Burning and recycling of waste is contaminating the environment with the lethal chemical dioxin, according to a three-year study conducted for Britain's Environment Agency by AEA Technology in Oxfordshire, UK. A 1991 European Union directive on waste management had led to the promotion of incinerators across Europe. But it overlooked a crucial aspect: dioxin is formed when materials containing chlorine are burned. Metals that have reacted with chlorine, when heated during recycling, are another potential source of dioxin that has been ignored by regulators. The report says that 2.5 to 13 tonnes of dioxin are released into the environment in Britain each year. In 1995, municipal waste incinerators in Britain produced 20 to 40 per cent of total dioxin emissions.

While the British government imposed tough standards on emissions, lowering the dioxin content of emissions would lead to an increase of the toxin in the ash. Since this ash is used as landfill, it would again find its way into the environment. Other sources of dioxin are pesticide manufacture and burning of timber treated with the preservative pentachlorophenol ( New Scientist , Vol 155, No 2102).