Chapter 14
Occurrence, Formation and Fate of Organoantimony
Compounds in Marine and Terrestrial Environments
P.J.Craig· S.N.Forster· R.O.Jenkins· D.P. Miller . N.Ostah· L.M.Smith· T.-A.Morris
14.1
Occurrence of Organoantimony Compounds in Marine and
Terrestrial Environments
Antimony is a relatively common group 15 metalloid, with world industrial production around 80 000 tonnes. It occurs at 0.2 ppm crustal abundance (arsenic at 1.8 ppm,
Carmalt and Norman 1997). The majority of antimony metal usage is in metallurgy
where it is used as an alloy to impart hardness to lead and other metals (Maeda 1994).
The main use of antimony compounds is as a flame retardant, with Sb20 3 being the
most commonly used compound (ca. 90% of the annual usage of Sb20 3 in the US and
Japan is as a flame retardant (Maeda 1994). The ubiquitous nature of such compounds
in consumer products can lead to worrying amounts of antimony in landfill sites and
in emissions from municipal incinerators. Organometallic antimony compounds -
unlike those of As, Sn and Pb - are not exposed to the natural environment during
usage. The only common use of organometallic antimony compounds is as precursors in the manufacture of semiconductors. This use is restricted to very controlled
environments, hence there is no obvious route for organometallic antimony compounds to enter the environment. Anthropogenic emissions of antimony to the atmosphere have been calculated at 6 tonnes per year, while that for arsenic is 31 tonnes;
natural emissions are 3 and 12 tonnes respectively.
Antimony is a heavy element and its toxicity is comparable to arsenic. The nature
of its toxicity, however, has not been fully investigated. The toxic nature of antimony
depends on the oxidation state, with the trivalent state being more toxic than the pentavalent state(Oehme 1979). The poor solubility of most antimony compounds slows
down excretion, thereby causing accumulation of antimony in the body. Antimony
compounds react with thiol groups in enzymes and other cellular constituents
and have particular affinity for the liver, kidney and thyroid (Maeda 1994). The toxicity of most antimony compounds has, as mentioned, been little investigated and for
organometallic compounds there is little information available regarding toxicity.
Antimony oxide has been shown to cause cancer in some studies (Jones 1994).
Relatively little is known about the chemistry of antimony, compared to that of arsenic. As mentioned above, the natural abundance of antimony is low compared to its
congener arsenic (Carmalt and Norman 1997). The natural chemistry of arsenic seems
to be much more diverse than that of other related heavy elements (e.g. Hg, Sn, Se, Te)
and encompasses large organic structures such as the arsenosugars, arsenobetaine
and arsenocholine (Cullen and Reimer 1989). These involve methyl arsenic moieties
being bonded to complex organic counter-ions. This may occur for other metals, including antimony, but nothing is known yet. The chemistry of organometallic anti-
Occurrence, Formation and Fate of Organoantimony
Compounds in Marine and Terrestrial Environments
P.J.Craig· S.N.Forster· R.O.Jenkins· D.P. Miller . N.Ostah· L.M.Smith· T.-A.Morris
14.1
Occurrence of Organoantimony Compounds in Marine and
Terrestrial Environments
Antimony is a relatively common group 15 metalloid, with world industrial production around 80 000 tonnes. It occurs at 0.2 ppm crustal abundance (arsenic at 1.8 ppm,
Carmalt and Norman 1997). The majority of antimony metal usage is in metallurgy
where it is used as an alloy to impart hardness to lead and other metals (Maeda 1994).
The main use of antimony compounds is as a flame retardant, with Sb20 3 being the
most commonly used compound (ca. 90% of the annual usage of Sb20 3 in the US and
Japan is as a flame retardant (Maeda 1994). The ubiquitous nature of such compounds
in consumer products can lead to worrying amounts of antimony in landfill sites and
in emissions from municipal incinerators. Organometallic antimony compounds -
unlike those of As, Sn and Pb - are not exposed to the natural environment during
usage. The only common use of organometallic antimony compounds is as precursors in the manufacture of semiconductors. This use is restricted to very controlled
environments, hence there is no obvious route for organometallic antimony compounds to enter the environment. Anthropogenic emissions of antimony to the atmosphere have been calculated at 6 tonnes per year, while that for arsenic is 31 tonnes;
natural emissions are 3 and 12 tonnes respectively.
Antimony is a heavy element and its toxicity is comparable to arsenic. The nature
of its toxicity, however, has not been fully investigated. The toxic nature of antimony
depends on the oxidation state, with the trivalent state being more toxic than the pentavalent state(Oehme 1979). The poor solubility of most antimony compounds slows
down excretion, thereby causing accumulation of antimony in the body. Antimony
compounds react with thiol groups in enzymes and other cellular constituents
and have particular affinity for the liver, kidney and thyroid (Maeda 1994). The toxicity of most antimony compounds has, as mentioned, been little investigated and for
organometallic compounds there is little information available regarding toxicity.
Antimony oxide has been shown to cause cancer in some studies (Jones 1994).
Relatively little is known about the chemistry of antimony, compared to that of arsenic. As mentioned above, the natural abundance of antimony is low compared to its
congener arsenic (Carmalt and Norman 1997). The natural chemistry of arsenic seems
to be much more diverse than that of other related heavy elements (e.g. Hg, Sn, Se, Te)
and encompasses large organic structures such as the arsenosugars, arsenobetaine
and arsenocholine (Cullen and Reimer 1989). These involve methyl arsenic moieties
being bonded to complex organic counter-ions. This may occur for other metals, including antimony, but nothing is known yet. The chemistry of organometallic anti-