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Peer review of a database of relative effect potencies of PCDDs, PCDFs and PCBs and preparing a review of the use of relative effect potencies for derivation of Toxic Equivalency Factors for dioxin-like compounds

Approximate launch date:
May 2021
  • Reference no.: NP/EFSA/SCER/2021/02
  • Budget: 70,000 €
  • Approximate launch date: End May 2021 
  • Deadline to register interest: 28/05/2021
  • Background: WHO has planned to re-evaluate the Toxic Equivalency Factors (WHO-TEFs) that are worldwide used to estimate the total dioxin-like activity of mixtures of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in an expert meeting in spring of 2022. WHO will take as starting point for their re-evaluation a database of Relative Effect Potencies (REP) updated using the same criteria for inclusion/exclusion of studies in the database as those applied in the 2005 evaluation by WHO (Fitch et al., 2019; Haws et al., 2006; Van den Berg et al., 2006). The WHO expert group that will conduct the re-evaluation of TEFs in 2022 considers it crucial that before the REP-database can be used, it is peer reviewed by an independent organisation to ensure that it contains REP data from studies selected on the basis of principles and criteria defined earlier by the WHO. Through this procurement procedure, EFSA aims to ensure and support the independent peer review of the before mentioned updated REP-database prior to the international re-evaluation of TEFs by the WHO in the spring of 2022. The second aim of this procurement procedure is to ensure the preparation of a working document to be used at the WHO expert meeting. This working document should critically review how the use of REP data derived from both in vivo and in vitro types of studies impact the derivation of TEFs for dioxin-like compounds. In addition, it should contain a review of the use of TEFs based on systemic levels (e.g. in plasma) of  dioxin-like compounds (systemic TEFs) for human risk assessment with the present state of art in toxicology for these compounds (Van Ede et al., 2016). This evaluation should also include a feasibility analysis of the use of in vitro and systemic REPs/TEFs for human risk assessment.
  • Objectives
    1. To carry out a peer review of the contents of a database of relative effect potencies of PCDDs, PCDFs and PCBs according to the criteria and guidance defined by WHO’s expert group in charge of the re-evaluation of TEFs in 2022.
    2. To prepare a working document for the upcoming WHO meeting in 2022 that evaluates the impact on dioxin TEF derivation of new REP data (including systemic plasma-based REPs) based on newly published in vitro and in vivo studies since the last WHO re-evaluation in 2005.
  • Selection criteria - technical and professional capacity:
    • Requirement 1: The tenderer overall must have extensive and demonstrable experience in toxicology and risk assessment in the area of dioxins and dioxin-like compounds, including PCBs, and;
    • Requirement 2: Ability to provide a team of experts compliant with these specific expertise requirements:
      • One senior toxicologist (at least 10 years of experience) with in-depth knowledge of dioxin-like toxicity and the TEF concept, i.e with particular emphasis on the use of REP data (including systemic plasma-based REPs) for dioxin-like compounds for the derivation of TEFs compared to 2,3,7,8-TCDD from in vivo and in vitro studies as shown by publications in these fields;
      • At least one additional toxicologist with demonstrable expertise in reviewing scientific studies and critically appraising scientific evidence based on toxicological (in vivo, in vitro and in silico) data for hazard characterisation of chemical substances, preferably in the area of dioxins and dioxin-like compounds, for human and animal health (at least 5 years of experience); 
  • Requirement 3: The team of experts and each individual expert must have an excellent level of spoken and written standard UK English. For non-native speakers, this should be demonstrated by at least 5 years of work in an English-speaking environment or by an official certificate of English proving a C1 level.

  • Requirement 4: The tenderer must have access to the following database for contract execution:

    • PubMed
    • Web of Science (including the following databases covering from 1998 onwards: Web of ScienceTM Core Collection, BIOSIS Citation IndexSM, CABI: CAB Abstracts®, Current Contents Connect®, Data Citation Index SM, FSTA®–the food science resource, MEDLINE®, SciELO Citation Index, Zoological Record®)
    • Access to the most relevant toxicological and public health journals that are relevant for dioxin-like toxicity and risk assessment.
  • References
    • Fitch, S., Wikoff, D., Franke, K., Ring, C., Harris, M., Haws, L. (2019). Systematic Update of the Mammalian Relative Potency Estimate (REP) Database for Dioxin-like Compounds (DLCs). Poster presented at DIOXIN 2019, Kyoto, August 25-30, 2019
    • Haws LC, Su SH, Harris M, Devito MJ, Walker NJ, Farland WH, Finley B and Birnbaum LS, 2006. Development of a refined database of mammalian relative potency estimates for dioxin-like compounds. Toxicol.Sci. 89, 4–30
    • Van den Berg, Martin, Linda S. Birnbaum, Michael Denison, Mike De Vito, William Farland, Mark Feeley, Heidelore Fiedler, Helen Hakansson, Annika Hanberg, Laurie Haws, Martin Rose, Stephen Safe, Dieter Schrenk, Chiharu Tohyama, Angelika Tritscher, Jouko Tuomisto, Mats Tysklind, Nigel Walker, and Richard E. Peterson (2006). The 2005 World Health Organization Reevaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-Like Compounds. Toxicol.Sci., 93(2), 223–224
    • Van Ede KI, van Duursen MBM and Van den Berg  (2016). Evaluation of relative effect potencies (REPs) for dioxin-like compounds to derive systemic or human-specific TEFs to improve human risk assessment. Arch.Toxicol. 90, 1293-1305

If you are interested in this procedure please send an email within the deadline to efsaprocurement [at] quoting the reference of the procedure and specifying the following:

  • your name/organisation’s name and address;
  • whether you participate as a physical person or an organisation/private company.