Officials said the contamination revealed serious shortcomings in European standards for ensuring the safety of animal feed, which mixes fat from a large variety of sources, including household, restaurant and slaughterhouse waste, with grain and silage.

One theory is that motor oil containing dioxin was mixed with fat at a plant near Ghent. That oil may have come from a source in the Netherlands, investigators believe, and to this extent Belgium was unlucky, as Mr. Van den Bossche said.

http://www.nytimes.com/1999/06/12/news/12iht-belg.2.t_6.html?pagewanted=all