Organotin compounds result from the addition of organic moieties to inorganic tin.Thus, one or more tin-carbon bonds exist in each organotin molecule. The organo-tin compounds are ubiquitous in the environment. Organotin compounds have many uses, including those as fungicides and stabilizers in plastics, among others in industry. The widespread use of organotins as antifouling agents in boat paints has resulted in pollution of freshwater and marine ecosystems. The presence of organotin compounds in freshwater and marine ecosystems is now understood to be a threat, because of the amounts found in water and the toxicity of some organotin compounds to aquatic organisms, and perhaps to humans as well. Organotin com-pounds are regarded by many to be global pollutants of a stature similar to biphenyl,mercury, and the polychlorinated dibenzodioxins. This stature results from the high toxicity, persistence, bioaccumulation, and endocrine disruptive features of even very low levels of selected organotin compounds.Efforts by selected governmental agencies and others have been undertaken to find a global solution to organotin pollution. France was the first country to ban the use of the organotins in 1980. This occurred before the international maritime organization (IMO) called for a global treaty to ban the application of tributyltin (TBT)-based paints. In this chapter, we review the organotin compounds with emphasis on the human exposure, fate, and distribution of them in the environment. The widespread use of the organotins and their high stability have led to contamination of some aquatic ecosystems. As a result, residues of the organotins may reach humans via food consumption. Notwithstanding the risk of human exposure, only limited data are available on the levels at which the organotins exist in foodstuffs consumed by humans. Moreover, the response of marine species to the organotins, such as TBT, has not been thoroughly investigated. Therefore, more data on the organotins and the consequences of exposure to them are needed. In particular, we believe the following areas need attention: expanded toxicity testing in aquatic species, human exposure, human body burdens, and the research to identify biomarkers for testing the toxicity of the organotins to marine invertebrates.

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Heavy metal concentrations in black mussels (Mytilus galloprovincialis) collected from Cape Town Harbour were determined using energy dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma-mass spectrometry (ICP-MS). EDXRF showed that tissue portions of the mussels contained K, Ca, Fe, Cu, Zn, Si, Sr, Al and Au, while the shell portion contained K, Ca, Fe, Cr, Zn, Si and Sr. In addition to these metals, EDXRF also revealed the presence of Al in the shells of the largest mussels. Highest concentrations of Cu and Zn were recorded in the tissues of the smallest mussels. Due to poorer detection limits of EDXRF, ultra-trace elements (Mn, Pb, As, Hg, V, Cr, Sn, Cd, Ni and Co) were determined in mussels using ICP-MS. The average metal concentrations found in the mussels are as follows; Pb (7.30 ± 0.67), Cd (1.98 ± 0.13), Hg (4.92 ± 0.60), As (6.94 ± 0.04), Sn (2.63 ± 0.13), Ni (1.88 ± 0.05), Cr (3.54 ± 0.05), V (4.17 ± 0.23), Co (0.74 ± 0.01) and Mn (35.20 ± 1.46). ANOVAs, Pearson correlation and principal component analysis (PCA) were employed in data analysis. The order of the abundance of metals in the mussels isThe average metal concentrations found in the mussels were higher than the permissible Food and Agriculture Organization (FAO) limits and other international guidelines.

This study investigated the use of lysosomal responses of hemocytes of the common garden snail, Helix aspersa, as biomarker of stress due to exposure to the fungicide copper oxychloride. The neutral red retention (NRR) time assay was employed for this purpose. Two groups of snails were exposed to 80 microg g(-1) and 240 microg g(-1) copper oxychloride in their food, respectively, for a period of 6 weeks. They were compared with a control group to which no copper oxychloride was added. The two groups exposed to the fungicide exhibited significantly higher (p < 0.001) whole body copper concentrations (200.85 +/- 53.5 and 272.24 +/- 67.15 microg g(-1) dry mass, respectively), and significantly shorter (p < 0.001) NRR times (10.22 +/- 3.53 and 2.67 +/- 2.83 min, respectively), after 6 weeks, compared to the control group (67.85 +/- 31.08 microg g(-1) dry mass and 24.44 +/- 8.35 min). In both exposure groups NRR times became progressively shorter as body copper concentrations increased over time. Thus, both exposure concentration and exposure time of copper oxychloride were shown to be important factors influencing lysosomal responses (and therefore NRR times) of H. aspersa hemocytes. It was concluded that these responses in this species, as measured by the NRR time assay, could be considered a useful cellular biomarker of stress resulting from exposure to copper oxychloride.

