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LC50 (lethal concentration, 50%) estimates LC50 values using the Trimmed Spearman-Karber Method.

  This program originated at Montana State University and has been modified by data processing staffs at the Duluth and Athens National Exposure Research Laboratories.

The Trimmed Spearman-Karber estimate of the LC50 is obtainable for most experiments. In order to estimate an LC50 the only requirement is that at least one mortality proportion must be less than or equal to 50% and at least one must be greater than or equal to 50%. That is, it is not possible to calculate the LC50 by the Spearman-Karber Method if the mortality proportions are all less than 50% or are all over 50%.

For reference, cite: Hamilton, M.A., R.C. Russo, and R.V. Thurston, 1977. Trimmed Spearman-Karber Method for Estimating Median Lethal Concentrations in Toxicity Bioassays. Environ. Sci. Technol. 11(7): 714-719; Correction 12(4):417 (1978).

File Size Download
LC50 Program and Dataset 7.45MB
LC50 installation image and data set, zipped -- Use this if you have a difficulty with EPA's installation program 0.15MB
LC50 FORTRAN source codes 22KB
LC50 User Manual (PDF format) 2.54MB