Firing clay in unvented kilns may be a source of exposure to dioxins

Oct 23, 2007

Firing clay in unvented kilns could be a significant source of dioxins in people exposed regularly and over long periods, a new study suggests.

The results came out of follow-up interviews with subjects who participated in the University of Michigan Dioxin Exposure Study, which measured dioxin levels in residents in Midland and the Tittabawassee River flood plain between Midland and Saginaw.

The two-year study, commissioned by Dow Chemical Co., was to determine if elevated dioxin levels in the soil caused elevated levels of dioxins in residents' bodies.

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.

Source: University of Michigan

Explore further: Tobacco firms get partial win over claims on smoking effects (Update)

Related Stories

Great white shark cruising East Coast becomes Twitter star

6 hours ago

They're gonna need a bigger Twitter. An organization studying great white sharks is enjoying some welcome attention after one of the creatures they've been monitoring started gaining a loyal social media following. @MaryLeeShark ...

New Japan volcano island 'natural lab' for life

21 hours ago

A brand new island emerging off the coast of Japan offers scientists a rare opportunity to study how life begins to colonise barren land—helped by rotting bird poo and hatchling vomit.

Recommended for you

Breastfeeding protects against environmental pollution

May 22, 2015

Living in a city with a high level of vehicle traffic or close to a steel works means living with two intense sources of environmental pollution. However, a study conducted by the UPV/EHU researcher Aitana ...

When it comes to hearing, diet may trump noise exposure

May 22, 2015

Although the old wives' tale about carrots being good for your eyesight has been debunked, University of Florida researchers have found a link between healthy eating and another of your five senses: hearing.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.