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ALARIE’S RULE: The only appropriate method
to calculate an LC50 (or LD50) and the 95% C.I. is as developed by
Thompson and Weil. See Weil, C. S., Biometrics, 8, 249-261, 1952. Maximum of 4
animals/group and minimum of 4 groups of animals are needed. Thus 16 animals, or at most 6
groups for a total of 24 animals. Don’t fool around getting an “approximate LC50'”
to save a few animals. Consult this reference and do it right. A recent paper giving a
computer method for the above method is Schaper, M. M., Thompson, R. D. and Weil, C. S.
Computer programs for calculation of median effective dose (LD50 or ED50) using the method
of moving average interpolation. Arch. Toxicol. 68, 332-337, 1994. |
