ABSTRACT
Ecotoxicology investigates the impact of toxic substances on the biota. This science has become more important as pollution increased in parallel to economic development. About 5 million different chemicals are known and about 80,000 of them are in use. 1 Information on the interaction of chemicals with plants, animals, and microorganisms is required to evaluate the toxic influence of these substances. The presence or absence of species in ecosystems can be used as an environmental quality indicator. In addition to the observation of populations or communities, many efforts have been made to culture and test organisms under laboratory conditions. This helps to predict possible future effects of pollutants and to evaluate observed effects in natural ecosystems. The direct effect of toxic substances on single species is used as a base for the evaluation of their ecotoxicological effects on the environment. Many toxicity tests have been developed to determine the effects of chemicals on single species under laboratory conditions. All biological toxicity tests are based on the same principle: living organisms are exposed to toxic agents and their response depending on the dose (exposure level of the toxic agent) is measured. Test organisms, realization, and conditions for different toxicity tests are defined in different guidelines such as the OECD (Organization of Economic Cooperation and Development) guidelines for testing chemicals2 in Europe or the U.S. EPA (United States Environmental Protection Agency) guideline3 in the United States.
