Toxic Effect Frequencies Resulting from Specific Exposure Levels

1 Toxic Effect Frequencies Resulting from Specific Exposure Levels 

The most common statistic obtained from animal toxicity testing is the median dose. To have meaning, the median dose needs to be reported in the context of the toxicity test from which it is derived. For example, if the toxicity test was for acute lethality, then the median dose is reported as the 50% lethal dose, or LD50 the species and route of exposure are also specified, e.g., LDgoo rraf If it is a long-term or chronic toxicity test with an endpoint other than death, e.g., liver disease, the median dose is reported as the 50% toxic dose, or TDsoorairat- 

The quantal dose-effect curve provides a guide to toxic effect frequencies relative to exposure under the conditions of the laboratory toxicity test. Doses corresponding to other toxic effect frequencies may be extrapolated from cumulative dose-effect curves. For example, the 10% toxic dose, or TD,q, represents a dose corresponding to a cumulative-effect incidence of 10% of the test population it is determined by finding the dose that corresponds to a 10% cumulative-effect frequency (in the sigmoidal curve) or 3.7 probit units (in the probit plot). The 75% toxic dose, or TD75, is the dose corresponding to 75% cumulative-effect incideuce or 5.8 probits. 

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