FIELD E ; Pathology Code 

 Columns 18, 19, 20, 21, 

 22, 23, 24, and 25 



CAUSES OF DISEASE 



Disease etiologies, classified under several categories 

 and assigned code symbols, to be used in constructing 

 Field E code symbols for specific pathologies. 



The following catalog of etiologies is divided into eight basic groups to which Symbols 2, 3, 4, 

 5, 6, 7, 8, and 9 have been assigned, to be coded in Column 22 as part of the total eight-unit symbol 

 identifying pathologies. To provide an adequate number of symbols for specific etiologies within each 

 category, the numerical symbols are combined with IBM zone punches, giving three letter symbols, in 

 addition to the numerical symbol, in each category. Therefore, the first category is represented by any 

 of Symbols 2, B, K, or S, the second category by any of Symbols 3, C, L, or T, the third by Symbols 4, 

 D, M, or U, etc. A general sub-classification has been made within some of the categories. For ex- 

 ample, within the first category. Symbols 2, B, and K have been reserved for specific extraneous poi- 

 sons and intoxicants, while Symbol S has been reserved for those materials to which individuals are 

 peculiarly sensitive (hypersensitive responses). 



Within each sub-category, however, each specific etiology is distinguished simply by assigning 

 it a sequential number for Column 23. Thus, lead was the first of the specific poisonous materials as 

 a cause of pathology listed in the category of poisons and was assigned Symbol 21; subsequently, the 

 next poisonous material added, carbon monoxide, was assigned Symbol 22, etc. 



The seventh major category (Symbols 8, H, Q, and Y in Column 22) differs somewhat from the 

 pattern of other categories for designating specific etiologies. This is a category for those diseases 

 for which causes have not been discovered or are highly conjectural (resembling in this respect the 

 sixth category. Symbols 7, G, P, and X) and which result less in morphological change than in physio- 

 logical disorders. The ciiterion for distinguishing diseases of this category lies, therefore, in the 

 physiological process affected by the disease and is not actually an etiological classification at all. 

 Here, it has seemed most practical to assign no specific meanings to symbols in Column 23, but rather 

 to allow the symbol in Column 22 to refer generally to functions of the anatomical part coded in Columns 

 19, 20, and 21. The normal physiological process of the anatomical part which is disrupted by the path- 

 ology is merely assigned a sequential number in Column 23. Thus, for each anatomical part coded dis- 

 tinctly in Columns 19, 20, and 21, a very large number of diseases (whose causes are unknown) can be 

 distinguished on the basis of the functional disturbance brought about by the disease. The alternative 

 to this would have been the assignment of specific functional disturbances to the 140 available symbols 

 within this category, only one or a few of which would be applicable to any one anatomical part coded 

 in Columns 19, 20, and 21. 



Symbols 2, B, K, and S 



Extraneous poisons, intoxicants, and materials to which 

 individuals are sensitive, as causes of pathology. 



Poisons and intoxicants 



Substances producing hypersensitive reactions 



21 Lead SI Anaphylactic response, 



substances producing, 



22 Carbon monoxide unspecified 



23 Arsenic S2 Allergic, hypersensitive 



reaction, substances 



24 Mercury producing, unspecified 



25 Snake venom, unspecified 



26 Chloroform 



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