Dried blood spot-based monitoring of immune and epigenetic biomarkers in occupational exposure studies

Background: Self-sampling of biomaterials is an important means for continuous remote occupational surveillance. Recently, we presented an overview of different self-sampling methods for occupational research. Dried blood spots (DBS), urine, saliva and oral buccal cells were matrices of choice for rapid, minimally invasive sample collection for analysis of a wide range of biomarkers. Objective: We set up pilot studies to optimise a suitable workflow for minimally invasive matrices in different occupational setups. Methods: A two-phase pilot study was conducted. In Phase 1, DBS samples were collected from 40 healthy participants according to written and video-recorded protocols. Samples were received intact and without visible damage. We surveyed participants on aspects related to ease of self-sampling and clarity of instructions. In Phase 2, a study of 15 participants, we further refined the protocols to characterise global DNA methylation, oxidative DNA damage (8-OHdG), and immunoarrays (IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, TNF-α, and CRP) in DBS and dried plasma spots (DPS) and assessed the effect of sample storage duration and shipment (stored immediately, and after one, two, four and six weeks). Results: DBS samples were used to optimise the DNA extraction protocol, which yielded good-quality DNA. We showed the stability for most of the markers up to six weeks. A large number of immune markers could be detected in DBS- and DPS-derived samples, and proteomics was feasible. Significance: With this study, we confirmed that minimally invasive techniques for good-quality biological sample collection are available for use in future occupational studies. Impact: This study establishes a robust framework for minimally invasive self-sampling in occupational health research, demonstrating the feasibility of dried blood and plasma spots for high-quality analysis of proteomic, immune, and DNA biomarkers. These methods support scalable, remote, and longitudinal biomolecular surveillance across diverse work environments. Evaluating biomarker stability is essential, as room temperature storage can affect data integrity. Our findings confirm robust proteomic profiling, stable DNA methylation markers, and promising immune marker detection, reinforcing the potential of dried blood spots for reliable long-term health monitoring.