is a metal not receiving much attention and relatively obscure for the non-specialist. The main reason for this is probably its limited use. Thallium is usually recovered as a byproduct of sulfide ore processing, however, due to the small demand many smelters, producing thallium, operate below capacity. Frequently thallium is not recovered and little is known about its fate in the waste products. Thallium is very toxic and has a history of human and animal poisonings. Consequently, it would be desirable to know more about its environmental levels and chronic toxicity. Thallium was recently detected in effluents from base-metal mines and may also be present in wastes from the processing of other minerals. Judging from the patent literature, the number of potential thallium applications is increasing and may lead to a wider dissemination nf thallium in the environment. This review summarizes chemical and toxicological properties and uses of thallium in order to stimulate further research of its environmental occurrence and possible pollution problems. OCCURRENCE The average concentration of thallium and several other metals in the lithosphere and in sea water is presented in Table 1. According to other estimates (Hampel 1968), the concentration of thallium in the earth crust may be up to 10 times higher than given in Table 1 which would make thallium more abundant than some other industrially important metals, such as mercury, antimony, bismuth, cadmium, and silver. TABLE 1. Average concentration of metals in lithosphere and in seawater. Lithosphere, \1g/g, Seawater (Lange and Forker, 1967) (Gaskell, 1971) 1-1etal \1g/~ t 9 Copper 70 3 5 x 10 9 Zinc 1 10 16 x 10 6 Cadmium 0.15 0.1 150 x 10 6 Mercury 0.5 0.003 46 x 10 6 Thallium 0.1 0.01 15 x 10 6 Lead 16 0.03 46 x 10 Thallium 0.0187* 0.0094-0.0166** *Matthews and Riley, 1969; **Matthews and Riley, 1970 3 • • Thallium ores, c ~ o~ ks it e, lo ~ an d i t e , and h utchinsoni t e are extremely rare. Thallium i s generaJly present in sulfide ores, such as galena (PbS), chalc opyrite (CuFeS ), sphalerite 2 (ZnS), and pyrite (FeS ). The average concentration of 2 thallium in ores and rocks is pre sented in Table 2. In TABLE 2. Thallium concentration in ores and rocks. C~ncentr a tion Material ~g/g Reference Galena 1.4-20 Kogan, 1970 Sphalerite 8-45 Kogan, 1970 Pyrite 5-23 Kogan, 1970 Calcareous-alkaline rocks 1.85-2.54 Dupuy et al., 1973 Granitic rocks 0.68-1.3 Mogarovskii et al., 1972 Sedimentary rocks 2.5 Nuriev and Dzhabbarova, 1973 Marine sediments 0.17-5.7 Matthews and Riley, 1970 Manganese nodules 1.85-199.8 Glasby, 1973 Mid-Atlantic Ridge basalts 0.20 DeAlbuquerque et al., 1972a Coal 0.05-10 Bowen, 1966 Limestone 0.5 Voskresenskaya, 1968 Silica-carbonate soil 2.7 Kothny, 1969 colloform varieties of sulfide ores the concentration of thallium may be as high as 10 mg/g (Robinson, 1973), and the occurrence of thallium in sulfide ores was extensively studied (Kiyoshi, 1966; Ivanov et al., 1967; Vershkovskaya et al., 1970; Ivanovet al., 1972). Thallium is also present in alkali-rich silicates such as alkali feldspars and micas. Sedimentary minerals such as manganese nodules contain relatively high levels of thallium and so do shales, in which thallium was probably deposited as a result of bacterial reduction (Voskresenskaya, 1972). Mathis and Kevern (1973) reported an average thallium conc entration of 8.1 ~g/g (range 2.1-23.1) in sediments of Wintergreen Lake, Michigan, and suggested that aerial fallout may be the primary source of thallium in this lake. Not much information is available on the levels of thallium in biological material (Table 3). As the data indicate, thallium is generally present only in extremely low concentra­ tions. 4 . TABLE 3. Tha ilium conten t of bie·logical material. Sample Concentration Reference Mammalian tissues 0.2-0.5 ).lg/g dry weight B.Jwe~l., 1966 Blood < 0.02 mg/Q, Bowen, 1966 Human body 0.1-0.6 ).lg/kg Goenechea and Sellier, 1967 Linaria triphylla 3800 ).lg/g ash Zyka, 1970 (Alsar, Yugoslavia) Kale 0.14 ).lg/g dry weight Kothny, 1969 PRODUC'TION The current world production of thallium is 10-12 t/year, of which Bt are produced in West Germany and 2-3t in the United States. In Canada, 60 kg of thallium per year was produced at Flin Flon, Manitoba, in 1944-1946, and 125 kg in 1955. More recent production data are not availaLle (Kogan, 1970). The world production capacity is estimated at 25t/year. The amount of potentially recoverable thallium is much higher but the recovery is not economical because of the low demand for thallium. The U.S. yearly consumption of thallium is about 3t (Robinson, 1973). Thallium is mainly recovered as a byproduct in the smelting of base-metal ores (Petrick et al., 1973), and from dust in the lithopone production (Kogan, 1970). Recovery is based on leaching with water or on distillation of the volatile chloride (Angelova et al., 1966; Angelova and Petkova, 1967), cementation and refining of thallium (Kogan, 1970; Petrova and Gladyshev, 1972; Ozols­ Kalnins and Purin, 1972; Oka et al., 1973). Thallium, containing only 0.3-5.5 ).lg/g of impurities, may be prepared (Wojtaszek and Lehman, 1973). The U.S. thallium reserves are estimate d at 240t in sulfide ores and 10B,000t in coal ash.