The 2005 World Health Organization re-evaluation of TEFs for dioxins and dioxin-like compounds — What are the consequences for German human background levels?

In 2005 the World Health Organization (WHO) re-evaluated toxicity equivalency factors (TEFs) for dioxins and dioxin-like compounds. WHO 2005 toxicity equivalent (TEq) levels were calculated based on our data on German background levels of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) in human blood and milk of the Duisburg birth cohort study.Levels of WHO 2005 TEq (PCDD/F+PCB) were in the range of 3.77–63.6 pg/glipid base (n=226, median: 19.38, arithmetic mean: 20.86) for blood, or 2.62–59.2 pg/glipid base (n=176, median: 19.78, arithmetic mean: 20.57) for milk, respectively. Compared to WHO 1998 TEq values WHO 2005 TEq levels were about 25% lower in both matrices. The shares of PCB (31% blood, 43% milk), especially of mono-ortho-substituted PCB (4% blood and milk), on total WHO 2005 TEq has become lower. If similar congener patterns can be assumed for certain matrices, appropriate multiplication factors can be used to convert TEq values of other TEF models sufficiently to WHO 2005 TEq values.