How is toxicity of water pollutants tested with aquatic animals?
Toxicity of chemicals in water can be tested with aquatic animals as indicators. Toxicity tests with aquatic animals are mainly concerned with direct uptake from water. The chemicals may be in solution, in suspension or both. To determine values for lethal concentrations organisms are exposed to different concentrations. When an effect occurs the effect-concentration of the chemical is noted. When the test-animal dies the lethal concentration is noted. This way the toxicity of a chemical is determined in a laboratory. When many of the test animals die at low concentrations of a chemical it means that the chemical in question is very toxic. When we know how toxic a chemical is, we also know the effects of this chemical when a certain concentration is present at a location. The toxicity of a chemical for certain aquatic organisms depends upon the present concentration of the chemical and the time of exposure to the chemical. The time of exposure to a chemical during a toxicity test depen
