Air quality in cities is generally lower than in the countryside. But does this the effect of vegetables grown there? Last summer some samples were taken from a rooftop garden alongside the highway A10 in Amsterdam to test for deposition of toxins.
These tests were anecdotal and aimed at getting a first impression of possible risks. The rooftop garden is placed on top of a 4-story industrial building. The altitude might affect the deposition of atmospheric pollutants.
Nearing the end of summer a number of crops was tested for Polycyclic aromatic hydrocarbons (PAHs) as well as the heavy metals cadmium, mercury and lead. Many of these pollutants were indeed found on the tested herbs mint, parsley and rosemary and chives, mostly in concentrations under the EU-food safety norm. The tested gooseberry and cabbage were free from contamination.
Because EU-references are based on rinsed product, a second assay was done with rinsed and un-rinsed mint. Here results show that the pollutants can indeed be rinsed off, giving a clean product. These small tests suggest that atmospheric pollutants can be found on crops grown in cities or near motorways, but can be easily rinsed off.
Tycho Vermeulen (Wageningen UR Glastuinbouw)