FIELD U 

 Columns 65 and 66 



exerts a non-lethal action which is coded in Fields T- 1 and T-2. To obtain a duration 

 of action value, observation must be made of the point of return to normal, as well as 

 the point at which the action begins subsequent to the end of administration. 



2. To express the ALTERATION IN SURVIVAL TIME caused by the test compound 



Use Number 2 represents a duration of action as well as does Use Number 1, as is implied 

 by including them both under Category A. The alteration of survival time (Use Number 2) 

 is the duration of delay of death (in the reverse case of speeding death, the alteration 

 of survival time is equivalent to the duration of delay of death, if the test compound 

 were not administered ); the "duration of action" (Use Number l)is the duration of any 

 action EXCEPT delay of death . 



When testing chemicals whose effect is to alter the time of death due to some lethal 

 factor, the test compound's protective or exacerbative effect can essentially begin only 

 at the point that untreated controls die. 



B. The time between beginning of administration of the test compound and the appearance of 

 the specific effect coded in Fields T- 1 and T-2. In contrast to Category A in which the uses 

 for Field U (Uses 1 and 2) involve time periods after the initiation of the test compound action, 

 the Field U uses included in Category B describe time periods prior to the action. The two 

 uses immediately following are essentially alike and consequently are classified here as a 

 single use (Number 3, separated into 3a and 3b); they differ only in the basic nature of the 

 specific response that the test compound produces at the end of the time period. Field U 



can be used: 



3a. To express the time required to produce a specific response OTHER THAN DEATH . This 

 time value must be coded in Field U when Criterion 10 or 58 is used in Field X. 



3b. To express the time required to KILL . This time value must be coded in Field U when 

 Criterion 11 or 59 is used in Field X. 



C. The time period over which a given deposit of test compound retains its ability to produce 

 repeatedly a response which was produced on first exposure to the organism, as evidenced 

 from a series of exposures of organisms to the same deposit. Thus, Field U can be used: 



4. To express the persistence of action of a compound in a residue test. Inasmuch as 

 this time period represents information about the test compound that is essentially 

 accessory and unrelated to information in any other coding field of the biology code 

 line in which it is entered, the entry of the value is always distinguished as an 

 irregular use by accompanying it with Symbol * in Column 66. 



The coder's selection of an appropriate Field U scale depends on the same factors as are used 

 in selecting an appropriate scale of Field P. This is explained in Division 1 of the Specific Directions 

 and Explanations of Field P, to which reference should be made. 



Specific Directions and Explanations 



1. Duration of action; coding in Field U with Field X Criterion 13 or 54 



Duration of action is defined in the section above, General Use (see specific Use Number 1). 

 Note that when the response coded in Field T is not actually produced by the test compound, Field U 

 could not be coded with "duration of action" (nor could Criterion 13 or 54 be used in Field X), since 

 the action was non-existent, though Field V ("time of evaluation" which, with negative data, is 

 actually duration of observation ) could be coded. Also note that the definition for "duration of action" 

 specifies a test compound administration of limited duration, only after the end of which can begin the 

 "duration of action" period; when administration is continuous , "duration of action" is not an applicable 

 concept, since the action could only (1) continue at a level as long as administration continued, in 

 which case the duration would be a meaningless measure, or (2) increase with time, which would be 



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