Ochratoxin A—a toxin produced by different Aspergillus and Penicillium species — is one of the most-abundant food-contaminating mycotoxins. It is also a frequent contaminant of water-damaged houses and of heating ducts. Human exposure can occur through consumption of contaminated food products, particularly contaminated grain and pork products, as well as coffee, wine grapes, and dried grapes. The toxin has been found in the tissues and organs of animals, including human blood and breast milk. Ochratoxin A, like most toxic substances, has large species- and sex-specific toxicological differences. Impact on human and animal health Carcinogenicity Ochratoxin A is potentially carcinogenic to humans (Group 2B), and has been shown to be weakly mutagenic, possibly by induction of oxidative DNA damage. The evidence in experimental animals is sufficient to indicate carcinogenicity of ochratoxin A. It was tested for carcinogenicity by oral administration in mice and rats. It slightly increased the incidence of hepatocellular carcinomas in mice of each sex. and produced renal adenomas and carcinomas in male mice and in rats (carcinomas in 46% of males and 5% of females). In humans, very little histology data are available, so a relationship between ochratoxin A and renal cell carcinoma has not been found. However, the incidence of transitional cell (urothelial) urinary cancers seems abnormally high in Balkan endemic nephropathy patients, especially for the upper urinary tract. The molecular mechanism of ochratoxin A carcinogenicity has been under debate due to conflicting literature, however this mycotoxin has been proposed to play a major role in reducing antioxidant defenses. Neurotoxicity Ochratoxin A has a strong affinity for the brain, especially the cerebellum (Purkinje cells), ventral mesencephalon, and hippocampal structures. The affinity for the hippocampus could be relevant to the pathogenesis of Alzheimer's disease, and subchronic administration to rodents induces hippocampal neurodegeneration. Ochratoxin causes acute depletion of striatal dopamine, which constitutes the bed of Parkinson's disease, but it did not cause cell death in any of brain regions examined. Teams from Zheijiang Univ. and Kiel Univ. hold that ochratoxin may contribute to Alzheimer's and to Parkinson's diseases. Nonetheless, their study was performed in vitro and may not extrapolate to humans. The developing brain is very susceptible to ochratoxin, hence the need for caution during pregnancy. Immunosuppression and immunotoxicity Ochratoxin A can cause immunosuppression and immunotoxicity in animals. The toxin's immunosuppressant activity in animals may include depressed antibody responses, reduced size of immune organs (such as the thymus, spleen,