The amount of cancer-causing chemicals being released by Britain's biggest factories has fallen by almost 40 per cent over the last three years according to an analysis of official pollution data by Friends of the Earth, published today. But the figures also reveal that over 9,000 tonnes of cancer causing gases are still released. Seventy per cent of the pollution is released by just 10 factories [10 companies owning factories with highest releases of recognised carcinogens, 1998 - 2000: Ineos Chlor, Associated Octel, Glaxo, Carpenter, Ineos Chlor, Acordis Acetate, Recticel Manufacturing, BASF, Vitafoam, Esso Petroleum]