Pesticide residues in olive oil

The attacks of pests and diseases and the presence of weeds make it necessary to apply pesticides to olive trees to ensure crop protection. Residues of these compounds may remain and contaminate the oil produced. For the analysis of pesticide residues in olive oil, the most common methods are multiresidue methods for fatty substrates, based on partitioning between hexane or light petroleum and acetonitrile. Recently, other methods have been applied, such as ready-to-use, disposable minicolumns or direct injection of oil into a capillary gas chromatograph equipped with a precolumn with an oil recovery tank. Although several pesticides are registered in oil-producing countries for use on olive trees, available literature on the level and fate of residues is very limited. However, it is clear that fat-soluble pesticides tend to concentrate in the oil, both after full coverage and bait spraying, and their use close to harvest should therefore be avoided. Because it is sometimes necessary to use such pesticides late in autumn because of their effectiveness in cases of severe attack, residue trials should be carried out to determine the residue concentration in oil and to set a reasonable preharvest safety interval. Data produced by such trials would permit the establishment of MRLs (tolerances) in olive oil to cover cases where the residues, although relatively high, are not of toxicological significance for consumers (risk assessment). Such is the case with corn oil and the fat-soluble insecticide methyl pirimiphos, registered in the U.S. for use on corn. The U.S. EPA tolerance for methyl pirimiphos in corn is 8 mg/kg, whereas it is 11 times higher (88 mg/kg) for corn oil because it is known to concentrate in the oil. Similar provisions for olive oil, based on data from residue trials according to Good Agricultural Practice, the long-term toxicity of each pesticide as expressed by its ADI for man, and olive oil consumption patterns, would facilitate international trade of this commodity. On the other hand, because of the high dietary and health value of olive oil, it is desirable that toxic pesticide residues be kept as low as possible. Therefore, it would be preferable not to rely only on chemical pest control treatments but to develop and apply alternative plant protection techniques such as Integrated Pest Management (IPM).(ABSTRACT TRUNCATED AT 400 WORDS)