(a) Imposition of penalties
Any person, partnership, or corporation who violates any provision of section 52(a) of this title shall, if the use of the commodity advertised may be injurious to health because of results from such use under the conditions prescribed in the advertisement thereof, or under such conditions as are customary or usual, or if such violation is with intent to defraud or mislead, be guilty of a misdemeanor, and upon conviction shall be punished by a fine of not more than $5,000 or by imprisonment for not more than six months, or by both such fine and imprisonment; except that if the conviction is for a violation committed after a first conviction of such person, partnership, or corporation, for any violation of such section, punishment shall be by a fine of not more than $10,000 or by imprisonment for not more than one year, or by both such fine and imprisonment: Provided, That for the purposes of this section meats and meat food products duly inspected, marked, and labeled in accordance with rules and regulations issued under the Meat Inspection Act [21 U.S.C. 601 et seq.] shall be conclusively presumed not injurious to health at the time the same leave official "establishments."

(b) Exception of advertising medium or agency
No publisher, radio-broadcast licensee, or agency or medium for the dissemination of advertising, except the manufacturer, packer, distributor, or seller of the commodity to which the false advertisement relates, shall be liable under this section by reason of the dissemination by him of any false advertisement, unless he has refused, on the request of the Commission, to furnish the Commission the name and post-office address of the manufacturer, packer, distributor, seller, or advertising agency, residing in the United States, who caused him to disseminate such advertisement. No advertising agency shall be liable under this section by reason of the causing by it of the dissemination of any false advertisement, unless it has refused, on the request of the Commission, to furnish the Commission the name and post-office address of the manufacturer, packer, distributor, or seller, residing in the United States, who caused it to cause the dissemination of such advertisement.