BURNING rubbish in open dustbins could be a major source of dioxins, according to researchers with the US Environmental Protection Agency. The dioxin emissions measured by the researchers were so high that rubbish burnt by fewer than 40 households produced as much dioxins as a purpose-built incinerator serving tens of thousands of people.
Dioxins are toxic chemicals that persist in the environment and can accumulate to dangerous levels in the food chain. The practice of burning household rubbish was common until the 1960s, although it is now banned by most towns and cities in both the US and Britain. However, the EPA estimates that some 20 million rural Americans still burn their rubbish.
The researchers measured emissions of several dozen pollutants when they burnt household waste in four partially filled 208-litre drums perforated at the bottom. Paul Lemieux of the EPA鈥檚 National Risk Management Laboratory in Research Triangle Park, North Carolina, says that emissions of dioxins were 鈥渟everal orders of magnitude higher鈥� than those from incinerators.
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The amount of dioxin emissions varied widely, depending on the type of rubbish being burnt. Emissions were at their lowest when recyclable materials such as newspapers, magazines, cardboard and glass were in the waste, probably because burning dry paper produces hotter flames that destroy the dioxins.
More work is needed to determine why emissions vary, says Dwayne Winters at the EPA鈥檚 headquarters in Washington DC. 鈥淲e鈥檙e trying to understand if it鈥檚 a medium problem, a big problem, or a big, big problem.鈥