FIELDS W, X, and Y 

 Columns 68; 69 and 



70; and 71 



of response in the individual organism ; for example, the definitions do not specify that the response is 

 the threshold response, or 50% response, or 80% response, etc. , in the individual . 



However, Criteria 51, 52, and 53 have been generally intended for evaluating responses of the 

 "all-or-none" type (which responses display no graduation of intensity — in particular, death ) or thresh- 

 old intensities of other responses. (See Division 14. ) As with Criterion 20, when the response is "death" 

 or other all-or-none response of the individual, the "potency" of the test compound for producing the re- 

 sponse in the individual can be expressed solely by the quantity needed to produce that intensity in the 

 individual. This quantitative dosage value, therefore, can be correlated with the third factor, the percent- 

 age of individuals responding; the percentage-of-individuals value might also be regarded as an "inten- 

 sity" of response, in terms of population response. When the response is not death or other all-or-none 

 response of the individual, Criterion 51, 52, or 53 can be used only by ignoring the factor of variation of 

 response intensity in the individual (or by redefining the criteria, setting this variable at a fixed inten- 

 sity level, such as 100% response in each individual). 



The quantity of test compound administered is expressed in Fields M, N, O, and P. Of these, 

 Fields M, N, and P (concentration, quantity per unit of administration, and duration of administration, 

 respectively) are most significant in expressing actual measure of total quantity. Variation in quantity 

 of the test compound can be in terms of variation in any of these fields. Thus, three criteria are pro- 

 vided to distinguish the terms in which the dosage is expressed: Criterion 51 (concentration vs. 

 percentage of organisms responding), Criterion 52 (quantity per administration or per unit time vs. 

 percentage of organisms responding), and Criterion 53 (duration of administration of a standard 

 concentration or quantity vs. percentage of organisms responding). It is not inconceivable that the 

 variant in an experimental dosage regimen might be the frequency of administration (Field O) rather 

 than dose concentration, quantity, or duration of administration. However, no special Criterion has 

 been established for correlating frequency of administration with percentage of individuals responding. 



To derive a code evaluation with Criterion 51, 52, or 53, the two factors involved are correlated 

 on the special Log-Probit Grid, described in Division 24. This Grid is used by the CBCC for all fields 

 of biology testing (insecticide, herbicide, enzyme, pharmacology, etc. ) when (and only when) the data 

 are expressed in terms of the two variable factors, (1) percentage of organisms responding to the test 

 compound vs. (2) either the dose causing that response (as in the case of Criterion 51, 52, or 53) or 

 a time factor (as in the case of Criterion 54). When administration has been made at only one dosage 

 level and the percentage of individuals responding has been determined, this single correlation can 

 be made on the Grid and the evaluation area(l, 3, 5, 7, or 9) in which the correlation point falls will 

 provide the symbol for coding Field Y. If a series of tests are run, each with different dosage levels, 

 and the percentages of organisms responding to each level are determined, each dosage can be correlated 

 with the percentage of individuals responding to that dosage; a line drawn to connect these several 

 points on the Grid will indicate, by its relation to the areas of the Grid, the evaluation symbol to be 

 used in Field Y, as described in Division 24. 



20. Criteria 54, 57, 58, and 59; evaluation of intensity of response expressed in terms of the 

 percentage of individuals affected relative to the time value (Field U) connected with the 

 response 



Reference should be made to Division 10 which describes Criteria 10, 11, 12, and 13 relative 

 to their expressing evaluations in terms of potency of the test compound for producing the response. 



Test compounds are frequently evaluated in terms of the relative speed by which they produce 

 a specific response, or by relative duration of the response they produce, etc. When evaluation is 

 based on only this time value, one of Criteria 10, 11, 12, or 13 is used. Further, when Criterion 10, 

 11, 12, or 13 is used, it is assumed that the determination was made on a single individual or that 

 it represents a general evaluation of response for all individuals of the test organism species. How- 

 ever, occasionally, tests demonstrate the incidence of a given time value in a group of individuals 

 administered a given dose (e. g. , the percentage of individuals which were killed within 10 minutes or 

 the percentage killed within 24 hours at the dose size administered). The test compound that kills 

 fewer organisms in a longer time is less valuable (as a killing agent) than a test compound that kills 

 more individuals in a shorter time, using a standard dose. 



To correlate this time value with the percentage of individuals responding, the CBCC uses the 

 same Log-Probit Grid as is used for Criteria 51, 52, and 53 (the latter criteria correlating dose size 

 with percentage of individuals responding). This correlation of time values with percentage of 



- 200 - 



