FIELD U 

 Columns 65 and 66 



In selecting a scale for coding the test compound's alteration of survival time in Field U, 

 choose the scale whose intervals represent increases or decreases over untreated controls that seem 

 reasonably to be significant. For example, if untreated controls die at about the 24th hour, Scale 8 

 would not be a very appropriate choice for Field U, because the shortest increase in survival time of 

 Scale 8 that would permit a coding evaluation showing any significant action of the test compound 

 would be 100% increase or more (Symbol 2, 24 hours to 2 days). A more appropriate scale for this 

 example would be Scale 5. Listed below are sample control survival times for which are suggested 

 Field U scales. 



Survival time of 



untreated controls Scale 



10 seconds 1 (or 2) 



1 minute 2 (or 3) 



10 minutes 3 (or 4) 



1 hour 4 (or 5) 



12 hours 5 (or 6) 



1 day 5 (or 6) 



3 days 6 (or 7) 



5 days 7 (or 6 or 8) 



1 week 9 (or 8) 



10 days 9 (or 8) 



>2 weeks 9 



3. Time to specific action; coding in Field U with Field X Criterion 10, 11, 58, or 59 



Between beginning of application of the test compound and manifestation of response, there is 

 conceivably always a time interval, even if it is often extremely brief. This interval may be due to any 

 of several factors other than an ability of the basic biological system for rapid response; for example, 

 it may reflect in part the time for distribution of the chemical from the point of administration or the 

 time for physical passage into cells, etc. In any case, the interval sometimes bears significance for 

 purposes of comparative evaluation and when this evaluation is made (Criteria 10, 11, 58, or 59 in 

 Field X), Field U is used to record the time interval value, as explained in Subdivisions A and B below. 



A. Time to specific action OTHER THAN DEATH; coding in Field U with Field X Criterion 10 or 58 



When a test is evaluated according to the time needed to produce a given response other 

 than death (even though death may follow this particular response, after another time interval ), 

 the time from the initial application to the first appearance of the response must be coded 

 in Field U. 



Note carefully that this time to specific response coded in Field U terminates with the first 

 appearance of the response; it is not the time to some subsequent degree of response (e. g. , 

 not the time to peak of the response or at a given time after application begins). Field V 

 is used, rather than Field U, to code the "time of evaluation" regardless of whether 

 evaluation is at the beginning of the specific action or after (or even before) the action 

 begins. In the case of making code evaluation by Criterion 10 or 58, the "time to specific 

 response" is also the "time to evaluation" and Fields U and V are coded with the identical 

 time values (though not with identical code symbols). 



When evaluation is made at some point after the beginning of a specific action (i. e. , by a 

 criterion other than Criterion 10 or 58, such as Criterion 01, 02, 03, 04, or 62), yet between 

 the application of the test compound and the beginning of the response there has been a 

 period of known duration, the question arises as to whether to record this latter time period 

 in Field U, since it is not to be used with Criterion 10 or 58 for evaluation. The CBCC does 

 not code the value in Field U under such circumstances, since, without some extra indicator 

 (such as a zone punch in Column 65), the meaning of an entry in Field U can not be deter- 

 mined without Criterion 1 0, 11, 12, 13, 54, 57, 58, or 59 in Field X. 



162 



