3.—(1) No person shall sell, for administration to an animal, any—
(a)stilbene or thyrostatic substance; or
(b)product which contains a stilbene or thyrostatic substance.
(2) Subject to paragraph (3) below, no person shall sell any beta-agonist, or any product which contains a beta-agonist, for administration to an animal which is, or any animal product of which is, intended for human consumption.
(3) The prohibition in paragraph (2) above shall not apply to the sale of a product which is, or which contains, a beta-agonist if that product complies with the requirements of sub-paragraphs (a) and (b) of regulation 25(1) and is for administration in accordance with regulation 27.
(4) If sold, any stilbene, thyrostatic substance or beta-agonist or any product which contains a stilbene, thyrostatic substance or beta-agonist, which is capable of being used for administration to animals shall be presumed, until the contrary is proven, to have been sold for administration to an animal and in the case of the sale of a beta-agonist or a product which contains a beta-agonist, that animal or an animal product derived therefrom shall, if that animal or animal product, as appropriate, is commonly used for human consumption, be presumed to be intended for human consumption.