Within the framework of task 5.2 of the European Joint Programme, HBM4EU, human biomonitoring guidance values (HBM-GVs) are derived for HBM4EU priority substances. The methodology applied to derive these values is described in the concept paper released in the HBM4EU task 5.2 workframe (HBM4EU concept paper) and published in a peer-reviewed journal (Apel et al., 2020).

For the time being, HBM-GVs are derived in HBM4EU under inclusion of experts from the 30 partner countries. Future use and implementation will be discussed among partne (...)

Within the framework of task 5.2 of the European Joint Programme, HBM4EU, human biomonitoring guidance values (HBM-GVs) are derived for HBM4EU priority substances. The methodology applied to derive these values is described in the concept paper released in the HBM4EU task 5.2 workframe (HBM4EU concept paper) and published in a peer-reviewed journal (Apel et al., 2020).

For the time being, HBM-GVs are derived in HBM4EU under inclusion of experts from the 30 partner countries. Future use and implementation will be discussed among partners and the EU Commission but are without prejudice to existing or ongoing risk assessment work in order to inform EU policy-making.

Several HBM-GVs for the general and occupational population have already been derived for some phthalates and a substitute (DEHP, DPHP, DnBP, DiBP, BBzP, DINCH, see Lange et al., 2021), bisphenols (BPA (Ougier et al., 2021), BPS), cadmium (Lamkarkach et al., 2020) and recently for aprotic solvents (NEP, NMP, DMF, DMAC, see Deliverable D 5.9).

During the production and the consultation phases of the deliverables describing the derivation of such HBM-GVs, interesting questions were raised and valuable comments have been received. Some of these comments may justify a refinement of the methodology of the derivation of HBMGVs as elaborated within HBM4EU by UBA and ANSES. Most of the HBM-GV proposals aimed to improve harmonization approaches for the two populations: general population and workers.

It was then decided within task 5.2 to organise a workshop that was initially aimed to take place at ANSES in spring 2020. However, due to the Covid-19 pandemic, the workshop was postponed and held virtually over three afternoons, from November 4th to 6th. Topics that have been discussed are related to:

• How to address the differences between the derivation of HBM-GVGenPop and HBM-GVworker?
• Toxicokinetics and modelling aspects
• Selection of (exposure) biomarkers (BM) and matrices
• Level of confidence (LoC) associated to HBM-GVs
• How to deal with non-threshold substances in the occupational field?
• The current status of the strategy to evaluate HBM results for mixtures, exemplary for phthalates

In the current deliverable, a summary of the main discussions and proposals for the refinement of the methodology for the derivation of the HBM-GVs is reported. These proposals will be taken up in future HBM-GV derivations, if appropriate and feasible, and can be seen as optional to the methodology paper (Apel et al., 2020).

The workshop was audio recorded to facilitate the reporting of the workshop and for subsequent research activities. The audio files and transcripts are stored safely on a secured server and are only distributed among the organisers of the workshop.

In the first instance, a draft report of the workshop has been produced. Participants were given the opportunity to give feedback on this draft report. A final report has then been produced as part of a deliverable for HBM4EU that will be made public on the website after approval of the Management Board and the European Commission.