Concerns were raised on BBC's Newsnight programme last week on the use of fly ash waste products from the Edmonton incinerator, contaminated with high levels of cancer-causing dioxins being mixed with bottom ash. The programme reported ash was no longer mixed but it was not known where the ash was used or what risk it may pose.
Today the mayor has written to the operators of the two large waste incinerators in London at Edmonton and Lewisham asking them to assure Londoners that it won't happen in the future.
The mayor said: 'I am extremely concerned by the revelations contained in the Newsnight programme. We know there is a potential health risk from flyash and there should be no question of it being reused in any way. It should be disposed of safely. I am asking the incinerator operators to fully cooperate with the investigation by the Environment Agency on the use of the ash in the past.'