FIELDS W, X, and Y 



Columns 68; 69 and 



70; and 71 



occurred is simply with Symbol L or, if the single dose level administered is known to be the maximum 

 tolerated, Symbol M. 



It is only when the data presented involve a series of tests in which a series of dosage levels 

 have been used that Symbol N, 0, or P is used. 



Symbol is used in any case when (1) the response intensity is demonstrated to be the greatest 

 the compound can produce and (2) the coded dose is known to be the minimum needed to cause that maxi- 

 mum response. Symbol N or P is used when such a series of tests with varying dosage levels has not 

 succeeded in demonstrating one of the following: (1) that the greatest intensity of response produced by 

 the series of tests is the maximum of which the compound is capable (Symbol P) or (2) that the lowest 

 dose tested in the series of tests is the minimum needed to cause the maximum response (Symbol N). 



Death itself is unique in that, in the individual organism, there is no "intensity" of death; the 

 minimum dose killing a single individual being tested represents the "peak" of the dosage-response 

 "curve" (a single point) and should always be coded with Symbol in Field W. (This lethal level may 

 be expressed in terms of either the minimum lethal level or maximum tolerated level, but either indicates 

 the level at which death has been demonstrated to occur in the individual. ) However, if a group of indi- 

 viduals is treated and the results are expressed in terms of a minimum lethal dose (or maximum tolerated 

 dose), the coding in Field W depends on the percentage of individuals killed in the group. If all (100% ) 

 were killed, Field W should be coded with Symbol 0, but if fewer were killed (i. e. , the minimum toxic 

 dose or the maximum tolerated dose for 50% of the individuals), Field W should be coded with Symbol P. 



To relate the preceding to Criteria 20 (threshold dose) and 21 (maximum tolerated dose), it will 

 be observed that only Symbol P or may be used with the criteria. When Criterion 20 or 21 is used in 

 Field X and "death" is the response coded in Field T, Symbol P is used in Field W only if administration 

 of the chemical was to a population and the threshold lethal dose kills less than 1 00% of the population; 

 in all other cases of "death" with Criterion 20 or 21 (when only a single individual is treated or when 

 application is to a population and the threshold dose kills 100% of the population), Symbol is used 

 in Field W. 



When Criterion 20 or 21 is used in Field X and the response is any response but "death" (i. e. , 

 any non-toxic or toxic-but-not-lethal response), only Symbol P is used in Field W. 



For the person assembling and studying data from the CBCC code files, then, either Symbol L, M, 

 or N always means that the compound produced the response at the dose level administered and coded in 

 Field M or N, but that its potency may be underestimated by the interpreter (who would relate the re- 

 sponse intensity coded in Field Y with the dose coded in Fields M and N)or understated by the evaluation 

 in Field Y (if the Field Y evaluation were based on a correlation with the dose in Field M or N), since a 

 lower dose might prove equally effective. In contrast, Symbols and P always indicate that a reasonable 

 relationship exists between (1) the coded dose in Field M or N and (2) the intensity of response in Field 

 Y--or that any Field Y evaluation that is based on a correlation between intensity of response and the 

 dose size administered is reasonable; a lower dose would produce a lower response or no response and 

 a larger dose would cause the same response or greater response. Symbol N or indicates that the in- 

 tensity of response to the dose administered and coded in Field M or N has been the maximum of which 

 the test compound is capable (barring toxicity), while Symbol L or P indicates that the response to the 

 dose coded in Field M or N has possibly been less than that maximum intensity of which the test com- 

 pound is capable. Symbol M is used when only one dose is tested and it can not be known therefore if 

 the dose is the minimum needed to cause the demonstrated response intensity. Symbol of Field W 

 designates the positive data most significant for comparison of compounds' potencies (i. e. , abilities or 

 capacities) for specific actions. 



In summary: 



Symbols of Field W 



The response intensity coded in Field Y is demonstrated to be the 



highest response intensity the test compound can cause M, N, or 



The response intensity coded in Field Y is not demonstrated to be 

 the highest response intensity the test compound can cause L or P 



The coded dose j_s ascertained to be the minimum dose needed for 

 producing the demonstrated response intensity . or P 



The coded dose is not ascertained to be the minimum needed for 

 producing the demonstrated response intensity L, M, or N 



- 175 - 



