An Assessment of Dioxin Levels in Processed Ball Clay from the U.S.
The presence of dioxin-like compounds in ball clay was discovered in 1996 as a result of an investigation to determine the sources of elevated levels of dioxin found in two chicken fat samples from a national survey of poultry. The investigation indicated that soybean meal added to chicken feed was the source of dioxin contamination. Further investigation showed that the dioxin contamination came from the mixing of a natural clay known as "ball clay" with the soybean meal as an anti-caking agent. The source of the dioxins found in ball clay has yet to be established. The plasticity of ball clays makes them an important commercial resource for a variety of commercial uses. EPA is examining the potential for the environmental release of dioxins from the processing/use of ball clays and evaluating potential exposure pathways. Part of this overall effort and the subject of this study includes the analysis of dioxin levels found in commercially available ball clays commonly used in ceramic art studios.
Ferrario, J; Byrne, C; Schaum, J. 2004. An Assessment of Dioxin Levels in Processed Ball Clay From the United States. Organohalogen Compounds 66: 1639-1644.