Which value should be used as the lethal concentration 50 (LC50) with bacteria?

Abstract

Computations of lethal concentration 50 (LC(50)) of a data-set of a toxicity study on an herbicide against a cyanobacterium were performed by general linear regression, Spearman-Karber and probit transformation methods, for evaluation of the methods used. It is shown that the linear regression method yields some faulty LC(50) value, while both of Spearman-Karber and probit methods yield similar and statistically respectable LC(50) values. In the Spearman-Karber method, a prerequisite of some uniform dose-interval of test-chemical and tiring calculations were involved. But, the probit method is less tiring and additionally computed LC(25) and LC(75) values help assess the solicited accuracy of the LC(50) value and other test-statistics, including minimum inhibitory concentration (MIC), highest-permissive concentration (HPC), and a few more with respect to lethal concentration 100 (LC(100)) without prerequisite of any uniform dose-interval of test-chemical. Further, the redundancy of computations of standard error (SE) and 95% confidence limits (CL) of the LC(50) value is suggested, as CL values are so wide to spoil LC(50) accuracy that is solicited in toxicology.

[C2mim][CH3SO3] – A Suitable New Heat Transfer Fluid? Part 1. Thermophysical and Toxicological Properties

“…The toxicology test with Artemia is presented in Figure . The lethal concentration was calculated with two different techniques, Probit analysis and mortality in function of log­([C 2 mim]­[CH 3 SO 3 ]). , The two methods agree very well, and the average lethal concentration seen in Table is 4.833 ± 0.001 mg/L. The lower LC 50 is indicative of increased toxicity, meaning that 4.833 mg/L of [C 2 mim]­[CH 3 SO 3 ] makes it more toxic when compared to an organic solvent, such as ethylene glycol, with an LC 50 of 112 mg/L .…”

A Simple Method to Determine Cytotoxicity of Water-Soluble Organic Compounds and Solid Particles from Biomass Combustion in Lung Cells in Vitro

“…The LC 50 was determined by linearly fitting (least squares method) the two data points closest above and below 50% cell viability, with axes scaled logarithmically in x and linearly in y . It was shown that LC 50 determination using other methods (e.g., Probit) is more accurate; however, any differences in LC 50 due to applying different fitting methods is expected to be lower than the uncertainties induced by the limited number of different concentrations per sample ( n = 4–6) and the use of average dose–response curves for each combustion condition with standard deviations for the cell viability of up to 35%.…”

Probit analysis of comparative assays on toxicities of lead chloride and lead acetate to in vitro cultured human umbilical cord blood lymphocytes

“…Toxicity values were obtained with different concentrations of PbCl 2 and lead acetate ( Figure 4 ). Percent lethality (PL) values of the third repeated experiment were transformed to probit values by Finney’s method, which were potted against corresponding log 10 values of PbCl 2 and lead acetate concentrations, as exemplified before (Rath et al ., 2011 ). Probits of observed lethality percentage values were from statistical tables of probit transformation.…”