Reinette G. Snyman

Human Exposure, Biomarkers, and Fate of Organotins in the Environment

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.

Fractionation mobility and multivariate statistical evaluation of metals in marine sediments of Cape Town Harbour, South Africa.

Abstract Distribution of possible chemical forms of Al, Si, Sn, Pb, Zn, Fe, Hg, Cd and Cu in marine sediments of Cape Town harbour was investigated using a modified Tessier’s sequential extraction procedure and ICP-MS and ICP-AES for heavy metals determination. The mean fractions for all metals at all locations were: 1.5–7196 mg kg-1 for Si, 7.79–7266 mg kg-1 for Al, 161-639 mg kg-1 for Cu, 19–41978 mg kg-1 for Fe, 2.83–5864 mg kg-1 for Zn, 1.45–13.26 mg kg-1for Cd, 9.87–223 mg kg-1 for Sn, 11.98-979 mg kg-1 for Pb and 0.13–5.93 mg kg-1 for Hg. Si, Al and Zn were mostly associated with Fe–Mn oxides, whereas Sn and Hg were mainly bound to residual and organic matter. Pb existed mainly in the residual and iron/manganese oxide phases while Cd was evenly distributed in all the five phases. The loading plots of heavy metals bound to the various chemical forms, as well as Pearson correlation coefficients, enabled the determination binding relationship. Pb, Sn and Hg exhibited similar binding behaviour which indicated an anthropogenic point source from wastes from the ship maintenance workshop, and the presence of Sn in the organic phase can be identified with the use of anti-fouling paints at the harbour, whereas Al, Fe, Si, Cu and Zn would probably be of natural origin. Lastly Cd probably came from a diffuse pollution sources in the harbour due to its unique binding characteristic. The mobility of heavy metals varied depending on location and the heavy metal type. The mobility of metals followed the order: Si > Zn > Fe > Cu> Al> Cd> Pb > Sn > Hg. The high percentage of Cd and Pb in the bioavailable forms suggested the need to keep close surveillance on these metals because of their high toxicity.

Effect of Cadmium on Haemocyte Viability of the Woodlouse Porcellio laevis (Isopoda, Crustacea)

This study investigated the effects of cadmium on haemocyte viability of the woodlouse Porcellio laevis, using the trypan blue exclusion assay. The ultimate aim is to determine the usefulness of this cellular response as biomarker of cadmium exposure. Results showed that exposure to sublethal concentrations of cadmium, with concomitant cadmium accumulation in the body, significantly lowered the percentages of viable haemocytes in P. laevis. This response was already observed after the first week of exposure and could therefore possibly serve as an early warning of cadmium exposure. A field study is needed to validate these findings.

Mineral analysis of an artificial pond sediment samples from the Western Cape Province, South Africa.

Mineralogical characterization was carried out to determine the major and minor constituent minerals present in sediment samples collected from five different locations at the Western Cape artificial pond sediment, South Africa by Fourier transform infrared (FT-IR) and X-ray diffractometry (XRD) techniques. The minerals were identified with the available literature from the IR absorption band of the locations of different peaks. The FT-IR technique was highly useful in identifying different minerals in sediments. The XRD analysis revealed that the minerals of artificial pond sediments in Western Cape are predominantly composed of quartz while carrolite was present in location one. The presence of pyrite could also suggest anoxia, which in turn will imply differential Fe (Iron) levels in the sediment as a function of the degree of anoxia in the sediment.

The effect of particle sizes on metal accumulation in the marine sediments of Cape Town harbour, South Africa

Abstract This study was carried out to assess the elemental concentration in sediment samples collected from six locations in the Cape Town Harbour. The effect of size variation was considered determinant on metals accumulated in sediments. An Inductively coupled plasma-Mass spectrometry (ICP-MS) instrument was used for the analysis. The following metals were investigated Mn, Cr, V, Ni, Co, and As. The order of heavy metal concentration in sediments was Mn > Cr > V > Ni > Co > As. Strong correlation was found between these metals (Mn and V in sizes <75 and ≥150), (As and Co in size ≥150), (Ni and Cr in size ≥150 and <75).