However, this information does not tell us if A or B is more toxic because we do not know which damage is more critical or harmful. We could say that nerve damage is observed when 10 grams of chemical A is administered, and kidney damage is observed when 10 grams of chemical B is administered. We could measure the amount of a chemical that causes kidney damage, for example, but not all chemicals will damage the kidney. Since different chemicals cause different toxic effects, comparing the toxicity of one with another is hard. Depending on how the chemical will be used, many kinds of toxicity tests may be required. Other durations of exposure (versus the traditional 4 hours) may apply depending on specific laws.Ĭhemicals can have a wide range of effects on our health. The concentrations of the chemical in air that kills 50% of the test animals during the observation period is the LC 50 value. The animals are clinically observed for up to 14 days. LC values usually refer to the concentration of a chemical in air but in environmental studies it can also mean the concentration of a chemical in water.Īccording to the (Organisation for Economic Cooperation and Development) (OECD) Guidelines for the Testing of Chemicals, a traditional experiment involves groups of animals exposed to a concentration (or series of concentrations) for a set period of time (usually 4 hours). The LD 50 can be found for any route of entry or administration but dermal (applied to the skin) and oral (given by mouth) administration methods are the most common. It is usually expressed as the amount of chemical administered (e.g., milligrams) per 100 grams (for smaller animals) or per kilogram (for bigger test subjects) of the body weight of the test animal. Toxicologists can use many kinds of animals but most often testing is done with rats and mice. The LD 50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. LD 50 is the amount of a material, given all at once, which causes the death of 50% (one half) of a group of test animals.
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