In July 1997, FDA found contamination of animal feeds with dioxin, which resulted in elevated levels of dioxin in chickens, eggs and catfish. Dioxins are potent carcinogens with potential additional toxic and reproductive properties. There are no tolerances or other administrative levels for dioxin in food or feed. Dioxin contamination was found in animal feeds distributed to over 3,400 consignees throughout the country.

After lengthy investigation, the source of the dioxin contamination was traced to a mined clay product called "ball clay," which is used as an anti-caking agent in soybean meal, in other feed components, and in complete animal feeds. CVM worked cooperatively with the affected industries to halt any further distribution and use of the feed known to be contaminated with dioxin. This was carried out across the country. FDA is taking steps to ensure that ball clay will not be used in food products in the future.

In FY 1998, FDA initiated steps to determine whether other mined clay products and naturally derived anticaking agents were contaminated with dioxin, similar to the findings in ball clay. Industry associations met with CVM to determine the type of information needed, which resulted in a compilation of industry sampling of anticaking agents for dioxins. FDA, with analytical assistance from EPA, surveyed mined feed ingredients for the presence of dioxins, as a supplement to industry sampling.

The evidence gathered thus far (Spring of 2000) suggests that a primary route for dioxin contamination in food-producing animals can be through their diet and that the non-fodder components of the animal diet deserve additional scrutiny. CVM has issued an assignment to the Field to collect samples of various animal feed ingredients, which will be used to better characterize exposure of animals to dioxins.