Survey of dioxins, dioxin-like PCBs and marker PCBs in German feeds of plant origin

Within a representative survey the levels of dioxins (PCDD/PCDF), dioxin-like PCBs and marker PCBs in 206 German feed samples were analysed in the years 2004/2005. The sampling plan included compound feed (N = 115) and roughage and succulent feed (N = 91) and reflected the representative feeding situation in Germany. The median content of WHO-PCB-TEQ in analysed feed samples was 0.017 ng/kg [88% dry matter (d.m.)] and consequently more than a factor of 10 below the action level of 0.35 ng/kg (88% d.m.). A differentiation between compound feed and roughage and succulent feed showed that compound feed [median 0.007 ng/kg (88% d.m.)] were significantly lower contaminated with dioxin-like PCBs than roughage and succulent feed [median 0.058 ng/kg (88% d.m.)]. The median sum contents of the six marker PCBs were 0.16 mu g/kg (88% d.m.) for compound feed and 0.56 mu g/kg (88% d.m.) for roughage and succulent feed. The median of the WHO-PCDD/F-TEQ was 0.03 ng/kg (88% d.m.), the maximum level of 0.75 ng/kg (88% d.m.) was not exceeded. The median of the WHO-PCDD/F-PCB-TEQ was 0.05 ng/kg (88% d.m.) and consequently a factor of 25 below the maximum level of 1.25 ng/kg. Additionally the samples of roughage and succulent feed were analysed according to their contents of ash insoluble in HCl, representing a degree of the proportion of earthy components in feed. A slight correlation was found between ash insoluble in HCl and WHO-PCDD/F-TEQ (R (2) = 0.59) whereas no correlation was found between ash insoluble in HCl and WHO-PCB-TEQ (R (2) = 0.06).