Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife

Martin Van Den Berg, Linda Birnbaum, Albertus T.C. Bosveld, Björn Brunström, Philip Cook, Mark Feeley, John P. Giesy, Annika Hanberg, Ryuichi Hasegawa, Sean W. Kennedy, Timothy Kubiak, John Christian Larsen, F. X.Rolaf Van Leeuwen, A. K.Djien Liem, Cynthia Nolt, Richard E. Peterson, Lorenz Poellinger, Stephen Safe, Dieter Schrenk, Donald TillittMats Tysklind, Maged Younes, Fredrik Wærn, Tim Zacharewski

Research output: Contribution to journalArticlepeer-review

2972 Scopus citations


An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, occachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties.

Original languageEnglish (US)
Pages (from-to)775-792
Number of pages18
JournalEnvironmental health perspectives
Issue number12
StatePublished - Dec 1998


  • Dioxins
  • Humans
  • PCBs
  • Polychlorinated biphenyls
  • TEFs
  • Toxic equivalency
  • Uncertainties
  • Wildlife

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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