FIELDS M and N 



Columns 45 and 46; 



47 and 48 



Occasionally, when data are being coded from a research program in which many compounds 

 were tested by a single method, it is desirable to code them so that the coding is comparable for all 

 tests of that particular testing program. A single scale most suitable to the data has been selected by 

 the CBCC in such cases and used consistently (e.g. , Scale 1, ppm) even if some of the tests used 

 dosages which are beyond the maximum limit of the scale's range (e. g. , beyond 252 5 ppm). 



When two or more of the four scales of Field M (Scales 1, 4, 5, and B) seem equally adequate 

 for expressing the dosage quantitatively, the field of biology which the data concern should be con- 

 sidered. Thus, if one of the units of measure seems a more reasonable expression of the dosage, 

 because that measure is more commonly used in that biological field, the choice should be made on that 

 basis. For example, pounds per 100 gallons (Scale 5) is the unit of measure most conspicuously 

 inappropriate for pharmacological data. 



In Field N, it is always best to express the dosage given per unit area or per unit mass of the 

 test organism (or host, if administration is to a host) when this is possible. A practical example is 

 the intravascular injection of 2 mg per 20-mg mouse (when each test mouse has been selected for 

 approximately 20 grams weight). In this case, it is possible to code merely that the dose was 2 mg, 

 with Scale 2 of Field N; however, in this expression, there is no correlation of the mass of the 

 organism with the given dose. The difference between distribution of 2 mg through 20 grams of mouse 

 and 40 grams of mouse (or through the 20-pound mass of a larger animal) is considerable and thus a 

 scale which represents a correlation between the dose and the organism size permits a more accurate 

 statement of the dosage to which each unit of the organism was exposed. Therefore, the CBCC coder 

 would calculate the per-kilogram dosage and use Scale 6. 



3. Dosage size as a basis for evaluation of a specific action or use 



Evaluation (Field Y) of a given chemical activity (Field T) based solely on dosage (Fields M 

 and N) is actually not possible unless test data on only one type of biological activity were being 

 collected and the experimental method remained comparatively standard. This is because compounds 

 tested for certain practical uses (agricultural chemicals, e. g. ) may deserve a high activity evaluation 

 when applied in comparatively large doses (because under the conditions of practical application only 

 such large applications of known chemicals produce the response). If the test evaluation of compounds 

 for such a practical use were made by reference to a standard dosage scale which was designed to 

 permit expression of test doses for all possible test data, the evaluation would be misleading, for it 

 would indicate only that since the dose was high, the relative chemical activity was poor and although 

 this may be chemically- biologically true, it is not an adequate expression of the evaluation of the 

 compound for the use for which it was tested. Although the preceding will be discussed again in 

 Field Y, it is pointed out here to permit explaining more clearly that the use of symbols assigned to 

 the nine ranges of each scale is primarily for expressing the most effective (or highest ineffective) 

 dose administered . The symbols can not be used as a sole means of arriving at the evaluation of the 

 compound for the specific action (i. e. , the specific use) for which it was tested . It might only be 

 used this way if data on a single specific action were being collected, coded, and filed and if the 

 dosage scale had been adjusted to evaluate chemicals for this one activity on a comparative basis. 

 (See also the discussion of the organization of Field P. ) 



Relative to the above statements, however, the final observation should be made that use of 

 such a scale as a basis in evaluating responses from test data on any and all chemical actions, would 

 not be entirely without significance, since there would be expressed thereby the comparative basic 

 sensitivities of the biological systems involved to each compound tested, varying only by the application 

 method. 



4. Dosage to be coded when application is to the (1) test organism, (2) host, or (3) parent 



When application of the test compound is made directly to the test organism, even if it is in 

 or on a host, the dosage to be coded in Fields M and N is that dosage applied to the test organism. 

 If the test organism is in or on a host or host environment coded in Field I and the application of the 

 test compound is directly to the host or host environment (and therefore only indirectly to the test 

 organism), the dosage coded in Fields M and N is the dosage applied to the host. Provision is made 

 Through Field S for application to an egg or developing embryo when the application is only indirectly 

 to the egg or embryonic stage but directly to the parent while the young stage is still intimately 



85 - 



