Even city dwellers like to eat home-grown vegetables. But this crop is not always healthier than the goods from the supermarket. For example, vegetables that are grown near a road often get contaminated with heavy metals such as lead, cadmium or mercury. Biologist Ina Säumel from the Technical University of Berlin has demonstrated as much. In urban areas with heavy traffic, EU limit values for lead were exceeded in 60% of the samples.
But vegetables cultivated away from roads are not above suspicion either, according to research by the ‘Amt für Umwelt’ in Freiburg. "Nine out of 27 soil samples contain problematic levels of heavy metals. Two other samples had lead levels so high that the gardens had to be closed," says study leader Barbara Gfeller.
These levels are not just caused by the exhaust from traffic and industry. "Earlier pollution, present in added soil and manure, is more important than the current location of the garden," experts say. Many growers have appended harmful chemicals to the soil themselves. For example, by improper use of fertilizer or by spreading ashes.
The investigators advise the public to call on professionals for soil protection.
