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Ancient Taint: Likely source of old dioxins identified

The burning of peat in coastal areas of Scotland could be responsible for the enigmatic concentrations of dioxins that scientists sometimes find in pre-20th-century European soil samples.

Dioxins are a class of more than 200 chlorine-rich organic chemicals that are highly toxic, trigger birth defects, and can cause cancer (SN: 5/15/99, p. 309). Presumed modern substances, dioxins typically are byproducts of the production of industrial chemicals such as polychlorinated biphenyls (PCBs) and some pesticides.

However, dioxins are also created during the incomplete combustion of organic carbon in the presence of chlorine. That's why they can spew from municipal incinerators and residential trash fires (SN: 1/29/00, p. 70: Backyard burning is recipe for dioxin). Now, biogeochemist Andrew A. Meharg and his colleague Kenneth Killham, both of the University of Aberdeen in Scotland, have shown that dioxins aren't just a modern problem.

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