What is "zeranol"

n. A mycotoxin derived from ''Fusarium'' fungi used as a nonsteroidal oestrogen agonist.

Zeranol (α-zearalanol) is a non- steroidal estrogen agonist. It is a mycotoxin, derived from fungi in the Fusarium family, and may be found as a contaminant in fungus-infected crops. It is 3-4x more potent as an estrogen agonist than the related compound zearalenone.

Zeranol is approved for use as a growth promoter in livestock, including beef cattle, in the United States. In Canada, it is approved for use in beef cattle only. Its application is not approved for use in the European Union. Merck Animal Health markets zeranol under the brand name Relgro.

Although zeranol may increase cancer cell proliferation in already existing breast cancer, dietary exposure from the use of zeranol-containing implants in cattle is insignificant.