Risk assessment of ochratoxin A residues in food.

Ochratoxin A is a mycotoxin that has been found to occur in foods of plant origin, in edible animal tissues and in human sera and tissues. The ability of ochratoxin A to move up the food chain is associated with its long half-life in certain edible animal species. In this presentation, approaches for the evaluation of the health risks due to the presence of ochratoxin A in food products are described. The major target for ochratoxin A toxicity in all mammalian species tested is the kidney, and endemic nephropathies affecting livestock as well as humans have been attributed to ochratoxin A. Ochratoxin A is also teratogenic, and in the fetus the major target is the developing central nervous system. Recent studies have provided 'clear evidence' for the carcinogenicity of ochratoxin A in two rodent species. It was found to be non-mutagenic in various microbial and mammalian gene mutation assays, but weak genotoxic activity to mammalian cells was noted. In addition, ochratoxin A was found to suppress immune function. On the basis of a carcinogenicity study with ochratoxin A in rats, reported from the National Toxicology Program in the USA, the estimated tolerable daily intake of ochratoxin A in humans ranges from 1.5 to 5.7 ng/kg bw per day, depending on the method of extrapolation used. The worst-case estimate for daily exposure to ochratoxin A from the consumption of pork-based food products and cereal foods for young Canadian children, the highest consumption group on a body weight basis, is probably less than 1.5 ng/kg body weight per day (mean of eaters). In view of the toxic properties of ochratoxin A, it is recommended that exposure to this toxin be kept to a minimum.