The emission of antimony into the human environment appears to be exclusively the result of human activity. Most emitted antimony is in the form of ATO, which is released as a result of coal burning or with fly ash when antimony-containing ores are smelted (Nriagu & Pacyna, 1988). Approximately 6400 tonnes of antimony are transported annually to oceans (Bowen, 1979).

The chemical behaviour of antimony is as complex as that of arsenic, its neighbour in the periodic table (Wiberg, 1985). It is speculated that antimony could be a natural co-contaminant with arsenic in some drinking-waters (Gebel, 1999b). Soluble forms of antimony (and arsenic) tend to be quite mobile in water, whereas less soluble species are adsorbed onto clay or soil particles and sediments, where they are mainly bound to extractable iron and aluminium (Crecelius et al., 1975). Although few data address the speciation of antimony in water, those that are available together with thermodynamic predictions indicate that the most favoured form in water will be the pentavalent oxo-anion, Sb(OH6)- (Mohammad et al., 1990; Cotton et al., 1999).