Sources of contamination by polycyclic aromatic hydrocarbons in Spanish virgin olive oils

The presence of polycyclic aromatic hydrocarbons (PAHs) in virgin olive oils results from contamination on olive skins and the oil itself during processing. Determination of nine PAHs was carried out by isolation of the hydrocarbon fraction and subsequent clean-up by solid phase extraction, followed by RP-HPLC analysis using a programmable fluorescence detector. Contamination of olive skins depends directly on environmental pollution levels and inversely on fruit size. In the oil mill, PAHs levels were increased by contamination from combustion fumes during the extraction process. Other procedures, such as washing or talc addition during extraction, did not affect PAHs levels. High concentrations of PAHs were only found as a consequence of accidental exposure to contamination, such as direct contact of olives with diesel exhaust and oil extraction in a polluted environment.