Should we worry about animal growth promoters?

Estrogens and compounds with estrogenic activity have been used for many years as animal growth promoters and to synchronize estrus in cows. The resorcylic acid lactones (RALS), which include zearalenone, are being used increasingly for these purposes. These estrogenic mycotoxins, now produced commercially, have teratogenic, mutagenic, and carcinogenic properties. There is some evidence that their residues could remain in certain organs at the time the animal products come to market, and this may be of medical significance.