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December 21, 1984

The LD50—A Tradition in Need of Change

Author Affiliations

Friends of Animals, Inc New York

JAMA. 1984;252(23):3249. doi:10.1001/jama.1984.03350230011006

To the Editor.—  Medicine has a glorious tradition to measure itself against, and this tradition can be a source of both pride and anxiety.Anxiety enters if the physician becomes overwhelmed by the high standards he must measure himself against. In the field of research, it becomes "publish or perish."Knowledge and skill are so hard earned it is no wonder that once established, the practitioner is careful before upsetting basic beliefs. Tradition is a comforting ballast. Yet, all professions must continually evaluate their mode of operation and, as the need arises, eliminate or revise what has become habitual and traditional.An example of a procedure that has outlived its usefulness is the median lethal dose (LD50) test. The LD50 test was first used in 1927 to assay the potency of digitalis. It has been used ever since with few changes to determine the acute toxicity of new