Polycyclic aromatic hydrocarbons (PAHs) are a large class of organic compounds produced from incomplete combustion. Many PAHs are mutagenic and some are carcinogenic and pose a health risk to humans. Dietary intake of PAHs is a major route of exposure, where fats and edible oils are important contributors to overall dietary PAH exposure. Composed of hundreds of individual compounds as a complex mixture, only 16 PAHs are typically monitored in food and the environment.

In this present study we analyzed 16 commercial olive oil samples from different countries of origin and type (virgin or refined oil) for their content of 45 PAHs using a high-performance liquid chromatograph coupled to a gas chromatograph with a mass spectrometric detector. The content of the 45 PAHs varied between 9.17–94.7 μg/kg (median: 30.1 μg/kg) in the different olive oil samples. Only one sample didn't meet the regulatory threshold levels for PAHs.

The compositional profile of PAHs across the olive oil samples showed a high abundance of PAHs of lower molecular weights, and a large contribution of alkylated PAHs regardless of olive oil type. Direct contact with diesel exhaust emissions from mechanical harvesters has previously shown to affect PAH levels in olive oils. Using diagnostic PAH ratios, biomass/coal combustion and/or petroleum/fossil fuel combustion were indicated as important sources. Source apportionment by positive matrix factorization revealed diesel exhaust emission and biomass combustion as the two major sources of PAHs followed by traffic emissions. This suggests that air quality may have a considerable impact on pollution levels in olive oils and thus indirectly affect dietary exposure.