[Code of Federal Regulations]
[Title 21, Volume 6]
[Revised as of April 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR556.1]

[Page 335-336]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES--(Continued)
 
PART 556--TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD--Table of Contents
 
                      Subpart A--General Provisions
 
Sec. 556.1  General considerations; tolerances for residues of new animal drugs in food.


    (a) Tolerances established in this part are based upon residues of 
drugs in edible products of food-producing animals treated with such 
drugs. Consideration of an appropriate tolerance for a drug shall result 
in a conclusion either that:
    (1) Finite residues will be present in the edible products--in which 
case a finite tolerance is required; or
    (2) It is not possible to determine whether finite residues will be 
incurred but there is reasonable expectation that they may be present--
in which case a tolerance for negligible residue is required; or
    (3) The drug induces cancer when ingested by man or animal or, after 
tests which are appropriate for the evaluation of the safety of such 
drug, has been shown to induce cancer in man or animal; however, such 
drug will not adversely affect the animals for which it is intended, and 
no residue of such drug will be found by prescribed methods of analysis 
in any edible portion of such animals after slaughter or in any food 
yielded by or derived from the living animal--in which case the accepted 
method of analysis shall be published or cited, if previously published 
and available elsewhere, in this part; or

[[Page 336]]

    (4) It may or may not be possible to determine whether finite 
residues will be incurred but there is no reasonable expectation that 
they may be present--in which case the establishment of a tolerance is 
not required; or
    (5) The drug is such that it may be metabolized and/or assimilated 
in such form that any possible residue would be indistinguishable from 
normal tissue constituents--in which case the establishment of a 
tolerance is not required.
    (b) No tolerance established pursuant to paragraph (a)(1) of this 
section will be set at any level higher than that reflected by the 
permitted use of the drug.
    (c) Any tolerance required pursuant to this section will, in 
addition to the toxicological considerations, be conditioned on the 
availability of a practicable analytical method to determine the 
quantity of residue. Such method must be sensitive to and reliable at 
the established tolerance level or, in certain instances, may be 
sensitive at a higher level where such level is also deemed satisfactory 
and safe in light of the toxicity of the drug residue and of the 
unlikelihood of such residue's exceeding the tolerance.