On the origin of benzene, toluene, ethylbenzene, and the xylenes in virgin olive oil--further results.

Investigations into the sources of contamination of virgin olive oil by gasoline components were concluded. Olives on the tree contained volatile aromatic hydrocarbons at concentrations exceeding those corresponding to the equilibrium with the environment. Present knowledge indicates that up to 10 micrograms/kg of benzene and 250 micrograms/kg for the sum of benzene, toluene, and the C2-benzenes must be considered as possible background concentrations. Aside from the oil mills, the rooms for intermediate storage of the olives were found to be an important source of contamination by gasoline vapours, since they often contain vehicles and other gasoline-driven engines. Parking of a small, hot grass mower into a similar room released an amount of gasoline that was sufficient to contaminate the oil in olives above the proposed limit by a factor of 100. Recommendations are derived for the producers to avoid contamination of olive oil with gasoline components.

On the origin of benzene, toluene, ethylbenzene and xylene in extra virgin olive oil.

Concentrations of benzene, toluene, C2-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4-10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism.