FIELD U 

 Columns 65 and 66 



Whether the administration has been a single or multiple terminated application or has 

 been continuous up to the first manifestation of response bears no influence on the value 

 coded in Field U as the time to specific action other than death (Criterion 10 or 58) or as 

 the killing time (Criterion 11 or 59). 



If a given response for which a chemical is being specifically tested does not occur (i. e. , 

 if the results are negative), evaluation can not be made by Criterion 10 or 58 and, 

 accordingly, Field U can not be coded with a time value; only Field V might be coded with 

 the period of observation. 



B. Killing time; coding in Field U with Field X Criterion 11 or 59 



When a test is evaluated according to the time taken to produce death (even though death 

 may be preceded by one or several other specific responses), the time from the initial 

 application to the death of the organism must be coded in Field U. If death does not result, 

 when the aim of the test was to find the lethal level, Criterion 1 1 or 59 can not be used in 

 Field X and, correspondingly, Field U can not be coded with a time value; only Field V 

 might be coded with the period of observation. 



4. Persistence of activity of a test compound as a residue; demonstrations of persistence of 

 activity of a residue and evaluations thereby are never coded except that this persistence 

 of activity value (i. e. , the time period over which a test compound retains its ability to 

 produce a response) may be coded in Field U, where it is distinguished as representing a 

 unique use of Field U by coding with it Symbol * in Column 66 



Chemicals are not infrequently applied to a substrate with the intent of affecting specific 

 organisms which subsequently contact the coated substrate. The manner of such application varies; 

 e. g. , spreading the pure compound- -or the compound in a paste- -over the substrate or applying the 

 compound in a volatile carrier which evaporates to leave the chemical as a deposit. In any case, the 

 material represents a residue whose effect on a biological system is evidenced only after an organism 

 makes contact with the residue, which may occur only after a considerable lapse of time. Thus, a 

 time factor is interposed which is unrelated to a biological organism and relates only to the chemical- - 

 the period over which the chemical retains its ability to produce a given response when an organism 

 contacts it. This may be a measure of its chemical stability or of its resistance to physical change 

 such as congealing, solidification, evaporation, etc. Regardless of what occurs to the chemical 

 between the time of application to the substrate and the time of contact with an organism, any inter- 

 vening alteration of the chemical can not be a biological activity nor a measure of biological activity. 



The procedure of determining the persistence of activity of a residue usually consists of per- 

 forming a series of tests on the same residue, exposing one or more test organisms to the residue at 

 given intervals after its deposit on the substate. Because these tests involve living organisms and 

 the author evaluates the compound on the basis of its ability to retain its efficacy as a residue, there 

 is a strong temptation to construct a biology code line in an effort to code in the evaluation code fields 

 (Fields W, X, and Y) the author's persistence evaluation. This is no more consistent with the purpose 

 of the CBCC coding of biological factors than to evaluate the chemical on the basis of its photostability, 

 or its relative cost, or the desirability of its odor. 



Rather than dismiss such test results entirely, the CBCC codes the data in the following 

 manner. 



A. A code line is constructed for the results of the first test of the series of tests demonstrating 

 persistence of the residue, since this first test measures, more accurately than later ones 

 of the series, the actual biological activity. In this code line, the biological response is 

 coded in Field T and the code evaluation depends on how much data is given by the author 

 for that first test. If per cent response, per cent kill, or comparison to action of a standard 

 compound are given, evaluation may be by that value. Otherwise, evaluation can be only 

 by Criterion 01 in Field X, and Field Y is coded to represent the degree of response in that 

 first test- - never to represent the author's evaluation of the test compound residue based on 

 its relative persistence as demonstrated by subsequent tests of the series. There is no way 

 of coding collectively the entire series of tests in a single code line and consequently no 

 way of coding the evaluation of the persistence of activity of the test compound as a residue. 



163 - 



