Illegal hormones are bought by organized criminal groups and sold to veterinarians, chemists and animal feed suppliers. The hormones accelerate animal growth. "Hormone" is an oversimplification; the drugs trafficked include thyroid inhibitors, anabolic steroids, beta-agonists and corticosteroids.
In Belgium, the "hormone mafia", said to comprise about 50 people, has been operating since the late 1970s. It obtains drugs from chemical laboratories in countries that were formerly part of the Soviet Union, or buys them via other countries. Attacks on veterinary inspectors in Belgium have been linked publicly to the hormone mafia.
In tests conducted in 1995, 36% of Spanish meat containing stimulants. More than 6% of 1000 Belgian beef steaks tested contained residues from synthetic hormones, and 25% contained suspiciously high levels of clenbuterol, a beta-agonist. Results from France were similar.