Dioxins: New Attempts to Smoke Them Out

SCIENCE NEWS June 22. 1996 pg. 390 Dioxins appear to be raining down from the atmosphere in quantities significantly higher than can be accounted for by all the major activities known to create them, a new study finds. Louis P. Brzuzy and Ronald A. Hites of Indiana University in Bloomington collected soils from 107 sites around the globe and analyzed them for dioxins and for furans, a group of chemicals similar to dioxins. These unintentionally produced families of chlorinated pollutants represent an almost ubiquitous toxic legacy of humanity's industrial activities.

Acknowledging large uncertainties associated with their estimates, Brzuzy and Hites nonetheless conclude in the June ENVIRONMENTAL SCIENCE & TECHNOLOGY that the worldwide rain of dioxins and furans onto land totals about 12,500 kilograms per year. That's roughly four times the amount suggested by estimates of emissions, which include 1,130 kg/yr from municipal waste incineration 1,000 kg/yr from cement kilns, and 350 kg/yr from burning trees and other plants, or biomass. This discrepancy, they say, suggests that there are major unknown sources, that diffuse sources may be larger than appreciated, or that known sources may be more variable than occasional measurements have suggested.

Valerie M. Thomas of Princeton University agrees that the new inventory is suggestive of unaccounted-for sources of dioxins.

8/10/96


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