The HHS secretary is responsible for identifying those agents which have the potential to pose a serious risk to public or animal health and safety. Three categories have been defined regarding select agent and toxin identification: HHS select agents and toxins, Overlap select agents and toxins, and USDA select agent and toxins. Those classified as HHS agents have the potential to pose a severe threat to public health and safety, and are governed by the CDC. Overlap select agents and toxins have the potential to pose a severe threat to public health and safety, to animal health or to animal products and are subject to regulation by both CDC and APHIS (Animal and Plant Health Inspection Service). USDA select agents and toxins have the potential to pose a severe threat to public health and safety, to animal or plant health, or to animal or plant products and are governed by APHIS.
A current listing of the biological agents and toxins subject to governmental regulations can be found on the Select Agent Web site. Any select agent or toxin listed, which has been genetically modified, is also covered under the Select Agent Program. Additionally, any genetic elements and recombinant nucleic acids that can produce infectious forms of any select agent viruses or express functional forms of any listed toxin in vivo or in vitro are also subject to governmental regulation.