Site Feedback

Title 21

Displaying title 21, up to date as of 8/17/2026. Title 21 was last amended 8/17/2026.
eCFR Content

The Code of Federal Regulations (CFR) is the official legal print publication containing the codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government. The Electronic Code of Federal Regulations (eCFR) is a continuously updated online version of the CFR. It is not an official legal edition of the CFR.

Learn more about the eCFR, its status, and the editorial process.

§ 500.86 Marker residue and target tissue.

(a) For each edible tissue, the sponsor shall measure the depletion of the residue of carcinogenic concern until its concentration is at or below Sm.

(b) In one or more edible tissues, the sponsor shall also measure the depletion of one or more potential marker residues until the concentration of the residue of carcinogenic concern is at or below Sm.

(c) From these data, FDA will select a target tissue and a marker residue and designate the concentration of marker residue (Rm) that the regulatory method must be capable of measuring in the target tissue. FDA will select Rm such that the absence of the marker residue in the target tissue above Rm can be taken as confirmation that the residue of carcinogenic concern does not exceed Sm in each of the edible tissues and, therefore, that the residue of carcinogenic concern in the diet of people does not exceed So.

(d) When a compound is to be used in milk- or egg-producing animals, milk or eggs must be the target tissue in addition to the tissue selected to monitor for residues in the edible carcass.

(Approved by the Office of Management and Budget under control number 0910-0228)