There are five hormones (progesterone, testosterone, estradiol-17B, zeranol and trenbolone acetate) currently approved for use in cattle implants in the United States, Australia, Canada and 30 other countries in the world. These implants have been officially prohibited in Europe since 1989. Use of these implants have been declared safe by the following groups:

• FDA, which has approved more than a dozen different formulations of these products in the last 50 years.
• The EEC Scientific Working Group on Anabolic Agents chaired by Dr. G.E. Lamming in 1987.
• Codex Committee on Residues of Veterinary Drugs in Foods in 1987.
• European Agricultural Commission Scientific Conference on Growth Promotion in Meat Production in 1995.
• FAO/WHO (Food and Agriculture Organization/World Health Organization Joint Expert Committee on Food Additives (JECFA) in 1981, 1983,1988, 1999.
• Sub-Group of the Veterinary Products Committee from the UK Ministry of Agriculture, Fisheries and Food in 1999.