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(T/EH099) Developing a method to simultaneously spike pyrene and cadmium onto algae (Desmococcus sp.) for toxicological studies. Howsam, Mike1, Verwiej, Rudo1, van Straalen, Nico1, 1 ABSTRACT- Toxicological studies often require a method of spiking contaminants onto a matrix (soil, sediment or food) that does not affect the matrix structure, its palatibility to the test organism, nor induce any toxic effects of its own. In studies involving poorly water-soluble compounds like polycyclic aromatic hydrocarbons (PAHs), the use of an organic solvent 'carrier' poses the main problem. Undiluted, organic solvents can affect matrix structure or palatability by solubilising organic matter or affecting cell integrity. In addition, the use of acetone has been shown to affect the survival and reproductive strategies of terrestrial invertebrates undergoing feeding trials (Van Brummelen, 1996, unpublished; Jack, 1999, unpublished). This problem has received significant attention with regard to the spiking of soils and sediments with organic contaminants (eg. Northcott & Jones, 2000, Environ. Toxicol. & Chem. 19, 2409 & 2418), but there remains a dearth of published data on the spiking of food-stuffs for ecotoxicological studies with animals. We tested two approaches to the problem of spiking pyrene onto algae (Desmococcus sp.) in order to feed mg g-1 algae concentrations of this PAH to Orchesella cincta (Collembola). The methods employed either small amounts of solvent in excess water, or else allowed the solvent to evaporate prior to introduction of the aqueous algae slurry. We further developed the method to include a cadmium (Cd) spike onto the algae, in preparation for a study of the mixture toxicity of these contaminants in O. cincta. Results from the spiking trial will be presented, while initial results from feeding trials with O. cincta have been submitted as a separate presentation to this conference. Key words: pyrene, cadmium, algae, spiking |
