Comparison of the toxicity thresholds of water pollutants to bacteria, algae, and protozoa in the cell multiplication inhibition test

Using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of 156 potential water pollutants was determined for model organisms of biological self-purification, i.e. bacteria of the species Pseudomonas putida, green algae of the species Scenedesmus quadricauda, and flagellate protozoa of the species Entosiphon sulcatum. From the number of 156 inorganic and organic pollutants tested, 23 exhibited a pronounced selective toxic action on bacteria of the species Pseudomonas putida, 47 on algae of the species Scenedesmus quadricauda, and 43 on flagellate protozoa of the species Entosiphon sulcatum. It is seen from the ratios found that a determination of the toxicity threshold of potential water pollutants for these three model organisms from the microbiological spectrum would provide a broader basis for assessing the damaging action of water pollutants to model organisms active in the biological self-purification of water. Ecotoxicological testing of potential water pollutants to evaluate their toxicity involving only one model organism of biological self-purification would give an incomplete and biased picture of the effects of pollutants.