The present paper describes results of a national survey conducted between 1982 and 1989 to determine residues of arsenic, cadmium, copper, mercury, lead, selenium, and zinc in Canadian slaughter animals. Liver and kidney tissues from cattle, swine, poultry, horses, calves, and sheep were tested. Arsenic was found in most avian and porcine samples, and their respective means of 0.36 and 0.26 μg/g in liver were 7 to 12 times higher than mean concentrations found in the other species. Cadmium was found in the tissues of all species; however, levels were consistently highest in equine samples with mean values of 3.09 and 27.7 μg/g in liver and kidney, respectively. Copper levels >150 μg/g were found predominantly in liver from calves and sheep, with values considerably lower in the remaining species. Mercury levels were low or not detected in all species except horses. Ninety % of equine kidneys and 54% of equine livers had mercury concentrations >0.01 μg/g, with mean values of 0.18 and 0.06 μg/g, respectively. Lead was found in tissues of all species; however, values >2 μg/g were found only in 2 kidneys from adult cattle and 1 kidney from a horse. Selenium, tested only in cattle, was found at mean concentrations of 0.28 μg/g in liver, and 0.92 μg/g in kidney. Relatively high zinc levels were found in livers of horses, pigs, and calves, with respective mean concentrations of 67.3, 65.6, and 70.2 μg/g.

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White Leghorn cockerels were fed commercial DDT at levels of 250, 500, and 1000 μg/day in the diet. The absorption, distribution, and metabolism of DDT in plasma, brain, liver, kidney, heart, breast muscle, intestinal tract, skin, and fat were investigated, using gas–liquid chromatography in the quantitation of the residues. To aid in assessing chlorinated hydrocarbon toxicity in wild birds, correlations between observed symptoms and the residue levels in possible target tissues were studied in conjunction with the mechanism of action of DDT. The results indicate that the sum of the residues of p,p′-DDD, o,p′-DDT, and p,p′-DDT (toxic residues) in the brain was the best parameter for diagnosing DDT poisoning in birds. Signs of DDT toxicity were observed in all birds with brain levels in excess of 35 p.p.m. The lowest level of toxic residues in the brains of dead birds was 27.7 p.p.m. The mean brain level of toxic residues in tremoring and dead birds was 54.2 p.p.m. Metabolism and the significance of the levels of DDT and metabolites detected in other tissues are discussed in relation to the physiological function and metabolic activity of the particular tissue.

During the 27-month period between January 1, 1992, and March 31,1994, Agriculture and AgriFood Canada analyzed 21 982 samples of fruit and vegetable commodities for pesticide residues. A multiresidue method capable of detecting over 200 analytes was used. In 5784 domestic samples a total of 676 residue findings were made. Of these, 32 (0.55%) were in violation of Canadian maximum residue limits (MRLs).In 16 198 imported products, 464 of 3193 residue findings exceeded MRLs, corresponding to a violation rate of 2.86%. One-half of domestic violations resulted from commodity–pes ticide combinations for which there are no Canadian approvals.

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