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The concentrations of metals in the mussel Mytilus galloprovincialis (Lamarck, 1819) prevalent along the west coast of the Cape Peninsula, Cape Town are presented. The mussels were sampled during the routine "Mussel Watch Programme" (MWP) between 1985 and 2008. Levels of Cu, Cd, Pb, Zn, Hg, Fe and Mn at Cape Point, Hout Bay, Sea Point, Milnerton and Bloubergstrand were analysed for autumn and spring and showed consistent similar mean values for the five sites. There was a highly significant temporal (annual and seasonal) difference between all metals as well as a significant difference in metal concentrations between the five sites. The concentrations of Zn, Fe, Cd and Pb were higher than previous investigations and possibly indicative of anthropogenic sources of metals. The results provide a strong motivation to increase efforts in marine pollution research in the area.

The adsorption of phenanthrene onto activated carbons produced from Vitis vinifera leaf litter (a waste plant biomass) was investigated in this study. Zinc chloride (ZnCl 2) and phosphoric acid (H 3 PO 4) were utilised as activating agents in producing the activated carbons. The characterisation of the activated carbons was achieved with Fourier transform infrared spectroscopy (for surface functional groups), scanning electron microscopy (for surface morphology) and Brunauer-Emmett-Teller (BET) (for surface area determination). The adsorption of phenanthrene onto the activated carbons was optimised in terms of solution pH, adsorbent dosage, initial concentration of adsorbate solution and contact time. Experimental results showed that H 3 PO 4 modified activated carbon gave better yield (up to 58.40%) relative to ZnCl 2 modified activated carbon (only up to 47.08%). Meanwhile, surface characterisation showed that ZnCl 2 modification resulted in higher BET surface area (up to 616.60 m 2 /g) and total pore volume (up to 0.289 cm 3 /g) relative to BET surface area of up to 295.49 m 2 /g and total pore volume of up to 0.185 cm 3 /g obtained from H 3 PO 4 modified activated carbons. Adsorption equilibrium data fitted well into Freundlich isotherm model relative to other applied isotherm models, with maximum K f value of 1.27 for ZnCl 2 modified activated carbon and 1.16 K f value for H 3 PO 4 modified activated carbon. The maximum adsorption capacity for ZnCl 2 and H 3 PO 4 activated carbons for the removal of phenanthrene were 94.12 and 89.13 mg/g, respectively. Kinetic studies revealed that dynamic equilibrium was reached at 80 min contact time. Experimental data fitted best into the Elovich kinetic model relative to other kinetic models, based on the correlation coefficient (R 2) values obtained from kinetic studies. Chemisorption was deduced as a major phenanthrene removal pathway from aqueous solution and the physicochemical characteristics of the adsorbents have major influence on phenanthrene removal efficiencies.

This study investigated the levels of polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples of the Diep River freshwater system of Western Cape Province, South Africa. A solid-phase extraction -gas chromatography -flame ionisation detection (SPE-GC-FID) method was utilised to simultaneously determine the 16 United States Environmental Protection Agency (US EPA) listed priority PAHs in water and sediment samples. The seasonal averages of individual PAH detected at the studied sites, ranged between not detected (Nd) and 72.38 AE 9.58 μg/L in water samples and between Nd and 16.65 AE 2.63 μg/g in the corresponding sediment samples. The levels of PAHs measured in water and sediment samples were subjected to probabilistic risk assessment to predict the possibility of regulatory values being exceeded. The average percentage exceedence of 63.26 was obtained for PAHs in water samples of the Diep River, while the corresponding average percentage exceedence obtained for sediment sample was 63.71. Sufficient exposure of humans and aquatic organisms to the exceedance levels obtained, would cause adverse health effect.