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Likely source of old dioxins identified. (Ancient Taint).


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 highly toxic Occupational medicine adjective Referring to a chemical that 1. Has a median lethal dose–LD50 of ≤ 50 mg/kg when administered orally to 200-300 g albino rats 2. , trigger birth defects birth defects, abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs in approximately 3% of all births. , 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 polychlorinated biphenyls, (pol´ēklôr´nā´tid bīfē´n  (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). Now, biogeochemist Andrew A. Meharg and his colleague Kenneth Killham, both of the University of Aberdeen The University of Aberdeen is an ancient university founded in 1495, in Old Aberdeen, Scotland and a world-renowned centre for teaching and research. It is the fifth oldest university in the United Kingdom and the wider English-speaking world.  in Scotland, have shown that dioxins aren't just a modern problem.

For their experiments, the researchers obtained peat samples from a site on the northwestern coast of Scotland. Each kilogram kilogram, abbr. kg, fundamental unit of mass in the metric system, defined as the mass of the International Prototype Kilogram, a platinum-iridium cylinder kept at Sèvres, France, near Paris.  of peat held about 114 nanograms of dioxins--probably from modern atmospheric contamination, says Meharg. However, the researchers found that the smoke and ash produced by burning each kilogram of peat included more than five times the original amount of dioxins. The chlorine required for this spike of dioxin dioxin

Aromatic compound, any of a group of contaminants produced in making herbicides (e.g., Agent Orange), disinfectants, and other agents. Their basic chemical structure consists of two benzene rings connected by a pair of oxygen atoms; when substituents on the rings are
 production came from oceanic salt spray that had permeated the peat before it was dried and used as fuel, the team speculates.

If historians' estimates are accurate, each household in the area burned about 20 tons of coastal peat per year. Therefore, the region produced about 1 kg of dioxin annually. For comparison, municipal incinerators throughout the United Kingdom today collectively produce only about 11 kg of dioxins annually, says Meharg. He and Killham report their results in the Feb. 27 Nature.

In the Scottish highlands
This article pertains to the geographic region of the Scottish Highlands. See Highlands and Highlander for alternate meanings


The Scottish Highlands (A' Ghàidhealtachd
 and islands in the 18th and 19th centuries, residents--most of them subsistence farmers--would have been exposed to dioxins in at least two ways. First, home heating came from a peat fire in the center of the floor in windowless structures known as blackhouses, which had low entrances, no chimney, and very little ventilation. Second, the farmers used peat ash as a fertilizer, a technique that would have permitted dioxins to contaminate con·tam·i·nate
v.
1. To make impure or unclean by contact or mixture.

2. To expose to or permeate with radioactivity.



con·tam·i·nant n.
 root crops such as potatoes and turnips.

The new measurements may solve the mystery of how dioxins came to be present in soils excavated and archived in the 19th century, says Ruth E. Alcock, a chemist with Environmental Research Solutions in Cumbria, England. As it turns out, however, blackhouse residents had more to worry about than dioxin exposure. They probably suffered from respiratory illnesses brought on by other chemicals and particulates prevalent in peat smoke, Alcock says.
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Title Annotation:smoke, ash from burning peat, chlorine from oceanic salt spray permeated peat
Author:Perkins, S.
Publication:Science News
Geographic Code:4EUUS
Date:Mar 1, 2003
Words:439
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