Sodium hypochlorite is found under the commercial name of bleach. It was first used as a bleaching agent, and it was discovered later on that it also has antimicrobial effects, which is why it is still widely used today for medical purposes. During the First and Second World Wars, it was also used for disinfecting wounds and burns. The concentrations used in healthcare are very low and do not have a harmful effect on humans and animals. However, since the chemical is easily accessible on the market at a very low price, it can quickly occur that due to the lack of awareness in people, higher concentrations, which are potentially toxic to aquatic organisms, are released in the environment. In the scope of this thesis, an acute toxicity test on water fleas (Daphnia magna) was conducted in accordance with the OECD Guideline. The immobilisation of the animals was observed after 24 and 48 hours and the LC50 value was determined. Daphnia magna is only one of the species used for standardized tests and it was selected due to its morphological and physiological characteristics. A 13 % aqueous solution of sodium hypochlorite was used for the test. Several literature sources report on the toxicity of sodium hypochlorite to animals. The data indicate that the toxicity of sodium hypochlorite depends primarily on the concentration and the pathway through which the chemical enters the body.
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