ItalyAlthough some articles report that it is possible to extrapolate from LD50 to NOAEL1, this approach is totally wrong because of several reasons:
- LD50 value is related to lethality (an endpoint that can't be classified as an adverse effect)
- LD50 is calculated from acute exposure studies, whereas the NOAEL is extrapolated from longer term ones.
LD50 is used to classify toxic agents and a threshold for non-adverse effect is totally missing from the experimental design of employed tests.
In a typical LD50 protocol, a large amount of test-substance is used within 24 hour period, on the other hand repeated dose toxicity tests employ lower dose-range (which, in turn, are calculated from the outcome of 14-days repeated dose toxicity test and LD50).
In a typical LD50 protocol, a large amount of test-substance is used within 24 hour period, on the other hand repeated dose toxicity tests employ lower dose-range (which, in turn, are calculated from the outcome of 14-days repeated dose toxicity test and LD50).
Bibliography
1Pieters et al. Regulatory Toxicology and Pharmacology, Volume 23, Issue 3, June 1996, Pages 249–255
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