A novel source for dioxins present in recycled fat from gelatin production

Within a survey on dioxins in animal fat used as feed ingredient, a sample originating from pigs offal was shown to contain 50 ng Toxic Equivalents (TEQ) PCDD/PCDFs kg −1 fat. Further investigation revealed fat samples with levels as high as 440 ng TEQ kg −1 fat and contaminated feed with a highest level of 8.4 ng TEQ kg −1 feed. The congener pattern was dominated by 1,2,3,7,8-PeCDD and 2,3,7,8-TCDD, and was not recognized from any previous incident or known dioxin source. Remarkably, 2,3,7,8-substituted congeners were much more abundant than their non-2,3,7,8-substituted counterparts. The sampled fat was derived from a gelatin production plant. Broken filters, used to clean the hydrochloric acid (HCl) used in the process, caused the dioxin contamination. The fat was primarily used for pig feed. A new physiologically-based pharmacokinetic (PBPK) model for lipophilic contaminants in growing slaughter pigs predicted levels at slaughter varying between 40 pg TEQ g −1 fat (worst-case) and 2.5–7 pg TEQ g −1 fat under more realistic scenarios. Almost 300 farms were temporarily blocked. Many fat samples of pigs were analyzed using a combined approach of DR CALUX ® and GC/HRMS. Levels in contaminated pig fat were around the EU-limit of 1 pg TEQ g −1 fat, with some samples up to 2–3 pg TEQ g −1 fat. Of 80 negative samples analyzed by DR CALUX ® and GC/HRMS no false-negatives were obtained, whereas 36 and 62 of the 80 samples classified suspected with the bioassay had GC/HRMS levels above respectively the tolerance and action limits. It is concluded that novel and unexpected dioxin sources remain a threat to the food chain and require the proper evaluation and monitoring of production processes, including chemicals used therein.