Proficiency and Interlaboratory Variability in the Determination of Phthalate and DINCH Biomarkers in Human Urine: Results from the HBM4EU Project

Abstract

A quality assurance/quality control program was implemented in the framework of the EU project HBM4EU to assess and improve the comparability of biomarker analysis and to build a network of competent laboratories. Four rounds of proficiency tests were organized for 15 phthalate and two DINCH urinary biomarkers (0.2–138 ng/mL) over a period of 18 months, with the involvement of 28 laboratories. A substantial improvement in performance was observed after the first round in particular, and by the end of the program, an average satisfactory performance rate of 90% was achieved. The interlaboratory reproducibility as derived from the participants’ results varied for the various biomarkers and rounds, with an average of 24% for the biomarkers of eight single-isomer phthalates (e.g., DnBP and DEHP) and 43% for the more challenging biomarkers of the mixed-isomer phthalates (DiNP, DiDP) and DINCH. When the reproducibility was based only on the laboratories that consistently achieved a satisfactory performance, this improved to 17% and 26%, respectively, clearly demonstrating the success of the QA/QC efforts. The program thus aided in building capacity and the establishment of a network of competent laboratories able to generate comparable and accurate HBM data for phthalate and DINCH biomarkers in 14 EU countries. In addition, global comparability was ensured by including external expert laboratories.

From science to policy: How European HBM indicators help to answer policy questions related to phthalates and DINCH exposure

“…Chemical analysis of the biomarkers in the HBM4EU Aligned Studies was quality controlled ( Esteban López et al, 2021 ; Mol et al, 2022 ) and was done for phthalates and DINCH by 7 different analytical laboratories ( Esteban López et al, 2021 ).…”

“…Under HBM4EU, comparable HBM data with European wide exposure coverage from different countries have been aligned and collated under the HBM4EU Aligned Studies ( Gilles et al, 2021 and Gilles et al, 2022 ). This harmonized data set ( Esteban López et al, 2021 ; Mol et al, 2022 ) has been used for further development of the indicators. Depending on which information they should provide final visualization of the indicators can be either in a number format, or as an infographic ( Buekers et al, 2018 ).…”

Urinary levels of parabens, phthalate metabolites, bisphenol A and plasticizer alternatives in a Belgian population: Time trend or impact of an awareness campaign?

“…These differences between results obtained in 2015 and 2021 would thus likely come from analytical variations rather than chemical degradation, and would therefore demonstrate the stability of these compounds under the storage conditions. Because the stability of DINCH metabolites seems to be comparable to phthalate metabolites (Mol et al, 2022;Silva et al, 2013), the urinary DINCH metabolite levels and by extrapolation the bisphenol levels were assumed to be stable under the present storage conditions although it could not be demonstrated.…”

Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs) for human biomonitoring of perfluoroalkyl substances (PFASs) in serum as part of the quality assurance programme under HBM4EU

“…Evaluation of the participants' performance as EQUAS was possible even if the number of participants was too small and their results were too heterogeneous for an evaluation as ICI. Furthermore, the inclusion of experienced laboratories from outside Europe in EQUAS increased reliance on accuracy and comparability at the international level (Mol et al, 2022). In the final round, however, an EQUAS evaluation was not possible for five biomarkers and their two CMs (Suppl.…”