Chapter 15
Toxic Effects of Organometallic Compounds towards
Marine Biota
1. Pellerito . R. Barbieri· R. Di Stefano· M. Scopelliti . C. Pellerito· T. Fiore· F. Triolo
15.1
Organometallic Derivatives
Organometallic derivatives are compounds containing a direct (J or 1T: carbon metal
linkage. Furthermore, the concept of the metallic atom must be extended to all the
elements that are less negative than the carbon atom. As a consequence, taking into
account all elements that are less negative than carbon and the number of existing
organic compounds, it is possible to synthesize millions of organometallic derivatives.
Several of these are extensively used in organic syntheses; others may find application in agriculture and in many other fields as pesticides, fire retardants, wood preservatives, antifouling agents, etc. In general, the organic derivatives of the metals are
more toxic than the parent inorganic metal, with the alkyl derivatives bearing greater
toxicity than the aryl ones. Furthermore, the mechanism of toxicity depends on the
co-ordination atoms present in the attached biological molecule.
This review will focus on a limited number of organometallic compounds, i.e. those
whose presence and toxicity have been evidenced in marine biota.
15.2
Organoarsenic
15.2.1
Organoarsenic Derivatives
Arsenic occurs mainly as inorganic arsenate in sea water (2-3 Jlg dm -3) and in marine
biota (up to 100 Jlg kg- 1 of wet weight), as arsenobetaine in marine animals (Fig. 15.1)
and as dimethylarsinylribosides (Fig. 15.1) in marine algae, in which arsenobetaine is
absent. The arsenical derivatives are mainly used as industrial chemicals (wood preservatives), agricultural chemicals (herbicides and desiccants), fining agents in glass
manufacturing, metallic arsenic in non-ferrous alloys, high-purity metallic arsenic for
the electronics industry, and finally a small amount of arsenic is used as additive in
animal food (Ishiguro 1992).
15.2.2
Biotransformation of Arsenic
The biotransformation of arsenic in marine ecosystems has been reported in several
recent papers (Kaise and Fukui 1992; Francesconi et al. 1992; Garman et al. 1993). Owing to the fact that the phosphate/arsenate concentrations may be close to equimolar
Toxic Effects of Organometallic Compounds towards
Marine Biota
1. Pellerito . R. Barbieri· R. Di Stefano· M. Scopelliti . C. Pellerito· T. Fiore· F. Triolo
15.1
Organometallic Derivatives
Organometallic derivatives are compounds containing a direct (J or 1T: carbon metal
linkage. Furthermore, the concept of the metallic atom must be extended to all the
elements that are less negative than the carbon atom. As a consequence, taking into
account all elements that are less negative than carbon and the number of existing
organic compounds, it is possible to synthesize millions of organometallic derivatives.
Several of these are extensively used in organic syntheses; others may find application in agriculture and in many other fields as pesticides, fire retardants, wood preservatives, antifouling agents, etc. In general, the organic derivatives of the metals are
more toxic than the parent inorganic metal, with the alkyl derivatives bearing greater
toxicity than the aryl ones. Furthermore, the mechanism of toxicity depends on the
co-ordination atoms present in the attached biological molecule.
This review will focus on a limited number of organometallic compounds, i.e. those
whose presence and toxicity have been evidenced in marine biota.
15.2
Organoarsenic
15.2.1
Organoarsenic Derivatives
Arsenic occurs mainly as inorganic arsenate in sea water (2-3 Jlg dm -3) and in marine
biota (up to 100 Jlg kg- 1 of wet weight), as arsenobetaine in marine animals (Fig. 15.1)
and as dimethylarsinylribosides (Fig. 15.1) in marine algae, in which arsenobetaine is
absent. The arsenical derivatives are mainly used as industrial chemicals (wood preservatives), agricultural chemicals (herbicides and desiccants), fining agents in glass
manufacturing, metallic arsenic in non-ferrous alloys, high-purity metallic arsenic for
the electronics industry, and finally a small amount of arsenic is used as additive in
animal food (Ishiguro 1992).
15.2.2
Biotransformation of Arsenic
The biotransformation of arsenic in marine ecosystems has been reported in several
recent papers (Kaise and Fukui 1992; Francesconi et al. 1992; Garman et al. 1993). Owing to the fact that the phosphate/arsenate concentrations may be close to equimolar