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Spirotox is a short-term acute toxicity test with a large ciliated protozoan Spirostomum ambiguum. The test was created in the Department of Environmental Health Sciences, Medical University of Warsaw, Poland, during the early 1990s. It was presented for the first time during the 6th International Symposium on Toxicity Assessment, in Berlin in 1993. S. ambiguum was very resistant to a wide range of environmental conditions, especially to pH and dissolved oxygen. Over the last 10 years the sensitivity of S. ambiguum to many classes of toxicants was evaluated. Spirotox was found to be very sensitive to heavy metals, fungicides, and pharmaceuticals used to cure diseases of the human nervous system. On the other hand, it was generally less sensitive than standard bioassays to simple organics. Spirotox was also used for analysis of cyanobacterial blooms. Though it was moderately sensitive to hepatotoxins, the test seems to be a good tool for evaluation of the entire toxicity of blooms. The last but not the least of the applications of the Spirotox test was evaluation of the toxicity of extracts from medical devices. Protozoa, which are the simplest eukaryotes, seem to be good screening bioassays for monitoring the technology of medical device production.

Significant effort has been directed toward developing in vitro alternatives, which can be the first step of toxicity analysis. Tissue culture assays are currently the most popular in vitro tests for evaluating acute toxicity. The possibility of applying two bioassays using microorganisms in assessing the toxicity of extracts of medical devices was investigated. The Microtox test system-a luminescent bacteria toxicity test-assesses changes in light output from a luminescent bacteria, Vibrio fischeri. Spirotox used a large ciliate protozoan: Spirostomum ambiguum. The most widely used extraction solvent, 0.9% NaCl, must be concentrated up to 2% for Microtox and diluted nine times for the Spirotox test.The organic solvents ethanol, DMSO, and polyethylene glycol 400 were not toxic in either test in concentrations of 1-2%. The toxicity of reference compounds Hg, Cd, Zn, Pb, and SDS was examined in various diluents. The sequence of toxicity of the tested compounds in Spirotox and Microtox was: Hg > Cd > Zn > Pb > SDS, and Hg > Pb = Zn > SDS > Cd, respectively. Addition of organic solvents changed the toxicity of compounds tested in 60% of Spirotox tests and only in 25% of Microtox tests. Changes were low, not exceeding 100% in almost all cases. No correlation was observed between diluent and toxicant in either bioassay.

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