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A 35-year ceramicist had by far the highest blood dioxin levels in the
study. Though the woman lived on contaminated soil, the contamination
fingerprint of her blood was a closer match to the clay rather than
the soil, said Dr. Alfred Franzblau, professor in the U-M School of
Public Heath and co-principal investigator on the Dioxin Exposure
Study. Franzblau said the woman worked with ball clay, which is used
in ceramics.
Ceramics clay, sometimes referred to as ball clay, is known to be
contaminated with dioxins, and Franzblau said the woman's clay
displayed the same pattern of contamination shown previously to exist
in ball clay tested in America and Europe. However, there are no
previous reports suggesting that dioxins in clay can be a direct
source of contamination for humans.
"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. Two other women who were ceramics enthusiasts also
had elevated dioxin levels, though not nearly as high as the first
woman. The two other women had kilns in their garages (not inside
their homes), and did not use them as often.
Franzblau said it's important not to overreact to the findings, but
that more study is needed to determine the impact. There may be
thousands of unvented kilns being used in schools, pottery workshops
and private homes.
"For most people this is not likely to result in any significant
exposure," Franzblau said. "My case was somebody who did this
regularly for 30 to 40 years. A child once a week in an art class is
in a radically different realm. But there are other people like her
and I think there needs to be more research to better characterize the
danger."
The Dioxin Exposure Study did not measure health effects of dioxin on
the 946 subjects who participated.
"Although we have been able to confirm that clay can be a dominant
source of exposure to dioxins, you can't draw conclusions about health
effects based on just three cases," said Franzblau, also an associate
professor of emergency medicine.
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