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Zeranol--a 'nature-identical' oestrogen?
Summary
Zeranol, a growth promoter, and myco-oestrogens have low estrogenic activity. Their combined dietary exposure is safe, with a safety margin over 500-fold compared to the no-observed-effect level.
Area of Science:
- Food safety
- Toxicology
- Endocrinology
Background:
- Zeranol is an anabolic growth promoter used in food animals, resulting in low tissue residues.
- Myco-oestrogens, like zearalenone, are common cereal contaminants with greater residues than zeranol.
- Zeranol, myco-oestrogens, and their metabolites share chemical and biological similarities.
Purpose of the Study:
- To compare the biological effects of zeranol and myco-oestrogens.
- To assess the toxicological profiles, including oestrogenicity, teratogenicity, genotoxicity, and carcinogenicity.
- To determine the safety margin for dietary exposure to these compounds.
Main Methods:
- Comparative analysis of chemical, steric, and biological properties.
- Evaluation of toxicological data related to oestrogenic activity.
- Calculation of safety margins based on expected dietary exposure and no-observed-effect levels (NOELs).
Main Results:
- Zeranol and related myco-oestrogens exhibit significantly lower hormonal activity (100-1000 times less) than oestradiol.
- No toxicological effects were observed that were not attributable to their oestrogenic properties.
- A likely no-observed-effect level (NOEL) was estimated between 0.05-0.1 mg/kg body weight/day.
Conclusions:
- Zeranol and myco-oestrogens are considered safe at expected dietary exposure levels.
- A substantial safety margin (greater than 500-fold) exists for combined exposure.
- Exposure to zeranol alone provides an even larger safety margin (over 35,000-fold).