Sterigmatocystin - Toxicity and Importance

Toxicity and Importance

The toxic effects of sterigmatocystin are much the same as those of aflatoxin B1. It is thus considered as a potent carcinogen, mutagen, and teratogen. It is less acutely toxic to rodents and monkeys but appears to be slightly more toxic to zebra fish. The LD50 in mice is in excess of 800 mg/kg. The 10 day LD50 in Wistar rats is 166 mg/kg in males, 120 mg/kg in females, and 60-65 mg/kg for ip. administration in males. The ip. 10 day LD50 for vervet monkeys is 32 mg/kg.

Chronic symptoms include induction of hepatomas in rats, pulmonary tumours in mice, renal lesions and alterations in the liver and kidneys of African Green monkeys. Rats fed 5-10 mg/kg of sterigmatocystin for two years showed a 90% incidence of liver tumours. It has been suggested that sterigmatocystin is about 1/10 as potent a carcinogen as aflatoxin B1.

Toxic effects of sterigmatocystin-fed laboratory animals have included kidney and liver damage and diarrhoea. Skin and hepatic tumours are induced in rats by dermal application. Cattle exhibiting bloody diarrhoea, loss of milk production and in some cases death were found to have ingested feed containing Aspergillus versicolor and high levels of sterigmatocystin of about 8 mg/kg. The acute toxicity, carcinogenicity, and metabolism of sterigmatocystin has been compared with those for aflatoxin and several other hepatotoxic mycotoxins.

The IARC-classification of sterigmatocystin is group 2B, which means it is carcinogenic in other species and is possiblycarcinogenic to humans, but that a definitive link between human exposure and cancer has not been proven.