Yesterday at Dioxin 2011, Janice Huwe of USDA’s ARS - Biosciences Research Laboratory in Fargo ND, gave a very interesting lecture, “PCDD/Fs, PCBs, and PBDEs in Catfish from US Commerce”. This study was unique in that it is the first time that chlorinated dioxins and furans, polychlorinated biphenyls, and polybrominated diphenyl ethers have been monitored in a food as part of the Pesticide Data Program (PDP). In general, the PCDD/F, PCB, and PBDE levels found in over 200 catfish samples was very low, and any contribution of these compounds to US humans from diet is much lower than what we get from consuming beef, poultry, and chicken, which are much higher in lipid content than catfish.
You always learn something new at any of these presentations, and this one was no exception. Apparently mineral clays are used in fish feed as anti caking agents and in the 90s some catfish contained significant levels of TCDD from contaminated “ball clay”. FDA now recommends close monitoring for dioxins of any mineral clays that will be used for animal feed. Interestingly, the catfish samples in Janice’s study had a very unique dioxin profile and contained very little furan compared to other types of samples.