HBM4EU ICI EQUAS report OPFR in urine round 2

Within the frame of the HBM4EU project, an External Quality Assurance Scheme (EQUAS) was organised on the determination of four OPFR biomarkers in urine. This was the 2nd ICI/EQUAS round for this substance group within the HBM4EU program.
In total 17 laboratories were invited for this 2nd ICI/EQUAS and only five laboratories (including three expert laboratories) submitted results. The number of OPFRs covered by the different laboratories varied widely from two to all four target biomarkers.
In November 2018, each participant received one tube for burdened control materials of human urine (low level – level 1), one tube for burdened control materials of human urine (high level – level 2) and one tube for “blank” urine (non spiked). The biomarker concentrations were approximately in the range 2-4 µg/L and 8-15 µg/L for level 1 and level 2, respectively. The concentrations were chosen according to the review of relevant data on the occurrence of OPFRs in urine of European population published mostly during last five years.
A homogeneity assessment showed that both materials were sufficiently homogeneous for EQUAS testing. No issues with stability of testing materials occurred for OPFRs.
The determination of expert value based on results from expert laboratories was not possible for any biomarker. The uncertainty of the expert-derived mean for DPHP and BDClPP was too high to be used as assigned value. For BClPP and BCEP the minimum number of expert results has not been reached.
Due to a limited number of obtained results, further evaluation of laboratory performance using Zscores was not able to be perform. The achieved data are present in the report for further comparison between participants and expert labs.