Firing clay may hike dioxin exposure

ANN ARBOR, Mich., Oct. 24 (UPI) -- Firing clay in unvented kilns might be a significant source of dioxins in people regularly involved in such activity, U.S. researchers have determined.

The finding was contained in a two-year University of Michigan Dioxin Exposure Study commissioned by the Dow Chemical Co. to determine if elevated dioxin levels in soil caused elevated levels of dioxins in residents' bodies.

A 35-year ceramicist had the highest blood dioxin levels in the study. Although the woman lived on contaminated soil, the contamination fingerprint of her blood was a closer match to the clay rather than the soil, said Professor Alfred Franzblau, the study's co-principal investigator.

Franzblau said the woman worked with ball clay, which is used in ceramics and is known to be contaminated with dioxins. However, there were no previous reports suggesting clay dioxins could be a direct source of human contamination.

"We think they breathed it in from the volatilization when they fired the kiln," Franzblau said.

The woman with the highest levels had three unvented kilns in her basement, so the fumes were released directly inside her home.

The researchers did not measure health effects of dioxin on the 946 subjects who participated.

The study is available online at http://www.ehponline.org/members/2007/10594/10594.pdf.