Mo. Rev. Stat. § 292.560
No person, firm or corporation shall knowingly sell or expose for sale any of the articles mentioned herein when such articles were made in violation of sections 292.550 to 292.570; and the director of the inspection section, his deputy or any officer appointed to enforce the provisions of sections 292.550 to 292.570, who shall find any such articles made in violation of the provisions of sections 292.550 to 292.570, or who shall find that the articles herein mentioned are made under unclean or unhealthy conditions, shall conspicuously affix thereto a label containing the words "tenement made" or "made under unhealthy conditions", as the case may be, printed in plain letters on a tag not less than two inches in length, and it shall be unlawful to remove such tag except by the permission of the director of the inspection section or the officer under whose direction such label was affixed.
§ 292.560, RSMo