More of us are living in cities and urban farming is on the rise. Can you be sure the city soil you’re growing in is clean enough? Industry and traffic can contaminate land, but there are ways to deal with the problem. Ruth Alexander finds out how to test soil, how to clean it, and which fruit and vegetables are the safest to grow on former industrial and commercial sites. If you would like to get in touch with the show, please email: thefoodchain@bbc.co.uk(Picture: A garden trowel with some soil on it)Producer: Hannah Bewley