Evaluation criteria for acute toxicity tests typically include the following:
1.Half lethal dose (LD50).
The half-lethal dose is the primary indicator for assessing acute toxicity. It represents a dose capable of causing 50% of the deaths in a group of experimental animals over a certain period of time (usually 24 hours). LD50 is usually expressed as a dose per unit of body weight, such as milligram kilograms (mg kg) body weight. The lower the LD50 value, the more toxic the test substance is. This value is calculated by statistical methods, such as the unit of probability method or the ** method.
2.Toxic reactions and symptoms of poisoning.
In addition to LD50, the acute toxicity test also observes and records the toxic reactions and poisoning symptoms of experimental animals after exposure to the test substance. These symptoms may include respiratory depression, cramps, coma, vomiting, diarrhea, irritation, etc. The timing, severity, and duration of these symptoms can all provide important information about the mechanism and intensity of the toxicity of the test substance.
3.Mortality and survival.
Acute toxicity experiments also record the death and survival of experimental animals, and calculate mortality and survival rates. These indicators provide a visual indication of the toxicity intensity of the test substance. A high mortality rate usually indicates a high toxicity of the test substance.
4.Weight changes.
During acute toxicity experiments, the body weight of the experimental animals is also measured periodically to observe changes in body weight. Significant weight loss may be an indicator of the toxic effects of the test substance on experimental animals.
5.Pathological changes.
At the end of the experiment, pathological examinations are usually performed on dead or surviving experimental animals to observe whether there are pathological changes in tissues or organs. These changes may include inflammation, necrosis, bleeding, etc. These pathological changes can provide further evidence for the toxic effects of the test substance.
It is important to note that these evaluation criteria are only part of the acute toxicity experiment, and they provide some basic information about the acute toxicity of the test substance. However, to fully evaluate the safety of a chemical substance or product, it is also necessary to combine other experimental methods and data, such as chronic toxicity experiments, reproductive toxicity experiments, carcinogenicity experiments, etc. In addition, factors such as the stability and bioaccumulation of the test substance in the environment need to be considered.
In addition, there are some other evaluation criteria and methods, such as **Index (TI) and Safety Index (SI), etc. The index is the ratio of LD50 to the effective dose (ED50) and represents the equilibrium relationship between the ** effect and the toxic effect of the test substance. The safety index is the ratio of LD1 to ED95 and is used to evaluate the safety of a test substance at an effective dose. The higher these indices, the safer the substance under test.