PCDD AND PCDF CONTAMINATION IN CATFISH FEED FROM ARKANSAS, USA

One combined catfish feed sample from Arkansas, USA, and its eight ing redients were analyzed for PCDDs and PCDFs. One of the ingredients, so ybean meal, was highly contaminated by PCDDs, especially the toxic 2,3 ,7,8-substituted congeners, e.g. 7.3 pg/g dry weight or 370 pg/g lipid for the 2,3,7,8-tetra CDD. The I-TEQ value for the soybean meal was 1 1.4 pg/g dry weight or 576 pg/g fat. The corresponding values for the combined catfish feed concentrations were approximately 3 times lower. The congener pattern, the congener profile and the ratio Sigma PCDDs/ Sigma PCDFs for the soybean meal were quite unique. We are not aware o f any environmental sample or technical product with similar character istics. As a result, natural formation of the PCDDs found in the soybe an meal cannot be ruled out. (C) 1998 Elsevier Science Ltd. All rights reserved.