A new PARC interlaboratory study provides practical guidance for making broad chemical screening methods more comparable across laboratories, while preserving the complementary approaches needed to identify a wider range of occupational exposure markers.

Accepted for publication in Environmental Sciences Europe, the study, “Comparative assessment of screening workflows for characterizing occupational exposure to chemicals in humans: an EU-PARC interlaboratory study ↗”, was developed within a PARC project focusing on novel occupational biomonitoring methods.

The research addresses an important challenge in occupational biomonitoring: how to assess workers’ exposure to complex mixtures of chemicals when conventional targeted methods can only analyse a limited number of predefined substances.

Suspect and non-target screening approaches based on high-resolution mass spectrometry can provide a broader picture of the chemicals present in biological samples. These approaches can screen for many substances simultaneously, support the identification of new markers of exposure and effect, and allow data to be revisited as new scientific knowledge becomes available. However, differences in sample preparation, analytical equipment, quality control and reporting can make results from different laboratories difficult to compare. The PARC study therefore examined how laboratories can follow shared minimum requirements while continuing to use complementary analytical methods. 

The aim was not to identify one method that every laboratory should use. It was to determine which shared requirements can make results more comparable while preserving the methodological diversity needed to cover a broad range of chemicals, says Baninia Habchi,  deputy project manager.

A European interlaboratory exercise 

The study brought together 11 laboratories from eight EU Member States. Urine and plasma samples containing 81 occupationally relevant exposure markers were analysed using 13 different laboratory methods. The selected markers represented potential exposure scenarios in healthcare and waste management and included, among others, hazardous medicines, industrial chemicals, plastic additives, flame retardants and per- and polyfluoroalkyl substances.

Rather than asking every laboratory to adopt the same analytical procedure, the researchers compared the laboratories’ established workflows, assessing their performance, comparability and complementarity.

When all methods were considered together, the laboratories detected:

• 79 of the 81 compounds in the quality-control mixture;
• 76 compounds in urine samples; and
• 75 compounds in plasma samples.

The findings showed that, although some methods offered broader overall coverage, other approaches were more effective for particular types of chemicals. Combining different techniques therefore increased the range of substances that could be detected. The study also found that positive and negative ionisation modes provided complementary information.

Our results show that harmonisation and analytical diversity should not be treated as opposing goals. A common quality framework can support comparable results, while complementary methods allow us to capture chemicals that would otherwise remain outside the scope of the analysis, adds Sophie Ndaw, project manager.

A central conclusion of the study is that no single analytical method can fully capture the chemical complexity of biological samples. The authors therefore recommend coordinating complementary approaches instead of imposing strict standardisation across all laboratories. Where it is not practical to distribute samples across many laboratories, the use of at least two complementary analytical methods and both ionisation polarities is proposed as a feasible minimum for achieving sufficiently broad chemical coverage.

The study also highlights the importance of shared quality-assurance and quality-control materials, procedural blanks and consistent reporting. These elements allow laboratories to assess performance and distinguish genuine exposure markers from possible contamination introduced during analysis. 

A minimum SOP for future biomonitoring studies

Based on the interlaboratory results, the researchers developed a minimum, fit-for-purpose standard operating procedure for biological sample analysis within PARC. It establishes common requirements for quality control, sample preparation, analytical sequences, file naming and data reporting, while leaving laboratories sufficient flexibility to retain complementary methods. This balance between shared requirements and analytical flexibility is intended to improve the reliability and comparability of results without reducing the range of chemicals that can be investigated. The document can also provide a useful reference for laboratories beginning to implement suspect and non-target screening in human biomonitoring. 

Supporting the next phase of PARC research 

The findings will guide the next phase of the project, in which participating laboratories will analyse biological samples collected from occupational cohorts in healthcare and waste management. More than 1,000 urine samples and 500 plasma samples per sector are expected to be analysed according to the laboratories’ capabilities, with methodological adjustments informed by this interlaboratory exercise.The screening approaches will complement targeted analyses of selected chemical families. Together, they are expected to provide a more comprehensive assessment of occupational exposures and support the identification of emerging exposure markers. By combining essential harmonisation with complementary analytical strategies, the study provides an important methodological foundation for large-scale occupational biomonitoring in Europe.