Backyard Burning Identified As Potential Major Source Of Dioxins

A family of four burning trash in a barrel in their backyard - still a common practice in many rural areas - can potentially put as much dioxin and furan into the air as a well-controlled municipal waste incinerator serving tens of thousands of households, according to a new study. Under intense scrutiny in recent years because of their varying degrees of toxicity, these polychlorinated compounds can be formed simply by burning common household trash at low temperatures.

The finding is reported in the Jan. 4 web edition of the journal Environmental Science & Technology by researchers from the United States Environmental Protection Agency and the New York State Department of Health. The peer-reviewed journal is published by the American Chemical Society, the world's largest scientific society. The report will appear in the journal's Feb. 1 print edition.

"Open burning of household waste in barrels is potentially one of the largest sources of airborne dioxin and furan emissions in the United States, particularly as EPA standards force major reductions in emissions from municipal and medical waste incinerators," says Paul Lemieux, Ph.D., one of the study's co-authors. He is with the EPA's National Risk Management Research Laboratory in Research Triangle Park, N.C.

Emission measurements from burning of "typical" household trash in 55-gallon drums were done at the EPA's Open Burning Test Facility in North Carolina. The composition of the trash included newspapers, books, magazines, junk mail, cardboard, milk cartons, food waste, various types of plastic, and assorted cans, bottles and jars. No paint, grease, oils, tires or other household hazardous wastes were included in the burning. The barrel burn results were compared with emission data from a "well-controlled incinerator performing better than the dioxin requirements set by recent EPA standards," according to Lemieux.

"Recognizing that there are varied wastes and methods of burning, this particular study found that under test conditions, more polychlorinated compounds were emitted from barrel burning than municipal incinerators because of lower incineration temperatures and poor combustion conditions (in barrels)," says Lemieux.

Under the conditions studied, and when using comparable weights of trash, "emissions from open burning are several orders of magnitude higher than for controlled combustion in a modern, clean-operating MWC (municipal waste combustor)," the article claims.

"Triggered by the study being reported, EPA has launched follow-up studies at its North Carolina test facility to better understand the nature and magnitude of backyard trash burning as a significant dioxin source," notes Lemieux.

The study could help resolve a long-standing discrepancy as a result of a 1994 EPA assessment that identified a "significant gap" between estimates of dioxin emissions and actual deposition measurements, according to the journal article. Emissions of dioxins and furans from burn barrels "may be an important missing link to help close the gap between measured deposition rates and the emissions inventories," the article points out.

Burning trash in open barrels is banned in most areas of the U.S., says Ann Brown of the EPA's Public Affairs Office in Research Triangle Park. "The areas of the country where burning trash is permitted are mostly confined to rural areas," she adds.

Although dioxins and furans have been shown to damage the health of laboratory animals, direct evidence of the compounds' effects in humans is less clear but still cause for concern, according to Scott Matsen, Ph.D., of the National Institute of Environmental Health Sciences in Research Triangle Park.

"Exposure to certain dioxins has been clearly shown to cause adverse effects in laboratory animals, such as immune dysfunction, cancer, hormonal changes and developmental abnormalities," says Matsen. "Although the available evidence for adverse effects in people is more limited than for laboratory animals, the sum total of the information is cause for concern about the human health hazards of environmental exposure to this class of chemicals."