(a) An application for a laboratory service may be rejected by the Administrator when deemed appropriate as follows:

(1) For non-compliance by the applicant with the regulations in this part,

(2) For non-payment of previous laboratory services rendered,

(3) When the sample is not properly identified by a code or other marks,

(4) When the samples are received in an unsatisfactory condition and are rejected for analysis,

(5) When there is evidence or knowledge of tampering with the sample,

(6) When it appears that to perform the analytical testing or laboratory service specified in this part would not be to the best interests of the public welfare or of the Government, or

(7) When it appears to the Administrator that prior commitments of the Department necessitate rejection of the application.

(b) Each such applicant shall be promptly notified by registered mail of the reasons for the rejection.

(c) A written petition for reconsideration of such rejection may be filed by the applicant with the Administrator if postmarked or delivered within 10 days after the receipt of notice of the rejection. Such petition shall state specifically the errors alleged to have been made by the Administrator in rejecting the application. Within 20 days following the receipt of such a petition for reconsideration, the Administrator shall approve the application or notify the applicant by registered mail of the reasons for the rejection thereof.