PAH contamination of the grass Lolium perenne exposed to vehicular traffic

The contamination of pastures by polycyclic aromatic hydrocarbons (PAHs) from vehicular emissions is the first step of the contamination of the food chain including the grazing ruminants producing dairy food. In this study, we measured PAH concentrations in grass exposed for 30 days and for 75 days using a standardised culture of Lolium perenne. This method allowed the comparison of the grass contamination between two sites of different daily traffic (highway and rural road) and two control sites: isolated pasture and climate chamber. The results showed that total PAH concentrations ranged from 18 ng/g DW to 414 ng/g DW (DW: dry weight). The highest concentration was detected along the rural road and appeared not to be directly linked to the vehicular flow but probably to the driving cycles of the vehicles. The PAH concentrations were not found to be time-dependent as the values remained similar for the ryegrass exposed for 30 days or 75 days.