Dioxin residues in the edible tissue of finishing pigs after dioxin feeding

Abstract

The aim of this study was to determine the contamination of finishing pigs with polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) after feeding either uncontaminated feed or feed contaminated with 0.75, 2 or 4 ng/kg toxic equivalents (TEQ; calculated by multiplying individual congener concentrations by congener-specific toxicity equivalency factors). The feed was mixed with pure substances of PCDD/Fs to get the intended contamination. Five groups of six piglets each were fed contaminated feed, one group of five piglets served as control. One group was fed contaminated feed (4 ng TEQ/kg) only for the rearing period (6 weeks), and another group for the first 8 weeks of the fattening period (4 ng TEQ/kg feed). The other groups received the contaminated feed during the 12-weeks fattening period. After slaughtering, the edible parts of the belly, loin and fore-end were collected and homogenized. The samples of group 2 and 4a were investigated uncooked as well as roasted. Fattening yield and feed conversion (kg feed/kg weight gain) of the animals of all groups were in the normal range (final weight 109.7 kg; feed conversion 2.55-2.69 kg). The PCDD/F-content in 1 kg fat of the belly, loin and fore-end in relation to the intake was between 0.016 (4 ng TEQ/kg feed for a 6-weeks rearing period) and 1.39% (fore-end; 2 ng TEQ/kg feed for 12-weeks fattening period). There was a decrease in dioxin residues after a 12-weeks period but not after a 4-weeks period of feeding an uncontaminated feed. When feed contaminated with 0.75, 2 and 4 ng TEQ/kg was given for a 12-weeks fattening period, the residue concentrations of PCDD/F-TEQ in 1 kg belly was 0.455, 1.07 and 1.55 ng, in 1 kg fore-end 0.04 ng, 0.32 ng and 0.34 ng and in 1 kg loin 0.015 ng, 0.07 ng and 0.30 ng respectively. Roasting had no influence on the dioxin-residues. The residues per g belly fat exceed the maximum limits for dioxin in food of 0.6 pg WHO-PCDD/F-TEQ/g fat (EC Recommendations 2002/201/EC), when feed containing 0.75 ng PCDD/F-TEQ/kg is given for 12 weeks. When feed containing 0.4 ng TEQ (maximum content; EC recommendations 2002/201/EC) is given for 12 weeks, approximately 0.55 pg TEQ/g fat can be expected in the food. This value is within the action level of 0.6 pg/g fat of porks. In conclusion, the results of the study allow prediction of dioxin residues in the edible tissue of pork, if the feed contamination is known and the amount of feed intake can be estimated.