Ochratoxin A as a contaminant in the human food chain: a Canadian perspective

Penetration of ochratoxin A into the human food chain in Canada was assessed by analysing stored grains, porcine blood and, finally, human blood. The potential for mycological growth and production of ochratoxin A was determined in 164 samples of stored grain (barley, wheat, maize and silage) collected from producers in Manitoba. A total of 34% were found to have the capacity to produce ochratoxin A; 14.5% had concentrations greater than 1.0 mg/kg. In 1988, 1200 blood samples were obtained from swine destined for slaughter in western Canada. High-performance liquid chromatography demonstrated that 3.6% of the 194 blood samples collected in February and March and 4.2% of the 1006 collected in May, June and July had concentrations of ochratoxin A that exceeded 20 ng/ml. In a subsequent survey of porcine blood carried out in 1989-90, 16-65% of the samples had detectable levels of ochratoxin A, at mean concentrations of 5.4-19.4 ng/ml. Subsequently, human blood samples were collected from 159 individuals, 69 of whom had some form of renal impairment. Of the latter, 40% had detectable levels of ochratoxin A, and 12% had concentrations greater than 0.5 ng/ml. Of the non-renal patients, 39% had detectable levels of ochratoxin A, and 11% had concentrations greater than 0.5 ng/ml. These studies demonstrate that ochratoxin A is present in the blood of people in Canada and that two possible points of entry of this toxin into the human food chain are contaminated grain and pork products.