(a) Whenever the Administrator determines that action is necessary to prevent an imminent hazard during the time required for cancellation or change in classification proceedings, but that the hazard does not constitute an emergency, he shall notify the registrant of his intention to suspend registration of the pesticide at issue.

(b) Such notice shall include findings pertaining to the question of imminent hazard and shall either be personally served on the registrant or be sent to the registrant by registered or certified mail, return receipt requested, and filed with the hearing clerk.