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Carcinogenicity of dietary aflatoxin M1 in male Fischer rats compared to aflatoxin B1
Abstract:
Aflatoxin M1 (AFM), an hydroxy metabolite of the potent carcinogenic mycotoxin aflatoxin B1 (AFB) is frequently found in milk and other dairy products. Sufficient amounts of AFM were produced to study the carcinogenicity of this compound. AFM was fed to male Fischer rats starting at 7 weeks up to 21 months of age. Agar-based semisynthetic diets contained 0.0, 0.5, 5.0, and 50.0 micrograms/kg of AFM or 50 micrograms/kg of AFB. Hepatocellular carcinomas were detected in two of 37 rats and neoplastic nodules were found in six of 37 rats fed 50 micrograms/kg AFM between 19 and 21 months. No nodules or carcinomas were observed in the lower AFM dose groups. Nineteen of 20 rats fed a diet containing 50 micrograms/kg of AFB developed hepatocellular carcinomas by 19 months of age. Carcinogenic potency of the aflatoxins was reflected by morphometric quantitation of foci detected in hematoxylin and eosin stained sections. Three rats fed the diet containing 50 micrograms/kg AFM developed intestinal carcinomas. None were observed in other groups. Under the conditions of this experiment AFM was found to be a weak hepatic carcinogen compared to AFB and to possess intestinal carcinogenicity.
Insights
Aflatoxin M1 (AFM), found in dairy, showed weak liver carcinogenicity in rats compared to Aflatoxin B1 (AFB). AFM also caused intestinal tumors, indicating a dual carcinogenic effect.
Area of Science:
- Toxicology
- Carcinogenesis
- Food Safety
Background:
- Aflatoxin M1 (AFM) is a metabolite of aflatoxin B1 (AFB), a known carcinogen, frequently found in milk and dairy products.
- Assessing the carcinogenic potential of AFM is crucial for public health, especially concerning dietary exposure.
Purpose of the Study:
- To evaluate the carcinogenicity of Aflatoxin M1 (AFM) in male Fischer rats.
- To compare the carcinogenic potency of AFM with that of Aflatoxin B1 (AFB).
Main Methods:
- Male Fischer rats were fed diets containing varying doses of AFM (0.0, 0.5, 5.0, 50.0 µg/kg) or AFB (50 µg/kg) for up to 21 months.
- Tumor incidence, specifically hepatocellular carcinomas and neoplastic nodules, was assessed.
- Morphometric quantitation was used to evaluate the carcinogenic potency of aflatoxins.
Main Results:
- Hepatocellular carcinomas and neoplastic nodules were observed in rats fed 50 µg/kg AFM, but not in lower dose groups.
- A high incidence of hepatocellular carcinomas (19/20 rats) was observed in rats fed 50 µg/kg AFB.
- Intestinal carcinomas were detected in three rats fed 50 µg/kg AFM, with none observed in other groups.
Conclusions:
- Aflatoxin M1 (AFM) is a weak hepatic carcinogen compared to Aflatoxin B1 (AFB).
- AFM exhibits intestinal carcinogenicity in rats under the experimental conditions.
- Findings highlight the potential risks associated with AFM exposure from dairy products.