FIELD T-2 

 Columns 58, 59, 60, and 61 



Death may be either a desired or an undesired response of a given organism to a chemical. In 

 the case of parasitism and pathogenicity, a complex situation exists in which death is ordinarily desired 

 for the parasitic organism and at the same time is ordinarily unwanted in the host. It is necessary to 

 make some distinctions relative to these aspects and the use of Symbols 11, 111, and 112, explained 

 as follows. 



Symbols 11, 111, and 112 are used when the intent of the testis to find compounds that will 

 kill an undesired test organism (e.g., rodenticides, molluscacides, herbicides); these symbols are 

 also used when the intent of the test is to find compounds that are safe for a test organism (i. e. , safe 

 for administration for another purpose such as therapy). However, in the case of the parasite-host 

 relationship, Symbols 11, 111, and 112 are never used when the intent of the test is to determine the 

 compound's ability to kill the parasites; instead, Symbols of the 17-- series are used to indicate that 

 the host has been relieved or freed of the parasite or the pathogen by the latter's death due to the test 

 compound. 



4. Symbols II, 111, and 112 vs. Symbol 1812; death of larger organisms vs. death of 

 microorganisms due to the test compound or secondary compound; a discussion of 

 reasons for this coding distinction 



The last sentence of the preceding division has pointed out that death of any pathogenic organism 

 or parasite due to the test compound or secondary compound while the pathogen is in its living host is 

 not coded by Symbol 11, 111, or 112, but only by symbols of the 17-- series. (See Division 13. ) A 

 further exception is the death (or, at least, a reduction of the population) of arthropods infesting living 

 hosts, which is not coded by Symbol 11, 111, or 112, but only by symbols of the 13-- series. (See 

 Division 10. ) 



Finally, the CBCC restricts the use of Symbols 11, 111, and 112 by never using the symbols for 

 coding lethal action on any microorganism, parasitic or not. (See Division 14. ) This general rule has 

 been observed even though no guide has been constructed for coders specifically designating size 

 limitations by which organisms will be defined as "microorganisms". Lethal action on microorganisms 

 is coded by Symbol 1812 (if the organisms are treated while on a non-living host) or it is coded by 

 Symbols 171 and 1711 (if the organisms are on a living host). 



The separation of lethal actions on all microorganisms came about as the result of Field T-2 

 having been developed from lists of biological responses compiled separately for the various biological 

 disciplines, pharmacology, pathology, microbiology, plant physiology, etc. The microbiological items 

 naturally included "cidal" actions of test compounds on bacteria, fungi, viruses, etc. ; in the list of 

 biological responses prepared for pharmacological and agricultural considerations, lethal action was 

 included, but with the emphasis on determinations of safe therapeutic levels as well as killing potency 

 ("toxicity" data), for larger animals and plants; items of the pathology list were concerned basically 

 with therapeutic actions including destructive action or any infectious microorganisms as causes of 

 treated pathologies. For microbiology, Symbol 18 was established for coding effects, including death , 

 demonstrated to be specifically on microorganisms whether pathogenic or not and whether or not they 

 were in or on a living host. For pharmacology, the symbols of the 11-- series (111 and 112) were 

 established for death . The 17-- symbol series was established for coding ameliorating effects on 

 diseases and, if the disease were an infectious disease, this was equivalent to coding at least a 

 suggestion of toxic or lethal effects on pathogenic microorganisms in their host. 



With the sixth mimeographed edition of the Code, the symbols of the 18-- series were changed 

 to their present definitions, rephrasing the definition for Symbol 171 so that it was (and is) to be used for 

 any lethal effect demonstrated on a pathological microorganism while it is in or on its living host ; this 

 leaves for the definitions of symbols of the 18-- series toxic effects on any microorganism not on a 

 living host . 



For the present edition, no change has been made from the original provision separating data 

 of lethal action on microorganisms (series 18--) from the "toxicity" data (series 11--), partly because 

 so much information has been coded and punched for CBCC files using these symbols that the task of 

 retrieval and correction would be prohibitively great. 



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