chemicals in unwashed/badly washed leeks

heard on ready, steady cook, chanel ten, yesterday the importance of washing leeks very thoroughly because of the soil they contain. you ask why - it was stated because of the chemicals in the soil. very interesting that a chef would make such a statement. seems we need to be very aware of the chemicals we use for farming crops and our water supplies. please think about these subjects when you are buying your fruit and vegies.

robyn